JPH0315167A - Solid state secondary battery - Google Patents

Abstract

PURPOSE:To prevent minor short circuit caused by pinholes by forming a layer mainly comprising a positive electrode material, and electrolyte, and a binder and a layer mainly comprising a negative electrode material, the electrolyte, and the binder at some intervals on one side of a layer mainly comprising the electrolyte and the binder. CONSTITUTION:Positive and negative carbon current collectors 2 are formed at some intervals on a base plate 1, and positive and negative electrodes 3 are formed on the carbon current collectors 2. Solid electrolyte layers 4 are formed by extending over the positive electrode 3 and the negative electrode 3. Since the solid electrolyte layer 4 which is not in contact with the electrode 3 exists between the electrodes, short circuit is avoided and self-discharge is also decreased. A copper chevrel compound is used as the electrode materials of both electrodes, and a copper ion conductor such as RbCu4IxCly solid electrolyte is preferably used as the electrolyte. AgxV2O5 may be used in the positive and negative electrodes and a silver ion conductor such as Ag6I4WO4 may also be used as the electrolyte.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to so-called solid-state secondary batteries whose structural materials are all solid.The present invention relates to so-called solid-state secondary batteries whose structural materials are all solid. So-called solid-state batteries have attracted attention as both primary and secondary batteries because they do not leak, are expected to be highly reliable, and can be made smaller and lighter.Currently, they are being considered mainly for memory backup in various devices. With this solid battery &yo Li゜ ion conductive solid electrolyte, A as a solid electrolyte for moving ions in the battery
g" ion conductive solid electrolyte, H ゜ ion conductive solid electrolyte and RbCu4r+.sC ls.s, CuI-
Although Cu" ion conductive solid electrolytes such as Cu20-MoOs have been discussed, positive electrode materials include Cus. + TiSa,
Ag@. tT i StSC us-+N b Ss,
Ags. +NbS*, W O s, and CuvMo*
Chevrel phase compounds such as S*-z, AgvMo@Sm-2 are listed.
In addition, Chevrel phase compounds similar to those used for positive electrodes have been tried.As for the structure of these batteries (like other batteries, the positive electrode and the negative electrode have layers mainly composed of an electrode active material and a binder on both sides). It is common to arrange a layer mainly containing an electrolyte and a binder in the center.A preferable example is a positive electrode.As an electrode material that also works with the negative electrode, for example, a Chevrel phase compound such as CuvMo●S●-2 is used. For use as electrolyte RbCu41 +.i
C l s. s When a copper ion conductive solid electrolyte is used, copper ions move from the positive electrode to the negative electrode during charging, and vice versa during discharge.In the battery using the copper ion conductive solid electrolyte mentioned as a preferable example, the circuit voltage i & 0. 5~0.6V,
The operating voltage is small at 0.1 to 0.5V (t) Household batteries are used at a voltage of 1.5V or higher, so they must be stacked for practical use.
Denho: If all solid electrolytes can be formed using a printing method, the number of layers can be freely changed just by changing the printing pattern.
High-voltage batteries can be manufactured easily, and the manufacturing method is industrially superior.However, the problem that the invention aims to solve is that, like other batteries, the electrode active material and the binder are used as the negative electrode. With the conventional structure described above, which has layers on both sides and a layer containing mainly electrolyte and binder in the center (top), it is difficult to obtain a battery with a high initial capacity due to the bottle holes in the electrolyte layer, which tends to cause short-circuited batteries. In addition, even if a certain initial capacity is obtained, there is a problem of large self-discharge, making it difficult to manufacture fully printed solid-state batteries. Instead of arranging a positive electrode and a negative electrode, a layer mainly containing an electrolyte and a binder is placed on one side, and a layer mainly containing a positive electrode material, an electrolyte, and a binder, and a layer mainly containing a negative electrode material, an electrolyte, and a binder. All of the solid electrolyte is formed using a printing method.In addition, in the process of forming these layers, pressure is applied by a press and a large amount of binder is applied. It is preferable to perform heating at a temperature higher than that at which softening occurs.As the electrode material, <1 CuvMo@S●-2, AgvMo
Siebrel phase compounds such as ss●-1 and A g
Even if eOs is raised, a positive electrode layer containing an electrolyte and a negative electrode layer also containing an electrolyte are formed on one side of the electrolyte layer with a distance maintained between them. Therefore, it depends on the width of the electrode layer.Compared to conventional battery construction, the distance between the electrodes is large, especially on the electrode layer on the opposite side of the counter electrode, and therefore it is not suitable for applications with large loads. I. %
Since there is an electrolyte layer between the two electrodes that does not contact the electrodes, there is no fear of short circuits when using a thin electrolyte layer as in the case of printing.I,Xo
Therefore, it is also advantageous in terms of self-discharge characteristics.
Since the layers of the five negative electrodes are formed only on one side of the electrolyte layer, if the set of five negative electrodes is the same, both electrodes can be printed on one side of the electrolyte layer at the same time, which greatly simplifies the manufacturing method. Figure (Friend) is a cross-sectional view of a solid-state secondary battery in one embodiment of the present invention, and even though it shows an example of a three-element stack, carbon paste is first applied on a polyethylene terephthalate substrate 1.
Copper Chevrell (C u 2Mo sS =) was used as the material for the electrodes.1. % RbCu4I+. as an electrolyte. iCls1 2 0
W t 9A Add a toluene solution of commercially available methyl methacrylate as a binder to a concentration of 8 wt % and stir thoroughly to obtain a paste. Spread this paste onto the positive and negative carbon current collectors 2. Dry the seal using a screen and form the positive and negative electrodes 3. Next, use RbCu4I+ as the electrolyte. sC lz
．． Using s1,＼ A toluene solution of commercially available methyl methacrylate was added as a binder to a concentration of 8 wt%, and the mixture was thoroughly stirred to create a paste. &E Negative electrode 3,
The solid electrolyte paste is printed across layers 3 using a metal screen to form solid electrolyte layer 4. Although the printing process is repeated three times in total, after drying at 130°C,
50Q} (g) through a roller press machine heated to 50℃
The electrodes 3 and the electrolyte layer 4 were both 0.10 mm thick. Positive and negative electrodes 3, 3
The size of both is 20 x 5 mm, and the weight is 2.
6mg is enough.Finally, cover the battery surface with polyacrylic resin! L Furthermore, a room-temperature-curing epoxy resin is applied on top of it to construct a battery, f, and this battery is A.
shall be.

Next, for comparison, a battery with a conventional structure consisting of an electrolyte and electrode layers formed on both sides was fabricated.A positive current collector was first printed on a ready-to-board polyethylene terephthalate substrate, and then A conventional battery was created by sequentially forming positive electrolyte, negative current collector, and negative current collector using a printing method and bonding them under heat.In this case, the printing process was performed five times.This battery was made into B
The areas and weights of the positive and negative electrodes were the same as those of A.I made 10 batteries each of A and B and compared their performance.First, I checked the discharge voltage and capacity during normal charging and discharging.
Charging to 1.5V at A and discharging to 0.9V at 50μA. All discharge capacity at A is 250μA.
On the other hand, in B, there were many short-circuits, and 7 batteries had a capacity of less than 10 μAh, and even the one with the highest capacity had a low performance of 120 μAh.Next, we looked at the self-discharge of each battery. Check the gender 7'=
After charging to 1.5V and leaving it at 30℃ for 1 month, we checked the capacity and found that the retention rate for A was 98%, which had hardly decreased, but for B, it had all decreased to less than 10%, which is also true for A.
The reason why the self-discharge is large in t and B is thought to be due to the presence of pinholes in the electrolyte layer, which causes minute short circuits.In order to reduce these pinholes, the electrolyte layer is printed twice, and the thickness of the electrolyte layer is increased. Self-discharge was also investigated for batteries that were nearly twice as thick as the battery.The performance improved slightly, with only three batteries having a capacity of 10μAh or less, and the largest having a capacity of 210μAh.
μAh was obtained.However, even batteries with a relatively large initial capacity had a large self-discharge, and in the same test as above, the maintenance rate was 2L.
% and A is still worse than 1%, and the embodiment with % or more is CuaMoS self and R b Cu a r as electrode 3.
+. sC I i. A mixture of RbCu4I+.s is used as the electrolyte of the solid electrolyte layer 4. sCls. The force t is the result when using s Ag●. AgsIJ using a mixture of TeV20s and AgsI4W○4 as an electrolyte.
Even when using WO4, the rate characteristics are inferior, but the same thing can be said.A horizontal solid-state secondary battery in which the positive and negative electrodes are arranged side by side has a good yield and a high initial capacity, and the self-discharge is also small, but the number of layers is Although we have described the case of 3 layers, it is possible to easily create a battery with more layers by changing the printing pattern.A battery with 60 layers stacked has a charging voltage of 30v1.
Although a high voltage battery with a final voltage of 15V has been obtained, the effects of the invention are as follows. Since the layer containing the negative electrode material, electrolyte, and binder are formed with a certain distance between each other, it is difficult to obtain excellent self-discharge characteristics due to the possibility of minute shorts caused by pinholes between the electrodes. The yield is high, high voltage products can be easily obtained, and the manufacturing method is simplified because it is entirely printed and the number of times of printing is small, which is a great advantage.

[Brief explanation of the drawing]

The figure is a partial longitudinal cross-sectional view of a solid state secondary battery in an embodiment of the present invention.

Claims (3)

[Claims] (1) In a solid secondary battery in which the current collector, electrode, and solid electrolyte are all formed by a printing method, the positive electrode material, electrolyte, and binder are coated on one side of the layer that mainly contains the electrolyte and binder. A solid secondary battery characterized in that a main layer and a layer mainly containing a negative electrode material, an electrolyte, and a binder are formed with an interval maintained between them. (2) The solid secondary battery according to claim 1, wherein the electrode material is a copper Chevrel phase compound for both the positive electrode and the negative electrode, and the electrolyte is a copper ion conductor such as an RbCu_4I_xCl_y solid electrolyte. (3) The electrode material of the solid-state secondary battery is Ag_ for both the positive and negative electrodes.
2. The solid secondary battery according to claim 1, wherein xV_2O_5 and the electrolyte is a silver ion conductor such as Ag_■I_4WO_4.