JPS61263051A - Solid electrolyte secondary battery - Google Patents

Abstract

PURPOSE:To obtain good charge-discharge cycle performance by constituting a solid electrolyte secondary battery with a negative electrode mainly comprising Cu, and Cu<+> ion conductive solid electrolyte, and a positive electrode obtained by replacing a part of NbS2 with In. CONSTITUTION:An all solid state solid electrolyte secondary battery is formed with a negative electrode 3 mainly comprising Cu, Cu<+> ion conductive solid electrolyte 2, and a positive electrode 1 comprising CuxNb1-yInyS2+1.5y (X=0.05-0.15, Y=0.01-0.10) which has layer crystal structure obtained by replacing a part of NbS2 which can dope and undoping Cu<+> ion between its layers with In and in which Cu is previously doped. Crystal distortion caused by doping and undoping of Cu<+> ions between S-S layers is reduced and the amount of doping between layers is increased. The drop in battery voltage during discharge is decreased and charge-discharge performance is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an all-solid state solid electrolyte secondary battery using a solid electrolyte having high ionic conductivity at room temperature.

Conventional technology Batteries using solid electrolytes that have high ionic conductivity at room temperature can be made into an all-solid state battery, so they are essentially free from leakage and have extremely low self-discharge during storage. It becomes a battery of credibility.

Conventionally, most of the proposed batteries have been primary batteries whose lifespan ends after one discharge. However, when the battery is used as a power source in the field of microelectronics, which is characterized by miniaturization of electric circuit elements, the battery is naturally required to be small. As batteries become smaller, their capacity decreases, so secondary batteries, which can be used repeatedly, are becoming more useful in place of primary batteries, whose lifespan runs out after one discharge.

A necessary requirement when constructing a secondary battery is that the positive electrode material and the negative electrode material have the ability to perform a reversible electrochemical reaction during charging and discharging of the battery.

In particular, it has been known for a long time that metal chalcogenides are useful as positive electrode materials in batteries using liquid electrolytes when an alkali metal such as Ll is used as the negative electrode. This metal chalcogenide has a layered crystal structure, and upon battery discharge, it occludes alkali metal ions and ions liberated from the negative electrode between the layers, and upon charging, it reversibly releases alkali metal ions from between the layers. It has the characteristic of being able to perform battery reactions.

Problems to be Solved by the Invention The metal chalcogenide described above can be used as a positive electrode material for an all-solid state secondary battery that has a negative electrode mainly made of copper and a Cu conductive solid electrolyte. As a person skilled in the art would easily think, which metal chalcogenides are
Furthermore, it was not at all clear to what extent Cu ions could be freely inserted and removed between the layers.

Means for Solving the Problems The present invention uses a negative electrode mainly composed of Cu, a Cu ion conductive solid electrolyte, and a positive electrode material in which part of NbS2, which allows Cu ions to be freely taken in and out between the layers, is replaced with indium. A novel compound with a layered crystal structure in which Cu is inserted in advance, CuxNb1yInys2+1,5y
(X:0-O6O-16, 7:0,010-10)
To provide a solid electrolyte secondary battery that exhibits good charge/discharge cycle characteristics.

Function: CuxNbl-yInysz+tsy, a novel positive electrode material according to the present invention, partially replaces Nb (ionic radius of 0.63 μm) in NbS 2 with In (ionic radius of 0.81 μm), and at the same time replaces Cu with S.
By inserting the Cu between the S-8 and S-8 layers, the crystal distortion caused by the insertion and removal of Cu between the S-8 and S-8 layers can be reduced.
During battery discharge, the amount of storage that can be stored between the cells, that is, the current exchange capacity can be increased either crystallically or electrostatically. The solid electrolyte secondary battery using the positive electrode material is
It can provide high capacity and good charge/discharge cycle characteristics.

Example (Example 1) Curve a in FIG. 1 shows RbCu41tsC7? as the CU ion conductive solid electrolyte. A negative electrode mainly made of Cu using xs, CuQ, jNbQ, 95InQ, 05S2.0
A solid electrolyte secondary battery with the cross-sectional structure shown in Figure 2, consisting of 8 positive electrodes, was charged at 100 μA until X=O, and then discharged at a constant current of 100 μA at 20°C. The change in battery voltage is shown with the X value on the horizontal axis. As can be seen from this curve a, the battery voltage shows a monotonous decrease as X increases, that is, as discharge progresses, and this decrease continues until X approaches 0.281, and a plateau appears when X exceeds 0.28. . In addition, x=o shown as a comparative example,
The curve is gentler than the curve showing the discharge characteristics of a battery using NbS 2 as the positive electrode, where y=o.

That is, G11zNb+-yInys2-H5y (
X: 0. O2N2.15. y:0. O1N0.10
) can maintain a single layered crystal structure until X is around 0.28, and can smoothly insert and remove Cu 2 ions until X is around 0.28.

For NbS2, the plateau of the cell voltage is X=0.25
It begins to appear near f-f, the battery voltage is lower than 8, and the ease with which Cu ions can be taken in and out is CuzNbl-yI.
It is inferior to nysz+tsy.

Curve a in FIG. 3 shows that a battery similar to the battery according to the present invention and exhibiting the characteristics shown in FIG. This figure shows the relationship between the battery voltage of the discharge bundle of each cycle and the number of charging/discharging cycles when repeated, and shows good cycle characteristics over 100 cycles.

The novel positive electrode material according to the present invention (Cu)(Nb1-7en7s2+157) is a mixture of metallic Nb powder, metallic In powder, and metallic Cu powder in a predetermined ratio, or an alloy powder of Nb, In, and Gu. Sulfur vapor is gradually introduced into the quartz glass container.
It can be obtained by heating reaction at 00°C, or as a simpler method, Nb82 powder and In2
S3 powder and Cu powder are mixed at a predetermined ratio, and about 7 citiesφ
It was molded into a pellet shape under a pressure of about 3 tons, and then vacuum sealed in a quartz glass tube at a pressure of 1 Torr or less.
It can also be obtained by heating reaction at 00'C for about 72 hours.

<Example 2> The y value is 0.01, 0,02.0,
05°0.10, 0.20, 0.30 CuO
, lNb1yInyS2++, sy are synthesized and these are used as positive electrode materials.
An 11 m solid electrolyte battery was constructed.

The above cathode powder, solid electrolyte powder, and anode powder are pressed into three layers under a pressure of about 3 tons to form a battery pellet, and then a current collector made of conductive carbon film and an electrode lead are placed on the cathode and anode sides. After heat-compression bonding, the battery was made by coating the entire battery with epoxy resin. Figure 2 shows a cross-sectional view of the solid electrolyte secondary battery made in this way, where 1 is a positive electrode layer, 2 is a solid electrolyte layer, 3 is a negative electrode layer,
4 is a current collector, 5 is an electrode lead, and 6 is a resin package.

Figure 4 shows the battery made in this way at 20°C.
It shows the relationship between the battery voltage at the end of discharge of each cycle and the number of charging/discharging cycles when charging and discharging is performed at a constant current value of 00 μm and the value of X is in the range of 0 to 0.26. According to the invention, the y value of In is 0.01, 0-02, 0.
cuo containing O5, 0,10, i Nb +-yIny
It can be seen that the battery using s2+t57 as the positive electrode provides excellent cycle characteristics.

<Example 3> The amount of CuO inserted in advance is X=O, O5゜0.1
．． cuxl'ibo which is 0.15, 9srno, os
s2. A solid electrolyte battery having a diameter of 7 mm and having the structure shown in FIG. 2 was constructed using these as positive electrode materials.

The weight and composition of the solid electrolyte material, negative electrode material, positive electrode, negative electrode, and solid electrolyte are the same as in Example 2. The method of assembling the battery is also the same as in Example 2.

Figure 5 shows the battery made in this way at 2°C, 1
Battery voltage at the end of discharge and charging/discharging at the end of each cycle when charging/discharging is performed with a constant current value of 00μ and the range of X is Q ~ 0.26
The relationship between the number of discharge cycles and the number of discharge cycles is shown, and all of the batteries exhibit excellent cycle characteristics over 100 cycles.

In the examples of the present invention, RbGu4It5CA3.5 was used as the Cu ion conductive solid electrolyte, but other Cu + ion conductive solid electrolytes, such as RbC
u4 engineering t25c huff 51 Rtlo7sKo, zsCu
4Its, (j?s,s) It goes without saying that the same effects as the present invention can be obtained by using a solid electrolyte, etc., in which a quaternary ammonium salt such as hexamethylenetetramine is added to CuBr.

Furthermore, as a negative electrode mainly composed of Cu, Cu +Cu
In addition to the mixture consisting of vsps + Cu + ion conductive solid electrolyte, there are also mixtures consisting of Gu + Cu ion conductive solid electrolyte, Cu'5M0636 + Cu
It goes without saying that the same effects as the present invention can be obtained by using a mixture of ionically conductive solid electrolytes.

Effects of the Invention According to the present invention, a solid electrolyte secondary battery having CuxNbl-yInys2+t5y as a positive electrode material, a negative electrode mainly composed of Cu, and a Cu+ ion conductive solid electrolyte has low polarization, that is, a The battery voltage drops slowly and provides excellent charging and discharging characteristics.

[Brief explanation of the drawing]

Figure 1 is a voltage change diagram during discharge of a solid electrolyte secondary battery according to an embodiment of the present invention, Figure 2 is a sectional view showing the structure of the battery, and Figure 3 is the charge/discharge cycle characteristics of the battery. Fig. 4 shows the charge/discharge cycle characteristics of the same battery, and Fig. 5 shows the charge/discharge cycle characteristics of the same pond. B...Battery of one embodiment of the present invention, b...
・Battery of comparative example, 1...Positive electrode layer, 2...
・Solid electrolyte layer, 3...Negative electrode layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure ρ, 6 10 χ I direct Figure 2 Figure 3...Negative polarity Figure 3 Katsu/Tatsutaku cycle number Figure 4 Noshi/decrepit cycle @Figure 5 circle/square i4L cycle (

Claims (1)

[Claims] A negative electrode mainly made of copper, a Cu^+ ion conductive solid electrolyte, and Cu_xNb_1_-_yIn_yS_2_+_1_. in which Cu is inserted in advance.
_5_ Sulfide represented by y (however, y: 0.01~
0.10, x: 0.05 to 0.15).