JP2005158612A - Positive-electrode subsidiary active material for nonaqueous electrolytic secondary battery, positive-electrode active material for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery, and manufacturing method for nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive-electrode subsidiary active material for nonaqueous electrolyte secondary batteries, a positive-electrode active material for nonaqueous electrolyte secondary batteries, a nonaqueous electrolyte secondary battery having superior battery characteristics, even under more severe usage environment, and also to provide a non-aqueous electrolyte secondary battery manufacturing method. <P>SOLUTION: The positive-electrode subsidiary active material for nonaqueous electrolyte secondary batteries is a lithium transition metal composite oxide of at least spinel structure. Each of the concentrations of boron, fluorine, and magnesium, existing in the surface of the subsidiary active material, is higher than that of boron, fluorine, and magnesium existing inside it. The concentration of the magnesium existing inside is higher than each of the concentrations of the boron and fluorine existing inside. Moreover, lithium exists at a site 16c of the crystal structure of the lithium transition metal composite oxide. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery (hereinafter also simply referred to as “positive electrode active material”), a positive electrode active material for a non-aqueous electrolyte secondary battery (hereinafter simply referred to as “positive electrode active material”). The present invention also relates to a “positive electrode active material”), a non-aqueous electrolyte secondary battery, and a method for manufacturing a non-aqueous electrolyte secondary battery. Specifically, production of a positive electrode secondary active material, a positive electrode active material, a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery having a spinel structure lithium transition metal composite oxide having excellent overdischarge characteristics, cycle characteristics, and load characteristics. Regarding the method.

Nonaqueous electrolyte secondary batteries are characterized by a higher operating voltage and higher energy density than conventional nickel cadmium secondary batteries, and are widely used as power sources for electronic devices. As the positive electrode active material of the non-aqueous electrolyte secondary battery, lithium transition metal composite oxides typified by LiCoO ₂ , LiNiO ₂ , LiMn ₂ O _{4 and the} like are used.
In particular, LiMn ₂ O ₄ is easily available as a raw material at low cost because manganese, which is a constituent element, is present in a large amount as a resource. In addition, there is a feature that the load on the environment is small. Furthermore, even if all the Li ions in the crystal are desorbed by the deintercalation reaction, the crystal structure exists stably. For this reason, the nonaqueous electrolyte secondary battery using LiMn ₂ O ₄ is excellent in thermal stability as compared with LiCoO ₂ and LiNiO ₂ .

Non-aqueous electrolyte secondary batteries using LiMn ₂ O ₄ having the advantages as described above have been used for mobile electronic devices such as mobile phones, notebook computers, digital cameras, etc. Battery characteristics sufficient for these applications were exhibited.
However, at present, the required characteristics of mobile electronic devices are becoming more severe due to high functionality such as various functions added and use at high and low temperatures. In addition, application to power sources such as batteries for electric vehicles is expected.

  By the way, in a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, a protection circuit is conventionally incorporated in the battery in order to prevent overdischarge. However, if this protection circuit can be eliminated, the space is reduced. The capacity can be increased by adding an active material to the. Further, the manufacturing cost can be reduced by omitting the protection circuit. Therefore, means for eliminating the protection circuit have been studied.

In order to eliminate the protection circuit, it is necessary to prevent various problems from occurring even when overdischarge occurs. In general, when overdischarge occurs, the potential of the negative electrode rises, and Cu used as a current collector for the negative electrode is eluted, so that battery characteristics are significantly deteriorated. The reason why Cu elutes will be specifically described.
FIG. 1 is a graph schematically showing changes in potential of the positive electrode and the negative electrode during a charge / discharge cycle of a lithium ion secondary battery. As shown in FIG. 1, in the conventional example, when the battery is charged, the potential of the positive electrode rises along the path indicated by arrow a, and the potential of the negative electrode falls along the path indicated by arrow b.
When the battery is discharged after charging, the potential of the negative electrode increases, but retention (a phenomenon in which lithium ions are not released) occurs in the negative electrode, and the path is as indicated by an arrow c. On the other hand, the potential of the positive electrode falls along the path indicated by the arrow d. Therefore, when overdischarge occurs, the potentials of the positive electrode and the negative electrode become equal at point A. Here, since the potential at point A is higher than the potential at which Cu used as the negative electrode current collector is eluted, Cu is eluted.

On the other hand, as a technique for preventing Cu from eluting even when overdischarged, Patent Document 1 discloses a main active material made of a first lithium compound having a potential nobler than the potential of the negative electrode current collector, and a negative electrode current collector. A positive electrode active material including a secondary active material made of a second lithium compound having a base potential lower than that of the electric body is described. Specifically, LiCoO ₂ is used as a main active material, and Li _x MoO ₃ A positive electrode active material having (x = 1 to 2) as a secondary active material is described.
However, in the positive electrode active material described in Patent Document 1, although improvement of overdischarge characteristics is observed, improvement of high temperature characteristics and improvement of electrode plate density that are currently required for mobile electronic devices can be realized. could not.

JP-A-2-265167

  An object of the present invention is to provide a positive electrode secondary active material for a nonaqueous electrolyte secondary battery, a positive electrode active material for a nonaqueous electrolyte secondary battery, a nonaqueous electrolyte secondary battery having excellent battery characteristics even in a more severe use environment, and It is providing the manufacturing method of a nonaqueous electrolyte secondary battery. That is, a positive secondary active material for a nonaqueous electrolyte secondary battery, a positive active material for a nonaqueous electrolyte secondary battery, a nonaqueous electrolyte secondary material having excellent battery characteristics, particularly overdischarge characteristics and high temperature characteristics and improved electrode plate density. It is providing the manufacturing method of a secondary battery and a nonaqueous electrolyte secondary battery.

  The present invention provides the following (1) to (8).

(1) A positive electrode active material for a non-aqueous electrolyte secondary battery having at least a lithium transition metal composite oxide having a spinel structure,
The concentration of boron present on the surface of the lithium transition metal composite oxide is greater than the concentration of boron present inside the lithium transition metal composite oxide,
The concentration of fluorine present on the surface of the lithium transition metal composite oxide is greater than the concentration of fluorine present inside the lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the lithium transition metal composite oxide is greater than the concentration of magnesium present inside the lithium transition metal composite oxide,
The concentration of magnesium present in the lithium transition metal composite oxide is greater than the concentration of boron present in the lithium transition metal composite oxide,
The concentration of magnesium present in the lithium transition metal composite oxide is greater than the concentration of fluorine present in the lithium transition metal composite oxide,
A positive electrode secondary active material for a nonaqueous electrolyte secondary battery, wherein lithium is present at the 16c site of the crystal structure of the lithium transition metal composite oxide.

(2) A positive electrode active material for a non-aqueous electrolyte secondary battery having a main active material having a first lithium transition metal composite oxide and a secondary active material having at least a second lithium transition metal composite oxide having a spinel structure Because
The concentration of boron present on the surface of the second lithium transition metal composite oxide is greater than the concentration of boron present inside the second lithium transition metal composite oxide,
The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present inside the second lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of fluorine present in the second lithium transition metal composite oxide,
A positive electrode active material for a non-aqueous electrolyte secondary battery, wherein lithium is present at the 16c site of the crystal structure of the second lithium transition metal composite oxide.

  (3) The first lithium transition metal composite oxide is composed of a 3b site where lithium is present, a 3a site where transition metal is present, and a 6c site where oxygen is present. Positive electrode active material for secondary battery.

  (4) The first lithium transition metal composite oxide is composed of an 8a site where lithium is present, a 16d site where transition metal is present, and a 32e site where oxygen is present. Positive electrode active material for secondary battery.

  (5) The first lithium transition metal composite oxide is at least one selected from the group consisting of a lithium cobalt composite oxide, a lithium nickel composite oxide, and a lithium manganese composite oxide. Positive electrode active material for water electrolyte secondary battery.

(6) A positive electrode active material for a nonaqueous electrolyte secondary battery having a main active material having a first lithium transition metal composite oxide and a secondary active material having at least a second lithium transition metal composite oxide having a spinel structure A positive electrode having
A non-aqueous electrolyte secondary battery comprising a negative electrode active material comprising a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions and a negative electrode current collector, wherein: Satisfy the formula,
The concentration of boron present on the surface of the second lithium transition metal composite oxide is greater than the concentration of boron present inside the second lithium transition metal composite oxide,
The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present inside the second lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide,
The non-aqueous electrolyte secondary battery, wherein a concentration of magnesium present in the second lithium transition metal composite oxide is greater than a concentration of fluorine present in the second lithium transition metal composite oxide.
The potential before the first charge of the second lithium transition metal composite oxide (vsLi / Li ⁺ ) <the oxidation potential of the negative electrode current collector (vsLi / Li ⁺ ) <the potential before the first charge of the first lithium transition metal composite oxide ( vsLi / Li ⁺ )

(7) A positive electrode active material for a non-aqueous electrolyte secondary battery having a main active material having a first lithium transition metal composite oxide and a secondary active material having at least a second lithium transition metal composite oxide having a spinel structure A positive electrode having
A negative electrode having a negative electrode active material and a negative electrode current collector made of a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions;
A separator present between the positive electrode and the negative electrode;
An electrolyte in which the positive electrode, the negative electrode and the separator are immersed, and a non-aqueous electrolyte secondary battery comprising:
When the battery voltage of the non-aqueous electrolyte secondary battery is 0V, the concentration of the element of the negative electrode current collector present in the electrolyte is 0 to 20 ppm,
The concentration of boron present on the surface of the second lithium transition metal composite oxide is greater than the concentration of boron present inside the second lithium transition metal composite oxide,
The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present inside the second lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide,
The non-aqueous electrolyte secondary battery, wherein a concentration of magnesium present in the second lithium transition metal composite oxide is greater than a concentration of fluorine present in the second lithium transition metal composite oxide.

(8) The concentration of boron present on the surface of the main active material having the first lithium transition metal composite oxide and at least the second lithium transition metal composite oxide having a spinel structure is such that the second lithium transition metal composite Greater than the concentration of boron present inside the oxide,
The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present inside the second lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of fluorine present in the second lithium transition metal composite oxide, and the second lithium transition metal composite oxide is present. Forming a positive electrode active material having a secondary active material in which lithium is present at the 16c site of the crystalline structure of the product on at least one side of the positive electrode current collector,
A step of producing a strip-shaped negative electrode by forming a negative electrode active material comprising a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions on at least one surface of the strip-shaped negative electrode current collector;
A spiral wound body in which the belt-like positive electrode and the belt-like negative electrode are wound a plurality of times in a state of being laminated via a belt-like separator, and the belt-like separator is interposed between the belt-like positive electrode and the belt-like negative electrode A process for producing a non-aqueous electrolyte secondary battery comprising:

In general, when a non-aqueous electrolyte secondary battery does not have a protection circuit for preventing overdischarge, when the battery voltage decreases to near 0 V due to overdischarge, the potential of the negative electrode increases, and the negative electrode current collector (for example, Cu, Ni Etc.) is deposited, the battery characteristics are significantly deteriorated.
On the other hand, in the present invention, since the positive electrode auxiliary active material in which lithium is present at the 16c site of the crystal structure of the lithium transition metal composite oxide is used as the positive electrode auxiliary active material, in addition to the lithium existing at the 8a site, Lithium present at the 16c site is also supplied to the negative electrode. Therefore, a larger amount of lithium can be supplied than when no lithium is present at the 16c site. Therefore, even when retention occurs in the negative electrode, the balance between the charge and discharge efficiencies of the positive electrode and the negative electrode can be maintained, and an increase in the potential of the negative electrode during overdischarge can be suppressed.
In FIG. 1, when the battery is discharged after charging, the potential of the negative electrode of the example of the present invention rises along the path indicated by the arrow c as in the conventional example, while the potential of the positive electrode falls along the path indicated by the arrow e. This is because lithium ions exist at the 16c site of the positive electrode as compared with the conventional example. Therefore, when overdischarge occurs, the potentials of the positive electrode and the negative electrode become equal at point B. Here, since the potential at point B is lower than the potential at which Cu used as the negative electrode current collector elutes, the elution of Cu is suppressed. That is, the nonaqueous electrolyte secondary battery using the positive electrode secondary active material of the present invention is excellent in overdischarge characteristics.
In addition, although the case where a collector is Cu is demonstrated using FIG. 1, it is not limited to the case where a collector is Cu.

However, lithium is present at the 16c site, and if the lithium present at the 16c site is supplied to the negative electrode as the retention amount of the negative electrode in addition to the lithium present at the 8a site, the potential of the negative electrode increases during overdischarge. Although it can be suppressed, it is difficult to improve the high temperature characteristics and electrode plate density of the positive electrode secondary active material.
Therefore, in the present invention, in addition to the above, it is defined by the concentrations of boron, fluorine and magnesium of the lithium transition metal composite oxide.

In order to improve the charge / discharge capacity of the battery, it is conceivable to increase the charge / discharge capacity per weight of the positive electrode active material, to improve the method of applying the positive electrode active material to the positive electrode, and to increase the electrode plate density. .
In addition, in the positive electrode secondary active material having a spinel-structure lithium transition metal composite oxide, when transition metal ions are eluted, the transition metal is deposited on the negative electrode. Therefore, it reacts with lithium ions contributing to charge / discharge, and lithium is dead activated, resulting in a disadvantage that charge / discharge capacity is reduced. Elution of transition metal ions tends to occur during battery operation at high temperatures.
In the positive electrode active material according to (1), the electrode plate density can be improved by satisfying the relationship of (1) above for the concentrations of boron, fluorine and magnesium in the lithium transition metal composite oxide. Thereby, the charge / discharge capacity per unit volume of the battery can be improved. Furthermore, since elution of transition metal ions can also be suppressed, gas generation during high-temperature storage can be suppressed, high-temperature cycle characteristics can be improved, and both these and electrode plate density can be improved. Can do.

  The positive electrode active material described in (2) is a positive electrode active material with improved overdischarge characteristics, high temperature characteristics, and electrode plate density.

  In the positive electrode active material according to (3), the first lithium transition metal composite oxide includes the 3b site where lithium is present, the 3a site where transition metal is present, and the 6c site where oxygen is present. By being the positive electrode active material as described in (2), it becomes a positive electrode active material with further improved energy density.

  In the positive electrode active material according to (4), the first lithium transition metal composite oxide includes the 8a site where lithium is present, the 16d site where transition metal is present, and the 32e site where oxygen is present. By being the positive electrode active material described in (2), the positive electrode active material is excellent not only in overdischarge characteristics, high temperature characteristics and electrode plate density but also in output characteristics.

In the positive electrode active material according to (5), the first lithium transition metal composite oxide is a positive electrode active material according to (2), which is a lithium cobalt composite oxide and / or a lithium nickel composite oxide. By being, it becomes a positive electrode active material with further improved energy density.
In addition, the first lithium transition metal composite oxide is a positive electrode active material according to the above (2) which is a lithium manganese composite oxide, so that not only the overdischarge characteristics, the high temperature characteristics and the electrode plate density are improved. It becomes a positive electrode active material excellent in output characteristics.

In the nonaqueous electrolyte secondary battery according to (6), the first lithium transition metal composite oxide has a potential before initial charge higher than the oxidation potential of the negative electrode current collector, and the second lithium transition metal composite oxide. By making the potential before the initial charge of the product lower than the oxidation potential of the negative electrode current collector, lithium is supplied from both the main active material and the sub active material to the negative electrode during charging. Therefore, the amount of lithium supplied to the negative electrode is excessive than the amount of lithium in the main active material. Therefore, even when retention occurs in the negative electrode, the balance between the charge and discharge efficiencies of the positive electrode and the negative electrode can be maintained, and an increase in the potential of the negative electrode during overdischarge can be suppressed.
However, the potential before the first charge of the first lithium transition metal composite oxide is higher than the oxidation potential of the negative electrode current collector, and the potential before the first charge of the second lithium transition metal composite oxide is equal to that of the negative electrode current collector. Although it is possible to suppress an increase in the potential of the negative electrode during overdischarge only by making it lower than the oxidation potential, it is difficult to improve the high temperature characteristics and the electrode plate density of the nonaqueous electrolyte secondary battery.
Therefore, in the present invention, in addition to the above, the electrode plate density can be improved by satisfying the relationship of (6) above for the concentrations of boron, fluorine and magnesium of the second lithium transition metal composite oxide. . Thereby, the charge / discharge capacity per unit volume of the battery can be improved. Furthermore, since elution of transition metal ions can also be suppressed, gas generation during high-temperature storage can be suppressed, high-temperature cycle characteristics can be improved, and both these and electrode plate density can be improved. Can do.

In the nonaqueous electrolyte secondary battery described in (7), when the battery voltage of the nonaqueous electrolyte secondary battery is 0 V, the concentration of the element of the negative electrode current collector present in the electrolyte is 0 to 20 ppm. Even if retention occurs in the negative electrode, the balance between the charge and discharge efficiency of the positive electrode and the negative electrode can be maintained, and an increase in the potential of the negative electrode during overdischarge can be suppressed.
However, when the battery voltage of the non-aqueous electrolyte secondary battery is set to 0 V, the concentration of the negative electrode current collector element present in the electrolyte is merely set to 0 to 20 ppm to suppress the negative electrode potential from increasing during overdischarge. Although it is possible, it is difficult to improve the cycle characteristics and load characteristics of the non-aqueous electrolyte secondary battery.
Therefore, in the present invention, in addition to the above, the electrode plate density can be improved by satisfying the relationship of (6) above for the concentrations of boron, fluorine and magnesium of the second lithium transition metal composite oxide. . Thereby, the charge / discharge capacity per unit volume of the battery can be improved. Furthermore, since elution of transition metal ions can also be suppressed, gas generation during high-temperature storage can be suppressed, high-temperature cycle characteristics can be improved, and both these and electrode plate density can be improved. Can do.

  According to the method for producing a nonaqueous electrolyte secondary battery described in (8), a nonaqueous electrolyte secondary battery having excellent overdischarge characteristics and high temperature characteristics and improved electrode plate density can be obtained. Moreover, this manufacturing method has a simple manufacturing process, and can make it hard to produce a crack of a positive electrode active material layer and a negative electrode active material layer, and peeling from a strip | belt-shaped separator.

  Hereinafter, a positive electrode active material for a nonaqueous electrolyte secondary battery, a positive electrode active material for a nonaqueous electrolyte secondary battery, a nonaqueous electrolyte secondary battery, and a method for producing a nonaqueous electrolyte secondary battery according to the present invention will be specifically described. To do. First, the positive electrode secondary active material of the present invention will be described.

The positive electrode side active material of the present invention has at least a lithium transition metal composite oxide having a spinel structure (spinel-type crystal structure). The “spinel structure” is one of the typical crystal structure types found in double oxide AB ₂ O ₄ type compounds (A and B are metal elements).
FIG. 2 is a schematic diagram showing a crystal structure of a spinel-structure lithium transition metal composite oxide. In FIG. 2, lithium atom 1 occupies a tetrahedral site 16c site of 8a site, oxygen atom 2 occupies 32e site, and transition metal atom 3 occupies an octahedral site of 16d site.

  Examples of the spinel structure lithium transition metal composite oxide include lithium manganese composite oxide, lithium titanium composite oxide, lithium / manganese / nickel composite oxide, and lithium / manganese / cobalt composite oxide. Among these, lithium manganese composite oxide is preferable.

  In the lithium transition metal composite oxide used for the positive electrode side active material of the present invention, lithium is present at the 16c site of the crystal structure. Since lithium is present at the 16c site, in addition to the lithium present at the 8a site, the lithium present at the 16c site is supplied to the negative electrode as a retention amount of the negative electrode, particularly during the first charge. It is possible to prevent the negative electrode current collector from being eluted.

In the present invention, as a method for analyzing the presence of lithium at the 16c site of the lithium transition metal composite oxide, for example, Rietveld analysis can be used.
Lithium may be present in any state. It may exist in a lithium atom state or may exist in a lithium ion state.

In the positive electrode active side active material of the present invention, the boron content is 0.3 to 55.6% by weight based on the total of boron, fluorine, and magnesium, and the fluorine content is boron, fluorine, and magnesium. The content of magnesium is preferably 3.5 to 97.0% by weight with respect to the total of boron, fluorine and magnesium.
When boron, fluorine, and magnesium each satisfy the above-mentioned contents, the electrode plate density can be further improved, and both the suppression of gas generation during high-temperature storage and the improvement of high-temperature cycle characteristics can be achieved.

In the positive electrode secondary active material of the present invention, the form of the lithium transition metal composite oxide is not particularly limited. Examples of the form of the lithium transition metal composite oxide include particles and films.
In the present invention, the lithium transition metal composite oxide is preferably in the form of particles. The concentration of boron present on the surface of the particle is greater than the concentration of boron present inside the particle, and the concentration of fluorine present on the surface of the particle is greater than the concentration of fluorine present on the interior of the particle. The concentration of magnesium present is greater than the concentration of magnesium present within the particle, the concentration of magnesium present within the particle is greater than the concentration of boron present within the particle, and the concentration of magnesium present within the particle. The concentration of magnesium present inside the particles is greater than the concentration of fluorine present inside the particles, so that the high-temperature characteristics and electrode plate density of the particles themselves are improved, so the improvement of overdischarge characteristics is impaired. Furthermore, the high temperature characteristics and the electrode plate density can be further improved.

The primary particle size is grown by increasing the concentration of boron present on the surface of lithium transition metal composite oxide particles (hereinafter also simply referred to as “particles”) to be higher than the concentration of boron existing inside the particles. Can do.
Since the concentration of fluorine existing on the surface of the particles is higher than the concentration of fluorine existing inside the particles, the growth of the primary particle diameter can be further improved by a synergistic effect with boron. Moreover, the dispersibility of primary particles can be improved.
The concentration of magnesium present on the surface of the particles is higher than the concentration of magnesium present inside the particles, thereby suppressing the elution of transition metal ions. Thereby, while suppressing gas generation at the time of high temperature preservation | save, a high temperature cycling characteristic can be improved. In addition, elution of transition metal ions can be further suppressed by a synergistic effect with fluorine. As a result, gas generation during high-temperature storage can be further suppressed, and high-temperature cycle characteristics can be further improved.
When the concentration of magnesium present inside the particles is higher than the concentration of boron present inside the particles, elution of transition metal ions can be suppressed without impairing the growth of the primary particle diameter. Thereby, while suppressing gas generation at the time of high temperature preservation | save, a high temperature cycling characteristic can be improved.
Since the concentration of magnesium present inside the particles is larger than the concentration of fluorine present inside the particles, the elution of transition metal ions can be further suppressed without impairing the improvement in dispersibility of the primary particles. . As a result, gas generation during high-temperature storage can be further suppressed, and high-temperature cycle characteristics can be further improved.

  In the present invention, the lithium transition metal composite oxide may be present in the form of particles composed of one or both of primary particles and secondary particles that are aggregates thereof. That is, the lithium transition metal composite oxide exists in the form of particles, and the particles may be composed only of primary particles, or may be composed only of secondary particles that are aggregates of primary particles. It may consist of both particles and secondary particles.

In the present invention, the lithium transition metal composite oxide is preferably a particle and a lithium transition metal composite oxide having boron and fluorine at least on the surface of the particle and having magnesium.
By having boron and fluorine on the surface of the particles, primary particles can be grown and the dispersibility of the primary particles can be improved. In addition, by containing magnesium, elution of transition metal ions is reduced without impairing the growth of the primary particle size and the improvement of dispersibility of the primary particles, suppressing gas generation during high temperature storage, and high temperature cycle characteristics. Can be improved. Thereby, an electrode plate density can be improved, the gas generation at the time of high temperature preservation | save can be suppressed, and a high temperature cycling characteristic can be improved.

In the present invention, the lithium transition metal composite oxide is a particle, and the lithium transition metal composite oxide has an element and / or compound that increases the primary particle diameter, and the volume cumulative frequency in the particle size distribution of the particle. It is preferable to have elements and / or compounds that increase all of D10, D50, and D90, where D10, D50, and D90 are the particle sizes reaching 10%, 50%, and 90%, respectively.
By having an element and / or a compound that increases all of D10, D50, and D90, the dispersibility of the particles can be improved. Having elements and / or compounds that increase the primary particle diameter and elements that increase all of D10, D50, and D90 can improve particle packing properties and improve electrode plate density.

In the present invention, the lithium transition metal composite oxide represents a general formula Li _{1 + a} Mg _b Mn _2-a-b B _c F _d O _{4 + e} (a represents a number satisfying −0.2 ≦ a ≦ 0.2, b Represents a number satisfying 0 ≦ b ≦ 0.1, c represents a number satisfying 0.002 ≦ c ≦ 0.02, d represents a number satisfying 0.0025 ≦ d ≦ 0.1, and e represents -Represents a number satisfying −0.5 ≦ e ≦ 0.5.
When boron, fluorine, and magnesium satisfy the above contents, the electrode plate density can be improved, gas generation during high-temperature storage can be suppressed, and high-temperature cycle characteristics can be improved.

In the present invention, when the particle size at which the volume cumulative frequency in the particle size distribution of the particles reaches 10%, 50% and 90% is D10, D50 and D90, respectively,
0.1 ≦ (D10 / D50) ≦ 1,
1 ≦ (D90 / D50) ≦ 3 and 5 μm ≦ D50 ≦ 40 μm
It is preferable to satisfy all of the above. When D10, D50, and D90 satisfy the above relational expression, the electrode plate density can be further improved without impairing the suppression of gas generation during high-temperature storage and the improvement of high-temperature cycle characteristics.

In the present invention, the specific surface area is preferably 0.2 to 1.5 m ² / g. When the specific surface area is this value, the electrode plate density can be further improved without impairing the suppression of gas generation during high temperature storage and the improvement of high temperature cycle characteristics.
In the present invention, the specific surface area diameter is preferably 3.0 to 5.0 μm. When the specific surface area diameter is this value, the electrode plate density can be further improved without impairing the suppression of gas generation during high-temperature storage and the improvement of high-temperature cycle characteristics.

  In the positive electrode secondary active material of the present invention, the following (i) to (iv) are mentioned as preferred embodiments of the lithium transition metal composite oxide.

(I) the general formula _{Li 1 + a + f Mg b} Mn 2-a-b B c F d O 4 + e (a represents the composition ratio of lithium present in 16d sites, f is represents the composition ratio of lithium present in the 16c sites, a represents a number satisfying −0.2 ≦ a ≦ 0.2, b represents a number satisfying 0.005 ≦ b ≦ 0.10, and c represents a number satisfying 0.002 ≦ c ≦ 0.02. D represents a number satisfying 0.0025 ≦ d ≦ 0.1, e represents a number satisfying −0.5 ≦ e ≦ 0.5, and f represents a number satisfying 0 <f <1.0. The aspect represented by.

Aspect (i) has a high electrode plate density, and is excellent in suppression of gas generation during high-temperature storage and high-temperature cycle characteristics.
In embodiment (i), a is preferably greater than 0. It is thought that high temperature cycle characteristics are improved by substituting a part of manganese with lithium.
In the embodiment (i), b is preferably 0.01 or more, more preferably 0.02 or more, and preferably 0.08 or less, and 0.07 or less. More preferred. If b is too large, the amount of magnesium that cannot be completely dissolved in the transition metal site increases, so the initial capacity decreases. If b is too small, elution of transition metal ions increases and gas generation occurs, so that the high temperature characteristics deteriorate.
In the embodiment (i), c is preferably 0.003 or more, and preferably 0.008 or less. If c is too large, the initial capacity decreases. In addition, the elution of transition metal ions increases, causing gas generation, resulting in deterioration of high temperature characteristics. If c is too small, the primary particle size does not grow, and the particle packing property is not improved.
In the embodiment (i), d is preferably 0.005 or more, more preferably 0.01 or more, and preferably 0.05 or less, and 0.03 or less. More preferred. When d is too large, the dispersibility of the particles is excessively increased, and the filling property is deteriorated. If d is too small, the primary particle size does not grow, and the particle packing property is not improved.

  (Ii) An embodiment in which the lithium transition metal composite oxide is a lithium manganese composite oxide having at least one selected from the group consisting of titanium, zirconium and hafnium, and having lithium present at the 16c site.

  By having at least one selected from the group consisting of titanium, zirconium and hafnium, it is considered that the mobility of lithium ions in the particles can be increased and the impedance can be reduced. For this reason, it is considered that the output characteristics are improved without impairing the improvement of the electrode plate density, the suppression of gas generation during high temperature storage and the improvement of the high temperature cycle characteristics.

(Iii) An embodiment in which the lithium transition metal composite oxide is a lithium manganese composite oxide having at least one selected from the group consisting of titanium, zirconium and hafnium, and sulfur, and lithium is present at the 16c site.

In the embodiment (iii), it is considered that the cycle characteristics and the load characteristics are further improved since the passage of electrons is improved by the presence of sulfur.
The sulfur content is preferably 0.02 to 0.3% by weight based on the total of the lithium transition metal composite oxide and sulfur. If the amount is less than 0.02% by weight, the resistance to movement of electrons may be difficult to reduce. If it exceeds 0.3% by weight, the battery may swell due to moisture adsorption.

Sulfur may be present in any form. For example, it may exist in the form of sulfate radicals.
The sulfate radical includes sulfate ions, a group of atoms obtained by removing the charge from sulfate ions, and sulfo groups. It is preferably based on at least one selected from the group consisting of alkali metal sulfates, alkaline earth metal sulfates, organic sulfates and organic sulfonic acids and salts thereof.
Among them, it is preferable to use at least one selected from the group consisting of alkali metal sulfates and alkaline earth metal sulfates, and more preferable to use alkali metal sulfates. This is because these are chemically stable because they are composed of strong acid strong base bonds.

In aspect (iii), the reason for containing elements other than sulfur is the same as in aspect (ii).
In the embodiment (iii), by containing each of the above elements, a positive electrode plate having a high charge / discharge capacity and excellent binding properties and surface smoothness can be obtained due to the synergistic effect of each element. .

The lithium transition metal composite oxide may have a sulfate group at least on the surface of the particle.
The presence of the sulfate radical on the surface of the lithium transition metal composite oxide particle makes the electron transfer resistance around the particle extremely small, and as a result, the ease of passing electrons is improved, and the cycle characteristics and load characteristics are improved. It is thought to improve.
In addition, when a high-voltage battery (for example, a battery using LiMn _1.5 Ni _0.5 O ₄ as a lithium transition metal composite oxide) is formed using the positive electrode secondary active material of the present invention, in a conventional high-voltage battery The decomposition of the electrolyte during charging, which was a problem, is suppressed, and as a result, the cycle characteristics are improved. The decomposition reaction of the electrolytic solution is thought to occur as a catalyst at the interface between the lithium transition metal composite oxide particles and the electrolytic solution, but the sulfate radical has no function of decomposing the electrolytic solution. Thus, it is considered that the entire surface or part of the surface of the lithium transition metal composite oxide particles reduces the contact area between the electrolytic solution and the catalyst and suppresses the reaction.

  In the present invention, the sulfate group exhibits the effect of the present invention regardless of the form of the sulfate group present on the surface of the lithium transition metal composite oxide particles. For example, even when the sulfate radical covers the entire particle surface of the lithium transition metal composite oxide, the sulfate radical covers a part of the particle surface of the lithium transition metal composite oxide. However, the cycle characteristics, load characteristics and thermal stability are improved.

Moreover, the sulfate radical should just exist in the surface of particle | grains at least. Therefore, a part of the sulfate radical may exist inside the particle.
Whether or not the sulfate radical is present on the surface of the lithium transition metal composite oxide particles can be analyzed by various methods. For example, it can be analyzed by Auger electron spectroscopy or X-ray photoelectron spectroscopy.
Moreover, various methods can be used for the determination of sulfate radicals. For example, it can be quantified by ICP emission spectrometry or titration.

  (Iv) A lithium-manganese composite in which the lithium transition metal composite oxide has at least one selected from the group consisting of titanium, zirconium and hafnium, sulfur, sodium and / or calcium, and lithium is present at the 16c site. The aspect which is an oxide.

In the embodiment (iv), by containing sodium and / or calcium, elution of manganese ions can be further suppressed by a synergistic effect with boron (preferably boron and sulfur), and the practical level is excellent. Cycle characteristics can be realized.
In embodiment (iv), the reason for containing an element other than sodium and / or calcium is the same as in embodiment (ii) and (iii).

  The lithium transition metal composite oxide preferably has an iron content of 25 ppm or less, more preferably 20 ppm or less, and even more preferably 18 ppm or less. If the iron content is too high, it may cause an internal short circuit of the battery.

  Although the manufacturing method of the positive electrode secondary active material of the present invention is not particularly limited, for example, it can be manufactured as in the following (1) to (3).

(1) Preparation of raw material mixture The compounds described later are mixed so that each constituent element has a predetermined composition ratio to obtain a raw material mixture. The compound used for the raw material mixture is selected according to the elements constituting the target composition.
The mixing method is not particularly limited, for example, a method of mixing powdery compounds as they are to obtain a raw material mixture; mixing in a slurry form using water and / or an organic solvent, and then drying to obtain a raw material mixture Method: A method in which an aqueous solution of the above-mentioned compound is mixed and precipitated, and the resulting precipitate is dried to obtain a raw material mixture; a method in which these are used in combination.

Below, the compound used for a raw material mixture is illustrated.
Lithium compound is not particularly limited, for _{example, Li 2 CO 3, LiOH,} LiOH · H 2 O, Li 2 O, LiCl, LiNO 3, Li 2 SO 4, LiHCO 3, Li (CH 3 COO), fluoride Examples include lithium, lithium bromide, lithium iodide, and lithium peroxide. Among these, Li ₂ CO ₃ , LiOH, LiOH · H ₂ O, Li ₂ O, LiCl, LiNO ₃ , Li ₂ SO ₄ , LiHCO ₃ , and Li (CH ₃ COO) are preferable.

The manganese compound is not particularly limited. For example, manganese metal, oxide (eg, MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ ), hydroxide, nitrate, carbonate (MnCO ₃ ), chloride salt, Examples thereof include manganese iodide, manganese sulfate, and manganese nitrate. Among these, manganese metal, MnCO ₃ , MnSO ₄ , and MnCl ₂ are preferable.

Magnesium compound is not particularly limited, for _{example, MgO, MgCO 3, Mg (} OH) 2, MgCl 2, MgSO 4, Mg (NO 3) 2, Mg (CH 3 COO) 2, magnesium iodide, perchlorate Examples include magnesium. Among these, MgSO ₄ and Mg (NO ₃ ) ₂ are preferable.

The boron compound is not particularly limited, and examples thereof include B ₂ O ₃ (melting point: 460 ° C.), H ₃ BO ₃ (decomposition temperature: 173 ° C.), lithium boron composite oxide, orthoboric acid, boron oxide, and boron phosphate. It is done. Among these, H ₃ BO ₃ and B ₂ O ₃ are preferable.

The fluorine compound is not particularly limited, and examples thereof include NH ₄ F, LiF, LiCl, LiBr, MnF ₂ , hydrogen fluoride, oxygen fluoride, hydrofluoric acid, chlorine fluoride oxide, and bromine fluorosulfate. Of these, NH ₄ F, LiF, and MnF ₂ are preferable.

The titanium compound is not particularly limited, and examples thereof include titanium fluoride, titanium chloride, titanium bromide, titanium iodide, titanium oxide, titanium sulfide, and titanium sulfate. Of these, TiO, TiO ₂ , Ti ₂ O ₃ , TiCl ₂ , and Ti (SO ₄ ) ₂ are preferable.

The zirconium compound is not particularly limited, and examples thereof include zirconium fluoride, zirconium chloride, zirconium bromide, zirconium iodide, zirconium oxide, zirconium sulfide, and zirconium carbonate. Of these, ZrF ₂ , ZrCl, ZrCl ₂ , ZrBr ₂ , ZrI ₂ , ZrO, ZrO ₂ , ZrS ₂ , Zr (OH) _{3 and the} like are preferable.

The hafnium compound is not particularly limited, and examples thereof include hafnium fluoride, hafnium chloride, hafnium bromide, hafnium iodide, hafnium oxide, and hafnium carbonate. Among these, HfF ₄ , HfCl ₂ , HfBr ₂ , HfO ₂ , Hf (OH) ₄ , Hf ₂ S and the like are preferable.

Sodium compound is not particularly limited, for _{example, Na 2 CO 3, NaOH,} Na 2 O, NaCl, NaNO 3, Na 2 SO 4, NaHCO 3, CH 3 CONa the like.

Calcium compound is not particularly limited, for _{example, CaO, CaCO 3, Ca (} OH) 2, CaCl 2, CaSO 4, Ca (NO 3) 2, Ca (CH 3 COO) 2 and the like.
Moreover, you may use the compound containing 2 or more types of each element mentioned above.

Hereinafter, a preferred method for obtaining the raw material mixture will be described in detail by taking as an example a positive electrode secondary active material which is a lithium manganese composite oxide having magnesium, boron and fluorine.
An aqueous solution containing manganese ions and magnesium ions having a predetermined composition ratio prepared from the above-described manganese compound and magnesium compound is dropped into pure water being stirred.
Next, an aqueous ammonium hydrogen carbonate solution is added dropwise to precipitate manganese and magnesium to obtain manganese and magnesium salts. In place of the ammonium hydrogen carbonate aqueous solution, an alkali solution such as a sodium hydroxide aqueous solution, a sodium hydrogen carbonate aqueous solution, a potassium hydroxide aqueous solution, or a lithium hydroxide aqueous solution can also be used.

  Next, the aqueous solution is filtered to collect a precipitate. The collected precipitate is washed with water and heat-treated, and then mixed with the above-described lithium compound, boron compound, and fluorine compound to obtain a raw material mixture.

(2) Firing and grinding of raw material mixture Next, the raw material mixture is fired. The firing temperature, time, atmosphere, and the like are not particularly limited, and can be appropriately determined according to the purpose.
The firing temperature is preferably 650 ° C. or higher, and more preferably 700 ° C. or higher. If the firing temperature is too low, unreacted raw materials may remain in the positive electrode active material, and the original characteristics of the positive electrode active material may not be utilized. The firing temperature is preferably 1100 ° C. or lower, and more preferably 950 ° C. or lower. If the firing temperature is too high, the particle size of the positive electrode active material may become too large, and the battery characteristics may deteriorate. In addition, by-products such as Li ₂ MnO ₃ and LiMnO ₂ are likely to be generated, which may lead to a decrease in discharge capacity per unit weight, a decrease in cycle characteristics, and a decrease in operating voltage.
In general, the firing time is preferably 1 to 24 hours, and more preferably 6 to 12 hours. When the firing time is too short, the diffusion reaction between the raw material particles does not proceed. If the firing time is too long, firing after the diffusion reaction is almost completed is wasted, and coarse particles may be formed by sintering.

  The firing may be divided into a plurality of firing steps. For example, a 1st baking process can be performed at 350-550 degreeC for 1 to 24 hours, and a 2nd baking process can be performed at 650-1000 degreeC for 1 to 24 hours.

  Examples of the firing atmosphere include air, oxygen gas, a mixed gas of these with an inert gas such as nitrogen gas and argon gas, an atmosphere in which the oxygen concentration (oxygen partial pressure) is controlled, and a weak oxidizing atmosphere. Among these, an atmosphere in which the oxygen concentration is controlled is preferable.

  After firing, if desired, the powder may be pulverized using a rough mortar, ball mill, vibration mill, pin mill, jet mill or the like to obtain a powder having a desired particle size. Thus, the specific surface area can be set to the above-described preferred range by grinding after firing.

(3) Organic treatment The obtained lithium transition metal composite oxide is reacted with an organic solution containing lithium. Then, the solution obtained by making it react is filtered and dried, and the positive electrode active material of this invention is obtained.
Drying may be performed in air, in a nitrogen gas atmosphere, an argon gas atmosphere, or in a vacuum state.

  The positive electrode active material of the present invention is suitably used for the positive electrode active material of the present invention described later.

Next, the positive electrode active material of the present invention will be described.
The positive electrode active material of the present invention includes a main active material having a first lithium transition metal composite oxide and a secondary active material having at least a second lithium transition metal composite oxide having a spinel structure.
The 1st lithium transition metal complex oxide used for the main active material of the positive electrode active material of this invention is not specifically limited.

The first lithium transition metal composite oxide preferably includes a 3b site where lithium is present, a 3a site where transition metal is present, and a 6c site where oxygen is present. By setting it as the 1st lithium transition metal complex oxide of this structure, it becomes a positive electrode active material of high energy density with high charge / discharge capacity, without impairing the improvement of overdischarge characteristics, cycle characteristics, and load characteristics.
The first lithium transition metal composite oxide is preferably a lithium transition metal composite oxide having at least a layered structure (layered crystal structure). The layered structure means that the crystal structure of the lithium transition metal composite oxide is layered. The layered structure is not particularly limited, and examples thereof include a layered rock salt structure and a zigzag layered rock salt structure. Among these, a layered rock salt structure is preferable.
FIG. 7 is a schematic view showing a crystal structure of a lithium transition metal composite oxide having a layered structure. In FIG. 7, lithium atoms 9 occupy 3b sites, oxygen atoms 8 occupy 6c sites, and transition metal atoms 7 occupy 3a sites.

The first lithium transition metal composite oxide is preferably composed of an 8a site where lithium is present, a 16d site where transition metal is present, and a 32e site where oxygen is present. By setting it as the 1st lithium transition metal complex oxide of this structure, it becomes a positive electrode active material excellent in output characteristics, without impairing the improvement of overdischarge characteristics, cycle characteristics, and load characteristics.
The first lithium transition metal composite oxide preferably has at least a spinel structure (spinel crystal structure) lithium transition metal composite oxide. The “spinel structure” is one of the typical crystal structure types found in double oxide AB ₂ O ₄ type compounds (A and B are metal elements).
FIG. 8 is a schematic diagram showing a crystal structure of a spinel-structure lithium transition metal composite oxide. In FIG. 8, lithium atom 1 occupies tetrahedral site 16c site of 8a site, oxygen atom 2 occupies 32e site, and transition metal atom 3 occupies octahedral site of 16d site.

The first lithium transition metal composite oxide is not limited to one type of lithium transition metal composite oxide.
In the positive electrode active material of the present invention, the first lithium transition metal composite oxide comprises lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobaltate, nickel cobalt lithium manganate, nickel cobalt lithium aluminate, nickel manganese It is preferably at least one selected from the group consisting of lithium acid acids.
Thereby, not only the improvement of the overdischarge characteristic, the cycle characteristic and the load characteristic, but also the charge / discharge capacity is increased, and a nonaqueous electrolyte secondary battery excellent in output characteristics can be obtained.
When the first lithium transition metal composite oxide is composed of two or more combinations, lithium cobaltate and lithium manganate, lithium cobaltate and nickel cobalt lithium manganate, lithium cobaltate and nickel cobalt lithium aluminate, cobalt acid Lithium and lithium nickel manganate, lithium manganate and nickel cobalt lithium manganate, lithium manganate and nickel cobalt lithium aluminate, lithium manganate and nickel nickel manganate, nickel cobalt lithium manganate and nickel cobalt lithium aluminate, nickel cobalt Preferably, it is one selected from the group consisting of lithium manganate and lithium nickel manganate, nickel cobalt lithium aluminate and nickel nickel manganate. Arbitrariness.

As the lithium cobalt oxide, lithium cobalt oxide represented by the general formula Li _{1 + x} CoO ₂ (x represents a number satisfying −0.5 ≦ x ≦ 0.5) is preferable. The lithium cobaltate is at least partially selected from the group consisting of magnesium, aluminum, calcium, vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, strontium, zirconium, niobium, molybdenum and tin. It may be substituted with one kind.

As lithium manganate, the general formula Li _a Mn _3-a O _{4 + f} (a represents a number satisfying 0.8 ≦ a ≦ 1.2, and f represents a number satisfying −0.5 ≦ f ≦ 0.5. And lithium manganate represented by the general formula Li _{1 + x} MnO ₂ (x represents a number satisfying −0.5 ≦ x ≦ 0.5) is preferable. This lithium manganate is at least partly selected from the group consisting of magnesium, aluminum, calcium, vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, strontium, zirconium, niobium, molybdenum and tin It may be substituted with one kind.

The lithium nickelate is preferably lithium nickelate represented by the general formula Li _{1 + x} NiO ₂ (x represents a number satisfying −0.5 ≦ x ≦ 0.5). This lithium nickelate is at least partly selected from the group consisting of magnesium, aluminum, calcium, vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, strontium, zirconium, niobium, molybdenum and tin. It may be substituted with one kind.

As the lithium / nickel / cobalt composite oxide, a general formula Li _x Ni _y Co _z X _(1-yz) O _w (X represents Al or Mn, x represents 0.95 ≦ x ≦ 1.10. Y represents a number satisfying 0.1 ≦ y ≦ 0.9, z represents a number satisfying 0.1 ≦ z ≦ 0.9, and w represents 1.8 ≦ w ≦ 2.2. The lithium / nickel / cobalt composite oxide represented by This lithium / nickel / cobalt composite oxide is partially composed of magnesium, aluminum, calcium, vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, strontium, zirconium, niobium, molybdenum and tin. It may be substituted with at least one selected from the group.

In the positive electrode active material of the present invention, the first lithium transition metal composite oxide is selected from the group consisting of lithium cobaltate, lithium nickelate, and lithium / nickel / cobalt composite oxide, where the amount of lithium manganate is A. When at least one amount is B, it is preferable to mix so as to be in the range of 0.2 ≦ B / (A + B) ≦ 0.8.
As a result, a positive electrode active material with improved output characteristics as well as overdischarge characteristics, cycle characteristics and load characteristics can be obtained.
In particular, it is more preferable to mix so that it may become the range of 0.4 <= B / (A + B) <= 0.6. This is because within this range, load characteristics and output characteristics are remarkably improved.

In the positive electrode active material of the present invention, the lithium manganate that is the first lithium transition metal composite oxide preferably contains lithium at the 16d site.
The presence of lithium at the 16d site of the first lithium transition metal composite oxide further improves the cycle characteristics without impairing the improvement of the overdischarge characteristics and the load characteristics.
Lithium may be present in any state. It may exist in a lithium atom state or may exist in a lithium ion state.

The secondary active material used for the positive electrode active material of the present invention is the positive electrode secondary active material of the present invention described above.

  The amount of the secondary active material in the positive electrode active material of the present invention is preferably 1 to 30% by weight with respect to the amount of the positive electrode active material. The amount of the secondary active material is more preferably 3% by weight or more, and more preferably 15% by weight or less. If the amount of the secondary active material is too small, the effect of the secondary active material is not sufficiently exhibited and the negative electrode current collector is eluted during overdischarge. If the amount of the secondary active material is too large, gelation or the like occurs, making handling difficult.

  The production method of the positive electrode active material of the present invention is not particularly limited, and can be produced, for example, as in the following (1) to (3).

(1) Preparation of main active material A compound is mixed so that each component may become a predetermined composition ratio, and a raw material mixture is obtained. The compound used for the raw material mixture is selected according to the elements constituting the target composition.
The mixing method is not particularly limited, for example, a method of mixing powdery compounds as they are to obtain a raw material mixture; mixing in a slurry form using water and / or an organic solvent, and then drying to obtain a raw material mixture Method: A method in which an aqueous solution of the above-mentioned compound is mixed and precipitated, and the resulting precipitate is dried to obtain a raw material mixture; a method in which these are used in combination.
Next, the raw material mixture is fired to obtain the main active material. The firing temperature, time, atmosphere, and the like are not particularly limited, and can be appropriately determined according to the purpose.
After firing, if desired, the powder may be pulverized using a rough mortar, ball mill, vibration mill, pin mill, jet mill or the like to obtain a powder having a desired particle size.

(2) Production of side active material A side active material can be obtained by the manufacturing method of the positive electrode side active material of this invention mentioned above.

(3) Mixing of main active material and sub-active material The obtained main active material and sub-active material can be mixed at a predetermined weight ratio to obtain the positive electrode active material of the present invention.
The method for mixing the main active material and the sub active material is not particularly limited. For example, it can be mixed with a high-speed agitator.

  The positive electrode active material of the present invention is suitably used for the nonaqueous electrolyte secondary battery of the present invention described later.

Next, the nonaqueous electrolyte secondary battery of the present invention will be described.
The positive electrode active material used in the nonaqueous electrolyte secondary battery of the present invention includes a main active material having a first lithium transition metal composite oxide and a secondary active having at least a second lithium transition metal composite oxide having a spinel structure. Substance.
In addition, the secondary active material used in the nonaqueous electrolyte secondary battery of the present invention has a boron concentration present on the surface of the second lithium transition metal composite oxide within the second lithium transition metal composite oxide. The concentration of fluorine greater than the concentration of boron present and present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present within the second lithium transition metal composite oxide, The concentration of magnesium present on the surface of the lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide, and is present inside the second lithium transition metal composite oxide. The concentration of magnesium is greater than the concentration of boron present inside the second lithium transition metal composite oxide and is present inside the second lithium transition metal composite oxide. The concentration of magnesium is greater than the concentration of fluorine present in the interior of the second lithium-transition metal composite oxide.
The secondary active material used for the nonaqueous electrolyte secondary battery of the present invention will be described.

In the nonaqueous electrolyte secondary battery of the present invention, the form of the second lithium transition metal composite oxide is not particularly limited. Examples of the form of the second lithium transition metal composite oxide include particles and films.
In the nonaqueous electrolyte secondary battery of the present invention, the second lithium transition metal composite oxide is preferably in the form of particles. By having a sulfate radical on the surface of the second lithium transition metal composite oxide particle, the resistance of electrons moving around the particle becomes extremely small. As a result, the ease of passing electrons is further improved, and the cycle characteristics are further improved. In addition, the load characteristics are considered to be improved. Therefore, the cycle characteristics and load characteristics can be further improved without impairing the improvement of the overdischarge characteristics.
In the nonaqueous electrolyte secondary battery of the present invention, the second lithium transition metal composite oxide may be present in the form of particles composed of one or both of primary particles and secondary particles that are aggregates thereof. Good. That is, the second lithium transition metal composite oxide exists in the form of particles, and the particles may consist only of primary particles or only secondary particles that are aggregates of primary particles. It may be composed of both primary particles and secondary particles.

  In the nonaqueous electrolyte secondary battery of the present invention, the following (i) to (iv) may be mentioned as preferred embodiments of the second lithium transition metal composite oxide.

(I) the general formula _{Li 1 + a Mg b Mn 2} -a-b B c F d O 4 + e (a represents a number satisfying -0.2 ≦ a ≦ 1.2, b is 0.005 ≦ b ≦ 0. 10 represents a number satisfying 10, c represents a number satisfying 0.002 ≦ c ≦ 0.02, d represents a number satisfying 0.0025 ≦ d ≦ 0.1, and e represents −0.5 ≦ e ≦ A number satisfying 0.5, and f representing a number satisfying 0 <f <1.0.

Aspect (i) has a high electrode plate density, and is excellent in suppression of gas generation during high-temperature storage and high-temperature cycle characteristics.
In embodiment (i), a is preferably greater than 0. It is considered that the cycle characteristics are improved by substituting a part of manganese with lithium.
In the embodiment (i), b is preferably 0.01 or more, more preferably 0.02 or more, and preferably 0.08 or less, and 0.07 or less. More preferred. If b is too large, the amount of magnesium that cannot be completely dissolved in the transition metal site increases, so the initial capacity decreases. If b is too small, elution of transition metal ions increases and gas generation occurs, so that the high temperature characteristics deteriorate.
In the embodiment (i), c is preferably 0.003 or more, and preferably 0.008 or less. If c is too large, the initial capacity decreases. In addition, the elution of transition metal ions increases, causing gas generation, resulting in deterioration of high temperature characteristics. If c is too small, the primary particle size does not grow, and the particle packing property is not improved.
In the embodiment (i), d is preferably 0.005 or more, more preferably 0.01 or more, and preferably 0.05 or less, and 0.03 or less. More preferred. When d is too large, the dispersibility of the particles is excessively increased, so that the filling property is deteriorated. If d is too small, the primary particle size does not grow, and the particle packing property is not improved.

  (Ii) An embodiment in which the second lithium transition metal composite oxide has at least one selected from the group consisting of titanium, zirconium and hafnium, and is a lithium manganese composite oxide.

  By having at least one selected from the group consisting of titanium, zirconium, and hafnium, the lattice constant of the unit cell of the lithium manganese composite oxide particle increases, the mobility of lithium ions in the particle increases, and the impedance decreases. I think it can be done. For this reason, it is considered that the output characteristics are improved without impairing the improvement of the electrode plate density, the suppression of gas generation during high temperature storage and the improvement of the high temperature cycle characteristics.

(Iii) A mode in which the second lithium transition metal composite oxide is a lithium manganese composite oxide having at least one selected from the group consisting of titanium, zirconium and hafnium and sulfur.

In the embodiment (iii), it is considered that the cycle characteristics and the load characteristics are further improved since the passage of electrons is improved by the presence of sulfur.
The sulfur content is preferably 0.02 to 0.3% by weight based on the total of the lithium transition metal composite oxide and sulfur. If the amount is less than 0.02% by weight, the resistance to movement of electrons may be difficult to reduce. If it exceeds 0.3% by weight, the battery may swell due to moisture adsorption.

Sulfur may be present in any form. For example, it may exist in the form of sulfate radicals.
The sulfate radical includes sulfate ions, a group of atoms obtained by removing the charge from sulfate ions, and sulfo groups. It is preferably based on at least one selected from the group consisting of alkali metal sulfates, alkaline earth metal sulfates, organic sulfates and organic sulfonic acids and salts thereof.
Among them, it is preferable to use at least one selected from the group consisting of alkali metal sulfates and alkaline earth metal sulfates, and more preferable to use alkali metal sulfates. This is because these are chemically stable because they are composed of strong acid strong base bonds.

In aspect (iii), the reason for containing elements other than sulfur is the same as in aspect (ii).
In the embodiment (iii), by containing each of the above elements, a positive electrode plate having a high charge / discharge capacity and excellent binding properties and surface smoothness can be obtained due to the synergistic effect of each element. .

The second lithium transition metal composite oxide may have a sulfate group at least on the surface of the particles.
The presence of the sulfate radical on the surface of the second lithium transition metal composite oxide particle results in extremely low electron transfer resistance around the particle, resulting in improved electron transit, It is considered that the load characteristics are improved.
Further, when the secondary active material of the present invention is used to form a high voltage battery (for example, a battery using LiMn _1.5 Ni _0.5 O ₄ as a lithium transition metal composite oxide), there is a problem in the conventional high voltage battery. The decomposition of the electrolyte during charging was suppressed, and as a result, the cycle characteristics were improved. The decomposition reaction of the electrolytic solution is considered to occur as a catalyst at the interface between the particles of the second lithium transition metal composite oxide and the electrolytic solution, but the electrolytic solution is decomposed. When the surface of the second lithium transition metal composite oxide particles is entirely or partially covered with sulfate radicals that do not act to reduce the contact area between the electrolyte and the catalyst, and the reaction is suppressed Conceivable.

  In the present invention, the sulfate group exhibits the effect of the present invention regardless of the form of the sulfate group present on the surface of the second lithium transition metal composite oxide particles. For example, even when the sulfate radical covers the entire particle surface of the second lithium transition metal composite oxide, the sulfate radical covers a part of the particle surface of the second lithium transition metal composite oxide. Even in this case, cycle characteristics, load characteristics and thermal stability are improved.

Moreover, the sulfate radical should just exist in the surface of particle | grains at least. Therefore, a part of the sulfate radical may exist inside the particle.
Whether the sulfate radical is present on the surface of the second lithium transition metal composite oxide particle can be analyzed by various methods. For example, it can be analyzed by Auger electron spectroscopy or X-ray photoelectron spectroscopy.
Moreover, various methods can be used for the determination of sulfate radicals. For example, it can be quantified by ICP emission spectrometry or titration.

  (Iv) A mode in which the second lithium transition metal composite oxide is a lithium manganese composite oxide having at least one selected from the group consisting of titanium, zirconium and hafnium, sulfur, sodium and / or calcium.

In the embodiment (iv), by containing sodium and / or calcium, elution of manganese ions can be further suppressed by a synergistic effect with boron (preferably boron and sulfur), and the practical level is excellent. Cycle characteristics can be realized.
In embodiment (iv), the reason for containing an element other than sodium and / or calcium is the same as in embodiment (ii) and (iii).

  The second lithium transition metal composite oxide preferably has an iron content of 25 ppm or less, more preferably 20 ppm or less, and even more preferably 18 ppm or less. If the iron content is too high, it may cause an internal short circuit of the battery.

In the non-aqueous electrolyte secondary battery of the present invention, the secondary active material preferably has a specific surface area of 0.2 to 1.5 m ² / g. The specific surface area is more preferably 0.25 m ² / g or more, more preferably 1.3 m ² / g or less, and even more preferably 1.15 m ² / g or less. When the specific surface area is too small, the discharge capacity decreases. If the specific surface area is too large, the high temperature cycle characteristics will not be excellent.
The specific surface area can be measured by a nitrogen gas adsorption method.

  In the nonaqueous electrolyte secondary battery of the present invention, the potential before the first charge and the oxidation potential can be measured by cyclic voltammetry using lithium as a reference electrode.

In the nonaqueous electrolyte secondary battery of the present invention, the element of the negative electrode current collector present in the electrolyte refers to an element that is a component of the negative electrode current collector. For example, Cu, Ni, etc. are mentioned. Preferably, it is Cu.
The element of the negative electrode current collector may exist in an ionic state or a compound state. The presence of these elements increases the electrical conductivity of the active material and provides a nonaqueous electrolyte secondary battery with improved load characteristics.
In the nonaqueous electrolyte secondary battery of the present invention, the concentration of the element of the negative electrode current collector present in the electrolyte is preferably 0 ppm or more, more preferably 1 ppm or more, and 20 ppm or less. Preferably, it is 15 ppm or less. If the concentration of the element of the negative electrode current collector present in the electrolyte is too high, it is not preferable because it causes an internal short circuit and a decrease in cycle characteristics.
The concentration of the element of the negative electrode current collector present in the electrolyte can be measured by various methods. For example, it can be quantified by inductively coupled plasma (ICP) spectroscopy, atomic absorption spectrometry, or fluorescent X-ray analysis.

  The non-aqueous electrolyte secondary battery of the present invention preferably has no protective circuit for preventing overdischarge. The positive electrode active material in the nonaqueous electrolyte secondary battery of the present invention described above can be placed in the space of the protection circuit, and not only the overdischarge characteristics, cycle characteristics and load characteristics are improved, but also a high capacity nonaqueous electrolyte secondary battery. It becomes.

  In the nonaqueous electrolyte secondary battery of the present invention, the main active material having the first lithium transition metal composite oxide is the main active material having the first lithium transition metal composite oxide in the positive electrode active material of the present invention described above. It is.

  The nonaqueous electrolyte secondary battery of the present invention can be manufactured as described in the following (1) to (3).

(1) Fabrication of positive electrode The concentration of boron present on the surface of the main active material having the first lithium transition metal composite oxide and at least the second lithium transition metal composite oxide having a spinel structure is the second lithium transition. The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of boron present in the metal composite oxide, and the concentration of fluorine present in the second lithium transition metal composite oxide The concentration of magnesium greater than the concentration and present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present within the second lithium transition metal composite oxide, and the second lithium transition metal composite oxide The concentration of magnesium present in the oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide, and the second lithium The concentration of magnesium present in the interior of the transition metal composite oxide is greater than the concentration of fluorine present in the interior of the second lithium transition metal composite oxide, and the crystal structure of the second lithium transition metal composite oxide is 16c. A positive electrode active material having a secondary active material in which lithium is present at the site is manufactured. This positive electrode active material can be obtained by the method for producing a positive electrode active material of the present invention described above.
A positive electrode active material layer using the obtained positive electrode active material is formed on at least one surface of the belt-like positive electrode current collector to produce a belt-like positive electrode.
At this time, it is preferable to manufacture a strip-shaped positive electrode by forming a positive electrode active material layer using the obtained positive electrode active material on both surfaces of the strip-shaped positive electrode current collector. By forming on both sides, the charge / discharge capacity is remarkably improved without impairing the improvement of the overdischarge characteristics, cycle characteristics and load characteristics.

(2) Production of negative electrode A negative electrode active material comprising a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions is formed on at least one surface of the negative electrode current collector to produce a negative electrode.
At this time, it is preferable to produce a strip-shaped negative electrode by forming a negative electrode active material layer using the obtained negative-electrode active material on both surfaces of the strip-shaped negative electrode current collector. Thereby, it becomes a nonaqueous electrolyte secondary battery excellent in charge / discharge capacity.
As the negative electrode active material, a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions can be used. Examples of the carbon material capable of occluding and releasing lithium ions include carbon materials such as graphite and graphite. Examples of the compound capable of occluding and releasing lithium ions include oxides such as tin oxide and titanium oxide.

(3) Production of non-aqueous electrolyte secondary battery The obtained strip-shaped positive electrode and the obtained strip-shaped negative electrode are wound with a plurality of turns in a state of being laminated via a strip-shaped separator, and a strip-shaped is formed between the strip-shaped positive electrode and the strip-shaped negative electrode. A non-aqueous electrolyte secondary battery of the present invention can be obtained by forming a spiral wound body with a separator interposed therebetween.
Examples of the separator include a porous film made of polyethylene or polypropylene.

Moreover, the positive electrode active material of this invention is used suitably for nonaqueous electrolyte secondary batteries, such as a lithium ion secondary battery and a lithium ion polymer secondary battery.
The non-aqueous electrolyte secondary battery may be the positive electrode active material of the present invention as at least a part of the positive electrode active material in a conventionally known non-aqueous electrolyte secondary battery, and other configurations are not particularly limited.

  As the negative electrode active material, a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions can be used. Examples of the carbon material capable of occluding and releasing lithium ions include carbon materials such as graphite and graphite. Examples of the compound capable of occluding and releasing lithium ions include oxides such as tin oxide and titanium oxide.

The electrolyte is not particularly limited as long as it is a compound that is not altered or decomposed by the operating voltage. The electrolyte includes an electrolytic solution.
Examples of the solvent for the electrolyte include dimethoxyethane, diethoxyethane, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl formate, γ-butyrolactone, 2-methyltetrahydrofuran, dimethyl sulfoxide, sulfolane, and the like. These organic solvents are mentioned. These can be used alone or in admixture of two or more.

Examples of the lithium salt of the electrolytic solution include lithium salts such as lithium perchlorate, lithium tetrafluoroborate, lithium tetrafluorophosphate, and lithium trifluoromethanoate.
The above-described solvent and lithium salt are mixed to obtain an electrolytic solution. Here, a gelling agent or the like may be added and used as a gel. Moreover, you may make it absorb and use a hygroscopic polymer.
Further, a solid electrolyte having conductivity of inorganic or organic lithium ions may be used.

  Examples of the separator include a porous film made of polyethylene or polypropylene.

  Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, polyamide acrylic resin, and the like.

Using the positive electrode active material of the present invention and the above-described negative electrode active material, electrolyte, separator, and binder, a lithium ion secondary battery can be obtained according to a conventional method.
Thereby, the outstanding battery characteristic which was not able to be achieved conventionally is realizable.

A preferred method for producing a positive electrode using the positive electrode active material of the present invention will be described below.
A positive electrode mixture is prepared by mixing the positive electrode active material powder of the present invention with a carbon-based conductive agent such as acetylene black and graphite, a binder, and a binder solvent or dispersion medium. The obtained positive electrode mixture is made into a slurry or a kneaded product, applied to or supported on a current collector such as an aluminum foil, and press-rolled to form a positive electrode active material layer on the current collector.
FIG. 3 is a schematic cross-sectional view of the positive electrode. As shown in FIG. 3, the positive electrode 13 is obtained by holding the positive electrode active material 6 on the current collector 12 with the binder 5.

It is considered that the positive electrode active material of the present invention is excellent in mixing with the conductive agent powder and has a low internal resistance of the battery. Accordingly, the charge / discharge characteristics, particularly the discharge capacity, are excellent.
In addition, the positive electrode active material of the present invention is excellent in fluidity when kneaded with a binder, and is easily entangled with a polymer of the binder and has excellent binding properties.
Furthermore, since the positive electrode active material of the present invention does not contain coarse particles and is spherical, the surface of the coating film surface of the produced positive electrode has excellent smoothness. For this reason, the coating film surface of a positive electrode plate is excellent in binding property, and becomes difficult to peel off. In addition, since the surface is smooth and lithium ions are uniformly introduced and exited on the surface of the coating film accompanying charging / discharging, the cycle characteristics are remarkably improved.

The shape of the lithium ion secondary battery is not particularly limited, and may be a cylindrical shape, a coin shape, a square shape, a laminate shape, or the like.
FIG. 4 is a schematic cross-sectional view of a cylindrical battery. As shown in FIG. 4, in the cylindrical battery 20, the positive electrode 13 in which the positive electrode active material layer is formed on the current collector 12, and the negative electrode 11 in which the negative electrode active material layer is formed on the current collector 12. Are repeatedly laminated via the separator 14.
FIG. 5 is a schematic partial cross-sectional view of a coin-type battery. As shown in FIG. 5, in the coin-type battery 30, the positive electrode 13 in which the positive electrode active material layer is formed on the current collector 12 and the negative electrode 11 are stacked via the separator 14.
FIG. 6 is a schematic perspective view of a prismatic battery. As shown in FIG. 6, in the square battery 40, the positive electrode 13 in which the positive electrode active material layer is formed on the current collector 12, and the negative electrode 11 in which the negative electrode active material layer is formed on the current collector 12. However, they are repeatedly laminated via the separator 14.

A nonaqueous electrolyte secondary battery having a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, wherein the following I is used as a positive electrode active material of the positive electrode and the following II is used as a negative electrode active material of the negative electrode Can do.
I: The positive electrode active material of the present invention described above.
II: A negative electrode active material for a non-aqueous electrolyte secondary battery comprising a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions.
This nonaqueous electrolyte secondary battery is excellent in overdischarge characteristics, cycle characteristics, and load characteristics.

The use of the nonaqueous electrolyte secondary battery using the positive electrode active material of the present invention is not particularly limited. For example, notebook computers, pen input computers, pocket computers, notebook word processors, pocket word processors, electronic book players, mobile phones, cordless phones, electronic notebooks, calculators, LCD TVs, electric shavers, electric tools, electronic translators, car phones , Portable printer, transceiver, pager, handy terminal, portable copy, voice input device, memory card, backup power supply, tape recorder, radio, headphone stereo, handy cleaner, portable compact disc (CD) player, video movie, navigation system, etc. It can be used as a power source for equipment.
Also, lighting equipment, air conditioner, TV, stereo, water heater, refrigerator, oven microwave, dishwasher, washing machine, dryer, game machine, toy, road conditioner, medical equipment, automobile, electric car, golf cart, It can be used as a power source for electric carts, power storage systems and the like.
Furthermore, the application is not limited to consumer use, and may be used for military use or space.

The positive electrode active material for nonaqueous electrolyte secondary batteries and the positive electrode active material for nonaqueous electrolyte secondary batteries of the present invention can be used in nonaqueous electrolyte secondary batteries. A nonaqueous electrolyte secondary battery can be produced by the method for producing a nonaqueous electrolyte secondary battery of the present invention.
The nonaqueous electrolyte secondary battery of the present invention can be used as a power source for mobile devices such as mobile phones, notebook computers, digital cameras, and batteries for electric vehicles.

FIG. 1 is a graph schematically showing changes in potentials of the positive electrode and the negative electrode during a charge / discharge cycle of a lithium ion secondary battery. FIG. 2 is a schematic diagram showing a crystal structure of a lithium transition metal composite oxide having a spinel structure in the positive electrode secondary active material. FIG. 3 is a schematic cross-sectional view of the positive electrode. FIG. 4 is a schematic cross-sectional view of a cylindrical battery. FIG. 5 is a schematic partial cross-sectional view of a coin-type battery. FIG. 6 is a schematic perspective view of a prismatic battery. FIG. 7 is a schematic diagram showing a crystal structure of the first lithium transition metal composite oxide having a layered structure. FIG. 8 is a schematic diagram showing the crystal structure of the first lithium transition metal composite oxide having a spinel structure.

Explanation of symbols

1 8a site 2 32e site 3 16d site 4 16c site 5 binder 6 positive electrode active material 7 3a site 8 6c site 9 3b site 11 negative electrode 12 current collector 13 positive electrode 14 separator 20 cylindrical battery 30 coin cell battery 40 square type battery

Claims (8)

A cathode secondary active material for a non-aqueous electrolyte secondary battery having at least a lithium transition metal composite oxide having a spinel structure,
The concentration of boron present on the surface of the lithium transition metal composite oxide is greater than the concentration of boron present inside the lithium transition metal composite oxide,
The concentration of fluorine present on the surface of the lithium transition metal composite oxide is greater than the concentration of fluorine present inside the lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the lithium transition metal composite oxide is greater than the concentration of magnesium present inside the lithium transition metal composite oxide,
The concentration of magnesium present in the lithium transition metal composite oxide is greater than the concentration of boron present in the lithium transition metal composite oxide,
The concentration of magnesium present in the lithium transition metal composite oxide is greater than the concentration of fluorine present in the lithium transition metal composite oxide,
A positive electrode secondary active material for a nonaqueous electrolyte secondary battery, wherein lithium is present at the 16c site of the crystal structure of the lithium transition metal composite oxide. A positive electrode active material for a nonaqueous electrolyte secondary battery, comprising: a main active material having a first lithium transition metal composite oxide; and a secondary active material having at least a second lithium transition metal composite oxide having a spinel structure. ,
The concentration of boron present on the surface of the second lithium transition metal composite oxide is greater than the concentration of boron present inside the second lithium transition metal composite oxide,
The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present inside the second lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of fluorine present in the second lithium transition metal composite oxide,
A positive electrode active material for a non-aqueous electrolyte secondary battery, wherein lithium is present at the 16c site of the crystal structure of the second lithium transition metal composite oxide. 3. The non-aqueous electrolyte secondary battery according to claim 2, wherein the first lithium transition metal composite oxide includes a 3b site where lithium is present, a 3a site where transition metal is present, and a 6c site where oxygen is present. Positive electrode active material. 3. The non-aqueous electrolyte secondary battery according to claim 2, wherein the first lithium transition metal composite oxide includes an 8a site where lithium is present, a 16d site where transition metal is present, and a 32e site where oxygen is present. Positive electrode active material. 3. The non-aqueous electrolyte 2 according to claim 2, wherein the first lithium transition metal composite oxide is at least one selected from the group consisting of a lithium cobalt composite oxide, a lithium nickel composite oxide, and a lithium manganese composite oxide. Positive electrode active material for secondary battery. A positive electrode having a positive active material for a non-aqueous electrolyte secondary battery having a main active material having a first lithium transition metal composite oxide and a secondary active material having at least a second lithium transition metal composite oxide having a spinel structure When,
A non-aqueous electrolyte secondary battery comprising a negative electrode active material comprising a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions and a negative electrode current collector, wherein: Satisfy the formula,
The concentration of boron present on the surface of the second lithium transition metal composite oxide is greater than the concentration of boron present inside the second lithium transition metal composite oxide,
The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present inside the second lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide,
The non-aqueous electrolyte secondary battery, wherein a concentration of magnesium present in the second lithium transition metal composite oxide is greater than a concentration of fluorine present in the second lithium transition metal composite oxide.
The potential before the first charge of the second lithium transition metal composite oxide (vsLi / Li ⁺ ) <the oxidation potential of the negative electrode current collector (vsLi / Li ⁺ ) <the potential before the first charge of the first lithium transition metal composite oxide ( vsLi / Li ⁺ ) A positive electrode having a positive active material for a non-aqueous electrolyte secondary battery having a main active material having a first lithium transition metal composite oxide and a secondary active material having at least a second lithium transition metal composite oxide having a spinel structure When,
A negative electrode having a negative electrode active material and a negative electrode current collector made of a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions;
A separator present between the positive electrode and the negative electrode;
An electrolyte in which the positive electrode, the negative electrode and the separator are immersed, and a non-aqueous electrolyte secondary battery comprising:
When the battery voltage of the non-aqueous electrolyte secondary battery is 0V, the concentration of the element of the negative electrode current collector present in the electrolyte is 0 to 20 ppm,
The concentration of boron present on the surface of the second lithium transition metal composite oxide is greater than the concentration of boron present inside the second lithium transition metal composite oxide,
The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present inside the second lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide,
The non-aqueous electrolyte secondary battery, wherein a concentration of magnesium present in the second lithium transition metal composite oxide is greater than a concentration of fluorine present in the second lithium transition metal composite oxide. The concentration of boron present on the surface of the main active material having the first lithium transition metal composite oxide and at least the second lithium transition metal composite oxide having the spinel structure is the same as that of the second lithium transition metal composite oxide. Greater than the concentration of boron present inside,
The concentration of fluorine present on the surface of the second lithium transition metal composite oxide is greater than the concentration of fluorine present inside the second lithium transition metal composite oxide,
The concentration of magnesium present on the surface of the second lithium transition metal composite oxide is greater than the concentration of magnesium present inside the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of boron present in the second lithium transition metal composite oxide,
The concentration of magnesium present in the second lithium transition metal composite oxide is greater than the concentration of fluorine present in the second lithium transition metal composite oxide, and the second lithium transition metal composite oxide is present. Forming a positive electrode active material having a secondary active material in which lithium is present at the 16c site of the crystalline structure of the product on at least one side of the positive electrode current collector,
A step of producing a strip-shaped negative electrode by forming a negative electrode active material comprising a carbon material capable of occluding and releasing lithium ions or a compound capable of occluding and releasing lithium ions on at least one surface of the strip-shaped negative electrode current collector;
A spiral wound body in which the belt-like positive electrode and the belt-like negative electrode are wound a plurality of times in a state of being laminated via a belt-like separator, and the belt-like separator is interposed between the belt-like positive electrode and the belt-like negative electrode A process for producing a non-aqueous electrolyte secondary battery comprising:

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