JPS6077304A - Lithium ion conductive solid electrolyte material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lithium ion conductive solid electrolyte material.

All-solid-state batteries (hereinafter referred to as solid-state batteries), which use lithium as the negative electrode active material and a lithium-conductive solid electrolyte as the electrolyte, have high energy density, do not leak, and can be made small and thin. , has many advantages.

The development of lithium ion conductive solid electrolyte materials is attracting attention for the purpose of industrial application of such solid-state batteries.

However, at present, no lithium ion conductive solid electrolyte material has been obtained, and only 40mo 1% 1
Only LSIs doped with 1.03 have been applied to lithium solid-state batteries and are in practical use.

Recently, LiaN%LixaZn (GeOa)
Although lithium ion conductive solid electrolyte materials such as a and Lis N-Li1 are attracting attention, it is difficult to say that they still fully satisfy the characteristics required for batteries.

and Eva, Lia N has low decomposition voltage, L4uZ
n(GeOa)a has low electrical conductivity at room temperature and is an unstable material, so none of them has been applied to solid-state batteries.

For this reason, there is a demand for the development of solid electrolyte materials that eliminate these drawbacks, particularly I materials that have high electrical conductivity and are chemically stable.

The present invention was made in view of the above-mentioned current situation, and an object of the present invention is to provide a lithium ion conductive solid electrolyte material that has high electrical conductivity and is chemically stable.

Therefore, the lithium ion conductive solid electrolyte material according to the present invention has the general formula: Lit + xNb1 + yl'l s + tOs (however,
-0.05≦X+LL≦0.05).

The lithium ion conductive solid electrolyte material according to the present invention has the advantages of relatively high lithium ion conductivity and stability against heat and moisture. By applying it to the electrolyte material of a solid-state battery, there is an advantage that the characteristics of the solid-state battery can be improved.

The present invention will be explained in more detail.

The general formula of the present invention is Li1 χNbz +yW 1 +tOs ・φ・(1
) (However, the composition represented by -0,05≦X+Y+Z+≦0.05> was produced by focusing on its crystal structure with the aim of producing a material with high lithium ion conductivity. We focused on the trirutile structure, and since the trirutile structure has gaps in the (001) direction, and it is thought that lithium ions can easily move in this direction, we focused on LiNbWOB-based materials that have this trirutile structure. .

In the above general formula (1), LiNbWO5 satisfies χ = y = z = 0, and is a typical substance in the above general formula (1).

For this LjNbWOa, the amount of Li, Nb, - is 5
When it is added excessively to the extent of %, or conversely when it is added too little, it almost becomes a phase with the trirutile structure of LtNMIOs, and both exhibit lithium ion conductivity. That is, the electrical conductivity of the lithium ion conductive solid electrolyte material according to the present invention varies slightly depending on the conditions of pre-firing, main baking, and hot pressing, but the electrical conductivity is maximum when χ-y=z-0, and X+y+Z is Relatively high ionic conductivity is maintained up to ±0.05.

However, if 1 has 1, ly l, ly l, 01
If it exceeds 05, different phases will be mixed in and the conductivity will be significantly reduced.

The method for manufacturing the lithium ion conductive solid electrolyte material according to the present invention is not limited in the present invention. For example, it can be manufactured by a normal porcelain firing method or a hot pressing method.

Specifically, it can be manufactured, for example, as follows.

First, commercially available special grade reagents Lit COa and Nb1! Os
, 03 as raw materials, and these raw materials as Liz+xNb
Based on the weighing formula t+γ-1+χ06, a predetermined amount is weighed, placed in an aluminum pot using a bot mill, and fired.

First, it is kept at 600°C for several hours to decompose LigCO3, and then fired in the air at a temperature of 700 to 760°C for 24 to 120 hours. After firing, the reaction product is taken out from the furnace, pulverized, and then molded into a molded body under a pressure of 1 to 5 L/cd.

This molded body is further baked at 760°C for 6 hours, or
Hot press firing is carried out at a temperature of 60-800° C. and a press pressure of 400 Kg/J for 2 hours.

The sintered body produced as described above is cut into the desired shape,
Used as a solid electrolyte material for solid batteries that use lithium as the negative electrode active material.

The present invention will be explained in detail below.

In the following examples, the conductivity was measured from a sintered body of 5
Cut out a rectangular parallelepiped of size x5 x4mm or 12
A disk-shaped sintered body having a diameter of m+gφ and a thickness of 21 cm was used as a sample, electrodes were attached to both sides, and the AC two terminal method was used.

In addition, the electron transfer number was determined from the conductivity determined by the direct method.

In the case of alternating current, an impedance analyzer was used as the measuring instrument, and the conductivity was determined by the multiple impedance method.

Example 1 According to the above manufacturing method, LiNbWOe (when X = y = z = 0 in the general formula (1)), Lf
+, esNVO6 (x = 0.05 + y = z = o)
, LiasNbWOe (x = -0°05, y =
z = o), LiNbtasWOs (x = z
=(LV=o.

/- pressure, mold to 12wφ, ~5mm diameter, 760
This is a graph showing the results of ``c''.

Example 2 According to the method described above, L, INbHOe was produced by the Hontopress method. After calcining the raw material powder, it is molded and
℃, 400 Kg/ctl, 2 hours in vacuum.

The measurement results of electrical conductivity are shown in FIG.

For comparison, 1
The results for NbWOs are also shown. In the figure, F is a graph showing the temperature dependence of the conductivity of LiNbWOe produced in Example 2.

As is clear from Fig. 2, the conductivity of the hot-pressed sample at 200°C is 6Xl0-6Ω-'c
m', which was found to be better than the firing method of Tsuji (Example 1).

For this sample, the ion blocking electrode PL
-The conductivity was determined by the direct current method with a Pd electrode attached, and the result was about 2×10-7Ω゛tC,-i at 200°C. In addition, the electron transport number of this LiNbWOe is 0°0
It was found that the conductivity of this sample was due to ions.

The difference in electrical conductivity between the samples obtained by the tπ firing method and the Botto press method is thought to be due to the difference in the sintered density of sample H.

Starting with the solid samples in the above examples, Lid÷, Nbs
+yll s +zOe (however, -0,05≦X+V
+2+≦0.05) samples were examined using the final X-ray diffraction method, and as a result, they were almost all single-phase trirutile phase of LjNbWOs. x = -0.05, y - ±0.0
In the case of 5.2=±0°05, an extremely weak different phase is observed. The reason why the conductivity of these samples is slightly lower than that of LiNb11Os is thought to be due to the different phase, and it was found that the trirutile structure allows ions to move easily in the direction of the gap.

As explained above, according to the present invention, Ijl+χNbl÷
A lithium ion conductive solid electrolyte material composed of γWz+xOe exhibits relatively high lithium ion conductivity by having a trirutile structure.

Furthermore, this lithium ion conductive solid electrolyte material is stable against heat and moisture, and has the advantage that it can improve the characteristics of solid-state batteries by using it as an electrolyte material for lithium solid-state batteries.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the temperature dependence of the electrical conductivity of a lithium ion conductive solid electrolyte material according to an example of the present invention, and FIG. FIG. 3 is a diagram showing the temperature dependence of the conductivity of LiNb1'10e. Applicant's agent Masaki Amemiya No. 1 Cause No. 2

Claims (1)

[Claims] General formula, Lid +xNb1+yHs +xOa (however, -0,
05≦X+V+Z+≦0.05).