JP6654793B2 - Positive electrode for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery and system thereof - Google Patents

Description

  The present invention relates to a nonaqueous electrolyte secondary battery having excellent charge / discharge cycle characteristics, a positive electrode for constituting the nonaqueous electrolyte secondary battery, and a system including the nonaqueous electrolyte secondary battery.

  Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries have a high voltage and a high energy density. Therefore, demands for drive power sources for portable devices and the like are increasing. At present, as a positive electrode active material of the nonaqueous electrolyte secondary battery, lithium cobalt oxide having a large capacity and good reversibility is mainly used.

  At present, non-aqueous electrolyte secondary batteries are required to have higher capacities in accordance with improvements in applied equipment. However, in a battery using lithium cobalt oxide, the battery capacity has almost reached the limit.

For these reasons, in order to achieve a further high capacity of the non-aqueous electrolyte secondary battery, such as LiNiO _2, but it has also been studied the use of large electrode active material of more capacity, for example LiNiO ₂ reversible crystal structure Because of its low performance, there is also a problem that the battery using this has low charge / discharge cycle characteristics.

  On the other hand, Patent Literature 1 discloses that Ni, Mn, and Mg are essential elements, further include at least one element selected from the group consisting of Nb, Mo, Ga, W, and V, and By using a lithium-containing composite oxide with a specific average valence as a positive electrode active material, it is possible to provide electrochemical devices such as nonaqueous electrolyte secondary batteries that have high capacity and excellent charge / discharge cycle characteristics. A technique has been proposed.

JP 2011-82150 A

  By the way, in recent years, it has been studied to respond to the demand for higher capacity of the non-aqueous electrolyte secondary battery by increasing the upper limit voltage at the time of charging as compared with the related art. However, on the other hand, when the charging voltage of the non-aqueous electrolyte secondary battery is increased, there is also a problem that the positive electrode active material is deteriorated and the charge / discharge cycle characteristics of the non-aqueous electrolyte secondary battery are reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a non-aqueous electrolyte secondary battery capable of exhibiting excellent charge / discharge cycle characteristics even when the upper limit voltage during charging is increased, and the non-aqueous electrolyte. It is an object of the present invention to provide a positive electrode for constituting a secondary battery and a system having the nonaqueous electrolyte secondary battery.

  The positive electrode for a non-aqueous electrolyte secondary battery of the present invention that has achieved the object is a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte secondary battery having a non-aqueous electrolyte, and a positive electrode active material. It has a positive electrode mixture layer containing a conductive auxiliary and a binder, and the positive electrode mixture layer is represented by the following general formula (1) as the positive electrode active material, and has a primary particle diameter of 0.5 μm or more. Containing the lithium-containing metal oxide (A) containing 50% by mass or more of the particles of the lithium-containing metal oxide (A) when the total amount of the positive electrode active material contained in the positive electrode mixture layer is 100% by mass. The content of A) is 5 to 80% by mass.

_{Li a Ni 1-b-c} -d Co b Mn c M 1 d Mg e O 2 (1)

In the general formula (1), M ¹ is a metal element other than Li, Ni, Co and Mn, and is at least one selected from the group consisting of Al, Ti, Sr, Zr, Nb, Ag and Ba. 0.9 ≦ a ≦ 1.10, 0.1 ≦ b ≦ 0.2, 0 ≦ c ≦ 0.2, 0.1 ≦ b + c ≦ 0.25, 0.003 ≦ d ≦ 0 .06 and 0 ≦ e ≦ 0.003.

  The non-aqueous electrolyte secondary battery of the present invention has a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein the positive electrode is a positive electrode for a non-aqueous electrolyte secondary battery of the present invention. Is what you do.

  Furthermore, the non-aqueous electrolyte secondary battery system of the present invention includes the non-aqueous electrolyte secondary battery of the present invention and a charging device, and has a voltage of 4.3 V or more with respect to the non-aqueous electrolyte secondary battery as an upper limit. It is characterized by performing charging.

  According to the present invention, a non-aqueous electrolyte secondary battery capable of exhibiting excellent charge / discharge cycle characteristics even when the upper limit voltage during charging is increased, a positive electrode for constituting the non-aqueous electrolyte secondary battery, and the non-aqueous electrolyte A system having a water electrolyte secondary battery can be provided.

FIG. 1 is a partial longitudinal sectional view schematically illustrating an example of a nonaqueous electrolyte secondary battery of the present invention. FIG. 2 is a perspective view of FIG. 1.

  The positive electrode for a non-aqueous electrolyte secondary battery of the present invention (hereinafter, simply referred to as “positive electrode”) has a positive electrode mixture layer containing a positive electrode active material, a conductive auxiliary, and a binder. It has a structure in which a layer is formed on one side or both sides of the current collector.

  The positive electrode of the present invention uses a lithium-containing metal oxide (A) represented by the general formula (1) and having a specific particle size as a positive electrode active material. Thereby, the positive electrode of the present invention can exhibit excellent charge / discharge cycle characteristics (particularly, charge / discharge cycle characteristics at high temperatures (about 40 to 60 ° C.)) even when the upper limit voltage during charging is increased. A secondary battery can be configured.

The lithium-containing metal oxide (A) has a ratio b of Co and a ratio c of Mn of 0.1 ≦ b ≦ 0 when the total amount of Ni, Co, Mn and the element M1 is ¹ , respectively. .2, 0 ≦ c ≦ 0.2 and 0.1 ≦ b + c ≦ 0.25, Co is present in the crystal lattice, or Co and Mn are present. Thereby, when the phase transition of the lithium-containing metal oxide (A) occurs due to the elimination and insertion of Li, the irreversible reaction due to the structural change is alleviated by the action of Co and Mn. The reversibility of the layered crystal structure of the lithium-containing metal oxide (A) represented is improved.

  In addition, in the lithium-containing metal oxide (A), Co is a component that contributes to the improvement of the charge-discharge cycle characteristics at high temperatures, particularly during charging at an upper limit voltage of 4.3 V or more. In the general formula (1), the amount b of Co is 0.1 or more, preferably 0.12 or more, from the viewpoint of ensuring the above effects. However, if the amount of Co in the lithium-containing metal oxide (A) is too large, the amount of other elements becomes small, and the effect of these elements cannot be secured well. Is not more than 0.2.

  Further, Mn may not be contained in the lithium-containing metal oxide (A), but when it is contained, the amount c of Mn in the general formula (1) is preferably from the viewpoint of ensuring the above-mentioned effects. Is preferably 0.005 or more. However, if the amount of Mn in the lithium-containing metal oxide (A) is too large, the amount of other elements decreases, and the effect of these elements cannot be secured satisfactorily. Is 0.2 or less, preferably 0.15 or less.

Further, the lithium-containing metal oxide (A) as the element ^{M 1, Al, Ti, Sr} , Zr, Nb, contains at least one element selected from the group consisting of Ag and Ba, of By containing the element, the stability can be enhanced, and a positive electrode capable of forming a battery having high charge / discharge cycle characteristics and high safety can be obtained. Such effect element ^{M 1} from the viewpoint of satisfactorily ensuring the amount d of the element ^{M 1} in the general formula (1) is 0.003 or more, preferably 0.01 or more. However, lithium-containing metal oxide as the amount of the element M ¹ in (A) is too large, becomes small amounts of other elements, for these by effects not satisfactorily ensured, the general formula (1) the amount d of the element ^{M 1} in is 0.06 or less, preferably 0.04 or less.

  Further, the lithium-containing metal oxide (A) contains Ni. When Ni is present in the crystal lattice of the lithium-containing metal oxide (A), desorption and insertion of Li during charging and discharging of the battery become easy, and the capacity of the lithium-containing metal oxide (A) can be increased. it can.

The general formula representing the lithium-containing metal oxide (A) (1), the amount of Ni, the amount of Co b, using the amounts c and amount of the element ^{M 1} d of Mn "1-b-c-d The Ni amount “1-b-cd” is, specifically, preferably 0.69 or more, and more preferably 0.897 or less.

  The lithium-containing metal oxide (A) may contain Mg. However, since Mg has a stronger effect of reducing the capacity of the lithium-containing metal oxide (A) than other metal elements, the amount of Mg is reduced. It is preferable to limit. Specifically, in the general formula (1) representing the lithium-containing metal oxide (A), the amount e of Mg is 0.003 or less, and preferably 0.002 or less. In addition, since the lithium-containing metal oxide (A) does not need to contain Mg, the lower limit of the amount e of Mg in the general formula (1) is 0.

  When the composition of the lithium-containing metal oxide (A) is particularly close to the stoichiometric ratio, the true density and the reversibility are enhanced, and a material having a higher capacity can be obtained. Therefore, in the general formula (1) representing the lithium-containing metal oxide (A), the amount a of Li is 0.9 or more and 1.10 or less, whereby the true value of the lithium-containing metal oxide (A) is reduced. Density and reversibility can be increased.

  The lithium-containing metal oxide (A) contains 50% by mass or more, preferably 70% by mass or more, particularly preferably 100% by mass, of particles having a primary particle size of 0.5 μm or more, based on the total amount of 100% by mass. . By using the lithium-containing metal oxide (A) containing the particles having a relatively large primary particle size in the above-described amount, the charge / discharge cycle characteristics of the battery at a high temperature can be improved. The lithium-containing metal oxide (A) used for producing the positive electrode of the present invention may be in the form of primary particles as long as it contains particles having a primary particle diameter of 0.5 μm or more in the specific amount. The primary particles may be in a state of secondary particles in which the primary particles are aggregated, or may be in a state in which primary particles and secondary particles are mixed.

  However, if the primary particle diameter of the lithium-containing metal oxide (A) is too large, the load characteristics may deteriorate and the capacity may decrease. Of the particles, the maximum value of the particle diameter (the maximum value of the primary particle diameter) is preferably 5 μm.

  The primary particle diameter of the lithium-containing metal oxide (A) referred to in this specification is a value measured by the following method (a).

(A) Method for measuring primary particle diameter of lithium-containing metal oxide (A) present in positive electrode mixture layer Regarding the cross section of the positive electrode (positive electrode mixture layer) processed by ion milling, a scanning electron microscope equipped with an EDX device Using a microscope, mapping is performed by an EDX device under the condition of an observation magnification of 500 times, and the particles having a high Ni concentration are further identified as a lithium-containing metal oxide (A) by elemental analysis. Then, when the particles of the lithium-containing metal oxide (A) present in the visual field are enlarged under the condition of 5,000 times magnification, the minor axis of the primary particle (the part orthogonal to the part having the maximum diameter in the primary particle) The primary particle diameter is determined by measuring the length of the diameter. Here, the proportion of the particles having a primary particle diameter of 0.5 μm or more in the lithium-containing metal oxide (A) is the proportion of the particles of 0.5 μm or more of the lithium-containing metal oxide (A) measured by the method described above. The number is obtained by dividing the number by the total number of primary particles in the visual field and expressed as a percentage, and the maximum value of the primary particle diameter is the diameter of the largest primary particle. In the examples described below, an “S-3400N scanning electron microscope” manufactured by Hitachi High-Technologies Corporation was used as the scanning electron microscope, the acceleration voltage during mapping was set to 15 kV, and the lithium-containing metal oxide ( The primary particle diameter of the lithium-containing metal oxide (A) in the positive electrode mixture layer was determined by setting the accelerating voltage at the time of observation of the particles of A) at 5,000 times to 2 kV.

  In addition, a lithium-containing metal oxide (A) containing 50% by mass or more of particles having a primary particle size of 0.5 μm or more, and a lithium-containing metal oxide (A) having a maximum primary particle size satisfying the preferred value described above Of the lithium-containing metal oxide (A) containing 50% by mass or more of particles having a primary particle diameter of 0.5 μm or more measured by the method of (b) below, and the following (b) )) Can be formed by using the lithium-containing metal oxide (A) whose maximum value of the primary particle diameter measured by the method of (1) satisfies the preferred value.

(B) Primary particle size of lithium-containing metal oxide (A) used for forming positive electrode mixture layer Powder of lithium-containing metal oxide (A) is crushed into primary particles, and a laser diffraction scattering particle size is obtained. By measuring the particle size distribution using a distribution measuring device, the proportion of particles having a primary particle diameter of 0.5 μm or more in the lithium-containing metal oxide (A) used for forming the positive electrode mixture layer, The maximum value of the primary particle diameter of the metal oxide (A) is determined. In the examples described later, “Microtrack HRA” manufactured by JGC Co., Ltd. was used as a laser diffraction / scattering type particle size distribution analyzer. The number was set to 20 times to reduce the number.

The lithium-containing metal oxide (A) includes a Li-containing compound (such as lithium hydroxide), a Ni-containing compound (such as nickel sulfate), a Co-containing compound (such as cobalt sulfate), a Mn-containing compound (such as manganese sulfate), and an element M ^1. And Mg-containing compounds (oxides, hydroxides, sulfates, etc.) are mixed, and this raw material mixture is calcined.

Incidentally, the synthesized lithium-containing metal oxide (A) at a higher purity, Ni, Co, Mn, complex compound containing a plurality of elements selected from the elements M ¹ and Mg (hydroxides, such as an oxide) And another raw material compound (such as a Li-containing compound), and then firing the raw material mixture.

  The firing conditions of the raw material mixture for synthesizing the lithium-containing metal oxide (A) can be, for example, 800 to 1050 ° C. for 1 to 24 hours, but once lower than the firing temperature (for example, 250 to 250 ° C.). (850 ° C.), and preheating is performed by maintaining the temperature at that temperature, and then the temperature is preferably raised to the firing temperature to allow the reaction to proceed. The preheating time is not particularly limited, but may be generally about 0.5 to 30 hours. The atmosphere during firing may be an atmosphere containing oxygen (that is, in the air), a mixed atmosphere of an inert gas (argon, helium, nitrogen, or the like) and oxygen gas, an oxygen gas atmosphere, or the like. In this case, the oxygen concentration (by volume) is preferably 15% or more, and more preferably 18% or more.

  Since the lithium-containing metal oxide (A) has a high Ni content, the alkali component to be mixed [unreacted material or lithium-containing alkali component among the alkali components which are the raw materials for synthesizing the lithium-containing metal oxide (A)] is used. Alkali component by-produced during the synthesis of the metal oxide (A)], which decomposes at high temperatures or during charging to generate gas, swells the battery, lowers capacity and lowers charge-discharge cycle characteristics at high temperatures. May be caused. Therefore, in the positive electrode of the present invention, when the total amount of the positive electrode active material contained in the positive electrode mixture layer is 100% by mass, the content of the lithium-containing metal oxide (A) is 80% by mass or less, preferably 40% by mass or less. % By mass or less, whereby the total amount of the alkali components contained in the positive electrode is reduced, thereby making it possible to suppress a decrease in charge / discharge cycle characteristics and capacity at high temperatures.

  In the positive electrode of the present invention, when the total amount of the positive electrode active material contained in the positive electrode mixture layer is 100% by mass, the content of the lithium-containing metal oxide (A) is 5% by mass or more, preferably 10% by mass or more. % By mass or more, whereby the above-described effect due to the use of the lithium-containing metal oxide (A) is well ensured.

In the positive electrode of the present invention, the positive electrode active material used in combination with the lithium-containing metal oxide (A) includes lithium cobalt oxide such as LiCoO ₂ ; lithium manganese oxide such as LiMnO ₂ and Li ₂ MnO ₃ ; lithium nickel oxide [Excluding those represented by the general formula (1) and those represented by the general formula (1) having a Ni content equal to or more than that]; LiMn ₂ O ₄ , Li _4/3 Ti _{5 / 3} O ₄ and other lithium-containing composite oxides; olivine-structured lithium-containing metal oxides such as LiFePO ₄ ; and oxides obtained by substituting the above-described oxides with the basic composition and various elements.

  Among such positive electrode active materials, it is preferable to use the lithium-containing metal oxide (B) represented by the following general formula (2) together with the lithium-containing metal oxide (A). A non-aqueous electrolyte secondary battery using a positive electrode in which a lithium-containing metal oxide (A) and a lithium-containing metal oxide (B) represented by the following general formula (2) are used in combination as a positive electrode active material is lithium. Charge and discharge at a high temperature when the upper limit voltage is set to 4.3 V or more as compared with the case where the metal oxide containing metal (A) is used alone or the case where the metal oxide containing lithium (B) is used alone. The cycle characteristics become particularly good.

^{_{Li f Co 1-g-h}} M 2 g M 3 h O 2 (2)

In the general formula (2), M ² is at least one element selected from the group consisting of Al, Mg and Er, and M ³ is Zr, Ti, Ni, Mn, Na, Bi, Ca, F , P, Sr, W, Ba, Mo, V, Sn, Ta, Nb and Zn, at least one element selected from the group consisting of 0.9 ≦ f ≦ 1.10 and 0.010 ≦ g. ≦ 0.1, 0 ≦ h ≦ 0.05, and g + h ≦ 0.12.

In the lithium-containing metal oxide (B), an element M ² Al, Mg and Er are hot during charging to suppress the elution of Co due to the charge and discharge of the battery, especially the upper limit voltage 4.3V or more It is a component that contributes to improving the charge / discharge cycle characteristics below. Lithium-containing metal oxide (B) is, Al as the element M ^2, it is sufficient only to contain at least one of Mg and Er, may contain plural kinds.

The effect of the by elements ^{M 2} from the viewpoint of satisfactorily ensuring the amount g of elements ^{M 2} in the formula (2) is preferably 0.010 or more, and more preferably 0.014 or more . However, since the amount of the element M ² in the lithium-containing metal oxide (B) is too large, becomes small amounts of other elements, not be satisfactorily secured them due to the effect, the general formula (2) the amount g of elements ^{M 2} in is preferably 0.1 or less, and more preferably 0.05 or less.

Further, the lithium-containing metal oxide (B), as the element ^{M 3, Zr, Ti, Ni} , Mn, Na, Bi, Ca, F, P, Sr, W, Ba, Mo, V, Sn, Ta, At least one element selected from the group consisting of Nb and Zn may be contained. These elements M ³ also contributes to the charge-discharge cycle characteristics improve at a high temperature, particularly in the time of charging to the upper limit voltage or 4.3 V.

However, since the amount of the element M ³ in the lithium-containing metal oxide (B) is too large, becomes small amounts of other elements, not be satisfactorily secured them due to the effect, the general formula (2) the amount h of the element ^{M 3} in is preferably 0.05 or less, more preferably 0.01 or less. Incidentally, the lithium-containing metal oxide (B) may not contain an element M ^3, but in case of containing these, from the viewpoint of better ensuring the effect of the by elemental M ^3, wherein the amount h of the element ^{M 3} in the general formula (2) is preferably 0.0005 or more.

In addition, in the lithium-containing metal oxide (B), Co is a component that contributes to capacity improvement. Therefore, the amount of the element M ² or the element M ³ is limited so that a sufficient amount of Co can be contained so that the lithium-containing metal oxide (B) can be contained. from the viewpoint of maintaining a large volume of metal oxide (B), the sum g + h and the amount h of the amount g and the element M ³ element M ² in the formula (2) is preferably 0.12 or less.

  Similarly to the lithium-containing metal oxide (A), the lithium-containing metal oxide (B) increases the true density and the reversibility, particularly when the composition is close to the stoichiometric ratio, to provide a higher capacity material. It becomes possible. Therefore, in the general formula (2) representing the lithium-containing metal oxide (B), the amount f of Li is preferably 0.9 or more and 1.10 or less, whereby the lithium-containing metal oxide (B) ) Can be improved.

Lithium-containing metal oxide (B) is, Li-containing compound (lithium hydroxide, etc.), Co-containing compound (such as cobalt sulfate), and the element M ² and the element M ³ compounds containing (oxides, hydroxides, sulfate Salt, etc.) and baking the raw material mixture.

Note that in order to synthesize a lithium-containing metal oxide (B) at a higher purity, Co, composite compound containing a plurality of elements selected from the elements M ² and the element M ³ (the hydroxides, oxides, etc.), It is preferable to mix the mixture with another raw material compound (such as a Li-containing compound) and calcine the raw material mixture.

  The firing conditions of the raw material mixture for synthesizing the lithium-containing metal oxide (B) can be, for example, 800 to 1,050 ° C. for 1 to 24 hours, but once lower than the firing temperature (for example, 250 to 250 ° C.). (850 ° C.), and preheating is performed by maintaining the temperature at that temperature, and then the temperature is preferably raised to the firing temperature to allow the reaction to proceed. The preheating time is not particularly limited, but may be generally about 0.5 to 30 hours. The atmosphere during firing may be an atmosphere containing oxygen (that is, in the air), a mixed atmosphere of an inert gas (argon, helium, nitrogen, or the like) and oxygen gas, an oxygen gas atmosphere, or the like. In this case, the oxygen concentration (by volume) is preferably 15% or more, and more preferably 18% or more.

  The content of the positive electrode active material in the positive electrode mixture layer is preferably from 94 to 98% by mass.

  Examples of the conductive assistant for the positive electrode include graphites such as natural graphite (such as flake graphite) and artificial graphite; and carbon blacks such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black. It is preferable to use carbon materials such as carbon fibers; conductive fibers such as metal fibers; carbon fluoride; metal powders such as aluminum; zinc oxide; conductive whiskers such as potassium titanate; A conductive metal oxide such as titanium oxide; an organic conductive material such as a polyphenylene derivative; and the like can also be used.

  The content of the conductive auxiliary agent in the positive electrode mixture layer suppresses the speed of lithium ion desorption at the positive electrode during charging, improves the balance with the speed of lithium ion reception at the negative electrode, and improves the charge and discharge of the battery. It is preferably 2.0% by mass or less, and more preferably 1.5% by mass or less from the viewpoint of highly suppressing the generation of lithium dendrite on the negative electrode surface due to the above, and further enhancing the charge / discharge cycle characteristics of the battery. Is more preferred. However, if the amount of the conductive auxiliary agent in the positive electrode mixture layer is too small, the conductivity in the positive electrode mixture layer may be reduced, and the capacity of the battery may be reduced. The content of the assistant is preferably more than 0.5% by mass, more preferably 1.0% by mass or more.

  Examples of the binder for the positive electrode include acrylonitrile, acrylates (eg, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate) and methacrylates (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate). A copolymer formed by two or more monomers including at least one monomer selected from the group consisting of: hydrogenated nitrile rubber; PVDF; vinylidene fluoride-tetrafluoroethylene copolymer (VDF-TFE); Hexafluoropropylene-tetrafluoroethylene copolymer (VDF-HFP-TFE); vinylidene fluoride-chlorotrifluoroethylene copolymer (VDF-CTFE); and only one of these. May be used, it may be used in combination of two or more thereof.

  The content of the binder in the positive electrode mixture layer is such that the positive electrode active material and the conductive auxiliary agent in the positive electrode mixture layer can be satisfactorily bound to prevent desorption from these positive electrode mixture layers. From the viewpoint of better enhancing the reliability of the battery used, the content is preferably 1% by mass or more. However, when the amount of the binder in the positive electrode mixture layer is too large, the amount of the positive electrode active material and the amount of the conductive auxiliary agent are reduced, and the effect of increasing the capacity may be reduced. Therefore, the content of the binder in the positive electrode mixture layer is preferably 1.6% by mass or less.

  In preparing the positive electrode, a paste mixture in which the positive electrode mixture containing the positive electrode active material, the conductive auxiliary agent, the binder, and the like is uniformly dispersed using a solvent such as N-methyl-2-pyrrolidone (NMP) is used. A slurry-like composition is prepared (the binder may be dissolved in a solvent), this composition is applied to the surface of the positive electrode current collector and dried, and if necessary, the thickness of the positive electrode mixture layer is reduced by pressing. And a method of adjusting the density. However, the method for producing the positive electrode of the present invention is not limited to the above method, and another method may be adopted.

  The material of the positive electrode current collector is not particularly limited as long as it is an electronic conductor that is chemically stable in the battery. For example, in addition to aluminum or an aluminum alloy, stainless steel, nickel, titanium, carbon, a conductive resin, and the like, a composite material or the like in which a carbon layer or a titanium layer is formed on the surface of aluminum, an aluminum alloy, or stainless steel can be used. . Among the positive electrode current collectors made of such materials, foils and films made of aluminum or an aluminum alloy are preferable.

  The thickness of the positive electrode current collector is 11 μm or less, preferably 10 μm or less. By reducing the thickness of the positive electrode current collector, the proportion of the internal volume of the nonaqueous electrolyte secondary battery occupied by the positive electrode current collector can be made as small as possible. In the formed non-aqueous electrolyte secondary battery, the amount of the non-aqueous electrolyte introduced into the inside can be increased.

  When the capacity is increased by setting the upper limit voltage of charging to 4.3 V or higher, the potential of the positive electrode in the charged state of the non-aqueous electrolyte secondary battery becomes extremely high. Oxidation decomposition of the non-aqueous electrolyte in the positive electrode occurs, and decomposition products are deposited on the surface layer of the positive electrode active material contained in the positive electrode, and ion conduction paths between particles are reduced. May cause the deterioration of the charge / discharge cycle characteristics of the battery. However, when the thin positive electrode current collector as described above is used and the amount of the nonaqueous electrolyte introduced into the nonaqueous electrolyte secondary battery is increased, the occurrence of the above problem is suppressed, and this problem is solved. It is possible to suppress a decrease in charge / discharge cycle characteristics due to the occurrence.

  However, if the positive electrode current collector is too thin, the strength is insufficient and productivity of the positive electrode and the battery may be impaired. Therefore, the thickness of the positive electrode current collector is preferably 6 μm or more.

  The thickness of the positive electrode mixture layer is preferably 30 to 80 μm per one surface of the current collector. In the positive electrode mixture layer, the filling rate is preferably 75% or more from the viewpoint of higher capacity. However, if the filling rate of the positive electrode mixture layer is too high, the porosity in the positive electrode mixture layer becomes too small, and the permeability of the nonaqueous electrolyte (nonaqueous electrolyte) into the positive electrode mixture layer decreases. Since there is a possibility that the filling rate is 83% or less. The filling rate of the positive electrode mixture layer is determined by the following equation.

    Filling rate (%) = 100 × (actual density of positive electrode mixture layer / theoretical density of positive electrode mixture layer)

The “theoretical density of the positive electrode mixture layer” in the above formula for calculating the filling rate of the positive electrode mixture layer is the density (positive electrode mixture) calculated from the density and content of each component of the positive electrode mixture layer. (The density obtained assuming that there are no pores in the layer), and the "actual density of the positive electrode mixture layer" is measured by the following method. First, cut a positive electrode to a size of 1 cm × 1 cm, a thickness micrometer _{(l 1),} measuring the mass _{(m 1)} a precision balance. Next, scraped off the positive electrode mixture layer, and extract only the collector, measuring the thickness of the current collector (l _c) mass (m _c) in the same manner as the positive electrode. From the obtained thickness and mass, the actual density (d _ca ) of the positive electrode mixture layer is determined by the following formula (the unit of the thickness is cm and the unit of mass is g).
_{d ca = (m 1 -m c} ) / (l 1 -l c)

  Further, a lead body for electrically connecting to other members in the non-aqueous electrolyte secondary battery may be formed on the positive electrode according to a conventional method, if necessary.

  The non-aqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, and may have the positive electrode of the present invention as a positive electrode, and other configurations and structures are not particularly limited. Each configuration and structure employed in a conventionally known nonaqueous electrolyte secondary battery can be applied.

  In the negative electrode according to the nonaqueous electrolyte secondary battery of the present invention, for example, a negative electrode mixture layer containing a negative electrode active material and a binder, and further, if necessary, a conductive auxiliary, on one or both surfaces of the current collector It is possible to use one having a structure having.

  Examples of the negative electrode active material include graphite [natural graphite such as flaky graphite; artificial graphite obtained by graphitizing easily graphitizable carbon such as pyrolytic carbons, mesophase carbon microbeads (MCMB), and carbon fibers at 2800 ° C. or more. ; Pyrolyzed carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesocarbon microbeads, carbon fiber, activated carbon, metals (Si, Sn, etc.) that can be alloyed with lithium or the like. Alloys, oxides, and the like can be given, and one or more of these can be used.

Among the above-mentioned negative electrode active materials, in order to increase the capacity of the non-aqueous electrolyte secondary battery in particular, a material containing Si and O as constituent elements (however, the atomic ratio x of O to Si is 0.5 ≦ x ≦ 1.5. Hereinafter, the material is preferably referred to as “SiO _x ”. In addition, by using such a high-capacity negative electrode active material, the capacity of the battery can be increased while the thickness of the negative electrode mixture layer is reduced.

SiO _x may include a microcrystalline or amorphous phase of Si, and in this case, the atomic ratio of Si to O is a ratio including the microcrystalline or amorphous phase of Si. That is, the SiO _x to SiO ₂ matrix of amorphous Si (e.g., microcrystalline Si) is include the dispersed structure, the SiO ₂ of the amorphous, dispersed therein It is sufficient that the above atomic ratio x satisfies 0.5 ≦ x ≦ 1.5, including the total of Si. For example, in the case of a structure in which Si is dispersed in an amorphous SiO ₂ matrix and the molar ratio of SiO ₂ to Si is 1: 1, x = 1, so the structural formula is represented by SiO. You. In the case of a material having such a structure, for example, in X-ray diffraction analysis, a peak due to the presence of Si (microcrystalline Si) may not be observed, but when observed with a transmission electron microscope, the presence of fine Si Can be confirmed.

The SiO _x is preferably a composite compounded with a carbon material. For example, the surface of the SiO _x is desirably coated with a carbon material. Since SiO _x has poor conductivity, when it is used as a negative electrode active material, from the viewpoint of securing good battery characteristics, a conductive material (conductive auxiliary agent) is used, and the SiO _x and the conductive material in the negative electrode are used. It is necessary to form a good conductive network by improving the mixing / dispersion with the compound. In the case of a composite in which SiO _x is combined with a carbon material, for example, the conductive network at the negative electrode is better than when a material obtained by simply mixing SiO _x and a conductive material such as a carbon material is used. Formed.

Examples of the composite of SiO _x and the carbon material include, as described above, a material in which the surface of SiO _x is coated with a carbon material, and a granulated body of SiO _x and a carbon material.

Further, by using the composite in which the surface of SiO _x is coated with a carbon material in combination with a conductive material (such as a carbon material), a more favorable conductive network can be formed in the negative electrode. Thus, a lithium secondary battery having higher capacity and more excellent battery characteristics (for example, charge / discharge cycle characteristics) can be realized. The complex of the SiO _x and the carbon material coated with a carbon material, for example, like granules the mixture was further granulated with SiO _x and the carbon material coated with a carbon material.

Further, as the SiO _x whose surface is coated with a carbon material, the surface of a composite (for example, a granulated body) of SiO _x and a carbon material having a lower specific resistance value than that is further coated with a carbon material. Those can also be preferably used. In the state where SiO _x and the carbon material are dispersed in the inside of the granule, a better conductive network can be formed.Therefore, in a non-aqueous electrolyte secondary battery having a negative electrode containing SiO _x as a negative electrode active material, Battery characteristics such as heavy load discharge characteristics can be further improved.

Examples of the carbon material may be used to form the complex with SiO _x, for example, as low-crystalline carbon, carbon nanotube, a carbon material such as vapor-grown carbon fibers are preferred.

As the details of the carbon material, at least one selected from the group consisting of a fibrous or coiled carbon material, carbon black (including acetylene black and Ketjen black), artificial graphite, easily graphitizable carbon, and non-graphitizable carbon Certain materials are preferred. A fibrous or coiled carbon material is preferred because it easily forms a conductive network and has a large surface area. Carbon black (including acetylene black and Ketjen black), graphitizable carbon, and non-graphitizable carbon have high electrical conductivity and high liquid retention, and even when the SiO _x particles expand and contract. It is preferable in that it has a property of easily maintaining contact with the particles.

When using SiO _x as the negative electrode active material, it is preferable that graphite is also used as the negative electrode active material as described later, but this graphite may also be used as a carbon material related to the composite of SiO _x and the carbon material. it can. Graphite, like carbon black, also has high electrical conductivity and high liquid retention, and also has the property of easily maintaining contact with SiO _x particles even if the particles expand and contract. and for that, it can be preferably used in the complex formation with SiO _x.

Among the carbon materials exemplified above, a fibrous carbon material is particularly preferable as the material used when the composite with SiO _x is a granulated material. Fibrous carbon material can follow the expansion and contraction of SiO _x with the charging and discharging of the battery due to the high shape is thin threadlike flexibility, also because bulk density is large, many and SiO _x particles This is because it can have a junction. Examples of the fibrous carbon include polyacrylonitrile (PAN) -based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, and carbon nanotube, and any of these may be used.

The fibrous carbon material can be formed on the surface of the SiO _x particles by, for example, a gas phase method.

Specific resistance of the SiO _x is ^normally whereas a ¹⁰ 3 ~10 7 kΩcm, the specific resistance value of the exemplary carbon material is ^usually 10 -5 ~10kΩcm. Further, the composite of SiO _x and the carbon material may further have a material layer (a material layer containing non-graphitizable carbon) covering the carbon material coating layer on the particle surface.

When a composite of SiO _x and a carbon material is used for the negative electrode, the ratio of the SiO _x to the carbon material is preferably in the range of 100 parts by mass of SiO _x from the viewpoint of favorably exhibiting the effect of the composite with the carbon material. The carbon material is preferably at least 5 parts by mass, more preferably at least 10 parts by mass. Further, in the composite, if the ratio of the carbon material to be composited with SiO _x is too large, it leads to a decrease in the amount of SiO _x in the negative electrode mixture layer, and the effect of increasing the capacity may be reduced. The carbon material is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, based on 100 parts by mass of SiO _x .

The composite of SiO _x and a carbon material can be obtained, for example, by the following method.

First, a manufacturing method in the case of compounding SiO _x will be described. A dispersion in which SiO _x is dispersed in a dispersion medium is prepared, sprayed and dried to produce composite particles including a plurality of particles. As the dispersion medium, for example, ethanol or the like can be used. It is usually appropriate to spray the dispersion in an atmosphere at 50 to 300 ° C. In addition to the above method, the same composite particles can be produced by a granulation method by a mechanical method using a vibration type or planetary type ball mill or rod mill.

Incidentally, the SiO _x, in the case of manufacturing a granulated body with small carbon material resistivity value than SiO _x is adding the carbon material in the dispersion liquid of SiO _x are dispersed in a dispersion medium, the dispersion The composite particles (granulated material) may be formed by the same method as in the case where SiO _x is composited using the liquid. Also, a granulated body of SiO _x and a carbon material can be produced by a granulation method using the same mechanical method as described above.

Next, when the surface of SiO _x particles (SiO _x composite particles or granules of SiO _x and a carbon material) is coated with a carbon material to form a composite, for example, the SiO _x particles and a hydrocarbon-based material may be used. The gas and the gas are heated in the gas phase, and carbon generated by thermal decomposition of the hydrocarbon-based gas is deposited on the surface of the particles. As described above, according to the vapor phase growth (CVD) method, the hydrocarbon-based gas spreads to every corner of the composite particles, and the surface of the particles and the pores on the surface contain a thin carbon material containing a conductive carbon material. Since a uniform film (carbon material coating layer) can be formed, a small amount of carbon material can impart conductivity to the SiO _x particles with good uniformity.

In the production of SiO _x coated with carbon material for vapor deposition (CVD) process temperature (ambient temperature), varies depending on the kind of hydrocarbon gas, usually, is suitably 600 to 1200 ° C. Especially, it is preferable that it is 700 degreeC or more, and it is more preferable that it is 800 degreeC or more. This is because the higher the treatment temperature, the smaller the amount of remaining impurities and the more the coating layer containing highly conductive carbon can be formed.

  As a liquid source of the hydrocarbon-based gas, toluene, benzene, xylene, mesitylene and the like can be used, but toluene which is easy to handle is particularly preferable. By evaporating these (for example, bubbling with nitrogen gas), a hydrocarbon-based gas can be obtained. Further, methane gas, acetylene gas, or the like can be used.

After the surface of SiO _x particles (SiO _x composite particles or granules of SiO _x and a carbon material) is covered with a carbon material by a vapor phase growth (CVD) method, a petroleum pitch or a coal pitch is coated. After attaching at least one organic compound selected from the group consisting of a thermosetting resin, and a condensate of a naphthalene sulfonate and an aldehyde to a coating layer containing a carbon material, the organic compound is attached. The particles obtained may be fired.

Specifically, a dispersion in which SiO _x particles (SiO _x composite particles or granules of SiO _x and a carbon material) coated with a carbon material and the organic compound are dispersed in a dispersion medium is prepared. The dispersion is sprayed and dried to form particles coated with the organic compound, and the particles coated with the organic compound are fired.

  As the pitch, an isotropic pitch can be used, and as the thermosetting resin, a phenol resin, a furan resin, a furfural resin, or the like can be used. As a condensate of a naphthalene sulfonic acid salt and an aldehyde, a naphthalene sulfonic acid formaldehyde condensate can be used.

As a dispersion medium for dispersing the SiO _x particles coated with the carbon material and the organic compound, for example, water and alcohols (such as ethanol) can be used. It is usually appropriate to spray the dispersion in an atmosphere at 50 to 300 ° C. Usually, the firing temperature is suitably from 600 to 1200 ° C., but preferably 700 ° C. or higher, more preferably 800 ° C. or higher. This is because the higher the treatment temperature, the smaller the amount of residual impurities and the higher the conductivity of the coating layer containing a high-quality carbon material. However, the treatment temperature is required to be less than the melting point of SiO _x.

When SiO _x (preferably, a composite of SiO _x and a carbon material) is used as the negative electrode active material, it is preferable to use graphite in combination. SiO _x, while a high capacity as compared with carbon materials are widely used as the negative electrode active material for a nonaqueous electrolyte secondary battery, because of the large volume change accompanying the charge and discharge of the battery, the content of SiO _x In a nonaqueous electrolyte secondary battery using a negative electrode having a high negative electrode mixture layer, the negative electrode (negative electrode mixture layer) undergoes a large volume change and deterioration due to repetition of charge and discharge, resulting in a decrease in capacity (ie, charge-discharge cycle characteristics Is reduced). Graphite, a non-aqueous are generally used as the negative electrode active material of electrolyte secondary battery, while a relatively large capacity, the volume change due to charging and discharging of the battery is small compared to the SiO _x. Therefore, by using SiO _x and graphite together as the negative electrode active material, it is possible to minimize the effect of improving the capacity of the battery as the amount of SiO _x used is reduced, and to reduce the charge / discharge cycle of the battery. Since deterioration in characteristics can be suppressed well, a nonaqueous electrolyte secondary battery having higher capacity and excellent charge / discharge cycle characteristics can be obtained.

The graphite used as a negative electrode active material with said SiO _x, for example, natural graphite such as flake graphite; pyrolytic carbon, mesophase carbon microbeads (MCMB), the 2800 ° C. or higher graphitizable carbon such as carbon fiber And artificial graphite which has been graphitized with the above.

When used in combination with complexes of SiO _x and the carbon material in the negative electrode active material, and graphite, from the viewpoint of satisfactorily ensuring the effect of the high capacity by using a SiO _x, SiO _x in total negative electrode active material in The content of the composite of carbon and the carbon material is preferably 0.01% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more. Further, from the viewpoint of better avoiding the problem due to the volume change of SiO _x due to charge and discharge, the content of the composite of SiO _x and the carbon material in all the negative electrode active materials may be 20% by mass or less. It is more preferably at most 15% by mass.

Examples of the binder for the negative electrode include the same binders as those exemplified above as those usable for the positive electrode, styrene-butadiene rubber (SBR), ethylene-acrylic acid copolymer or a Na ⁺ ion crosslinked product of the copolymer, ethylene A methacrylic acid copolymer or a Na ⁺ ion crosslinked product of the copolymer, an ethylene-methyl acrylate copolymer or a Na ⁺ ion crosslinked product of the copolymer, an ethylene-methyl methacrylate copolymer or the copolymer A combined Na ⁺ ion crosslinked product can be used. Further, as the conductive auxiliary agent for the negative electrode, the same ones as exemplified above as usable for the positive electrode can be used.

  For the negative electrode, for example, a negative electrode mixture-containing composition in the form of a paste or slurry in which a negative electrode active material and a binder, and furthermore, a conductive auxiliary used as necessary, is dispersed in a solvent such as NMP or water is prepared. (However, the binder may be dissolved in a solvent.) It is manufactured through a step of applying this on one or both sides of the current collector, drying, and, if necessary, performing a pressing treatment such as a calendering treatment. . However, the negative electrode is not limited to one manufactured by the above-described manufacturing method, and may be manufactured by another method.

  Further, a lead body for electrically connecting to other members in the non-aqueous electrolyte secondary battery may be formed on the negative electrode according to a conventional method, if necessary.

  The thickness of the negative electrode mixture layer is preferably, for example, 10 to 100 μm per one surface of the current collector. Further, as the composition of the negative electrode mixture layer, for example, it is preferable that the negative electrode active material be 80.0 to 99.8% by mass and the binder be 0.1 to 10% by mass. Further, when the negative electrode mixture layer contains a conductive auxiliary, the amount of the conductive auxiliary in the negative electrode mixture layer is preferably 0.1 to 10% by mass.

  As the current collector of the negative electrode, a copper or nickel foil, a punched metal, a net, an expanded metal, or the like can be used, and usually, a copper foil is used. When the thickness of the entire negative electrode is reduced in order to obtain a battery having a high energy density, the negative electrode current collector preferably has an upper limit of 30 μm and a lower limit of 5 μm to ensure mechanical strength. Is desirable.

  As the non-aqueous electrolyte, for example, a solution (non-aqueous electrolyte) prepared by dissolving a lithium salt in the following solvent can be used.

Examples of the solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), and γ-butyrolactone (γ-
BL), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, dimethylsulfoxide (DMSO), 1,3-dioxolan, formamide, dimethylformamide (DMF), dioxolan, acetonitrile, nitromethane Aprotic compounds such as methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether and 1,3-propanesultone The organic solvent can be used alone or as a mixed solvent obtained by mixing two or more kinds.

The lithium salt according to the non-aqueous electrolyte solution, for _{example, LiClO 4, LiPF 6, LiBF} 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 (SO 3) 2, Selected from lithium salts such as LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC _n F _{2n + 1} SO 3 (n ≧ 2), LiN (RfOSO ₂ ) ₂ [where Rf is a fluoroalkyl group] At least one of them. The concentration of these lithium salts in the non-aqueous electrolyte is preferably 0.6 to 1.8 mol / l, and more preferably 0.9 to 1.6 mol / l.

  Non-aqueous electrolytes used in non-aqueous electrolyte secondary batteries include vinylene carbonate, vinyl ethylene carbonate, and anhydrous ethylene for the purpose of further improving charge / discharge cycle characteristics and improving safety such as high-temperature storability and overcharge prevention. Additives such as acids, sulfonic esters, dinitrile, 1,3-propanesultone, diphenyl disulfide, cyclohexylbenzene, biphenyl, fluorobenzene and t-butylbenzene (including their derivatives) can also be added as appropriate.

  Further, as the non-aqueous electrolyte of the non-aqueous electrolyte secondary battery, a non-aqueous electrolyte prepared by adding a known gelling agent such as a polymer to the above-described non-aqueous electrolyte and gelling (a gel electrolyte) can also be used.

  In the nonaqueous electrolyte secondary battery of the present invention, a separator containing the nonaqueous electrolyte is disposed between the positive electrode and the negative electrode. As the separator, an insulating microporous thin film having high ion permeability and predetermined mechanical strength is used. Further, a material having a function of increasing the resistance by closing the pores by melting the constituent material at a certain temperature or higher (for example, 100 to 140 ° C.) (that is, a material having a shutdown function) is preferable.

  Specific examples of such a separator include a sheet (porous sheet), a nonwoven fabric, or a woven fabric made of a material such as polyethylene or polypropylene having organic solvent resistance and hydrophobicity, or a material such as glass fiber; And a porous body in which fine particles of a polyolefin-based polymer are fixed with an adhesive.

  The pore size of the separator is preferably such that the active material of the positive and negative electrodes detached from the positive and negative electrodes, the conductive auxiliary agent, the binder, and the like do not pass, and for example, desirably 0.01 to 1 μm. The thickness of the separator is generally 8 to 30 μm, but is preferably 10 to 20 μm in the present invention. The porosity of the separator is determined according to the constituent material and thickness, but is generally 30 to 80%.

  In the non-aqueous electrolyte secondary battery of the present invention, the positive electrode of the present invention and the negative electrode are laminated electrode bodies laminated via the separator, or laminated via the separator, and then wound in a spiral. It is used as a wound electrode body.

  The non-aqueous electrolyte secondary battery of the present invention is, for example, a stacked electrode body or a wound electrode body is loaded in an exterior body, and the non-aqueous electrolyte is further injected into the exterior body to immerse the electrode body in the non-aqueous electrolyte. Thereafter, it is manufactured by sealing the opening of the exterior body. As the outer package, a steel (aluminum, aluminum, or aluminum alloy) tubular can (such as a rectangular tube or a cylindrical tube) can be used, or a package formed of a laminated film on which metal is deposited can be used.

  The nonaqueous electrolyte secondary battery of the present invention can be used with the upper limit voltage during charging set to about 4.2 V, similarly to the conventional nonaqueous electrolyte secondary battery. It may be used in a method of performing charging with an upper limit voltage of 0.3 V or more, and even when used in such a method, good charge / discharge cycle characteristics (particularly, charge / discharge cycle characteristics at high temperatures) can be exhibited. Therefore, the non-aqueous electrolyte secondary battery of the present invention has a large capacity for a long time even if charging and discharging are repeatedly performed under such conditions while increasing the upper limit voltage during charging to achieve high capacity. It is possible to maintain. The upper limit voltage for charging the nonaqueous electrolyte secondary battery of the present invention is preferably 4.7 V or less.

  The non-aqueous electrolyte secondary battery system of the present invention includes the non-aqueous electrolyte secondary battery of the present invention and a charging device, and the upper limit of the voltage applied by the charging device to the non-aqueous electrolyte secondary battery. The battery is charged under the condition that the value is 4.3 V or more (preferably 4.7 V or less). Such a system allows the non-aqueous electrolyte secondary battery of the present invention to be used at a higher capacity. Regarding the charging device according to the non-aqueous electrolyte secondary battery system of the present invention, the charging of the non-aqueous electrolyte secondary battery of the present invention is performed under the condition that the upper limit voltage is 4.3 V or more (preferably 4.7 V or less). As long as it is possible, a conventionally known charging device for a non-aqueous electrolyte secondary battery, for example, a charging device capable of performing constant voltage charging after constant current charging or a pulse charging can be performed. A charging device or the like can be used.

  The non-aqueous electrolyte secondary battery of the present invention has a high capacity and excellent charge / discharge cycle characteristics (particularly, charge / discharge cycle characteristics at high temperatures). The present invention can be preferably applied to various uses in which a conventionally known nonaqueous electrolyte secondary battery is employed.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

Example 1
<Preparation of positive electrode>
LiNi _0.78 Co _0.20 Al _0.02 O _{2 as the} positive electrode active material [Lithium-containing metal oxide (A), particles having a primary particle diameter of 0.5 μm or more determined by the measurement method of (b) above] 50 mass%, the largest primary particle diameter is 2 μm] and LiCo _0.984 Al _0.008 Mg _0.006 Ti _0.001 Zr _0.001 O ₂ [lithium-containing metal oxide (B)] (Mass ratio 20:80): 97.3 parts by mass, a conductive additive (carbon black and graphite, the use ratio is 80:20 by mass ratio): 1.5 parts by mass, and PVDF as a binder: 1 .2 parts by mass to form a positive electrode mixture, NMP as a solvent was added to this positive electrode mixture, and the number of revolutions was determined using "Meartech CLM 0.8 (trade name)" manufactured by M Technique. 10000min ¹ performs 30-minute treatment, to obtain a paste mixture. NMP as a solvent was further added to this mixture, and the mixture was treated at a rotation speed of 10,000 min ^-1 for 15 minutes to prepare a positive electrode mixture-containing composition.

The above-mentioned positive electrode mixture-containing composition is applied to both surfaces of an aluminum alloy foil (thickness: 10.0 μm) as a current collector, vacuum-dried at 80 ° C. for 12 hours, and further subjected to a press treatment to collect the current. A positive electrode having a positive electrode mixture layer having a thickness of 56 μm on both surfaces of the body was produced. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.85 g / cm ³ , and the filling factor was 77.7%.

  A sample for measuring the primary particle diameter of the lithium-containing metal oxide (A) was taken from a part of the obtained positive electrode, and the primary particle diameter in the lithium-containing metal oxide (A) was measured by the method (a). Was determined, and the particle diameter of the largest primary particle (the maximum value of the primary particle diameter) was determined.

<Preparation of negative electrode>
A mixture of natural graphite: 97.5% by mass, SBR: 1.5% by mass, and carboxymethylcellulose (CMC, thickener): 1% by mass was mixed with water to obtain a slurry-like negative electrode mixture-containing composition. Prepared. This negative electrode mixture-containing composition is applied to both surfaces of a copper foil (thickness: 8 μm) as a current collector, vacuum-dried at 120 ° C. for 12 hours, and further subjected to a press treatment, so that both surfaces of the current collector are coated. A negative electrode having a negative electrode mixture layer having a thickness of 63 μm was prepared.

<Preparation of electrode body>
The positive electrode and the negative electrode are overlapped with each other via a separator (a polyethylene porous film having a thickness of 17 μm and an air permeability of 300 seconds / 100 cm ³ ), and after being spirally wound, the cross section becomes flat. To produce a flat wound electrode body.

<Preparation of non-aqueous electrolyte>
LiPF ₆ was dissolved at a concentration of 1.2 mol / l in a mixed solvent of methyl ethyl carbonate, diethyl carbonate and ethylene carbonate (volume ratio 0.5: 2: 1), and LiBF ₄ : 0.05% by mass. , Vinylene carbonate: 2% by mass and propane sultone: 0.2% by mass to prepare a non-aqueous electrolyte (non-aqueous electrolyte).

<Assembly of battery>
The above-mentioned electrode body is inserted into a rectangular battery case made of an aluminum alloy having an outer dimension of a thickness of 3.75 mm, a width of 52.8 mm, and a height of 61.3 mm, and the lead body is welded. The plate was welded to the open end of the battery case. Thereafter, the nonaqueous electrolytic solution is injected from an injection port provided in the cover plate, and left standing for 1 hour. Then, the injection port is sealed, and the rectangular nonaqueous liquid having the structure shown in FIG. An electrolyte secondary battery was manufactured.

  FIG. 1 is a partial cross-sectional view, in which a positive electrode 1 and a negative electrode 2 are spirally wound via a separator 3 and then pressed so as to be flat to form a flat wound electrode body 6 having a square shape ( The non-aqueous electrolytic solution is accommodated in an outer can 4 having a rectangular tube shape. However, FIG. 1 does not show a metal foil or a non-aqueous electrolyte as a current collector used in manufacturing the positive electrode 1 or the negative electrode 2 in order to avoid complication.

  The battery case 4 is made of an aluminum alloy and constitutes a battery exterior. The exterior can 4 also functions as a positive electrode terminal. An insulator 5 made of a polyethylene sheet is disposed at the bottom of the battery case 4, and connected to one end of each of the positive electrode 1 and the negative electrode 2 from a flat wound electrode body 6 composed of the positive electrode 1, the negative electrode 2 and the separator 3. The drawn positive electrode lead 7 and negative electrode lead 8 are drawn out. Further, a stainless steel terminal 11 is attached to an aluminum alloy sealing cover plate 9 for sealing the opening of the battery case 4 via a polypropylene insulating packing 10, and an insulator 12 is attached to the terminal 11. A lead plate 13 made of stainless steel is attached via the intermediary.

  Then, the lid plate 9 is inserted into the opening of the battery case 4, and the joint of the two is welded, whereby the opening of the battery case 4 is sealed and the inside of the battery is sealed. In addition, in the battery of FIG. 1, a non-aqueous electrolyte injection port 14 is provided in the cover plate 9, and the sealing member is inserted into the non-aqueous electrolyte injection port 14, for example, by laser welding or the like. To seal the battery, thereby ensuring the tightness of the battery. Further, the lid plate 9 is provided with a cleavage vent 15 as a mechanism for discharging the gas inside to the outside when the temperature of the battery rises.

  In the battery of Example 1, the battery case 4 and the cover plate 9 function as positive terminals by directly welding the positive lead 7 to the cover plate 9, and the negative lead 8 is welded to the lead plate 13. The terminal 11 functions as a negative electrode terminal by conducting the negative electrode lead body 8 and the terminal 11 via the lead plate 13. However, depending on the material of the battery case 4, the polarity is reversed. There is also.

  FIG. 2 is a perspective view schematically showing the appearance of the battery shown in FIG. 1. FIG. 2 is intended to show that the battery is a prismatic battery. 1 schematically shows a battery, and only specific components of the battery are shown. Also, in FIG. 1, the section on the inner peripheral side of the electrode body is not shown in cross section.

Example 2
Lithium-containing metal oxide (A) was converted to LiNi _0.82 Co _0.15 Al _0.03 O ₂ [50% by mass of particles having a primary particle size of 0.5 μm or more was the largest primary particle size. Was changed to 2 μm], and a positive electrode was produced in the same manner as in Example 1. A prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Example 3
LiNi _0.75 Co _0.10 Mn _0.14 Al _0.01 O ₂ [The ratio of particles having a primary particle diameter of 0.5 μm or more is 50% by mass and the maximum primary A positive electrode was produced in the same manner as in Example 1 except that the particle diameter was changed to 2 μm], and a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Example 5
LiNi _0.80 Co _0.10 Mn _0.097 Nb _0.003 O ₂ [The ratio of particles having a primary particle diameter of 0.5 μm or more was 50% by mass and the maximum primary concentration was LiNi _0.80 Co _0.10 Mn _0.097 Nb _0.003 O _2. A positive electrode was produced in the same manner as in Example 1 except that the particle diameter was changed to 2 μm], and a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Example 6
Lithium-containing metal oxide (A) was the same as Example 1 except that the ratio of particles having a primary particle diameter of 0.5 μm or more was changed to 80% by mass and the maximum primary particle diameter was changed to 3 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Example 7
Lithium-containing metal oxide (A) was the same as Example 1 except that the ratio of particles having a primary particle diameter of 0.5 μm or more was changed to 100% by mass and the maximum primary particle diameter was changed to 4 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Example 8
Lithium-containing metal oxide (A) was the same as Example 1 except that the ratio of particles having a primary particle diameter of 0.5 μm or more was changed to 100% by mass and the maximum primary particle diameter was changed to 5 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Example 9
A positive electrode was produced in the same manner as in Example 1 except that the mixing ratio of the lithium-containing metal oxide (A) and the lithium-containing metal oxide (B) was changed to 5:95 by mass ratio. Further, a negative electrode was produced in the same manner as in Example 1, except that the thickness of the negative electrode mixture layer was changed to 72 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the above-mentioned positive electrode and the above-mentioned negative electrode were used. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.90 g / cm ³ , and the filling rate was 78.4%.

Example 10
Same as Example 1 except that the mixing ratio of the lithium-containing metal oxide (A) and the lithium-containing metal oxide (B) was changed to 40:60 by mass and the thickness of the positive electrode mixture layer was set to 57 μm. To produce a positive electrode. Further, a negative electrode was produced in the same manner as in Example 1, except that the thickness of the negative electrode mixture layer was changed to 72 μm. Then, a positive electrode was prepared in the same manner as in Example 1 except that the above-described positive electrode and the above-described negative electrode were used, and a prismatic nonaqueous electrolyte secondary battery was formed in the same manner as in Example 1 except for using this positive electrode. Produced. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.80 g / cm ³ , and the filling rate was 77.3%.

Example 11
Except that the amount of the positive electrode active material used in the preparation of the positive electrode mixture-containing composition was 96.5 parts by mass, the amount of the conductive additive was 2 parts by mass, and the amount of the binder was 1.5 parts by mass, A positive electrode was produced in the same manner as in Example 1. Further, a negative electrode was produced in the same manner as in Example 1, except that the thickness of the negative electrode mixture layer was changed to 72 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the above-mentioned positive electrode and the above-mentioned negative electrode were used. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.83 g / cm ³ , and the filling rate was 77.8%.

Example 12
The amount of the positive electrode active material used in the preparation of the positive electrode mixture-containing composition was 98.7 parts by mass, and only carbon black was used as the conductive additive, and the amount was 0.5 parts by mass. A positive electrode was produced in the same manner as in Example 1 except that the amount was 0.8 parts by mass, and a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode was used. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.87 g / cm ³ , and the filling rate was 77.3%.

Example 13
Complex the SiO surface is coated with a carbon material average particle size d ₅₀ is a negative electrode active material is 8 [mu] m (amount of 10% by weight of the carbon material in the composite body. Hereinafter, it referred to SiO / carbon material composite.) And, the graphite average particle size _{d 50} is 16 [mu] m, the mixture amount of SiO / carbon material composite is mixed in an amount of 1.5 wt%: and 97.5 parts by weight, a binder SBR: 1 Water and 0.5 part by mass and 1 part by mass of CMC as a thickener were added and mixed to prepare a slurry-like negative electrode mixture-containing composition. This negative electrode mixture-containing composition is applied to both surfaces of a copper foil (thickness: 8 μm) as a current collector, vacuum-dried at 120 ° C. for 12 hours, and further subjected to a press treatment, so that both surfaces of the current collector are coated. A negative electrode having a negative electrode mixture layer having a thickness of 72 μm was prepared.

  Further, a positive electrode was produced in the same manner as in Example 1, except that the thickness of the positive electrode mixture layer per one surface of the current collector was changed to 58 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode and the above-mentioned negative electrode were used.

Example 14
Except that the mixture used as the negative electrode active material was changed to one in which the amount of the SiO / carbon material composite was 3.0% by mass, and the thickness of the negative electrode mixture layer per one surface of the current collector was changed to 71 μm. A negative electrode was produced in the same manner as in Example 13. Further, a positive electrode was produced in the same manner as in Example 1 except that the thickness of the positive electrode mixture layer per one surface of the current collector was changed to 59 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1, except that this positive electrode and the above-mentioned negative electrode were used.

Example 15
A positive electrode was produced in the same manner as in Example 10, except that the thickness of the positive electrode mixture layer was changed to 58 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 14 except that this positive electrode was used.

Example 16
The lithium-containing metal oxide (A) was changed to a lithium-containing metal oxide having a primary particle diameter of 0.5 μm or more in a proportion of 100% by mass and a maximum primary particle diameter of 4 μm. A positive electrode was produced in the same manner as in Example 1, except that the mixing ratio of A) and the lithium-containing metal oxide (B) was changed to 60:40 by mass ratio, and the thickness of the positive electrode mixture layer was changed to 58 μm. . A negative electrode was produced in the same manner as in Example 14, except that the thickness of the negative electrode mixture layer was changed to 72 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the above-mentioned positive electrode and the above-mentioned negative electrode were used. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.75 g / cm ³ , and the filling rate was 76.9%.

Example 17
The lithium-containing metal oxide (A) was changed to a lithium-containing metal oxide in which the ratio of particles having a primary particle diameter of 0.5 μm or more was 100% by mass and the maximum primary particle diameter was 5 μm. A positive electrode was produced in the same manner as in Example 1, except that the mixing ratio of A) and the lithium-containing metal oxide (B) was changed to 80:20 in mass ratio, and the thickness of the positive electrode mixture layer was changed to 58 μm. A negative electrode was produced in the same manner as in Example 14, except that the thickness of the negative electrode mixture layer was changed to 72 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the above-mentioned positive electrode and the above-mentioned negative electrode were used. The density (actual density) of the positive electrode mixture layer after the press treatment obtained by the above method was 3.70 g / cm ³ , and the filling rate was 75.9%.

Comparative Example 1
LiNi _0.47 Co _0.019 Mn _0.29 Mg _0.05 O ₂ was used instead of the lithium-containing metal oxide (A), and the thickness of the positive electrode mixture layer on one side of the current collector was changed to 58 μm. Except for the above, a cathode was produced in the same manner as in Example 1. Further, a negative electrode was manufactured in the same manner as in Example 1, except that the thickness of the negative electrode mixture layer per one surface of the current collector was changed to 72 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this negative electrode and the above-mentioned positive electrode were used. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.80 g / cm ³ , and the filling rate was 77.3%.

Comparative Example 2
A positive electrode was produced in the same manner as in Example 1 except that LiNi _0.91 Co _0.03 Mn _0.02 Al _0.02 Mg _0.02 O ₂ was used instead of the lithium-containing metal oxide (A). A prismatic nonaqueous electrolyte secondary battery was fabricated in the same manner as in Example 1 except that this positive electrode was used.

Comparative Example 3
Instead of the lithium-containing metal oxide (A), LiNi _0.78 Co _0.20 Al _0.02 O ₂ , the ratio of particles having a primary particle diameter of 0.5 μm or more is 30% by mass, and the maximum primary A positive electrode was produced in the same manner as in Example 1 except that the particles having a particle diameter of 1 μm were used, and a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this positive electrode was used. .

Comparative Example 4
A positive electrode was prepared in the same manner as in Comparative Example 3 except that LiCo _0.992 Mg _0.006 Ti _0.001 Zr _0.001 O ₂ was used instead of the lithium-containing metal oxide (B). A prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except for the difference.

Comparative Example 5
The positive electrode active material was changed to only LiCo _0.984 Al _0.008 Mg _0.006 Ti _0.001 Zr _0.001 O ₂ which is a lithium-containing metal oxide (B), and the positive electrode active material per one side of the current collector was changed. A positive electrode was produced in the same manner as in Example 1, except that the thickness of the agent layer was changed to 55 μm. Further, a negative electrode was manufactured in the same manner as in Example 1, except that the thickness of the negative electrode mixture layer per one surface of the current collector was changed to 72 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this negative electrode and the above-mentioned positive electrode were used. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.95 g / cm ³ , and the filling rate was 79.0%.

Comparative Example 6
The positive electrode active material was changed to only LiNi _0.78 Co _0.20 Al _0.02 O _2, which is a lithium-containing metal oxide (A), and the thickness of the positive electrode mixture layer on one side of the current collector was reduced to 57 μm. A positive electrode was produced in the same manner as in Example 1, except for the change. Further, a negative electrode was produced in the same manner as in Example 1, except that the thickness of the negative electrode mixture layer per one surface of the current collector was changed to 76 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this negative electrode and the above-mentioned positive electrode were used. The density (actual density) of the positive electrode mixture layer after the press treatment determined by the above method was 3.60 g / cm ³ , and the filling factor was 75.1%.

Reference experiment example 1
A positive electrode was produced in the same manner as in Example 1, except that the thickness of the positive electrode mixture layer per one surface of the current collector was changed to 60 μm. Further, a negative electrode was produced in the same manner as in Example 1, except that the thickness of the negative electrode mixture layer per one surface of the current collector was changed to 68 μm. Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this negative electrode and the above-mentioned positive electrode were used.

Reference Experimental Example 2
A positive electrode was produced in the same manner as in Reference Example 1 except that LiNi _0.91 Co _0.03 Mn _0.02 Al _0.02 Mg _0.02 O ₂ was used instead of the lithium-containing metal oxide (A). Then, a prismatic nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Experimental Example 2 except that this positive electrode was used.

Table 1 shows the configuration of the positive electrode active material according to the positive electrode used in the nonaqueous electrolyte secondary battery of Example, and Table 2 shows the configuration of the negative electrode active material of the negative electrode used in the nonaqueous electrolyte secondary battery of Example. Table 3 shows the configuration of the positive electrode active material according to the positive electrode used in the nonaqueous electrolyte secondary batteries of the comparative example and the reference experimental example, and the negative electrode active material related to the negative electrode used in the nonaqueous electrolyte secondary batteries of the comparative example and the reference experimental example. Table 4 shows the constitutions of the substances. Note that LiNi _0.47 Co _0.019 Mn _0.29 Mg _0.05 O ₂ used in the positive electrode according to the battery of Comparative Example 1 and LiNi ₀ used in the positive electrode according to the batteries of Comparative Example 2 and Reference Experimental Example 2 _.91 Co _0.03 Mn _0.02 Al _0.02 Mg _0.02 O ₂ and LiNi _0.78 Co _0.20 Al _0.02 O ₂ used in the positive electrodes of the batteries of Comparative Examples 3 and 4. , And lithium-containing metal oxide (A), but in Table 3, these are also described in the column of “lithium-containing metal oxide (A)” for convenience. LiCo _0.992 Mg _0.006 Ti _0.001 Zr _0.001 O ₂ used in the positive electrode of the battery of Comparative Example 4 does not correspond to the lithium-containing metal oxide (B). For convenience, these are also described in the column of “lithium-containing metal oxide (B)”.

  In Tables 1 and 3, the “ratio” of the lithium-containing metal oxide (A) and the lithium-containing metal oxide (B) means their content in the total amount of the positive electrode active material. In Tables 1 and 2, the “proportion of particles having a primary particle diameter of 0.5 μm or more” and “the maximum particle diameter of primary particles” of the lithium-containing metal oxide (A) are determined according to the method (a). Is the value obtained in

  The following evaluations were performed on the nonaqueous electrolyte secondary batteries of the examples and comparative examples.

<1C discharge capacity measurement>
Each of the batteries of Examples 1 to 16 and Comparative Examples 1 to 6 was charged at a constant current of 1 C up to 4.4 V in an environment of 25 ° C., and then charged at a constant voltage until the total charging time became 2.5 hours. Subsequently, constant current discharge was performed at 1 C until the battery voltage reached 2.75 V, and the discharge capacity (1 C discharge capacity) was measured. The 1C discharge capacity of each of the batteries of Reference Experimental Examples 1 and 2 was measured under the same conditions as those of the battery of Example 1 except that the charging voltage was set to 4.2 V.

<Evaluation of charge / discharge cycle characteristics at 45 ° C>
Each of the batteries of Examples 1 to 16 and Comparative Examples 1 to 6 was charged at a constant current of 1 C up to 4.4 V in an environment of 45 ° C., and then charged at a constant voltage until the total charging time became 2.5 hours. Subsequently, a series of operations for performing constant current discharge at 1 C until the battery voltage reached 3.3 V was defined as one cycle, and these operations were repeated many times, and the discharge capacity at the 300th cycle was measured. Further, for each of the batteries of Reference Experimental Examples 1 and 2, the discharge capacity at the 300th cycle was measured under the same conditions as those of the battery of Example 1 except that the charging voltage was set to 4.2V. Then, for each battery, a value obtained by dividing the discharge capacity at the 300th cycle by the 1C discharge capacity was expressed as a percentage, and the capacity retention rate was obtained.

  Tables 5 and 6 show the evaluation results. In Tables 5 and 6, the 1C discharge capacity of each non-aqueous electrolyte secondary battery and the capacity retention rate at the time of evaluation of the charge / discharge cycle characteristics at 45 ° C. are shown assuming that the result of the battery of Example 1 is 100. Shown as a relative value.

  As shown in Tables 1 to 6, a positive electrode containing a lithium-containing metal oxide (A) having a proper composition and containing particles having a primary particle diameter of 0.5 μm or more in a proper ratio in a proper amount. The non-aqueous electrolyte secondary batteries of Examples 1 to 16 using the positive electrode provided with the mixture layer have a large 1C discharge capacity and a high capacity, and a capacity retention rate at the time of evaluation of charge / discharge cycle characteristics at 45 ° C. And the charge / discharge cycle characteristics at high temperatures were excellent.

  On the other hand, the battery of Comparative Example 1 using the positive electrode active material having a large amount of Mn and Mg instead of the lithium-containing metal oxide (A), and having a small amount of Co instead of the lithium-containing metal oxide (A) The battery of Comparative Example 2 using a positive electrode active material having a large amount of Mg, Comparative Example 3 using a low percentage of particles having a primary particle diameter of 0.5 μm or more instead of the lithium-containing metal oxide (A), The battery of Comparative Example 4, the battery of Comparative Example 5 not using the lithium-containing metal oxide (A), and the battery of Comparative Example 6 using only the lithium-containing metal oxide (A) were charged and discharged at 45 ° C. The capacity retention at the time of characteristic evaluation was low, and the charge / discharge cycle characteristics at high temperatures were inferior.

  The nonaqueous electrolyte secondary battery of Reference Experimental Example 1 has the same configuration as the battery of Example 1 except that the thicknesses of the positive electrode mixture layer and the negative electrode mixture layer are slightly different. The non-aqueous electrolyte secondary battery of No. 2 has the same configuration as the battery of Comparative Example 2 except that the thicknesses of the positive electrode mixture layer and the negative electrode mixture layer are slightly different. As for the batteries of Reference Experimental Examples 1 and 2, 1C discharge capacity was measured with the upper limit voltage at the time of charging set to 4.2 V as described above. As shown in Table 3, the capacity was small. That is, as can be seen from the comparison between the battery of Comparative Example 2 and the battery of Reference Experimental Example 2, when the upper limit voltage during charging is increased from 4.2 V to 4.3 V or more (4.4 V), the 1C discharge capacity increases. On the other hand, the charge-discharge cycle characteristics at high temperatures are reduced, but as can be seen from the evaluation results of the battery of Example 1, the battery has an appropriate composition and a primary particle diameter of 0.5 μm By using a positive electrode provided with a positive electrode mixture layer containing an appropriate amount of the lithium-containing metal oxide (A) containing the above particles in an appropriate ratio, a decrease in charge / discharge cycle characteristics at high temperatures is suppressed. While increasing the capacity.

1 positive electrode 2 negative electrode 3 separator

Claims (7)

Positive electrode, a negative electrode, a positive electrode used for a non-aqueous electrolyte secondary battery having a separator and a non-aqueous electrolyte,
Positive electrode active material, having a positive electrode mixture layer containing a conductive auxiliary and a binder,
The positive electrode mixture layer has the following general formula (1) as the positive electrode active material.
_{Li a Ni 1-b-c} -d Co b Mn c M 1 d Mg e O 2 (1)
[In the general formula (1), M ¹ is a metal element other than Li, Ni, Co, and Mn, and is at least one selected from the group consisting of Al, Ti, Sr, Zr, Nb, Ag, and Ba. Seed element, 0.9 ≦ a ≦ 1.10, 0.1 ≦ b ≦ 0.2, 0 ≦ c ≦ 0.2, 0.1 ≦ b + c ≦ 0.25, 0.003 ≦ d ≦ 0.06 and 0 ≦ e ≦ 0.003], and a lithium-containing metal oxide (A) containing 50% by mass or more of particles having a primary particle size of 0.5 μm or more ;
The following general formula (2)
^{_{Li f Co 1-g-h}} M 2 g M 3 h O 2 (2)
[In the general formula (2), M ² is at least one element selected from the group consisting of Al, Mg and Er, and M ³ is Zr, Ti, Ni, Mn, Na, Bi, Ca, At least one element selected from the group consisting of F, P, Sr, W, Ba, Mo, V, Sn, Ta, Nb, and Zn; 0.9 ≦ f ≦ 1.10, 0.010 ≦ g ≦ 0.1, 0.0005 ≦ h ≦ 0.05, g + h ≦ 0.12], and a lithium-containing metal oxide (B) represented by the formula :
When the total amount of the positive electrode active material contained in the positive electrode mixture layer is 100% by mass, the content of the lithium-containing metal oxide (A) is 5 to 80% by mass. Positive electrode for secondary batteries. The positive electrode for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the content of the conductive auxiliary agent in the positive electrode mixture layer is more than 0.5% by mass and 2.0% by mass or less. The positive electrode for a non-aqueous electrolyte secondary battery according to claim 1 or 2 , wherein the positive electrode mixture layer is formed on both surfaces of a metal current collector having a thickness of 11 µm or less. A non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein the positive electrode is the positive electrode for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3. Non-aqueous electrolyte secondary battery. The negative electrode contains a material containing Si and O as constituent elements (where the atomic ratio x of O to Si is 0.5 ≦ x ≦ 1.5) and graphite as a negative electrode active material. The non-aqueous electrolyte secondary battery according to claim 4 , which has a mixture layer. The non-aqueous electrolyte secondary battery according to claim 4 or 5 the upper limit voltage during charging is set to more than 4.3 V. A non-aqueous electrolyte secondary battery according to any one of claims 4 to 6 , and a charging device,
A non-aqueous electrolyte secondary battery system comprising: charging the non-aqueous electrolyte secondary battery with a voltage of 4.3 V or more as an upper limit.

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