JPH09102321A - Solid electrolyte battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the discharge characteristic of a solid electrolyte battery having a polymeric solid electrolyte between positive and negative electrodes and to suppress deterioration of electrode materials caused by charge and discharge to provide the battery with excellent charge/discharge and charge- discharge cycle characteristics by enabling the battery to be charged and discharged at large currents even when used as a secondary battery. SOLUTION: This solid electrolyte battery has a polymeric solid electrolyte between positive and negative electrodes. They are aligned so that the particle diameters of electrode materials in the positive and/or negative electrode are large at their interfaces with the polymeric solid electrolyte and small on the opposite side to the interfaces, and a fluidized material for the polymeric solid electrolyte is supplied to the electrode material where the particle diameters are large, and is hardened to form the polymeric solid electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte battery having a polymer solid electrolyte between a positive electrode and a negative electrode, and a method for manufacturing such a solid electrolyte battery, and more particularly to a polymer solid electrolyte. The present invention relates to a solid electrolyte battery having excellent battery characteristics, which is formed by penetrating into the inside of an electrode material in a positive electrode or a negative electrode and can be charged and discharged with a large current, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, an aqueous or non-aqueous electrolyte has been generally used as an electrolyte in a battery. In recent years, instead of such a liquid electrolyte, a polymer solid composed of a polymer has been used. Attention has been focused on solid electrolyte batteries using electrolytes. That is, in such a solid electrolyte battery, since the electrolyte is not a liquid, there is no fear of liquid leakage, the corrosiveness is small, and there is no need to inject the electrolytic solution, the battery structure is simple, and its assembly is easy. There were advantages such as becoming.

In order to manufacture such a solid electrolyte battery, various methods have been conventionally used. For example, powder is used as the electrode material for the positive electrode and the negative electrode,
After producing a positive electrode or a negative electrode from an electrode material made of this powder, a fluid monomer material that constitutes a polymer solid electrolyte is applied onto these electrodes, and then this monomer material is cured to give a polymer solid electrolyte. Were formed on these electrodes.

[0004]

However, in the solid electrolyte battery in which the polymer solid electrolyte is formed as described above, the discharge characteristics are poor, and when it is used as a secondary battery, it is charged and discharged at a large current. However, there was a problem that the electrode material gradually deteriorated due to charge and discharge, the charge and discharge capacity decreased, and the charge and discharge cycle characteristics deteriorate.

In the present invention, it is an object to solve such a problem in a solid electrolyte battery having a polymer solid electrolyte between a positive electrode and a negative electrode, and to improve the discharge characteristics in the solid electrolyte battery as described above. In addition, when used as a secondary battery, it is possible to charge and discharge with a large current, and the charge and discharge capacity does not decrease as the electrode material gradually deteriorates due to charge and discharge. Another object is to obtain an excellent solid electrolyte battery.

[0006] Therefore, the present inventors, in the solid electrolyte battery formed with the polymer solid electrolyte as described above,
Upon examining the causes of the problems described above, the powders used in the electrode materials for the positive and negative electrodes contained various particle sizes. If a fluid monomer material that constitutes the polymer electrolyte is applied on the positive electrode or the negative electrode after manufacturing the negative electrode or the negative electrode, the monomer material does not sufficiently penetrate into the inside of the electrode, When a solid polymer electrolyte is prepared by curing the material, it is found that the contact property between the solid polymer electrolyte and the electrode is poor, which deteriorates the discharge characteristics, and also causes deterioration of the electrode material due to charge and discharge, It came to complete this invention.

[0007]

In the solid electrolyte battery of the present invention, in order to solve the above problems, in a solid electrolyte battery in which a polymer solid electrolyte is provided between a positive electrode and a negative electrode, Alternatively, the particle size of the electrode material in the negative electrode is large on the interface side with the solid polymer electrolyte,
The size is made smaller on the side opposite to this interface.

In the method for producing a solid electrolyte battery according to the present invention, when producing a solid electrolyte battery having a polymer solid electrolyte between a positive electrode and a negative electrode, the particle size of the electrode material in the positive electrode and / or the negative electrode is high. The polymer solid electrolyte is arranged so that it is large on the interface side with the molecular solid electrolyte and small on the opposite side, and the fluid material for the polymer solid electrolyte is supplied to the electrode material side with a large particle size. The fluid material for use was cured to form a solid polymer electrolyte.

Here, as shown in the solid electrolyte battery and the method for manufacturing the solid electrolyte battery in the present invention, the particle size of the electrode material in the positive electrode and / or the negative electrode is large on the interface side with the solid polymer electrolyte, and If they are arranged so that they are smaller on the opposite side, the space between the electrode materials on the interface side with the solid polymer electrolyte becomes larger, while the space on the opposite side to this interface becomes smaller, and the fluid material for the solid polymer electrolyte is made smaller. When supplied, the fluid material for polymer solid electrolyte permeates well from the interface side to the inner side, and when the fluid material for polymer solid electrolyte is cured in this state, the polymer solid electrolyte becomes an electrode. It will be formed in a state of fully penetrating to the inside.

When the polymer solid electrolyte is formed in such a state that it has penetrated into the electrode sufficiently, the contact between the electrode material and the polymer solid electrolyte is increased, and the two are composited. In addition to improving the discharge characteristics, when used as a secondary battery, it becomes possible to charge and discharge with a large current, and the deterioration of the positive electrode material during charge and discharge is reduced, and the charge and discharge cycle characteristics are improved. .

Here, in order to arrange the particle size of the electrode material so that it is large on the interface side with the solid polymer electrolyte and small on the opposite side to this interface as described above, the solid polymer electrolyte reaches the inside of the electrode. In order to improve the contact property between the electrode material and the solid polymer electrolyte to be sufficiently formed, the particle size on the interface side with the solid polymer electrolyte should be 10 μm or more, while the particle size should be opposite to this interface. Side surface, for example, the particle size on the surface that contacts the current collector is 1μ
The particle size of the electrode material is preferably m or less, and more preferably arranged so that the particle size of the electrode material gradually decreases from the interface side of the solid polymer electrolyte toward the opposite side.

As the polymer constituting the above-mentioned polymer solid electrolyte, those having a high ionic conductivity with respect to lithium ions and the like are preferable, and polyethylene oxide, polypropylene oxide, polyethyleneimine and the like can be preferably used.

In the solid electrolyte battery, the kind of ions to be moved is not particularly limited. For example, when lithium ions are moved, the negative electrode material is metallic lithium or an alloy capable of inserting and extracting lithium,
Metal oxides, carbon materials, etc. are used. Here, as the above-mentioned alloy, for example, Li-Al alloy, Li-In alloy, Li-Sn alloy, Li-Pb alloy, Li-Bi alloy, Li-Ga alloy, Li-Sr alloy, Li-Si alloy , Li-Zn alloy, Li-Cd alloy, Li-Ca alloy, a lithium alloy such as Li-Ba alloy, and as the metal oxide, for _{example, Fe 2 O 3, TiO 2} , N
Metal oxides such as b ₂ O ₃ and WO ₃ can be used, and as the carbon material, for example, natural graphite, artificial graphite, amorphous carbon and the like can be used.

On the other hand, a metal oxide containing at least one of manganese, cobalt, nickel, vanadium and niobium can be used as the positive electrode material in the case of moving lithium ions as described above.

In the case where lithium ions are transferred as described above, examples of solutes to be added to the polymer solid electrolyte include lithium trifluoromethanesulfonate LiCF ₃ SO ₃ , lithium hexafluorophosphate LiPF ₆ , tetrafluoromethane. Lithium borate LiBF
₄ , lithium perchlorate LiClO ₄ , trifluoromethanesulfonic acid imide lithium LiN (CF ₃ SO ₂ ) ₂
Etc. can be used.

Further, when adding the above-mentioned solute to the polymer solid electrolyte, it is also possible to add a solvent for dissolving the above-mentioned solute to make the above-mentioned polymer solid electrolyte into a gel state and use it. As the solvent, for example, propylene carbonate, ethylene carbonate, γ-butyrolactone, butylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate, diethyl carbonate or the like can be used.

[0017]

EXAMPLES Examples of the solid electrolyte battery and the method for producing the same according to the present invention will be specifically described below,
Comparative examples will be given to clarify that the solid electrolyte batteries in the examples of the present invention are excellent in discharge characteristics and charge / discharge cycle characteristics. The present invention is not limited to those shown in the following embodiments, and can be carried out by appropriately changing it without departing from the scope of the invention.

[Examples 1 to 3] In these Examples, a positive electrode, a negative electrode and a polymer solid electrolyte were produced as follows, and a flat type solid electrolyte secondary battery as shown in FIG. 1 was prepared. I got it.

(Preparation of Positive Electrode) In these examples, powder of lithium-containing cobalt dioxide LiCoO ₂ heat-treated at a temperature of 700 to 900 ° C. was used as the positive electrode material, and the powder of the positive electrode material was granulated by sieving or the like. The positive electrode material, carbon powder that is a conductive agent, and fluororesin powder that is a binder are mixed in a weight ratio of 85: 10: 5, and the positive electrode material 5 is mixed on the positive electrode current collector 5 by a doctor blade method. The positive electrode material is coated in order from the smallest particle size and then heat-treated at 100 to 150 ° C. to a thickness of about 70 μm.
A disk-shaped positive electrode 1 having a diameter of m and a diameter of 10 mm was produced. Here, in order to apply the positive electrode material on the positive electrode current collector 5 in order from the smallest particle size, the positive electrode material of Example 1 has a particle size of 1 μm or less on the positive electrode current collector 5 side, It is about 5 μm in the central portion and 10 μm or more on the interface side in contact with the solid polymer electrolyte 3, and in Example 2, it is 1 μm or less on the positive electrode current collector 5 side and about 3 μm in the central portion.
μm, 10 μm on the interface side in contact with the solid polymer electrolyte 3
As described above, and in Example 3, a layer having a particle size of 1 μm or less and a layer having a particle size of about 3 μm were provided from the positive electrode current collector 5 side toward the interface in contact with the solid polymer electrolyte 3. ,
A layer having a particle size of about 7 μm and a layer having a particle size of 10 μm or more were sequentially formed. In addition, ferritic stainless steel was used for the positive electrode collector 5. The particle size of the positive electrode material is shown by the average particle size obtained by the laser beam particle size distribution measuring method after the particle size is made uniform by a sieve as described above.

(Production of Negative Electrode) As the negative electrode material, graphite powder having an average particle size of about 10 μm was used, and the graphite powder and a fluororesin as a binder were mixed at a weight ratio of 95: 5, and this mixture was mixed. After coating on the negative electrode current collector 6 by the doctor blade method, this is subjected to vacuum heat treatment at 100 to 150 ° C.,
A disk-shaped negative electrode 2 having a thickness of about 50 μm and a diameter of 10 mm was obtained. In addition, ferritic stainless steel was used for the negative electrode current collector 6.

(Preparation of Solid Polymer Electrolyte) An acrylate-based monomer having a molecular weight of about 1000 shown in the following chemical formula 1 was used as a monomer material in the solid polymer electrolyte, and ethylene carbonate and dimethyl carbonate were added to the monomer material. In a mixed solvent having a ratio of 4: 6, 1 mol / l of lithium perchlorate LiClO ₄ was mixed at a weight ratio of 1: 3 to prepare a polymer solid electrolyte solution. A solution for solid polymer electrolyte is applied onto each positive electrode 1 produced as described above so as to have a thickness of 25 to 100 μm, and then this solution for forming solid polymer electrolyte is applied from an electron curtain electron beam irradiation apparatus. An electron beam is irradiated at an output of 200 kV and an irradiation dose of 2 to 5 Mrad to polymerize the above-mentioned monomer materials to form a gel on each of the above-mentioned positive electrodes 1. Polymer solid electrolyte 3 was prepared.

[0022]

Embedded image

(Production of Battery) Next, in producing each of the solid electrolyte batteries of Examples 1 to 3, on the solid polymer electrolyte 3 produced on each positive electrode 1, as shown in FIG. The above-mentioned negative electrodes 1 are stacked, respectively, and the solid polymer electrolyte 3 is sandwiched between the positive electrodes 1 and the negative electrodes 2 and housed in the battery case 4 formed by the positive electrode can 4a and the negative electrode can 4b. The positive electrode 1 is connected to the positive electrode can 4a via the body 5, while the negative electrode 2 is connected to the negative electrode can 4b via the negative electrode current collector 6, and the positive electrode can 4a and the negative electrode can 4b are insulated from each other by the insulating packing 7
The electric energy is electrically insulated by means of and the chemical energy generated inside the battery is taken out as electric energy from both terminals of the positive electrode can 4a and the negative electrode can 4b.

[Comparative Example 1] In this comparative example, only the solid electrolyte batteries of Examples 1 to 3 and the positive electrode 1 were changed, and the other components were the same as those of Examples 1 to 3 described above. An electrolyte battery was produced.

Here, in producing the positive electrode 1 in this Comparative Example 1, as in the case of Examples 1 to 3 above,
A lithium-containing cobalt dioxide powder heat-treated at a temperature of 700 to 900 ° C. is used as a positive electrode material, and this positive electrode material powder is used as it is without being made uniform in particle size by sieving. 85: 10: 5 carbon powder and fluororesin powder as a binder
In a weight ratio of 100 to 150, and the mixture is applied onto the positive electrode current collector 5 by the doctor blade method.
A heat treatment was carried out at a temperature of ℃ to produce a disk-shaped positive electrode 1 having a thickness of about 70 μm and a diameter of 10 mm.

Next, Example 1 manufactured as described above was used.
~ 3 and each solid electrolyte battery of Comparative Example 1 under a temperature of 25 ℃ atmosphere, charging current density 500μ
After being charged to 4.20 V at A / cm ^2, it was discharged to 2.50 V at a discharge current density of 500 μA / cm ² , and such a charging / discharging cycle was repeated to change the discharge capacity with the increase in the number of cycles. Is measured to examine the charge / discharge cycle characteristics of each solid electrolyte battery, and the results are shown in FIG.
It was shown to.

As a result, an example in which the particle size of the positive electrode material was increased on the interface side with the solid polymer electrolyte 3 and decreased on the positive electrode current collector 5 side opposite to the interface with the solid polymer electrolyte 3 Compared with the solid electrolyte battery of Comparative Example 1 in which the particle size of the positive electrode material was not controlled, each of the solid electrolyte batteries 1 to 3 had a significantly smaller decrease in discharge capacity with an increase in the number of cycles, and the charge / discharge The cycle characteristics were greatly improved.

When the solid electrolyte batteries of Examples 1 to 3 are compared, the particle size of the positive electrode material increases in order from the positive electrode current collector 5 side toward the interface with the polymer solid electrolyte 3. As described above, the charge / discharge cycle characteristics of the solid electrolyte battery of Example 3 in which a large number of layers having different particle sizes of the positive electrode material were provided were superior to those of the solid electrolyte batteries of Examples 4 and 5.

Next, the solid electrolyte batteries of Example 3 and Comparative Example 1 were charged to 4.20 V at a charging current density of 500 μA / cm ² in an atmosphere at a temperature of 25 ° C.
After discharging to 2.50 V at a discharge current density of 500 μA / cm ² , the charge / discharge characteristics of each of these solid electrolyte batteries were examined. Here, in examining the charge / discharge characteristics of these solid electrolyte batteries, the vertical axis represents the battery voltage and the horizontal axis represents the charge / discharge capacity, and the change in the battery voltage due to the charge / discharge capacity was investigated. The results are shown in FIG. It was In the figure, the results of the solid electrolyte battery of Example 3 are represented by solid lines,
The results of the solid electrolyte battery of Comparative Example 1 are shown by broken lines, the results of discharging are shown by thick lines, and the results of charging are shown by thin lines.

As a result, the solid electrolyte battery of Example 3 had less variation in battery voltage during discharge than the solid electrolyte battery of Comparative Example 1, and was superior in discharge characteristics to the battery of Comparative Example 1. .

[Examples 4 to 6] In these Examples, a positive electrode, a negative electrode and a solid polymer electrolyte were prepared as follows, and the flattened surface shown in FIG. Type solid electrolyte secondary battery.

(Production of Positive Electrode) In these examples, a lithium-containing cobalt dioxide powder heat-treated at a temperature of 700 to 900 ° C. was used as a positive electrode material, and the positive electrode material powder and carbon as a conductive agent were used. The powder and a fluororesin powder as a binder are mixed in a weight ratio of 85: 10: 5, and this mixture is applied on the positive electrode current collector 5 by the doctor blade method, and then heat treated at 100 to 150 ° C. Then, a disk-shaped positive electrode 1 having a thickness of about 70 μm and a diameter of 10 mm was produced. In addition, ferritic stainless steel was used for the positive electrode collector 5.

(Preparation of Negative Electrode) Graphite powder was used as the negative electrode material, and the particle size of the graphite powder was made uniform by sieving, and the graphite powder and the fluororesin as the binder were mixed at 95:
5 in a weight ratio of 5 and sequentially applied onto the negative electrode current collector 6 by a doctor blade method, starting from the one having the smallest particle size of the graphite powder, and then subjected to vacuum heat treatment at 100 to 150 ° C. Disc-shaped negative electrodes 2 having a diameter of about 50 μm and a diameter of 10 mm were obtained. Here, in order to apply the graphite powder on the negative electrode current collector 6 in order from the smallest particle size of the graphite powder, in the case of Example 4, the graphite powder had a particle size of negative electrode current collector 6.
1 μm or less on the side, about 5 μm on the central portion, and 10 μm or more on the interface side in contact with the solid polymer electrolyte 3, and in Example 5, 1 μm or less on the negative electrode current collector 6 side,
The thickness is about 3 μm in the central portion and 10 μm or more on the interface side in contact with the solid polymer electrolyte 3, and in Example 6, from the negative electrode current collector 6 side toward the interface in contact with the solid polymer electrolyte 3. , A layer with a particle size of 1 μm or less and a particle size of about 3
A layer having a particle size of 7 μm, a layer having a particle size of about 7 μm, and a layer having a particle size of 10 μm or more are sequentially formed. In addition, ferritic stainless steel was used for the negative electrode current collector 6. Also,
The particle size of the above graphite powder is also shown by the average particle size obtained by the laser beam particle size distribution measuring method, as in the case of the positive electrode materials in Examples 1 to 3 above.

(Preparation of Polymer Solid Electrolyte) As the monomer material in the polymer solid electrolyte, an acrylate-based monomer having a molecular weight of about 1000 shown in Chemical formula 1 above is used, and ethylene carbonate and dimethyl carbonate are added to the monomer material. To prepare a polymer solid electrolyte forming solution in which an electrolyte solution in which lithium perchlorate LiClO ₄ was dissolved at a ratio of 4: 6 and 1 mol / l was mixed at a weight ratio of 1: 3, This polymer solid electrolyte forming solution is applied to each of the negative electrodes 2 produced as described above in an amount of 25 to 10
It is applied so as to have a thickness of 0 μm, and then the solution for forming a polymer solid electrolyte is irradiated with an electron beam at an output of 200 kV and an irradiation dose of 2 to 5 Mrad to polymerize the above monomer materials. Then, a gelled polymer solid electrolyte 3 was produced on each of the above negative electrodes 2.

(Production of Battery) Next, the polymer solid electrolyte 3 produced on each negative electrode 2 as described above is sandwiched between the positive electrode 1 and the negative electrode 2 so that the positive electrode can 4a and the negative electrode can 4 are formed. 4b
The battery pack is housed in the battery case 4 formed by
Flat solid-state batteries of Examples 4 to 6 similar to those in Examples 1 to 3 were produced.

[Comparative Example 2] In this comparative example, only the solid electrolyte batteries of Examples 4 to 6 and the negative electrode 2 were changed, and the other components were the same as those of Examples 4 to 6 described above. An electrolyte battery was produced.

Here, in Comparative Example 2, the graphite powder used in Examples 4 to 6 was used as it was without making the particle diameter of the graphite powder uniform by sieving, and the graphite powder and the binder were used. With the fluororesin which is 95:
5 in a weight ratio, and the mixture is applied onto the negative electrode current collector 6 by the doctor blade method.
Vacuum heat treatment was performed at ˜150 ° C. to obtain a disk-shaped negative electrode 2 having a thickness of about 50 μm and a diameter of 10 mm.

Next, Example 4 produced as described above.
~ 6 and the solid electrolyte batteries of Comparative Example 2 in the same manner as in Examples 1 to 3 and Comparative Example 1 above, the charge and discharge cycle characteristics of these solid electrolyte batteries were examined.
The result is shown in FIG.

As a result, the particle size of the graphite powder in the negative electrode 2 is increased on the interface side with the solid polymer electrolyte 3, while the negative electrode current collector 6 opposite to the interface with the solid polymer electrolyte 3 is formed.
Each of the solid electrolyte batteries of Examples 4 to 6 having a smaller size on the side has a significantly smaller decrease in discharge capacity with an increase in the number of cycles as compared with the solid electrolyte battery of Comparative Example 2 in which the particle size of the graphite powder was not controlled. And the charge / discharge cycle characteristics were greatly improved.

When the solid electrolyte batteries of Examples 4 to 6 are compared, the particle size of the graphite powder increases from the negative electrode current collector 6 side toward the interface with the polymer solid electrolyte 3. As described above, the charge / discharge cycle characteristics of the solid electrolyte battery of Example 6 provided with many layers of graphite powder having different particle sizes were superior to those of the solid electrolyte batteries of Examples 4 and 5.

[0041]

As described above in detail, in the present invention, the particle size of the electrode material in the positive electrode and / or the negative electrode is large on the interface side with the solid polymer electrolyte and small on the opposite side. In the arrayed state, the fluid material for the solid polymer electrolyte was supplied to the electrode to cure the fluid material for the solid polymer electrolyte, so that the solid polymer electrolyte sufficiently penetrated into the electrode. , The contact property between the electrode material and the solid polymer electrolyte is improved, which improves the discharge characteristics.When used as a secondary battery, it can be charged and discharged with a large current, and can also be charged and discharged. Deterioration of the electrode material at the time was also suppressed, and the charge / discharge cycle characteristics were significantly improved.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing the structure of each solid electrolyte battery of Examples 1 to 6 and Comparative Examples 1 and 2 of the present invention.

FIG. 2 is a diagram showing charge / discharge cycle characteristics in each of the solid electrolyte batteries of Examples 1 to 3 and Comparative Example 1 of the present invention.

FIG. 3 is a diagram showing charge / discharge characteristics in each solid electrolyte battery of Example 3 and Comparative Example 1 of the present invention.

FIG. 4 is a diagram showing charge / discharge cycle characteristics in each of the solid electrolyte batteries of Examples 4 to 6 and Comparative Example 2 of the present invention.

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode 3 Polymer solid electrolyte

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koji Nishio 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. In a solid electrolyte battery in which a solid polymer electrolyte is provided between a positive electrode and a negative electrode, the particle size of the electrode material in the positive electrode and / or the negative electrode is large on the interface side with the solid polymer electrolyte, and A solid electrolyte battery characterized in that it is smaller on the opposite side. 2. The solid electrolyte battery according to claim 1, wherein the particle size of the electrode material is 10 μm or more on the interface side with the solid polymer electrolyte, while the particle size on the surface opposite to the interface is 1 μm or less. A solid electrolyte battery characterized in that 3. When manufacturing a solid electrolyte battery having a polymer solid electrolyte between a positive electrode and a negative electrode, the particle size of the electrode material in the positive electrode and / or the negative electrode is large on the interface side with the solid polymer electrolyte, and this interface The fluid material for the solid polymer electrolyte is supplied to the electrode material side having a large particle size, and the fluid material for the polymer solid electrolyte is cured to solidify the polymer solid. A method for producing a solid electrolyte battery, which comprises forming an electrolyte.