JP2005259682A - Non-aqueous electrolyte secondary battery current collector, electrode plate for non-aqueous electrolyte secondary battery using the same, and method for producing electrode plate for non-aqueous electrolyte secondary battery - Google Patents

Abstract

A current collector for a non-aqueous electrolyte secondary battery that suppresses the corrosion reaction of an electrode plate caused by an alkaline paste, has a uniform mixture layer, and has excellent battery characteristics, and a non-aqueous electrolyte secondary battery using the same The manufacturing method of the electrode plate for a nonaqueous electrolyte and a nonaqueous electrolyte secondary battery is provided, and the characteristic improvement, such as resistance reduction of a nonaqueous electrolyte secondary battery, and stabilization are achieved.
A current collector having a surface with an oxide layer having a withstand voltage of 2.1 V or more as a current collector for a non-aqueous electrolyte secondary battery, the current collector being made of aluminum, It is preferable to have an aluminum oxide layer on the surface.
[Selection] Figure 2

Description

  The present invention relates to a method for producing a positive electrode of a nonaqueous electrolyte secondary battery.

  In recent years, electronic devices are rapidly becoming smaller and lighter, and there is an increasing demand for smaller, lighter, and higher capacity batteries as a power source. High energy density lithium secondary batteries Has been actively researched and developed, and has been put to practical use.

  In addition to these small-sized consumer applications, technology development for large-capacity large-sized batteries such as for power storage and electric vehicles has been accelerated. In particular, the development of lithium-ion secondary batteries for hybrid electric vehicles (HEV) has been rapidly progressing. It is advanced to. Furthermore, even for batteries that require a very high output such as a power source for driving an electric tool, development of a high-output type lithium ion secondary battery is urgently replacing the conventional nickel-cadmium battery and nickel-metal hydride battery.

  Here, the lithium ion secondary battery for HEV is greatly different in use and required performance from those of small consumer applications, and it is necessary to perform engine power assist or regeneration instantly with a limited capacity. Input / output characteristics are required. Therefore, it is necessary for the battery to minimize internal resistance as much as possible. Therefore, not only the development of active materials and electrolytes, but also the electrode by reducing the resistance of battery structural parts such as reviewing the electrode current collection structure and making the electrodes thinner and longer Significantly higher input / output is achieved by increasing the reaction area.

In addition, a small battery using a lithium cobalt composite oxide as a positive electrode active material is widely used. However, as a positive electrode active material for a lithium ion secondary battery for HEV, a lithium nickel composite oxide is cheaper than a cobalt-based material. Things are seen as promising.
JP 11-162470 A

  In a lithium secondary battery for HEV that is required to have higher performance and lower cost, if water is used as a solvent for paste preparation, material costs and manufacturing equipment costs are significantly reduced compared to organic solvents. It becomes possible to contribute to lowering the cost of the battery, but if the weight and thickness of the mixture layer applied on the core material is not uniform, the charge / discharge reaction is not uniform. Uniformity of the weight and thickness of the mixture layer, such as an increase in battery resistance or deterioration in life characteristics, is an extremely important factor in achieving improvement and stabilization of battery characteristics.

  Battery development using lithium-nickel composite oxide has been actively conducted to improve battery performance and cost. However, a mixture paste prepared using this lithium-nickel composite oxide and inexpensive water as a solvent is used. When the pH is about 12 and shows very strong alkalinity, and this paste is applied on the current collector, corrosion reaction of the current collector due to alkali occurs.

  Here, a thin initial oxide film layer exists on the surface of the current collector aluminum foil, and this oxide film protects against the erosion of the pure aluminum substrate by alkali, but usually the oxide film thickness is thin. In such an alkaline area, the protective action is small, and when the aluminum substrate under the initial oxide film layer comes into contact with the alkaline paste, the corrosion reaction proceeds at once, and the dehydration during the coating drying process A new oxide layer and hydrogen gas are generated by the reaction.

  Then, due to the foaming of hydrogen gas, a phenomenon that cavities occur in the mixture during the drying process occurs, the mixture layer on the current collector becomes densified, the mixture coating density decreases, the battery resistance increases, or Problems such as deterioration in cycle life characteristics occur.

  In Patent Document 1, the surface of the aluminum foil is roughened in order to improve the adhesion between the mixture and the aluminum foil, and further, the withstand voltage is zero on the surface in order to stabilize the current collector in charge / discharge of the battery. Although it is shown that an oxide film having a thickness of 5 to 2.0 V is formed, the aluminum surface oxide film is resistant to the corrosion reaction. However, in the oxide film, the corrosion reaction is performed in the coating process of an alkaline paste having a pH of 10 or more. It does not lead to suppression, and eventually causes a decrease in the mixture density.

  Therefore, in the present invention, by suppressing such a corrosion reaction of the current collector and making the mixture layer thickness uniform, it is possible to improve the battery characteristics such as reducing the resistance of the lithium secondary battery. A positive electrode for a secondary battery is provided.

  The present invention relates to a current collector for a non-aqueous electrolyte secondary battery having an oxide layer with a withstand voltage of 2.1 V or more on the surface, and the corrosion reaction of the current collector base by providing an oxide film on the current collector surface As a result, a uniform mixture layer can be obtained and good battery characteristics can be obtained.

  The present invention provides a positive electrode plate for a lithium secondary battery that suppresses a corrosion reaction due to an alkaline paste, has a uniform mixture layer, and has excellent characteristics, and a method for producing the same. There is an effect that improvement and stabilization can be achieved.

  The present invention relates to a current collector for a non-aqueous electrolyte secondary battery having an oxide layer with a withstand voltage of 2.1 V or more on the surface, and the corrosion reaction of the current collector base by providing an oxide film on the current collector surface As a result, a uniform mixture layer can be obtained and good battery characteristics can be obtained.

  Furthermore, the withstand voltage of the current collector of the present invention is preferably 3.0 V or less. This is because when the oxide film withstand voltage on the current collector surface is less than 2.1 V, the oxide film thickness is insufficient. In an alkaline paste having a pH of 10 or more, the density of the mixture is reduced due to the corrosion reaction and the mixture coating density. This is because the resistance of the electrode plate increases due to a decrease in the resistance, and the formation of a new oxide film due to the corrosion reaction of the current collector substrate, and the battery resistance increases. On the other hand, when the withstand voltage of the oxide film exceeds 3.0 V, the initial oxide film thickness is thick, so the corrosion protection action is high. However, this initial oxide film thickness increases the resistance as an electrode plate, which is contrary to the battery characteristics. This is to have an adverse effect.

In addition, the current collector for a secondary battery for nonaqueous electrolyte of the present invention is preferably made of aluminum having an aluminum oxide layer on the surface, and the tensile strength of aluminum is preferably 50 N / mm ² or more.

  The method for producing a non-aqueous electrolyte secondary battery electrode plate according to the present invention includes a step of forming an oxide layer having a withstand voltage of 2.1 V or more on the surface of the current collector, and applying an alkaline paste to the current collector. The electrode plate is formed, and the electrode plate is dried. The corrosion reaction of the current collector due to alkali can be suppressed, and an electrode plate with a uniform mixture layer can be provided. It becomes.

  Furthermore, in the method for producing an electrode plate for a non-aqueous electrolyte secondary battery according to the present invention, the alkaline paste has a pH of 10 or more, and the current collector is made of aluminum having an aluminum oxide layer on its surface. In addition, the above-described effects can be exhibited.

Moreover, it is preferable that the tensile strength of aluminum is 50 N / mm ² or more.

As the oxide layer, an oxide layer of aluminum, silicon, titanium, or the like can be used. In order to obtain an oxide film layer, a heat treatment method, an anodic oxidation method, a sputtering method, a vapor deposition method, a CVD, a UV ozone irradiation method, an oxygen plasma treatment method, a corona treatment method, coating, printing, and the like can be exemplified. . In addition, the surface oxide film thickness varies depending on the temperature and time in the heat treatment, but the strength of the aluminum foil is reduced by annealing depending on the temperature and time. Therefore, it is desirable to use an aluminum foil having a tensile strength of 50 N / mm ² or more.

  The present invention also provides a nonaqueous electrolyte secondary battery having a mixture layer containing a lithium nickel composite oxide on both surfaces of a sheet-like current collector having an oxide layer having a withstand voltage of 2.1 V or more on the surface. A first thickness ratio B / A when the maximum thickness of the mixture layer on one of the electrode plates is A and the minimum thickness is B, and the maximum thickness of the mixture layer on the other of the electrode plates C and the second thickness ratio D / C when the minimum thickness is D are both 0.5 or more, and the battery characteristics can be improved and stabilized.

  In addition, the mixture layer is applied using water as a solvent, and the battery characteristics can be improved without corrosion of the current collector even in application with strong alkalinity.

  Hereinafter, the present invention will be described with reference to the drawings.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of a cross section of a positive electrode after coating with a mixture when a corrosion reaction has progressed. Thus, voids 9 are generated in the mixture due to foaming of hydrogen gas due to the progress of corrosion, and the coating density is lowered. Further, a new oxide film layer 8 is formed due to corrosion at the interface between the mixture and the current collector, and the electrode plate resistance increases due to these factors.

  FIG. 2 is a schematic view of a cross section of the electrode plate of the present invention, in which a mixture is applied on an aluminum foil having a surface with an oxide film having a certain thickness provided in advance. As described above, in the positive electrode of the present invention, the applied oxide film has an effect of suppressing the corrosion reaction, and voids in the mixture are not generated, and a more uniform mixture layer can be obtained. Although the applied oxide film is eroded by alkali, the paste does not reach the current collector base, so that a new oxide film is not generated by corrosion.

  FIG. 3 shows a schematic diagram of a cross section of the electrode plate for a non-aqueous electrolyte secondary battery. In the present invention, as shown in FIG. 1, the maximum thickness in one mixture layer of the electrode plate is A, the ratio B / A when the minimum thickness is B, the maximum thickness of the mixture layer in the other electrode plate. C, the use of an electrode plate having a second thickness ratio D / C where the minimum thickness is D is 0.5 or more, the charge / discharge reaction is made uniform, and the non-aqueous electrolyte secondary battery It is possible to achieve improved characteristics and stabilization.

  In the present embodiment, the specific value of the ratio D / C of the maximum thickness C and the minimum thickness D in the other mixture layer of the electrode plate is omitted, but satisfies the characteristics of the present invention. This does not hinder the present invention. In addition, when the mixture layer has a cavity when measuring the thickness, the thickness is measured at a portion excluding the cavity portion.

  FIG. 4 is a cross-sectional view of a lithium secondary battery produced using the electrode plate of the present invention, and is composed of a positive electrode, a negative electrode, a separator, a non-aqueous electrolyte, and other members. Hereinafter, each element will be described in detail.

  The positive electrode is composed of a positive electrode mixture layer such as a positive electrode active material, a conductive material and a binder on an aluminum foil as a current collector. First, a positive electrode active material, a conductive material, a binder, and a solvent are kneaded for the purpose of adjusting viscosity to produce a positive electrode mixture paste, and the positive electrode mixture paste is applied to an aluminum foil current collector and dried. . Thereafter, the sheet is processed into a predetermined size by pressing and slitting as necessary to produce a sheet-like positive electrode.

Lithium metal composite oxides such as LiCoO ₂ , LiNiO ₂ , Li ₂ MnO ₄ are used for the positive electrode active material, but a part of the above Co, Ni or Mn is further substituted with Co, Mn, Al, etc. Other element substitution types such as those substituted with Li can also be used, and these positive electrode active materials can be used as long as they are active materials capable of occluding and releasing lithium and capable of charge / discharge reactions. It is not limited to the above. However, particularly when LiNiO ₂ system is used as an active material and a paste is prepared using water as a solvent, the elution of LiOH is strong, and this mixture paste exhibits a strong alkalinity of about pH 12. Therefore, particularly when this active material is used. Demonstrate the effect.

  In addition, the conductive material is for enhancing electrical conductivity in order to efficiently perform the charge / discharge reaction of the positive electrode mixture. For example, a carbon material such as acetylene black, ketjen black, or graphite is used alone or in combination. Can be used.

  In addition, the binder has a bonding function between the mixture and an adhesion function between the mixture and the core material. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), or the like is used. When water is used as a solvent, a water-soluble dispersion of PTFE is particularly used. As the thickener, for example, a water-soluble polymer such as carboxymethyl cellulose can be used.

  In addition, a mixture paste is prepared by kneading these materials, and the mixture mixture ratio can be arbitrarily adjusted according to the suitability of the battery.

  On the other hand, the negative electrode is composed of a negative electrode active material and a negative electrode mixture layer such as a binder on a copper foil as a current collector, and a mixture paste is prepared in the same manner as the positive electrode. Then, it is processed into a predetermined size by pressing and slitting as necessary to obtain a sheet-like negative electrode.

  As the negative electrode active material, a material capable of inserting and extracting lithium ions is used. For example, a carbon material such as natural graphite, artificial graphite, or coke can be used. Although metallic lithium can be used, there are problems such as poor charge / discharge efficiency. As the binder, PVdF, styrene butadiene rubber (SBR) or the like is used, and an organic solvent such as N-methyl-2-pyrrolidone (NMP) or water is used as a solvent for dispersing these active materials and the binder. Can do.

  The separator has a function of insulating between the positive electrode and the negative electrode and further holding an electrolyte solution, and the separator can be a thin microporous film such as polyethylene, polypropylene, or a laminate thereof. The present invention is not limited to these as long as the necessary functions are obtained.

The electrolytic solution is obtained by dissolving a lithium salt in an organic solvent. Examples of the organic solvent include cyclic carbonates such as ethylene carbonate and propylene carbonate, and chain carbonates such as diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate. A mixed system is used. As the lithium salt, LiPF ₆ , LiBF ₄ , LiClO ₄ or the like can be used.

  Although it is a lithium secondary battery comprised as mentioned above, the shape may be any shape, such as a cylindrical shape, a square shape, or a laminated type, and an electrode is formed by laminating a positive electrode and a negative electrode via a separator. A group is prepared, a current collector terminal to the outside is connected to the positive electrode current collector and the negative electrode current collector, inserted into a battery outer case, an electrolyte is injected, and the battery is sealed to produce a battery.

  As a more specific embodiment of the present invention, a 17500 type cylindrical battery manufactured using various electrode plates will be described below.

(Example 1)
A ternary solution is prepared by adding a predetermined ratio of Co and Al sulfate to an aqueous NiSO ₄ solution to prepare a saturated aqueous solution, and slowly dropping and neutralizing an alkaline solution in which sodium hydroxide is dissolved while stirring the saturated aqueous solution. A precipitate of nickel hydroxide Ni _0.7 Co _0.2 Al _0.1 (OH) ₂ was produced by coprecipitation. The precipitate was filtered, washed with water, and dried at 80 ° C. The obtained nickel hydroxide had an average particle size of about 10 μm.

Thereafter, the obtained Ni _0.7 Co _0.2 Al _0.1 (OH) ₂ was heat-treated in the atmosphere at 900 ° C. for 10 hours to obtain nickel oxide Ni _0.7 Co _0.2 Al _0.1 O. The obtained nickel oxide was confirmed to be single phase nickel oxide by powder X-ray diffraction. Then, lithium hydroxide monohydrate is added so that the sum of the number of atoms of Ni, Co, and Al and the number of atoms of Li are equal, and a heat treatment is performed at 800 ° C. for 10 hours in dry air. A lithium nickel composite oxide represented by the formula LiNi _0.7 Co _0.2 Al _0.1 O ₂ was obtained as a positive electrode active material.

The obtained lithium nickel composite oxide was confirmed by powder X-ray diffraction to have a single-phase hexagonal layered structure, and Co and Al were dissolved. Then, a positive electrode active material powder was obtained through pulverization and classification. The average particle size was 9.5 μm, and the specific surface area by the BET method was 0.4 m ² / g.

  Acetylene black is used as the conductive agent, PTFE water-soluble dispersion liquid is used as the binder, and CMC is used as the thickener. These active materials, conductive agent, binder, and thickener are in a solid content ratio of 88: 9. The mixture was adjusted to a mixing ratio of 2: 1% by weight, and 75% of the solid content was mixed with water as a solvent to prepare a positive electrode mixture paste. As a result of measuring the pH of the prepared paste with a pH meter (F-22II manufactured by HORIBA) in an environment of 20 ° C., it showed strong alkalinity of pH 11.9.

  In this embodiment, heat treatment of the aluminum foil was performed in order to form an oxide film on the surface of the aluminum foil. As the aluminum foil base material, an alloy 1N30, tempered H18, and 20 μm thick aluminum foil was used. An aluminum foil obtained by heat-treating this aluminum foil in an air atmosphere at 250 ° C. for 15 hours in a drying furnace was used as a positive electrode current collector. A method for measuring the surface oxide film withstand voltage indicating the oxide film thickness will be described later.

  The positive electrode mixture paste was applied to both sides of an aluminum foil positive electrode current collector, dried, and then rolled and slitted to produce a positive electrode plate having a thickness of 0.080 mm, a mixture width of 37 mm, and a length of 380 mm.

  Moreover, after this electrode plate was hardened with resin and cross-section polishing was performed, the cross-section was observed with a laser microscope, the maximum thickness and the minimum thickness of one mixture layer were measured, and the thickness ratio B / A was calculated.

For the negative electrode, artificial graphite was used as the active material, and SBR water-soluble dispersion was used as the binder. CMC is used as the thickener, and the active material, the binder, and the thickener are each 96:
The mixture was adjusted at a ratio of 3: 1% by weight, and 100% of the solid content was blended with water as a solvent, and kneaded to prepare a negative electrode mixture paste. This was applied to both sides of a 10 μm thick copper foil, dried, and then rolled and slitted to produce a negative electrode plate having a thickness of 79 μm, a mixture width of 37 mm, and a length of 400 mm.

After the aluminum and nickel current collector leads were joined to the positive electrode and the negative electrode, they were dried in a drying furnace at 100 ° C. for 10 hours and 80 ° C. for 10 hours, respectively, for the purpose of removing residual moisture. Thereafter, a group in which the positive electrode and the negative electrode were wound through a 27 μm-thick polyethylene separator (E27MMS manufactured by Tonen Chemical Co., Ltd.) was produced. The group was inserted into the battery case, the negative electrode lead was resistance welded to the bottom of the case, and the positive electrode lead was laser welded to the sealing plate. Then, in the case, 1 mol / dm ³ of lithium hexafluorophosphate (LiPF ₆ ) was used as a solute in a mixed solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a mixing ratio of 1: ³ . After injecting the electrolytic solution dissolved at a concentration, the case was sealed with a sealing plate to produce a 17500 battery.

(Example 2)
A battery produced in the same manner as Battery A was designated as Battery B, except that the heat treatment was performed at 250 ° C. for 30 hours.

(Example 3)
A battery produced in the same manner as Battery A was designated as Battery C, except that the heat treatment was performed at 250 ° C. for 50 hours.

Example 4
A battery produced in the same manner as Battery A except that the heat treatment was performed at 250 ° C. for 100 hours was designated as Battery D.

(Example 5)
Battery E was prepared in the same manner as Battery A except that heat treatment was performed at 250 ° C. for 120 hours.

(Comparative Example 1)
A battery produced in the same manner as Battery A was designated as Battery F except that the heat treatment was performed at 250 ° C. for 10 hours.

(Comparative Example 2)
A battery G was prepared in the same manner as Battery A except that the heat treatment was performed at 250 ° C. for 8 hours.

(Comparative Example 3)
A battery produced in the same manner as battery A except that no heat treatment was performed on the aluminum foil was designated as battery H.

  The measurement procedure of the oxide film withstand voltage of each battery is shown below.

Put an aqueous solution of ammonium adipate (150 g / dm ³ ) in a stainless steel bath, set the test temperature to 25 ° C., heat treated aluminum foil of 1 cm width and 5 cm length as the test electrode, the counter electrode as the stainless steel bath, and the reference electrode as platinum. did. The potential of the test electrode (vs platinum electrode) was swept at a rate of 20 mV / sec using a potentiostat, and the current flowing during that time was measured to obtain a current-potential curve. FIG. 5 shows a current-potential curve of the aluminum foil used in battery A. As shown in FIG. 4, when the potential is gradually increased, a current rising portion in which the current value increases rapidly is recognized. The current rising portion in the current-potential curve is approximated by a straight line, the intersection of the straight line and the horizontal axis (potential axis) is obtained by extrapolation, and the potential at this intersection is taken as the rising potential. This potential depends on the thickness of the oxide film on the aluminum surface, and the potential difference between this potential and the standard hydrogen electrode potential was defined as the oxide film withstand voltage.

  Table 1 shows the oxide film withstand voltage and tensile strength of the aluminum foil of each battery measured by the above method. The tensile strength was measured on a test piece having a width of 15 mm using a tensile compression tester (SV-301-E-SM) manufactured by Imada Seisakusho. As is apparent from Table 1, the withstand voltage of the oxide film is increased by increasing the heat treatment time, which indicates that the thickness of the oxide film is increased. Further, the tensile strength of the aluminum foil tends to decrease with the heat treatment time.

  Moreover, regarding the electrode plates of the batteries A to H, Table 2 shows the thickness ratio B / A of the mixture layer. Note that the thickness ratio tends to increase with the processing time.

  FIG. 4 shows the relationship between the mixture coating density after applying and drying the positive electrode mixture obtained using these aluminum foils and the oxide film withstand voltage measured by the above method.

  FIG. 6 shows the density of a mixture layer obtained by applying and drying the above-mentioned various mixtures on a pet film on which no corrosion reaction occurs, and plotting the density of each mixture by the ratio to the density. As can be seen from FIG. 4, by increasing the withstand voltage of the oxide film, the coating density of the mixture gradually increases due to the effect of inhibiting the corrosion reaction. Has been obtained. The mixture layer thickness ratio at that time is 0.5 or more.

Next, charging and discharging were repeated for 3 cycles under the conditions of a charge upper limit voltage of 4.2 V and a discharge lower limit voltage of 3.0 V at a constant current of 40 mA in the environment of 25 ° C. All the capacities were around 200 mAh. In order to measure the DC internal resistance of these batteries, a current-voltage characteristic test was performed according to the following procedure.

  Here, each battery was charged at a constant current up to 60% charge under an environment of 25 ° C., and charged and discharged pulses were applied to the battery for 10 seconds at various constant currents in the range of 200 to 2000 mA. The voltage at 10 seconds after application was measured and plotted against the current value. Each voltage plot on the discharge pulse side was linearly approximated by the method of least squares, and the slope value was defined as the DC internal resistance.

  FIG. 6 shows the relationship between the internal resistance obtained as a result and the withstand voltage of the aluminum foil oxide film before application of the mixture. FIG. 7 plots the battery resistance of the battery H produced using the unheated aluminum foil as 100, and the oxide film withstand voltage is 2.8 V and the resistance is the lowest for the battery of the untreated aluminum foil. It shows a value, and the resistance increases as the withstand voltage is further increased.

  That is, when the oxide film thickness is increased, the mixture coating density is increased due to the corrosion reaction suppressing effect, and a coating density of 80% or more and a thickness ratio of 0.5 or more are obtained at 2.1V or more. Battery resistance is also greatly reduced at 2.1V. On the other hand, when the withstand voltage is 2.0 V or less, the coating density is 80% or less, but compared with the battery H, there is an effect of improving density by inhibiting corrosion, but the battery internal resistance is not greatly reduced. Corrosion reaction is suppressed by the applied oxide film, but since the oxide film thickness is not enough, the corrosion reaction proceeds to some extent from weak parts such as irregularities and oxide film defects, and new oxide film formation by that reaction and initial application It is presumed that the resistance balance due to the oxidized film was not greatly different from the state of the battery H, and as a result, the battery resistance was not reduced. The mixture thickness ratio is 0.3 or less, which is greatly affected by corrosion.

  On the other hand, when the breakdown voltage is 2.1 V or more, the initial oxide film is sufficient, almost no oxide film is newly formed, and it is assumed that the resistance is reduced as a result. Further, when the withstand voltage is 3.0 V or more, the coating density is high, but the battery resistance tends to increase. This is presumed that the applied oxide film thickness is too thick, and the resistance of the aluminum foil is increased due to the influence, leading to an increase in battery resistance.

  From the above results, it can be said that the withstand voltage of the aluminum foil oxide film is 2.1 V or more has an effect on inhibiting corrosion and an effect of improving battery performance. Further, the withstand voltage of the oxide film is preferably 2.1 V or more and 3.0 V or less. The mixture layer thickness ratio at that time is 0.5 or more.

Further, when the heat treatment time is lengthened, the tensile strength is lowered, and in the battery E, it is difficult to handle the aluminum foil at the time of manufacture. Therefore, it is considered that the tensile strength is preferably 50 N / mm ² or more.

  From the above, it was found that a lithium secondary battery having good characteristics can be obtained by using a positive electrode plate manufactured using the current collector of the present invention. The method for obtaining the above range is not limited to the heat treatment method and the composition of the positive electrode active material described in this example, and the same effect can be obtained as long as the numerical value within the range can be obtained. it can. The same effect can be obtained by using oxides such as silicon and titanium in addition to the oxide of aluminum as the oxide layer.

  The electrode plate of the present invention is useful as a positive electrode plate for a lithium secondary battery.

Schematic diagram of the cross section of the positive electrode plate when applying a conventional mixture Schematic diagram of a cross section of a positive electrode plate during mixture application according to an embodiment of the present invention Sectional drawing of the electrode plate for nonaqueous electrolyte secondary batteries which concerns on the Example of this invention Sectional drawing of the lithium secondary battery produced using the electrode plate of this invention Current-potential curve of aluminum foil potentiostat used for battery A The figure which shows the relation between the withstand voltage of aluminum foil surface oxide film and the mixture coating density Diagram showing the relationship between the withstand voltage of the aluminum foil surface oxide film and the battery resistance

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Case 5 Sealing plate 6 Mixture layer 7 Current collector base 8 Current collector surface oxide film layer 9 Cavity

Claims (9)

A current collector for a non-aqueous electrolyte secondary battery having an oxide layer with a withstand voltage of 2.1 V or more on the surface. The current collector for a non-aqueous electrolyte secondary battery according to claim 1, comprising aluminum having an aluminum oxide layer on a surface thereof. The current collector for a non-aqueous electrolyte secondary battery according to claim 2, wherein the aluminum has a tensile strength of 50 N / mm ² or more. Non-aqueous electrolyte secondary battery electrode having a mixture layer containing a lithium-nickel composite oxide on both surfaces of a non-aqueous electrolyte secondary battery current collector having an oxide layer with a withstand voltage of 2.1 V or more on the surface The thickness ratio B / A of the maximum thickness (A) and the minimum thickness (B) of the mixture layer on one surface of the electrode plate, and the maximum thickness of the mixture layer on the other surface of the electrode plate An electrode plate for a non-aqueous electrolyte secondary battery in which the thickness ratio D / C between (C) and the minimum thickness (D) is 0.5 or more. The electrode plate for a nonaqueous electrolyte secondary battery according to claim 4, wherein the solvent of the mixture layer is water. A step of forming an oxide layer having a withstand voltage of 2.1 V or more on the surface of the current collector, a step of forming an electrode plate by applying an alkaline paste to the current collector, and a step of drying the electrode plate Manufacturing method of electrode plate for water electrolyte secondary battery. The method for producing an electrode plate for a nonaqueous electrolyte secondary battery according to claim 6, wherein the pH of the alkaline paste is 10 or more. The method for producing an electrode plate for a nonaqueous electrolyte secondary battery according to claim 6, wherein the current collector is made of aluminum having an aluminum oxide layer on the surface. The method for producing an electrode plate for a non-aqueous electrolyte secondary battery according to claim 8, wherein the tensile strength of aluminum is 50 N / mm ² or more.

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