JP2780391B2 - Manufacturing method of solid state secondary battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a solid state secondary battery.

2. Description of the Related Art Among batteries used as various power sources, so-called solid batteries, in which all constituent materials are solid, have no liquid leakage, and therefore can be expected to have high reliability and can be reduced in size and weight for any reason. Both batteries have attracted attention. At present, it is mainly used for memory backup of various devices.

This solid state battery is especially important solid electrolyte for moving ions in the battery, LiI, Li ⁺ ion conductive solid electrolyte such as _{Li 3 N, RbAg 4 I 5} , Ag-Ag 2 O, Ag-MoO Ag ⁺ ion conductive solid electrolyte such as _3, RbCu ₄ I _1.5 Cl _3.5 therewith H ⁺ ion conductive solid electrolyte, C, such as CuI-Cu ₂ O-MoO ₃
u ⁺ ion conductive solid electrolyte and the like.

In addition, as materials for the positive electrode, Cu _0.1 TiS ₂ , Ag _0.1 TiS ₂ , Cu
_0.1 NbS ₂ , Ag _0.1 NbS ₂ , WO _{3 and} Cu _y Mo ₆ S _8-z , Fe _y Mo ₆ S
Chevrel phase compounds such as _8-z are mentioned.

On the other hand, for the negative electrode, Cu, Ag, Li _1.5 WO ₃ and the same chevrel phase compound as for the positive electrode have been tried.

There are many methods for manufacturing these batteries, as with other batteries. One industrially effective method is to form a layer mainly composed of an electrode material and a binder and a layer mainly composed of an electrolyte and a binder. After arranging the conductive layers containing a binder on the both sides and arranging the layers on the outside thereof, the above-mentioned layers may be heated and integrated at a time by heating.

Problems to be Solved by the Invention However, in this conventional production, since the whole is integrated under pressure at a time under heating, it is more difficult to integrate the conductive layer on the electrode layer and the electrolyte layer after integrating the electrode layer and the electrolyte layer thereon. Although the process can be simplified, if the number of layers is too large, simply applying pressure under heating may result in an insufficiently adhered portion, resulting in variations in the essential life.

An object of the present invention is to provide a method for manufacturing a solid state secondary battery capable of solving such a problem.

Means for Solving the Problems The method for producing a solid-state secondary battery of the present invention comprises, on both sides, a layer mainly composed of an electrode material and a binder, and disposing a layer mainly composed of an electrolyte and a binder in the center, A conductive layer containing a binder is provided on the outside, and when integrated by heating, the whole is pressurized and integrated under heating all at once, and returned to normal pressure at a temperature below the softening point of the binder. It is.

Action As described above, a layer mainly composed of an electrolyte and a binder is provided, and a conductive layer containing a binder is provided outside the layer. Since the pressure is integrated, there is no portion where the adhesion is insufficient.

Examples Hereinafter, examples of the present invention will be described.

Copper Chevrel a (CuxMo6S8) used as an electrode material, 20 Wt% of RbCu ₄ I _1.5 Cl _3.5 as the electrolyte added this, so polyethylene is 7 wt% as a binder, thoroughly stirred and a paste was added and the hot benzene solution And

On the other hand, a copper chevrel (Cu ₂ Mo ₆ S ₈ ) is also used for the negative electrode, and the electrolyte is RbCu ₄ I _1.5 Cl _3.5 at 20 Wt% in the same manner as the positive electrode.

Also, RbCu ₄ I _1.5 Cl _3.5 is used as an electrolyte, and a paste is also formed with the same binder. Using these pastes, a positive electrode, a negative electrode, and an electrolyte sheet are manufactured by a known doctor blade method. The thickness of the electrode was 0.25 mm, and the thickness of the electrolyte was 0.16 mm.

A positive electrode layer and a negative electrode layer are disposed on both sides of the electrolyte layer at the center, and a commercially available carbon film in which graphite fibers having a length of 30 to 100 μm and a diameter of 7 to 8 μm are dispersed in polyethylene is applied as a current collector to the outside thereof. First, a roller press machine heated to 170 ° C. was passed under a condition of 500 kg / cm ² to apply pressure, and immediately passed through a roller press machine heated to 130 ° C. under a condition of 500 kg / cm ² , then 110 ° C., and finally 70 ° C. C. and the same pressure are applied to complete the pressure integration. This is punched out into a coin with a diameter of 25 mm.

Thereafter, a Cu plate having a diameter of 0.3 mm and a diameter of 30 mm is applied and bonded. Finally, the periphery of the battery was first covered with a polyacrylic resin, and a room temperature-curable epoxy resin was applied thereon to form a battery. This battery is designated as A.

Next, for comparison, 500 kg with a press machine heated to 170 ° C
The battery was pressurized under the condition of / cm ² , returned to normal pressure as it was, and a battery manufactured under the same conditions as A except for B was added.

With respect to the above two batteries, the discharge voltage and the capacity at 60 ° C. charge / discharge were first compared. 0.58V constant voltage charge -0.5mA
When constant current discharge was performed up to 0.3 V, the average voltage of A was 0.48 V and the discharge capacity was 5.9 mAh,
Were 0.47V and 5.6mAh, respectively, and A was slightly superior in each case.

Therefore, the life characteristics were examined under the same charge and discharge conditions at an ambient temperature of 70 ° C. As a result, the number of cycles in which the discharge capacity deteriorated to 60% of the initial value was 880 to 930 in A, whereas 700 to 780 in B. As is evident from the results, A had a long life and there was little variation in life.

In Example A, since the battery was obtained in a state where the electrode and the electrolyte layer were firmly pressed, the phenomenon of expansion during the charge / discharge process was suppressed, and the capacity did not decrease with a relatively small number of cycles. .

In the embodiment, the unit cell is shown as an example. However, the same method can be used for a battery having a laminated structure which is usually adopted to increase the capacity and the voltage.

As described above, according to the present invention, a sheet mainly composed of an electrode material and a binder is disposed on both sides, a sheet mainly composed of an electrolyte and a binder is disposed in the center, and a binder is included outside the sheet. A conductive sheet is placed, the whole is pressurized and integrated under heating at a time, and the pressure is returned to normal pressure at a temperature below the softening point of the binder, thereby suppressing an increase in internal resistance during charging and discharging of the battery , The service life can be extended.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01M 10/36-10/40

Claims (3)

(57) [Claims] An electrode material and a layer mainly composed of a binder are disposed on both sides of a layer mainly composed of an electrolyte and a binder, and a conductive layer containing a binder is disposed outside the layer. A method for producing a solid secondary battery, wherein the above-mentioned layers are pressure-integrated under heating at a time, and the pressure is returned to normal pressure at a temperature lower than the softening point of the binder. 2. The method according to claim 1, wherein the pressure is integrated by a roller press method.
The method for producing a solid secondary battery according to the above. 3. The method for producing a solid secondary battery according to claim 2, wherein the roller pressing method comprises a plurality of roller pressing machines which are sequentially heated from a high temperature to a low temperature.