JP2003017037A - Non-aqueous electrolyte secondary battery and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a battery characteristic such as a discharging load characteristic and a cycle characteristic. SOLUTION: This non-aqueous electrolyte secondary battery is provided with a positive electrode 4 formed by laminating a first positive electrode mix layer 10a containing the first positive electrode active material and a second positive electrode mix layer 10b containing the second positive electrode active material having a granular diameter larger than that of the first positive electrode active material in order on the main surface of a positive electrode collector 9, a negative electrode 5 formed of a negative electrode mix layer 12 containing the negative electrode active material, and the non-aqueous electrolyte 6 interposed between the positive electrode 4 and the negative electrode 5. With this structure, electrical resistance in the positive electrode 4 and the dope/de-dope efficiency of the lithium ion are improved, and the internal resistance of the non-aqueous electrolyte secondary battery 1 is restricted to improve the battery characteristic such as a discharging load characteristic and a cycle characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery having a positive electrode and a negative electrode active material capable of doping / dedoping lithium ions, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, for example, a notebook type portable computer, a mobile phone, a camera-integrated VTR (vi
In addition to the rapid development and popularization of portable electronic devices such as deo tape recorders), the development of lightweight, high energy density and highly safe secondary batteries as power sources for such electronic devices has been advanced. In such a secondary battery, for example, lithium ion is doped / doped as an electrode active material on the negative electrode side.
There is a lithium ion secondary battery that uses a carbon material that can be dedoped and that uses a lithium composite metal oxide such as lithium cobalt oxide, lithium nickel oxide, and spinel type lithium manganate as an electrode active material on the positive electrode side. .

In this lithium ion secondary battery,
The electrodes such as the negative electrode and the positive electrode are produced by forming the electrode mixture layer containing the above-mentioned electrode active material on the main surfaces of the electrode collectors of the negative electrode and the positive electrode, respectively. Specifically, an electrode mixture coating solution is prepared by adding an organic solvent to an electrode active material, an additive such as a conductive agent, a binder, etc. and kneading and dispersing the mixture. A negative electrode and a positive electrode are manufactured by apply | coating and drying on the main surface of an electrical power collector to uniform thickness, and cutting into a predetermined dimension.

[0004]

By the way, in the electrode manufactured as described above, particularly in the positive electrode, the area density increases when it becomes a lithium ion secondary battery. The resistance increases.

Therefore, in the lithium ion secondary battery using such a positive electrode, the potential difference between the surface of the positive electrode mixture layer and the vicinity of the positive electrode current collector becomes large, so that the internal resistance increases and the battery There was a problem that the characteristics deteriorate.

Therefore, according to the present invention, in the positive electrode, it is possible to improve battery characteristics such as large current discharge load characteristics and charge / discharge cycle characteristics by suppressing electrical resistance and improving lithium ion doping / dedoping efficiency. It is an object of the present invention to provide a non-aqueous electrolyte secondary battery and a method for manufacturing the same.

[0007]

A non-aqueous electrolyte secondary battery of the present invention is a first positive electrode active material containing a first positive electrode active material capable of doping / dedoping lithium ions on the main surface of a positive electrode current collector. And a second positive electrode mixture layer containing a second positive electrode active material capable of being doped / dedoped with lithium ions and having a particle size larger than that of the first positive electrode active material. A laminated positive electrode, a negative electrode in which a negative electrode mixture layer containing a negative electrode active material capable of doping / dedoping lithium ions is formed on the main surface of a negative electrode current collector, and a positive electrode and a negative electrode And a non-aqueous electrolyte interposed therebetween.

In this non-aqueous electrolyte secondary battery, the positive electrode is a first positive electrode material mixture layer containing a first positive electrode active material capable of lithium ion doping / dedoping, and lithium ion doping / dedoping is possible. And a structure in which a second positive electrode mixture layer containing a second positive electrode active material having a particle size larger than that of the first positive electrode active material is sequentially laminated on the main surface of the positive electrode current collector. ing.

Thus, in this non-aqueous electrolyte secondary battery, the first positive electrode material mixture layer facilitates impregnation of the non-aqueous electrolyte to improve the conductivity of lithium ions and suppress the electrical resistance on the positive electrode side. be able to. Further, in this non-aqueous electrolyte secondary battery, the second positive electrode mixture layer increases the gap between the particles of the second positive electrode active material to improve the efficiency of lithium ion doping / dedoping in the positive electrode. You can

Further, according to the method for producing a non-aqueous electrolyte secondary battery of the present invention, the first positive electrode active material containing the first positive electrode active material capable of doping / dedoping lithium ions is provided on the main surface of the positive electrode current collector. A positive electrode mixture layer and a second positive electrode mixture layer that can be doped / dedoped with lithium ions and that contains a second positive electrode active material having a particle size larger than that of the first positive electrode active material are sequentially laminated. A first step of forming a positive electrode by forming
Between the second step of forming a negative electrode by forming a negative electrode mixture layer containing a negative electrode active material capable of doping / dedoping lithium ions on the main surface of the negative electrode current collector, and between the positive electrode and the negative electrode. And a third step of producing a battery element by interposing a non-aqueous electrolyte therein.

In this method for manufacturing a non-aqueous electrolyte secondary battery,
On the main surface of the positive electrode current collector, a first positive electrode mixture layer containing a first positive electrode active material capable of doping / dedoping lithium ions, and a layer capable of doping / dedoping lithium ions And a second positive electrode mixture layer containing a second positive electrode active material having a particle size larger than the particle size of the positive electrode active material, the first positive electrode mixture layer is impregnated with the non-aqueous electrolyte. The conductivity of lithium ions is easily improved to suppress the electrical resistance on the positive electrode side, and the second positive electrode material mixture layer increases the gaps between the particles of the second positive electrode active material to increase lithium in the positive electrode. A non-aqueous electrolyte secondary battery having improved ion doping / dedoping efficiency is manufactured.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the present invention will be described below. In addition, in the drawings used in the following description, in order to make the features easy to understand, the characteristic portions may be enlarged and illustrated, and the dimensional ratios of the respective constituent elements are not always the same as the actual ones.

A non-aqueous electrolyte secondary battery (hereinafter referred to as a battery) 1 to which the present invention shown in FIGS. 1 and 2 is applied is a battery element 2 which is a power generating element, and an exterior material which encloses the battery element 2. 3 and 3. Note that FIG. 2 shows a schematic cross section of the battery 1 along the line segment A1-A2 in FIG.

The battery element 2, which is a power generating element, has a substantially plate-shaped positive electrode 4, a pair of negative electrodes 5 arranged on both main surfaces of the positive electrode 4, and a space between the positive electrode 4 and the negative electrode 5. And the non-aqueous electrolyte 6 disposed in the. In this battery element 2, the positive electrode 4 and the negative electrode 5 are laminated with the nonaqueous electrolyte 6 interposed therebetween.

In this battery element 2, a positive electrode 4 is connected to a positive electrode terminal 7, and a negative electrode 5 is connected to a negative electrode terminal 8. And these positive electrode terminal 7 and negative electrode terminal 8
Is sandwiched by the sealing region 3a which is the peripheral portion of the exterior material 3 shown by the hatched portion in the figure, and the sealing region 3a is fused.

The positive electrode 2 is formed on the both main surfaces of the positive electrode current collector 9 with the first
First positive electrode mixture layer 1 containing the positive electrode active material and the binder
0a and a second positive electrode mixture layer 10b containing a second positive electrode active material having a particle size larger than that of the first positive electrode active material and a binder.
And are sequentially stacked. The positive electrode current collector 9 is made of, for example, a metal foil such as aluminum having a thickness of about 20 μm, which has a small influence on the battery capacity and a sufficient mechanical strength.

The first contained in the first positive electrode mixture layer 10a
As the positive electrode active material, a material having a particle size in the range of approximately 2 μm to 7 μm is used. As the first positive electrode active material, for example, lithium-cobalt oxide, lithium-nickel oxide, lithium-manganese oxide, spinel type lithium-manganese composite oxide, or a part of these lithium composite oxides is used. Lithium substituted with other transition metal
A transition metal composite compound, a transition metal compound such as manganese dioxide or vanadium pentoxide, a transition metal chalcogen compound such as iron sulfide, or the like is used.

The second positive electrode active material contained in the second positive electrode mixture layer 10b may be the same as the above-mentioned first positive electrode active material, and the particle size thereof is 7 μm to 1 μm.
A material having a range of about 5 μm is used.

For example, the particle size of the first positive electrode active material is 2 μm.
If the particle size is smaller, the particle size is too small, so that it takes too much time for the work such as sizing, and the handling may be complicated and the cost may increase.

On the other hand, the particle size of the second positive electrode active material is 15 μm.
If it is larger, the particle size is too large, and therefore the particles expand and contract in the charge / discharge reaction of doping / dedoping lithium ions, resulting in insufficient electrical contact between the positive electrode 4 and the nonaqueous electrolyte 6, The resistance may increase.

Therefore, in the positive electrode 4, the particle size of the first positive electrode active material is preferably in the range of 2 μm to 7 μm, and the particle size of the second positive electrode active material is preferably in the range of 7 μm to 15 μm.

The binder contained in the first positive electrode mixture layer 10a and the second positive electrode mixture layer 10b is as follows.
Usually, a known binder contained in the positive electrode mixture layer of the battery, for example, polyvinylidene fluoride, polyvinyl pyridine, polytetrafluoroethylene or the like can be used, and the positive electrode mixture layers 10a and 10b can be made of, for example, acetylene. Known additives such as conductive materials such as black and graphite can be added.

In the negative electrode 5, a negative electrode mixture layer 12 containing a negative electrode active material and a binder is formed on one main surface of the negative electrode current collector 11. The negative electrode current collector 11 is made of, for example, a metal foil of copper or the like that has a small influence on the battery capacity and a mechanical strength of about 20 μm.

The negative electrode active material contained in the negative electrode mixture layer 12 is, for example, lithium, a lithium alloy, or a carbon material capable of doping / dedoping lithium when a lithium primary battery or a lithium secondary battery is formed. To be As a carbon material capable of doping / dedoping lithium, for example, a low crystalline carbon material obtained by firing at a relatively low temperature of 2000 ° C. or lower, an artificial graphite obtained by firing a raw material easily crystallized at a high temperature of around 3000 ° C., and the like. A highly crystalline carbon material or the like can be used. Specifically, carbon materials such as pyrolytic carbons, cokes, graphites, glassy carbon fibers, organic polymer compound fired bodies, carbon fibers, and activated carbon can be used. The cokes include pitch coke, needle coke, petroleum coke, and the like. Further, the above-mentioned organic polymer compound fired body refers to one obtained by firing a phenol resin, a furan resin or the like at an appropriate temperature to carbonize.

As the negative electrode active material, in addition to the above-mentioned carbon material, a polymer such as polyacetylene or polypyrrole or an oxide such as SnO ₂ can be used as a material capable of doping / dedoping lithium. Also, as a lithium alloy,
A lithium-aluminum alloy or the like can be used.

The binder contained in the negative electrode mixture layer 12 is usually a known binder contained in the negative electrode mixture layer of a battery, such as polyvinylidene fluoride, polyvinyl pyridine, polytetra. In addition to fluoroethylene and the like, known additives and the like can be added to the negative electrode mixture layer 12.

As the non-aqueous electrolyte 6, a non-aqueous electrolytic solution prepared by dissolving the electrolyte in a non-aqueous solvent, a polymer solid electrolyte having a separability and an adhesive property, or a gel electrolyte obtained by adding a plasticizer to the polymer solid electrolyte is used. Etc. can be used. For example, a polymer solid electrolyte has an electrolyte salt dispersed in a matrix polymer.

The electrolyte salt is LiPF ₆ , LiClO ₄ ,
LiCF ₃ SO ₃ , LiAsF ₆ , LiBF ₄ , LiN
(CF ₃ SO ₃ ) ₂ , C ₄ F ₉ SO ₃ Li, LiSbF
₆ or the like can be used alone or in combination. Among them, LiPF ₆ is preferably used from the viewpoint of ionic conductivity and the like.

As the non-aqueous solvent, various non-aqueous solvents conventionally used in non-aqueous electrolytic solutions can be used. For example, cyclic carbonic acid esters such as propylene carbonate and ethylene carbonate, chain carbonic acid esters such as diethyl carbonate and dimethyl carbonate, carboxylic acid esters such as methyl propionate and methyl butyrate, γ-butyl lactone, sulfolane, 2
Ethers such as methyltetrahydrofuran and dimethoxyethane can be used. These non-aqueous solvents may be used alone or in combination of two or more. Among them, it is particularly preferable to use carbonate ester from the viewpoint of oxidation stability.

As the matrix polymer, a polymer alone or a gel electrolyte using the polymer is 1 ms / cm at room temperature.
The chemical structure is not particularly limited as long as it exhibits the above ionic conductivity. As the matrix polymer, polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polysiloxane compound, polyphosphazene compound, polypropylene oxide,
Examples thereof include polymethylmethacrylate, polymethacrylonitrile, and polyether compounds. Alternatively, it is also possible to use a material obtained by copolymerizing the above polymer with another polymer.

The gel electrolyte contains an electrolyte salt, a matrix polymer, and a swelling solvent as a plasticizer. As the plasticizer using the polymer solid electrolyte as a gel electrolyte, the above-mentioned non-aqueous solvent or the like can be used alone or in combination.

The exterior material 3 is formed by laminating two or more layers of a metal layer and an insulating layer and adhering them by, for example, laminating, so that the inner surface of the battery serves as an insulating layer.

As the metal layer, for example, aluminum, stainless steel, nickel, iron or the like formed in a foil shape, a plate shape or the like is used.

The material of the insulating layer is not particularly limited as long as it has adhesiveness to the positive electrode terminal 7 and the negative electrode terminal 8, but polyethylene, polypropylene, modified polyethylene, modified polypropylene and copolymers thereof, etc. may be used.
A material made of a polyolefin resin is used.

In the battery 1 to which the present invention having the above-mentioned structure is applied, the positive electrode 4 is provided on both main surfaces of the positive electrode current collector 9.
The first positive electrode material mixture layer 10a containing the first positive electrode active material having a particle size in the range of about 2 μm to 7 μm, and the particle size is larger than the particle size of the first positive electrode active material. It has a structure in which a second positive electrode mixture layer containing a second positive electrode active material in the range of about 7 μm to 15 μm is sequentially laminated.

In this case, in the first positive electrode mixture layer 10a,
Since the particle size of the first positive electrode active material is smaller than that of the second positive electrode active material, the specific surface area of the first positive electrode active material is improved and the impregnation of the non-aqueous electrolyte 6 is facilitated. The concentration of lithium ions doped / dedoped on the surface of the particles of the positive electrode active material increases. Therefore, the first positive electrode mixture layer 10
In a, since the lithium ion concentration in the layer is increased and the ionic conductivity is improved, the electric resistance in the layer is suppressed. In the first positive electrode mixture layer 10a, the particle size of the first positive electrode active material is small, so that the specific surface area of the first positive electrode active material is improved and the area in contact with the positive electrode current collector 9 is increased. Therefore, the electrical resistance between the positive electrode current collector 9 and the positive electrode current collector 9 is reduced.

On the other hand, in the second positive electrode mixture layer 10b, the second
Since the particle size of the positive electrode active material is larger than that of the first positive electrode active material, the gap formed by adjoining at least three particles of the second positive electrode active material becomes large. The movement of lithium ions is facilitated, and the efficiency of doping / dedoping lithium ions is improved.

Therefore, in the battery 1, the first positive electrode mixture layer 10a facilitates the impregnation of the non-aqueous electrolyte 6 to improve the conductivity of lithium ions and suppress the electric resistance of the positive electrode 4, and The positive electrode material mixture layer 10b increases the gaps between the particles of the second positive electrode active material to improve the efficiency of doping / dedoping lithium ions in the positive electrode 4, so that the internal resistance is suppressed and large current discharge is performed. It is possible to improve battery characteristics such as load characteristics and cycle characteristics.

Further, in the battery 1 to which the present invention is applied,
The thickness of the first positive electrode mixture layer 10a formed on one main surface of the positive electrode current collector 9 is in the range of 10 μm or more and 50 μm or less, and more preferably 20 μm or more and 40 μm or less.

The thickness of the first positive electrode mixture layer 10a is 10 μm.
When it becomes thinner, the thickness of the first positive electrode mixture layer 10a is too thin with respect to the particle size of the first positive electrode active material.
It becomes difficult to form the positive electrode mixture layer 10a.

On the other hand, the thickness of the first positive electrode mixture layer 10a is 5
When the thickness is more than 0 μm, the thickness of the first positive electrode mixture layer 10a is too thick, the impregnation of the non-aqueous electrolyte 6 is not promoted, and it is difficult to suppress the electrical resistance in the first positive electrode mixture layer 10a. Becomes

Therefore, in the battery 1 to which the present invention is applied, the thickness of the first positive electrode mixture layer 10a formed on one main surface of the positive electrode current collector 9 is set in the range of 10 μm to 50 μm. Thus, the non-aqueous electrolyte 6 is appropriately impregnated into the first positive electrode mixture layer 10a, so that the electric resistance in the first positive electrode mixture layer 10a can be suppressed. In the battery 1, the battery characteristics are further improved by setting the thickness of the first positive electrode mixture layer 10a formed on one main surface of the positive electrode current collector 9 to be in the range of 20 μm or more and 40 μm or less. Is possible.

Further, in the battery 1 to which the present invention is applied, the second electrode formed on one of the first positive electrode mixture layers 10a.
The thickness of the positive electrode mixture layer 10b is 10 μm or more and 50 μm or less, more preferably 20 μm or more,
It is in the range of 40 μm or less.

The thickness of the second positive electrode mixture layer 10b is 10 μm.
When it becomes thinner, the thickness of the first positive electrode mixture layer 10b is too thin with respect to the particle size of the first positive electrode active material.
It becomes difficult to form the positive electrode mixture layer 10b.

On the other hand, the thickness of the second positive electrode mixture layer 10b is 5
When the thickness is more than 0 μm, the thickness of the second positive electrode mixture layer 10b is too thick and the migration distance of lithium ions becomes long, which makes it difficult to improve the efficiency of doping / dedoping lithium ions in the positive electrode 4. Become.

Therefore, in the battery 1 to which the present invention is applied, the second electrode formed on one of the first positive electrode material mixture layers 10a.
By setting the thickness of the positive electrode mixture layer 10b in the range of 10 μm or more and 50 μm or less, the second positive electrode mixture layer 10b
Since the thickness of the lithium ion is appropriate and the movement of lithium ions is smoothly performed, it is possible to improve the efficiency of doping / dedoping lithium ions in the positive electrode 4. Then, in the battery 1, the battery characteristics are further improved by setting the thickness of the second positive electrode mixture layer 10b formed on the one first positive electrode mixture layer 10a to be in the range of 20 μm or more and 40 μm or less. It becomes possible.

Furthermore, in the battery 1 to which the present invention is applied, the first positive electrode mixture layer 10a and the second positive electrode mixture layer 10b formed on the one main surface side of the positive electrode current collector 9 as described above.
The thickness of each positive electrode current collector 9
The total thickness of the first positive electrode mixture layer 10a and the second positive electrode mixture layer 10b on the one main surface side is 20 μm or more, 6
The range is preferably 0 μm or less.

When the total thickness of the first positive electrode material mixture layer 10a and the second positive electrode material mixture layer 10b is set to be smaller than 20 μm, the amount of the positive electrode active material in the positive electrode 4 becomes small, which is suitable. It becomes difficult to obtain the battery capacity.

On the other hand, when the total thickness of the first positive electrode mixture layer 10a and the second positive electrode mixture layer 10b is greater than 60 μm, the nonaqueous electrolyte 6 is impregnated to the vicinity of the positive electrode current collector 9. It becomes difficult to cause the positive electrode 4 and the potential difference between the surface of the positive electrode 4 and the vicinity of the positive electrode current collector 9 to increase, so that the positive electrode 4
The electrical resistance of will increase.

Therefore, in the battery 1 to which the present invention is applied, the total thickness of the first positive electrode mixture layer 10a and the second positive electrode mixture layer 10b on the one main surface side of the positive electrode current collector 9 is 20 μm or more. , 60 μm or less, an appropriate battery capacity can be obtained, and the electrical resistance of the positive electrode 4 is suppressed, so that the battery characteristics can be improved.

The battery 1 to which the present invention as described above is applied is manufactured as follows.

When manufacturing the battery 1 to which the present invention is applied,
First, the first positive electrode mixture layer 1 is formed on both main surfaces of the positive electrode current collector 9.
0a and the second positive electrode mixture layer 10b are sequentially laminated to form the positive electrode 4.

In producing this positive electrode 4, first, the above-mentioned lithium composite oxide having a particle size in the range of about 2 μm to 7 μm as the first positive electrode active material, and a conductive agent,
A first positive electrode mixture coating liquid containing a binder is evenly applied on both main surfaces of a metal foil such as aluminum or the like which becomes the positive electrode current collector 9, dried and then pressed. The first positive electrode mixture layer 10a is formed.

Next, as the second positive electrode active material, the particle size is 7 μm.
A second positive electrode mixture coating liquid containing the above-described lithium composite oxide in the range of about m to 15 μm, a conductive agent, and a binder is applied on both main surfaces of the positive electrode current collector 9. On the formed first positive electrode mixture layer 10a, each is uniformly applied,
The second positive electrode mixture layer 10 is obtained by pressing after drying.
b is formed and cut into a predetermined size.

The positive electrode 4 is produced as described above.
As the conductive agent and the binder contained in the first and second positive electrode mixture coating liquids, known conductive agents and binders can be used, and the first and second positive electrodes can be used. Known additives and the like can be added to the mixture coating liquid.

Next, the negative electrode 5 is prepared. In producing the negative electrode 5, first, a negative electrode mixture coating liquid containing the above-described carbon material as a negative electrode active material and a binder is used as a negative electrode current collector made of, for example, a metal foil such as copper. The negative electrode material mixture layer 12 is formed by uniformly applying it on one main surface 11 and drying it, and then pressing it to cut it into a predetermined size.

The negative electrode 5 is manufactured as described above.
As the binder contained in the negative electrode mixture coating liquid,
Known binders can be used, and known additives and the like can be added to the above negative electrode mixture coating liquid.

Next, the battery element 2 is formed. When manufacturing the battery element 2, first, the electrolyte salt described above is dissolved in the non-aqueous solvent described above. Next, the above-mentioned matrix polymer is added to the non-aqueous solvent in which the electrolyte salt is dissolved and dissolved by heating to prepare a solution of the non-aqueous electrolyte 6, specifically, a gel electrolyte solution. Next, the gel electrolyte solution is applied to the second electrode of the positive electrode 4.
On the second positive electrode mixture layer 10b and the negative electrode mixture layer 12 of the negative electrode 5 by applying evenly on the positive electrode mixture layer 10b and the negative electrode mixture layer 12 of the negative electrode 5 and drying. A layer portion made of the electrolyte 6 is formed by lamination. Next, the positive electrode 4 and the negative electrode 5
And are pressed against each other with the surfaces on which the layer portions made of the non-aqueous electrolyte 6 are formed facing each other.

As described above, the battery element 2 in which the positive electrode 4 and the negative electrode 5 are laminated via the non-aqueous electrolyte 6 is produced.

Next, in the negative electrode terminal connecting portion 9a formed by extending one end of the positive electrode current collector 9 with respect to the battery element 2,
A positive electrode terminal 7 having a predetermined size and a negative electrode terminal 8 having a predetermined size are connected to a negative electrode terminal connecting portion 11a formed by extending one end of the negative electrode current collector 11.

Next, the positive electrode terminal 7 provided in this battery element 2
The negative electrode terminal 8 and the negative electrode terminal 8 are led out to the outside, and are housed inside the exterior material 3 formed of a metal layer and an insulating layer. At this time, the exterior material 3 accommodates the battery element 2 such that the above-described insulating layer having adhesiveness is inside the positive electrode terminal 7 and the negative electrode terminal 8.

Next, the battery element 2 is housed in the exterior material 3 by adhering the peripheral portion of the exterior material 3 in which the battery element 2 is housed, specifically, the sealing area 3a shown by the hatched area in FIG.
Enclose in. The battery 1 to which the present invention is applied is manufactured as described above.

In the method of manufacturing the battery 1 to which the present invention is applied as described above, the particle size is 2 μm on both main surfaces of the positive electrode current collector 9.
To the first positive electrode active material mixture layer 10a containing the first positive electrode active material in the range of about 7 μm to 7 μm, and having a particle size larger than the particle size of the first positive electrode active material, specifically 7 μm to 15 μm
A battery 1 is manufactured using a positive electrode 4 in which a second positive electrode mixture layer containing a second positive electrode active material within a certain range is sequentially laminated.

Thus, in the method of manufacturing the battery 1 to which the present invention is applied, the first positive electrode mixture layer 10a facilitates the impregnation of the non-aqueous electrolyte 6 and improves the lithium ion conductivity.
While suppressing the electrical resistance of the positive electrode 4, the second positive electrode mixture layer 10b increases the gaps between the particles of the second positive electrode active material to improve the efficiency of lithium ion doping / dedoping in the positive electrode 4. By doing so, it becomes possible to manufacture the battery 1 in which the internal resistance is lowered and the battery characteristics such as the large current discharge load characteristic and the cycle characteristic are improved.

The battery to which the present invention is applied is not particularly limited in its shape such as a cylindrical shape, a rectangular shape, a coin shape, a button shape, and various sizes such as thin shape and large size. It is also possible to

Further, in the above-described embodiment, the case in which the metal layer and the insulating layer are bonded to each other has been described as an example of the exterior material 3, but the present invention is not limited to this. For example, a metal cylindrical can, a square can, a thin can, and the like, and a metal lid fitted to these via an insulating material may be used.

[0067]

EXAMPLES Hereinafter, examples in which a non-aqueous electrolyte lithium secondary battery to which the present invention is applied are actually manufactured will be described. A comparative example prepared for comparison with these examples will be described.

<Example 1> To manufacture a positive electrode, first,
LiCoO having an average particle size of 5 μm as the first positive electrode active material
₂ , 92 parts by weight, polyvinylidene fluoride resin (hereinafter, referred to as PVDF) as a binder, 5 parts by weight, graphite as a conductive agent, 3 parts by weight, and N-methyl-2-pyrrolidone as a solvent (hereinafter, referred to as PVDF). , NMP)) and kneaded and dispersed by a planetary mixer to prepare a first positive electrode mixture coating liquid. Next, the obtained first positive electrode mixture coating liquid was uniformly applied to both sides of a strip-shaped aluminum foil having a thickness of 20 μm to be a positive electrode current collector using a die coater as a coating device, and after drying, It was compressed with a roll press machine to form a first positive electrode mixture layer.

Next, 92 parts by weight of LiCoO ₂ having an average particle size of 10 μm was used as the second positive electrode active material, 5 parts by weight of PVDF was used as the binder, and 3 parts of graphite was used as the conductive agent.
A part by weight and NMP as a solvent were added, and the mixture was kneaded and dispersed by a planetary mixer to prepare a second positive electrode mixture coating liquid. Next, the obtained second positive electrode mixture coating liquid was uniformly applied onto the first positive electrode mixture layer formed on both main surfaces of the positive electrode current collector using a die coater as a coating device. After being dried, it was compressed with a roll press to form a second positive electrode material mixture layer and cut into a predetermined size.

As described above, a positive electrode was prepared in which the first positive electrode mixture layer and the second positive electrode mixture layer were sequentially laminated on both main surfaces of the positive electrode current collector. At this time, the first per side
The thickness of the positive electrode material mixture layer of 50 μm and the second
And the total thickness of the positive electrode is 1 μm.
It was 40 μm.

Next, in producing the negative electrode, first, 95 parts by weight of natural graphite was used as the negative electrode active material, and PV was used as the binder.
5 parts by weight of DF and NMP as a solvent were added, and the mixture was kneaded and dispersed by a planetary mixer to prepare a negative electrode mixture coating liquid. Next, the obtained negative electrode mixture coating liquid was used as a coating device using a die coater to form a negative electrode current collector with a thickness of 20.
After being uniformly applied on one main surface of a copper foil having a band shape of μm, and dried, it was compression-molded by a roll press machine and cut into a predetermined size. As described above, a negative electrode having a total thickness of 80 μm was produced.

Next, in order to manufacture a battery element, first, LiP was mixed in a mixed solvent having a volume mixing ratio of propylene carbonate and diethyl carbonate of 1: 1 to a concentration of 1 mol / liter.
F ₆ was dissolved, PVDF was added as a matrix polymer, and the mixture was heated and dissolved in an oven furnace to prepare a gel electrolyte solution. Next, the obtained gel electrolyte solution is uniformly applied on the second positive electrode mixture layer of the positive electrode and the negative electrode mixture layer of the negative electrode,
By drying, the nonaqueous electrolyte layer was formed on the positive electrode mixture layer and the negative electrode mixture layer. Next, the positive electrode and the negative electrode were pressed against each other with their surfaces on which the nonaqueous electrolyte layers were formed facing each other. As described above, a battery element in which the positive electrode and the negative electrode were laminated via the non-aqueous electrolyte was produced.

Next, a length of 20 is attached to the negative electrode terminal connecting portion formed by extending one end of the positive electrode current collector with respect to this battery element.
mm, width 5 mm, thickness 0.05 mm, and a positive electrode terminal made of aluminum, and a negative electrode terminal connecting portion formed by extending one end of a negative electrode current collector, with a length of 20 mm, a width of 5 mm, and a thickness of 0.0.
A 5 mm nickel negative electrode terminal was connected by ultrasonic welding.

Next, while the positive electrode terminal and the negative electrode terminal provided in this battery element are led out to the outside, an aluminum foil having a thickness of 50 μm and a thickness of 3 are provided on a propylene resin film having a thickness of 20 μm.
The nylon resin film having a thickness of 0 μm was housed inside the outer packaging material, which was sequentially laminated by laminating. At this time, the exterior material is
The battery element was housed so that the propylene resin film having adhesiveness was on the inside of the positive electrode terminal and the negative electrode terminal.

Next, the battery element was enclosed in the outer packaging material by bonding the peripheral edges of the outer packaging material containing the battery element inside.

As described above, a sheet-shaped non-aqueous electrolyte lithium ion secondary battery having a vertical dimension of 62 mm and a horizontal dimension of 35 mm was produced. In the following description, the non-aqueous electrolyte lithium secondary battery is simply referred to as a battery for convenience.

Example 2 In Example 2, when the positive electrode was produced, the thickness of the first positive electrode mixture layer was set to 40 μm and the second positive electrode mixture layer was formed.
A positive electrode was produced in the same manner as in Example 1 except that the thickness of the positive electrode material mixture layer was set to 20 μm. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

<Example 3> In Example 3, when the positive electrode was produced, the thickness of the first positive electrode mixture layer was set to 20 μm, and the second
A positive electrode was produced in the same manner as in Example 1 except that the thickness of the positive electrode material mixture layer was changed to 40 μm. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

<Example 4> In Example 4, when the positive electrode was produced, the thickness of the first positive electrode mixture layer was set to 50 μm, and the second positive electrode mixture layer was formed.
A positive electrode was produced in the same manner as in Example 1 except that the thickness of the positive electrode material mixture layer was set to 10 μm. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

<Comparative Example 1> In Comparative Example 1, when the positive electrode was produced, the thickness of the first positive electrode mixture layer was set to 60 μm and the second positive electrode mixture layer was formed.
A positive electrode was produced in the same manner as in Example 1 except that the positive electrode material mixture layer was not formed. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Comparative Example 2 In Comparative Example 2, a positive electrode was manufactured in the same manner as Comparative Example 1 except that the particle size of the first positive electrode active material was 10 μm when manufacturing the positive electrode. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Comparative Example 3 In Comparative Example 3, a positive electrode was manufactured in the same manner as Comparative Example 1 except that the particle size of the first positive electrode active material was 15 μm when manufacturing the positive electrode. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Comparative Example 4 In Comparative Example 4, a positive electrode was manufactured in the same manner as Comparative Example 1 except that the particle size of the first positive electrode active material was 20 μm when manufacturing the positive electrode. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Comparative Example 5 In Comparative Example 5, the thickness of the first positive electrode material mixture layer was set to 55 μm and the second
A positive electrode was produced in the same manner as in Example 1 except that the thickness of the positive electrode material mixture layer was set to 5 μm. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Comparative Example 6 In Comparative Example 6, except that the thickness of the first positive electrode mixture layer was set to 5 μm and the thickness of the second positive electrode mixture layer was set to 55 μm when the positive electrode was produced. A positive electrode was produced in the same manner as in Example 1. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

<Comparative Example 7> In Comparative Example 7, when the positive electrode was produced, the particle size of the first positive electrode active material was set to 10 μm, and the second positive electrode active material was used.
A positive electrode was produced in the same manner as in Example 2 except that the particle size of the positive electrode active material in (5) was changed to 5 μm. Then, a battery was produced in the same manner as in Example 1 except that this positive electrode was used.

Next, with respect to the batteries of Examples 1 to 4 and Comparative Examples 1 to 7 produced as described above, the internal resistance was 3C, and the capacity retention ratio when discharged was 10%.
The capacity retention rate after 0 cycle was measured.

The initial charging conditions were set such that the charging current was set to 0.2 CmA, which is the rated capacity, and the charging voltage was set to 4.2 V, and the charging was performed for 5 hours at a constant current and constant voltage in the atmosphere of 23 ° C. The initial discharge conditions were set so that the discharge current was set to 1 CmA, which is the rated capacity, in the atmosphere of 23 ° C., and discharge was performed up to the discharge end voltage of 3.0 V. The charging and discharging conditions for the second and subsequent times were set to charge and discharge in the same manner as the initial charging and discharging conditions, except that the charging current was 1 CmA, which is the rated capacity.

Table 1 shows the evaluation results of the internal resistance, the capacity retention rate at 3C discharge, and the capacity retention rate after 100 cycles in each example and each comparative example.

[0090]

[Table 1]

In Table 1, the capacity retention ratio at 3C discharge is the ratio of the discharge capacity when the discharge current is 3 CmA, which is the rated capacity, to the discharge end voltage of 3.0 V with respect to the initial discharge capacity. Shows. Further, the capacity retention rate after 100 cycles indicates the ratio of the discharge capacity after 100 cycles to the initial discharge capacity.

From the evaluation results shown in Table 1, Example 1 using the positive electrode in which the first positive electrode mixture layer and the second positive electrode mixture layer were sequentially laminated on both main surfaces of the positive electrode current collector were used. In Example 4, as compared with Comparative Examples 1 to 4 using the positive electrode in which only the first positive electrode mixture layer was formed on both main surfaces of the positive electrode current collector,
It can be seen that the internal resistance is low and the capacity retention ratio after 3 C discharge and after 100 cycles is high.

In Comparative Example 1 in which the thickness of the first positive electrode mixture layer was 60 μm, the first positive electrode mixture layer was so thick that impregnation of the gel electrolyte solution was not promoted. Since it becomes difficult to suppress the electrical resistance and there is no second positive electrode material mixture layer containing the second positive electrode active material having an average particle diameter of 10 μm, it is possible to dope / de-dope lithium ions in the positive electrode. It becomes difficult to improve efficiency. As a result, in Comparative Example 1, the internal resistance was high and 3C
The battery characteristics such as the capacity retention rate after discharging and after 100 cycles are inferior to those of Examples 1 to 4.

The thickness of the first positive electrode mixture layer is 60 μm.
In Comparative Example 2 in which the particle size of the positive electrode active material is 10 μm, since the first positive electrode mixture layer is thick and the migration distance of lithium ions is long, the efficiency of doping / dedoping lithium ions in the positive electrode is improved. It will be difficult to make them.
In Comparative Example 2, the first layer having an average particle size of 5 μm
Since there is no positive electrode material mixture layer containing the positive electrode active material, the contact area between the positive electrode current collector and the second positive electrode active material does not increase, and it becomes difficult to reduce the electrical resistance of the positive electrode. . As a result, in Comparative Example 2, the internal resistance was high and 3
The battery characteristics such as the capacity retention rate during C discharge and after 100 cycles are inferior to those in Examples 1 to 4.

Further, the thickness of the first positive electrode mixture layer is 60 μm.
In Comparative Example 3 and Comparative Example 4 in which the particle size of the positive electrode active material is 15 μm or more, the first positive electrode material mixture layer is thick and the migration distance of lithium ions is long. It becomes difficult to improve the efficiency of dedoping. Then, in Comparative Example 3 and Comparative Example 4,
Since the particle size of the positive electrode active material is too large, the expansion and contraction of the particles in the charging / discharging reaction of doping / dedoping lithium ions is large, the electrical contact between the positive electrode and the non-aqueous electrolyte becomes insufficient, and the internal resistance increases. There is a risk that it will grow. As a result, in Comparative Examples 3 and 4, the internal resistance was high and 3
The battery characteristics such as the capacity retention rate during C discharge and after 100 cycles are inferior to those in Examples 1 to 4.

On the other hand, the average particle size of the first positive electrode active material is 5 μm.
In Examples 1 to 4 in which m is set to m, the first positive electrode active material of the first positive electrode mixture layer is made smaller than the particle size of the second positive electrode active material, Since the specific surface area is improved and impregnation with the gel electrolyte solution is facilitated,
The concentration of lithium ions doped / dedoped on the particle surface of the positive electrode active material is increased. Therefore, since the lithium ion concentration in the first positive electrode mixture layer is increased and the ionic conductivity is improved, the electrical resistance of the positive electrode can be suppressed.

In Examples 1 to 4, the first positive electrode active material has an average particle size of 5 μm.
Since the specific surface area of the positive electrode active material is improved and the area of contact between the positive electrode current collector and the first positive electrode active material is increased, the electrical resistance of the positive electrode can be reduced.

Further, the average particle size of the second positive electrode active material is 1
In Examples 1 to 4 in which the thickness is set to 0 μm, the second positive electrode active material of the second positive electrode mixture layer is made larger than the particle size of the first positive electrode active material, so that at least three second positive electrodes are formed. Since the gap portion formed by the particles of the active material adjoining each other becomes large, the movement of lithium ions in the positive electrode is facilitated, and the efficiency of doping / dedoping of lithium ions can be improved.

Therefore, in Examples 1 to 4,
The first positive electrode material mixture layer facilitates impregnation with the gel electrolyte solution to improve the conductivity of lithium ions and suppresses the electric resistance of the positive electrode, and the second positive electrode material mixture layer forms the second positive electrode active material. Since the gap between the particles is increased to improve the efficiency of doping / dedoping lithium ions in the positive electrode, the internal resistance is suppressed and the battery characteristics such as the capacity retention ratio during 3C discharge and after 100 cycles are improved. It becomes possible.

From the above, when using a positive electrode for a battery, a positive electrode in which a first positive electrode mixture layer and a second positive electrode mixture layer are sequentially formed on both main surfaces of a positive electrode current collector is used. It is clear that this is very effective in producing a battery that can improve battery characteristics.

From the evaluation results shown in Table 1, the thickness of the first positive electrode mixture layer was set in the range of 10 μm to 50 μm, and the thickness of the second positive electrode mixture layer was set to 10 μm to 50 μm.
In Examples 1 and 4 using the positive electrode having the following range and the total thickness of the positive electrode being 140 μm, the thickness of the first positive electrode mixture layer was 55 μm and the thickness of the second positive electrode mixture layer was 5 μm.
m and the total thickness of the positive electrode was 140 μm.
It can be seen that the capacity retention rate after 00 cycles is high.

In Comparative Example 5 in which the first positive electrode mixture layer has a thickness of 55 μm, since the first positive electrode mixture layer is thick and impregnation of the gel electrolyte solution is not promoted, the electrical conductivity in the first positive electrode mixture layer is increased. It becomes difficult to suppress the resistance, and it is difficult to form the second positive electrode mixture layer having a thickness of 5 μm with respect to the particle size of the second positive electrode active material having an average particle size of 10 μm. . As a result, in Comparative Example 5, the internal resistance was high and 3C
The battery characteristics such as the capacity retention rate after discharging and after 100 cycles are inferior to those of Examples 1 to 4.

On the other hand, the thickness of the first positive electrode mixture layer is 10 μm.
As described above, Examples 1 to 4 in which the range is 50 μm or less
Then, since the thickness of the first positive electrode mixture layer is appropriate,
While the gel electrolyte solution is easily impregnated into the first positive electrode mixture layer to suppress the electric resistance in the first positive electrode mixture layer,
The thickness of the second positive electrode mixture layer is 10 μm or more and 50 μm with respect to the particle size of the second positive electrode active material having an average particle size of 10 μm.
By setting the content in the following range, the second positive electrode material mixture layer that improves the efficiency of doping / dedoping lithium ions in the positive electrode can be appropriately formed.

Therefore, in the first to fourth embodiments,
The first positive electrode mixture layer facilitates impregnation of the gel electrolyte solution to improve the conductivity of lithium ions, suppresses the electrical resistance of the positive electrode, and the second positive electrode contained in the second positive electrode mixture layer. Since the gap between the particles of the active material is increased to improve the efficiency of doping / dedoping lithium ions in the positive electrode, the internal resistance is suppressed and at the time of 3 C discharge and 10
It is possible to improve the battery characteristics such as the capacity retention ratio after 0 cycle.

Further, based on the evaluation results shown in Table 1, the thickness of the first positive electrode mixture layer was set in the range of 10 μm to 50 μm, and the thickness of the second positive electrode mixture layer was set to 10 μm to 50 μm.
In Examples 1 and 4 in which the positive electrode has a total thickness of 140 μm and a thickness of m or less, the thickness of the first positive electrode mixture layer is 5 μm and the thickness of the second positive electrode mixture layer is 55
It can be seen that the internal resistance is low and the capacity retention rate at 3 C discharge and after 100 cycles is high as compared with Comparative Example 6 using a positive electrode having a total thickness of 140 μm and a positive electrode of 140 μm.

Comparative Example 6 in which the first positive electrode mixture layer has a thickness of 5 μm
Then, it is difficult to form the first positive electrode mixture layer having a thickness of 5 μm with respect to the particle size of the first positive electrode active material having an average particle size of 5 μm, and the second positive electrode mixture layer is formed. Is 55μ
Since m is thick and the migration distance of lithium ions is long, it is difficult to improve the efficiency of doping / dedoping lithium ions in the positive electrode. As a result, in Comparative Example 6, the battery characteristics such as the high internal resistance and the capacity retention ratio after 3 C discharge and after 100 cycles are inferior to those of Examples 1 to 4.

On the other hand, the thickness of the first positive electrode mixture layer is 10 μm.
As described above, Examples 1 to 4 in which the range is 50 μm or less
Then, with respect to the particle size of the first positive electrode active material having an average particle size of 5 μm, the thickness of the first positive electrode mixture layer is 10 μm or more, 50
Since the thickness is in the range of μm or less, the first positive electrode mixture layer that suppresses the electric resistance of the positive electrode is appropriately formed, and the thickness of the second positive electrode mixture layer is 10 μm or more and 50 μm.
When the content is in the following range, the movement of lithium ions in the positive electrode becomes easy, and the doping / dedoping efficiency of lithium ions can be improved.

Therefore, in the first to fourth embodiments,
The first positive electrode material mixture layer facilitates impregnation with the gel electrolyte solution to improve the conductivity of lithium ions and suppresses the electric resistance of the positive electrode, and the second positive electrode material mixture layer forms the second positive electrode active material. By increasing the gap between the particles and improving the efficiency of lithium ion doping / dedoping in the positive electrode, the internal resistance is suppressed, and the battery characteristics such as the capacity retention ratio during 3C discharge and after 100 cycles are improved. It becomes possible.

From the above, when using a positive electrode for a battery, a thickness of 10 μm or more on both main surfaces of the positive electrode current collector,
A first positive electrode mixture layer having a thickness of 50 μm or less and a second positive electrode mixture layer having a thickness of 10 μm or more and 50 μm or less are sequentially laminated, and a positive electrode having a total thickness of 140 μm is used. It is clear that is extremely effective in producing a battery that can improve the battery characteristics.

Furthermore, from the evaluation results shown in Table 1, the average particle size of the first positive electrode active material contained in the first positive electrode mixture layer was set to 5 μm and contained in the second positive electrode mixture layer. In Example 2 using the positive electrode in which the average particle size of the second positive electrode active material was 10 μm, the average particle size of the first positive electrode active material contained in the first positive electrode mixture layer was 10 μm, The internal resistance is lower than that of Comparative Example 7 using the positive electrode in which the average particle diameter of the second positive electrode active material contained in the positive electrode mixture layer is 5 μm.
It can be seen that the capacity retention rate during discharge and after 100 cycles is high.

In Comparative Example 7 in which the average particle size of the first positive electrode active material was 10 μm, the first positive electrode active material was larger than the average particle size of the second positive electrode active material, and the positive electrode current collector was used. Since the specific surface area of the first positive electrode active material in contact with the second positive electrode active material is smaller than the second specific surface area, the area of contact between the positive electrode current collector and the first positive electrode active material does not increase, and the electrical resistance of the positive electrode does not increase. Is difficult to reduce. As a result, in Comparative Example 7, the battery characteristics such as the high internal resistance and the capacity retention ratio after 3 C discharge and after 100 cycles are inferior to those in Example 2.

On the other hand, the average particle size of the first positive electrode active material is 5 μm.
In Example 2 in which m is set, the first positive electrode active material is smaller than the average particle size of the second positive electrode active material, and the specific surface area of the first positive electrode active material in contact with the positive electrode current collector is the second. Since the specific surface area is larger than the specific surface area, the contact area between the positive electrode current collector and the first positive electrode active material increases, and the electrical resistance of the positive electrode can be reduced.

Therefore, in Example 2, the first positive electrode material mixture layer suppresses the electric resistance of the positive electrode, so that the internal resistance is suppressed and the battery characteristics such as the capacity retention ratio after 3 C discharge and after 100 cycles are obtained. It is possible to improve.

From the above, when a positive electrode is used in a battery, a first positive electrode material mixture layer containing a first positive electrode active material having an average particle size of 5 μm is formed on both main surfaces of a positive electrode current collector. Using a positive electrode in which a second positive electrode mixture layer containing a second positive electrode active material having an average particle diameter of 10 μm is sequentially laminated is very effective in producing a battery that can improve battery characteristics. It is clear that

[0115]

As is apparent from the above description, according to the present invention, the positive electrode is the first positive electrode mixture layer containing the first positive electrode active material capable of doping / dedoping lithium ions, On the main surface of the positive electrode current collector, a second positive electrode material mixture layer capable of being doped / dedoped with lithium ions and containing a second positive electrode active material having a particle size larger than that of the first positive electrode active material is provided. In this structure, the layers are sequentially laminated. Therefore, according to the present invention, the first positive electrode mixture layer can facilitate impregnation of the non-aqueous electrolyte, improve the conductivity of lithium ions, and suppress the electrical resistance on the positive electrode side. Further, according to the present invention, the second positive electrode mixture layer can increase the gap between the particles of the second positive electrode active material to improve the efficiency of lithium ion doping / dedoping in the positive electrode.
Therefore, according to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery in which the battery internal resistance is suppressed and the battery characteristics such as large current discharge load characteristics and charge / discharge cycle characteristics are good.

[Brief description of drawings]

FIG. 1 is a perspective plan view showing a configuration example of a non-aqueous electrolyte secondary battery according to the present invention.

FIG. 2 is a schematic cross-sectional view taken along the line A1-A2 in FIG. 1 showing the internal structure of the non-aqueous electrolyte secondary battery.

[Explanation of symbols]

1 non-aqueous electrolyte secondary battery, 2 battery elements, 3 exterior materials,
3a Sealing area, 4 Positive electrode, 5 Negative electrode, 6 Non-aqueous electrolyte, 7
Positive electrode terminal, 8 Negative electrode terminal, 9 Positive electrode current collector, 10a
First positive electrode mixture layer, 10b Second positive electrode mixture layer, 11
Negative electrode current collector, 12 Negative electrode mixture layer

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H029 AJ02 AJ05 AK02 AK03 AK05                       AL06 AL07 AL12 AM03 AM04                       AM05 AM07 AM16 BJ03 BJ12                       EJ01 EJ04 EJ12 HJ04                 5H050 AA02 AA07 BA17 BA18 CA02                       CA08 CA11 CB07 CB08 CB12                       EA02 EA09 EA24

Claims (6)

[Claims] 1. A first positive electrode material mixture layer containing a first positive electrode active material capable of doping / dedoping lithium ions and a lithium ion doping / dedoping layer on the main surface of the positive electrode current collector. And a second positive electrode mixture layer containing a second positive electrode active material having a particle size larger than the particle size of the first positive electrode active material, which is sequentially laminated, and a main component of the negative electrode current collector. A negative electrode having a negative electrode mixture layer containing a negative electrode active material capable of doping / dedoping lithium ions on the surface, and a non-aqueous electrolyte interposed between the positive electrode and the negative electrode. Water electrolyte secondary battery. 2. The positive electrode, wherein the thickness of the first positive electrode mixture layer is in the range of 10 μm or more and 50 μm or less.
The non-aqueous electrolyte secondary battery described. 3. The positive electrode, wherein the thickness of the second positive electrode mixture layer is in the range of 10 μm or more and 50 μm or less.
The non-aqueous electrolyte secondary battery described. 4. A first positive electrode material mixture layer containing a first positive electrode active material capable of doping / dedoping lithium ions and a lithium ion doping / dedoping layer on the main surface of the positive electrode current collector. And a second positive electrode mixture layer containing a second positive electrode active material having a particle size larger than the particle size of the first positive electrode active material is sequentially laminated to form a positive electrode.
And a second step of forming a negative electrode by forming a negative electrode mixture layer containing a negative electrode active material capable of doping / dedoping lithium ions on the main surface of the negative electrode current collector, and the positive electrode And a third step of producing a battery element by interposing a non-aqueous electrolyte between the negative electrode and the negative electrode, and a method for producing a non-aqueous electrolyte secondary battery. 5. The method for producing a non-aqueous electrolyte secondary battery according to claim 4, wherein in the first step, the thickness of the first positive electrode mixture layer is in the range of 10 μm or more and 50 μm or less. 6. The method for producing a non-aqueous electrolyte secondary battery according to claim 4, wherein in the first step, the thickness of the second positive electrode mixture layer is in the range of 10 μm or more and 50 μm or less.