JP2003100287A - Method for manufacturing positive electrode or negative electrode and battery made using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a battery that has such mechanical strength as handling is not hard even when thickness of a collector decreases, and has increased battery capacity. SOLUTION: In this method for manufacturing a positive electrode or a negative electrode, given positive electrode active material, positive electrode active material precursor, negative electrode active material or negative electrode active material precursor is formed on the surface of a thin film collector in such a state that a polymer film for reinforcement removable in the following step is formed, and the above polymer film is removed while the active material is sintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery having a positive electrode body and a negative electrode body with an electrolyte layer in between, and more particularly to a method for manufacturing a positive electrode body or a negative electrode body.

[0002]

2. Description of the Related Art FIG. 2 is a schematic view of a laminated battery in which an electrode body, specifically, a positive electrode body and a negative electrode body are laminated. In this laminated battery, a plurality of electrode bodies are generally laminated in multiple layers. However, FIG. 2 illustrates an example of only one layer for easy understanding. This battery is one in which a positive electrode body 2 and a negative electrode body 4 are laminated with a solid electrolyte 3 interposed therebetween. For example, the positive electrode body 2 has the positive electrode active material 22 provided on the surface of the positive electrode current collector 21. The positive electrode body 2 is connected to the positive electrode terminal of the battery can 8 via the positive electrode lead 5 connected to the positive electrode current collector 21. Next, in the negative electrode body 4, the negative electrode active material 42 is provided on the surface of the negative electrode current collector 41.
The negative electrode body 4 is connected to the negative electrode terminal of the battery can 8 via the negative electrode lead 6 connected to the negative electrode current collector 41. A battery using such a technique is disclosed in Japanese Patent Laid-Open No. 8-148141.
It is described in Japanese Patent Publication No.

[0003]

These batteries are required to have a larger battery capacity. However, the size and shape are limited depending on the battery type. Therefore, as a method of increasing the battery capacity, there is a method of increasing the amount of the active material and reducing the thickness of the current collector that does not contribute only to the increased amount of the active material.

However, when the thickness of the current collector is reduced, the mechanical strength of the current collector is insufficient and it becomes difficult to handle in the manufacturing process. Furthermore, since the solvent contained in the active material precursor is acidic, when the active material is applied to the current collector, the surface of the current collector is corroded.
Therefore, there is a problem of increasing the internal resistance.

An object of the present invention is to obtain a battery in which the thickness of the current collector is reduced, the mechanical strength is maintained so that handling is not difficult, and the battery capacity is increased. Further, it is intended to prevent the internal resistance of the battery from increasing by preventing the current collector from being corroded by the solvent in the active material.

[0006]

In order to achieve the above object, the invention according to claim 1 provides a thin film current collector with a predetermined polymer reinforced film which is removable in a subsequent step. A method for producing a positive electrode body or a negative electrode body, which comprises forming a positive electrode active material or a negative electrode active material and causing the polymer reinforcing film to disappear when the active material is baked. Therefore, it is possible to obtain a battery in which the thickness of the current collector can be reduced, the mechanical strength that does not make the handling difficult is maintained, and the battery capacity is increased. Furthermore, since the corrosion of the surface of the current collector can be prevented, the internal resistance of the battery can be prevented from increasing.

Next, in the invention as set forth in claim 2, a step of forming a reinforcing member on one side or both sides of the current collector to prepare a current collecting reinforcement, and a positive electrode active material on one side or both sides of the current collecting reinforcement. A step of forming a positive electrode member by forming a substance or a positive electrode active material precursor, or a step of forming a negative electrode member by forming a negative electrode active material or a negative electrode active material precursor on one surface or both surfaces of the current collector reinforcement, And a step of firing the positive electrode member or the negative electrode member to prepare a positive electrode body or a negative electrode body. as a result,
It is possible to obtain a battery in which the thickness of the current collector can be reduced, the mechanical strength that does not make handling difficult is maintained, and the battery capacity is increased. Furthermore, since the corrosion of the surface of the current collector can be prevented, the internal resistance of the battery can be prevented from increasing.

Next, in the invention according to claim 3, the reinforcing member according to claim 1 is a positive electrode body or a negative electrode body made of at least one kind of polyether, polyester, acrylic resin, epoxy resin and styrene resin which are high molecular compounds. It is a manufacturing method. Therefore, the thickness of the current collector can be reduced,
Further, it is possible to obtain a battery having increased mechanical capacity and maintaining mechanical strength that does not make handling difficult.

Further, the invention according to claim 4 is the invention according to claim 1,
A battery having at least one of the positive electrode body and the negative electrode body described in 2 and 3. As a result, a battery with increased battery capacity can be obtained.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION <Embodiment 1> FIG. 1 is a sectional view for explaining a method for manufacturing an electrode body according to the present invention. The electrode body is a positive electrode body or a negative electrode body. (1) First, the positive electrode current collector 21 is prepared. The positive electrode current collector 21 is a thin film aluminum material having a length of about 5 cm, a width of about 8 cm, and a thickness of about 2 μm. On one surface of this positive electrode current collector 21, a polyether of a polymer compound, specifically, a 2 wt% acetonitrile solution of polyethylene oxide (Mw = 1,000,000) is applied, and the acetonitrile solvent is naturally dried at 80 ° C. Therefore, polyethylene oxide is fixed on the current collector. As a result, since the reinforcing member 7 is formed on the surface of the positive electrode current collector 21, mechanical strength can be secured. Therefore, handling of the positive electrode current collector 21 becomes easy. (2) Next, the positive electrode active material precursor 22 of LiCoO 2 was formed on the reinforcing member 7 of the positive electrode current collector 21 by the sol-gel method.
The details of the formation of the positive electrode active material precursor 22 are as follows: 100 parts by weight of isopropanol as a solvent, 10 parts by weight of lithium isopropoxide as an active material, 10 parts by weight of cobalt carbonate as an active material, 20 parts by weight of acetic acid as a catalyst, and 50 parts of water. By weight, 30 parts by weight of polyvinylpyrrolidone as a dispersion stabilizer were mixed and stirred for 1 hour to prepare a solution of the positive electrode active material precursor, and subsequently, the solution of the positive electrode active material precursor 22 was applied onto the reinforcing member 7.

Therefore, since the acidic positive electrode active material precursor 22 is provided on the surface of the positive electrode current collector 21 through the reinforcing member 7, corrosion of the surface of the positive electrode current collector 21 can be prevented.

Other than the sol-gel method, there are the following methods. For example, it is a method of applying the positive electrode active material 22 in which the positive electrode active material powder, the binder, and the solvent are mixed onto the reinforcing member 7 of the positive electrode current collector 21. (3) Subsequently, the positive electrode active material precursor 22 or the positive electrode current collector 21 coated with the positive electrode active material 22 was baked in an air atmosphere at 600 ° C. for 10 minutes to manufacture the positive electrode member 2. Therefore, the polyethylene oxide, which is the reinforcing member 7, was burned and vaporized. Since the polyethylene oxide is burned and vaporized, the conductive resistance between the current collector and the active material is eliminated, and good electrical continuity is secured. Further, since the positive electrode active material precursor 22 or the solvent in the positive electrode active material 22 is also combusted and vaporized, even if the positive electrode active material 22 is formed on the surface of the positive electrode current collector 21, corrosion of the surface of the positive electrode current collector 21 can be prevented. (4) The positive electrode active material 22 was formed to a film thickness of 10 μm by repeating the above coating process and baking process in sequence.

Next, a method of manufacturing a laminated battery will be described with reference to FIG. (5) Li2O-SiO on the cathode body 2 prepared as described above
The solid electrolyte 3 of 2-P2O5 was prepared by the sol-gel method.
Details of the solid electrolyte 3 are as follows. 77 parts by weight of ethanol as a solvent, 10 parts by weight of lithium ethoxide as an electrolyte material, 40 parts by weight of tetraethoxysilane as an electrolyte material, 20 parts by weight of triethyl phosphite as an electrolyte material, 25 parts by weight of polyvinylpyrrolidone as a dispersion stabilizer, and as a catalyst. It was prepared by mixing at a composition ratio of 40 parts by weight of acetic acid for 1 hour. (6) Next, the solid electrolyte 3 is coated on the positive electrode body 2.
It was baked at 600 ° C. (7) Subsequently, the coating treatment and the firing treatment were repeated to form the solid electrolyte 3 with a thickness of 1 μm.

Next, a method of manufacturing the negative electrode body 4 will be described. (8) First, the negative electrode current collector 41 is prepared. The negative electrode current collector 41 is a thin film copper material having a vertical width of about 5 cm, a horizontal width of about 8 cm, and a thickness of about 2 μm. Then, the negative electrode current collector 41 provided with the reinforcing member 7 was manufactured in the same procedure as that of the positive electrode described above. Therefore, the negative electrode current collector 41 can be easily handled. Further, it is possible to prevent corrosion of the surface of the negative electrode current collector 41 due to the acidic active material.

Next, a Li4Ti5O12 negative electrode active material precursor 42 was formed on the reinforcing member 7 of the negative electrode current collector 41 by the sol-gel method. The details of the formation of the negative electrode active material precursor 42 are as follows: 77 parts by weight of ethanol as a solvent, 10 parts by weight of lithium ethoxide as a negative electrode material, and titanium (IV) tetraethoxide as a negative electrode material.
40 parts by weight, 25 parts by weight of polyvinylpyrrolidone as a dispersion stabilizer, 40 parts by weight of acetic acid as a catalyst and 40 parts by weight of water as a composition ratio 1
After mixing for a time, a solution of the negative electrode active material precursor was prepared. Subsequently, a solution of the negative electrode active material precursor was applied onto the reinforcing member 7. Other than the sol-gel method, there are the following methods. For example, it is a method of applying the negative electrode active material 42, which is a mixture of the negative electrode active material powder, the binder, and the solvent, onto the reinforcing member 7 of the negative electrode current collector 41.

Therefore, the acidic negative electrode active material precursor 42 or the negative electrode active material 42 is provided on the surface of the negative electrode current collector 41 through the reinforcing member 7.
Since the above is provided, it is possible to prevent corrosion of the surface of the negative electrode current collector 41.

Next, the negative electrode active material precursor 42 or the negative electrode current collector 41 on which the negative electrode active material 42 was formed was baked for 10 minutes in an air atmosphere at 600 ° C. to prepare the negative electrode member 4. Therefore, the polyethylene oxide, which is the reinforcing member 7, was burned and vaporized. As a result, the negative electrode current collector 41 and the negative electrode active material 42
Conductive resistance between and is eliminated, and good electrical continuity is secured. And the negative electrode active material precursor 42 or the negative electrode active material 4
Since the solvent in 2 is also vaporized by combustion, even if the negative electrode active material 42 is formed on the surface of the negative electrode current collector 41, corrosion of the surface of the negative electrode current collector 41 can be prevented. (9) The positive electrode body 2 and the negative electrode body 4 described above are laminated via the solid electrolyte 3. Then, the positive electrode body 2 is connected to the positive electrode terminal of the battery can 8 via the positive electrode lead 5 connected to the positive electrode current collector 21. Next, the negative electrode body 4 is connected to the negative electrode terminal of the battery can via the negative electrode lead 6 connected to the negative electrode current collector 41. Finally, the battery can 8 is sealed. <Example 2> Example 2 is different from Example 1 in that the reinforcing member 7 is replaced with an acrylic resin. Others are Example 1
A battery was prepared in the same manner as in. <Comparative Example> The comparative example is different from Example 1 in that the positive electrode member and the negative electrode member were prepared without using the reinforcing member 7 according to the present invention. For details of each current collector, the positive electrode current collector is an aluminum current collector with a thickness of 20 μm, and the negative electrode current collector is
This is a 10 μm copper current collector. A solid electrolyte 3, a negative electrode active material 42 and a positive electrode active material 22 other than these were manufactured by the same manufacturing method as in Example 1. That is, it is the same as the conventional technique. <Evaluation Test> Table 1 shows the volume energy densities of the batteries of Examples 1 and 2 and Comparative Example.

[0018]

[Table 1]

Referring to Table 1, the volume energy density of the battery of Example 1 was 1.2 times that of the comparative example because the thickness of the current collector was reduced and the amount of the active material was increased. Has a volume energy density of 1.15 times that of the comparative example. As a result, the volumetric energy density is greatly improved. Moreover, since the active material was applied through the reinforcing member 7 and then the reinforcing member 7 was combusted and vaporized, the current collector was not affected by the acid. Therefore, the internal resistance of Example 1 was 0.9 times that of the comparative example, and the internal resistance of Example 2 was 0.94 times that of the comparative example. Therefore, the internal resistance is greatly improved.

As the substitute for the polyether of the above embodiment, at least one kind of polymer compounds such as polyester, acrylic resin, epoxy resin and styrene resin can be used.

That is, specific examples of the polyether include polypropylene oxide and polyethylene oxide.
At least one kind of polypropylene oxide copolymer can be used. Next, the polyester is, for example, polyethylene terephthalate. Further, the acrylic resin is specifically polymethylmethacrylate. Subsequently, the epoxy resin is bisphenol A. Next, the styrene resin is polystyrene.

Further, at least one of V2O5, LiMn2O4, LiNiO2, Nb2O5, and substitution products thereof can be used as a substitute for LiCoO2 of the positive electrode active material of the above-mentioned embodiment. That is, any material that can store and release alkali metal ions may be used.

Next, the negative electrode active material of the above embodiment, Li4Ti5O12
As a substitute for the above, at least one kind of carbon compounds capable of occluding and releasing alkali metal ions, for example, natural graphite, artificial graphite, coke, mesophase spherules, PAN-based carbon fibers and the like can be used. That is, any material that can store and release alkali metal ions may be used.

Subsequently, the solid electrolyte Li 2 O-SiO 2 of the above-mentioned embodiment was used.
As an alternative to 2-P2O5, transition metal oxides such as Li4Ti2 (PO4) 4, oxide glasses such as Li2O-SiO2 and SiO2-Li3BO3, Li2S
-At least one kind of sulfide glass such as Li4SiS2 can be used. That is, any material having alkali ion conductivity may be used.

[0025]

As described above, according to the battery of the present invention, it is possible to obtain a battery having a mechanical strength that facilitates handling and an increased battery capacity even when the thickness of the current collector is reduced. You can Further, it is possible to prevent corrosion of the surface of the current collector due to the solvent in the active material and prevent an increase in internal resistance of the battery.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a method of manufacturing an electrode body according to the present invention.

FIG. 2 is a schematic view of a laminated battery in which a positive electrode body and a negative electrode body are laminated.

[Explanation of symbols]

1 battery, 2 cathode body, 21 positive electrode current collector, 22 positive electrode active material, 3 solid electrolyte, 4 negative electrode body, 41 Negative electrode current collector, 42 negative electrode active material, 5 positive electrode lead, 6 negative lead, 7 reinforcement members, 8 battery cans,

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H017 AA03 AS00 CC01 DD06 EE00                       EE05                 5H029 AJ01 AJ03 AJ06 AJ14 AK03                       AL03 AM12 BJ04 BJ12 BJ13                       CJ02 CJ12 CJ22 DJ07 EJ01                       EJ12                 5H050 AA08 AA12 AA14 AA19 BA15                       CA08 CB03 DA07 DA08 FA02                       FA18 GA02 GA12 GA22

Claims (4)

[Claims] 1. A predetermined positive electrode active material, a positive electrode active material precursor, a negative electrode active material or a negative electrode active material precursor is formed on a surface of a thin film current collector with a polymer reinforcing film that can be removed in a subsequent step. A method for producing a positive electrode body or a negative electrode body, which comprises forming and eliminating the polymer reinforcing film during firing of the active material. 2. A step of forming a reinforcing member on one side or both sides of a current collector to form a current collecting reinforcement, and forming a positive electrode active material or a positive electrode active material precursor on one side or both sides of the current collecting reinforcement. To form a positive electrode member, or to form a negative electrode member by forming a negative electrode active material or a negative electrode active material precursor on one surface or both surfaces of the current collector reinforcement, and firing the positive electrode member or the negative electrode member And a step of producing a positive electrode body or a negative electrode body, the method for producing a positive electrode body or a negative electrode body. 3. A method for producing a positive electrode body or a negative electrode body, wherein the reinforcing member according to claim 1 is made of at least one kind of polymer compound polyether, polyester, acrylic resin, epoxy resin and styrene resin. 4. A battery comprising at least one of the positive electrode body and the negative electrode body according to claim 1.