JPH06333577A - Lithium solid electrolytic battery - Google Patents

Abstract

PURPOSE:To provide a lithium solid electrolytic battery capable of taking out a high output and stably operating even in the air. CONSTITUTION:A lithium solid electrolytic battery has a bulkhead 5 consisting of a lithium ion conductor; a non-metallic positive electrode active material 6 capable of receiving lithium ion; and a nonmetallic negative electrode active material 7 capable of releasing lithium ion. The lithium ion conductor is formed of a composite oxide having perovskite structure, the half or more of the site A of the perovskite is occupied by lithium and trivalent metal atoms. When lithium metal or a lithium alloy is used as the negative electrode active material 7, a reaction preventing film is put between the negative electrode active material 7 and the bulkhead 5. In a specified perovskite structure, this reaction preventing film is not required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery using a lithium ion conductive solid electrolyte.

[0002]

2. Description of the Related Art Liquid electrolytes, in which an inorganic electrolyte such as lithium perchlorate (LiClO ₄ ) is dissolved in an organic electrolyte, are used in lithium ion batteries currently in practical use. However, if a solid can be used as the electrolyte, there is no liquid leakage, evaporation, etc., and it is extremely advantageous in terms of storage stability, long-term reliability, and the like. However, at present, a solid electrolyte having high lithium ion conductivity has not been obtained, and a large current cannot be taken out.

For example, there is a method of contacting a negative electrode of Li and a positive electrode of poly-2-vinylpyridine.nI ₂ to generate LiI. However, the conductivity of LiI is on the order of 10 ⁻⁷ S / cm. Li / LiI (Al ₂ O ₃ ) / PbI
_{The 2-} PbS battery uses an electrolyte in which Al ₂ O ₃ is mixed with LiI, but the conductivity is on the order of 10 ⁻⁷ S / cm. Therefore, various substances have been searched for solid electrolytes having high lithium ion conductivity.

However, LiI, LiBr, LiI-Al
₂ O _{3 and the} like are unstable in the air and have a hygroscopic property. Li ₃ N and its derivatives are unstable in air. On the other hand, oxygen salt-based lithium ion conductors have high application value because they are stable in air, and many studies have been conducted. LISICON also belongs in this. Among these types of compounds, Li _3.5 V _0.5 Ge _0.5 O ₄
Has the highest lithium ion conductivity at room temperature (σ = 5 × 10 ^-5
S / cm).

Latie et al.
Magazine: J. Solid State Chem. "51, 293, 1984
Li_xLn_1/3Nb_1-XTi_XO₃(Ln = La,
Nd, x ≦ 0.1), the ionic conductivity was measured, and N
I have investigated the ion conduction mechanism by MR. This Io
We will briefly touch on conduction. Ln_1/3NbO ₃smell
, Niobium exists in the center of the octahedron of oxygen, and
Two vacant sublattices appear alternately at the position to be turned.
Therefore, Latti and others are Nb⁵⁺Part of Ti⁴⁺Replaced a little with
And L corresponding to this₁ ⁺Introduced into the vacant sublattice
is doing. L₁ ⁺Conducts a vacant sublattice. The best
The composition of the ionic conductor is Li_0.05La_1/3Nb_0.95Ti
_0.05O₃It was said that.

[0006]

However, at present, it is hard to say that the ionic conductivity of a known lithium ion conductor is still sufficiently high in practical use. Therefore, a lithium solid electrolyte battery that can compete with a lithium battery using an organic electrolytic solution in terms of output cannot be obtained.

An object of the present invention is to provide a lithium solid electrolyte battery which can take out a high output and can operate stably even in the air.

[0008]

The present invention is a lithium ion conductor comprising a complex oxide having a perovskite structure, in which more than half of the A sites of the perovskite structure are occupied by lithium and trivalent metal atoms. Relating to a lithium solid electrolyte battery, comprising a partition wall made of a lithium ion conductor, a non-metal positive electrode active material capable of receiving lithium ions, and a non-metal negative electrode active material capable of releasing lithium ions. Is.

Further, the present invention is a lithium ion conductor comprising a complex oxide having a perovskite structure, in which more than half of the A sites of the perovskite structure are occupied by lithium and trivalent metal atoms. A partition wall made of a conductor; a non-metal positive electrode active material capable of receiving lithium ions; a negative electrode active material made of lithium metal or a lithium alloy; and a reaction preventive film sandwiched between the negative electrode active material and the partition wall. The present invention relates to a lithium solid electrolyte battery including:

Further, according to the present invention, (D _y Li _x ) (Mg _0.5 W _0.5 ) O ₃ (D is a trivalent metal atom having a perovskite structure. 0 <x ≦ 1/2, 1/2 ≦ y ≦ 2/3, 1/2
<X + y ≦ 1, 1.6 ≦ x + 3y ≦ 2.2) partition wall;
The present invention relates to a lithium solid electrolyte battery including a non-metal positive electrode active material capable of receiving lithium ions; and a negative electrode active material made of lithium metal or a lithium alloy.

The present inventor discovered in the process of studying the physical properties of a complex oxide having a perovskite structure that the perovskite structure having the above specific composition has extremely high lithium ion conductivity.

Specifically, it is necessary that at least half of the A site is occupied by lithium and a trivalent metal atom. That is, the vacancy at the A site needs to be half or less.

Furthermore, the average valence at the A site is 1.6.
It is preferably about 2.2. Further, the average valence at the B site is preferably 3.5 to 4.0.

The trivalent metal atom occupying the A site includes neodymium, praseodymium, samarium, yttrium, bismuth, lanthanum, cerium, promethium, europium, cadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Is preferred. Furthermore, neodymium,
Praseodymium, samarium and lanthanum are preferred.

On the other hand, the metal atom occupying the B site is preferably a tetravalent one such as titanium, zirconium or hafnium. Alternatively, two or more kinds of metal atoms can be used, but in this case also, the average valence of the two or more kinds of metal atoms is preferably tetravalent. Further, Ti ⁴⁺ , (Mg ²⁺ _1/2 W ⁶⁺ _1/2 ) is preferable.

Further, those having a composition represented by the following general formula are particularly preferable.

[Formula 1] Li_xLa_yTiO₃, (D_yLi_x) (Mg_0.5W
_0.5) O₃ (In particular, Li_xLa _y(Mg_0.5W_0.5)
O₃)

In these general formulas, the oxygen number is defined as "O ₃ ".
However, this is in accordance with the custom when displaying a complex oxide having a perovskite structure, and in reality, some oxygen atoms may be deficient or may go in and out depending on the atmosphere and temperature changes. .

In the above general formula, 0 <x≤1 / 2 and 1 / 2≤y≤2 / 3. Of course, when the lithium substitution amount x increases, the lanthanum substitution amount y decreases.
If the average valence at the A site is 2, y
= (2 / 3-x / 3). However, the average valence at the A site can fluctuate in the range of 1.6 to 2.2. Therefore, the relationship between x and y is as follows.

[0019]

## EQU00002 ## 0 <x.ltoreq.1 / 2. 1/2 ≦ y ≦ 2/3. 1/2 <x + y ≦ 1. 1.6 ≤ x + 3y ≤ 2.2.

In the above general formula, the substitution amount x of lithium x
The increase in γ tends to increase the lithium ion conductivity. However, when 0.7 ≦ x + y ≦ 0.9, the lithium ion conductivity is highest. Furthermore, the present inventor has found that when x is in the range of 0.26 to 0.34, lithium ion conductivity is significantly improved. Further, it was found that the maximum lithium ion conductivity was obtained when x was 0.28 to 0.32.

According to the present invention, a lithium solid electrolyte battery having a large output can be obtained by using the above new lithium ion conductor as a partition. Also, the conductor is stable in air and can operate at high temperatures.

On the other hand, the present inventor has found the following problem with the above lithium ion conductor. That is,
When this perovskite structure was brought into contact with lithium metal, a reaction with lithium metal occurred, and the perovskite structure changed from white to a bluish black color. By this reaction,
It has been found that the perovskite structure becomes electronically conductive and cannot be used as an ion conductive partition of a lithium battery.

Therefore, in the present invention, a non-metal positive electrode active material capable of accepting lithium ions and a non-metal negative electrode active material capable of releasing lithium ions are used. Alternatively, when lithium metal or a lithium alloy is used as the negative electrode active material, the reaction preventive film is sandwiched between the lithium metal or the lithium alloy and the partition wall, and the perovskite structure does not come into contact with the lithium metal or the lithium alloy. To do so.

Further, the present inventor has searched for a material that does not easily react with lithium metal within the frame of the above perovskite structure. As a result, as described above, (D _y Li _x ) (Mg
_{0 .5} W _0.5) O ₃ (in _{particular, Li x La y (Mg 0.5} W 0.5)
It has been found that O ₃ ) has lithium ion conductivity and hardly reacts with lithium metal.

As a result, it has become possible to produce a lithium solid electrolyte battery by using lithium metal or a lithium alloy as the negative electrode active material and bringing this into contact with a chemically stable perovskite structure.

[0026]

Example (Production of Sample) La ₂ O ₃ , Li ₂ CO ₃ and TiO ₂ were used as starting materials. The amount of metal in La ₂ O ₃ was measured by quantitative analysis using EDTA. These starting materials were stirred in ethanol. The molar ratio of La: Li: Ti was 1: 1: 2. This mixed powder is heated to 800 ° C in air.
It was calcined for 4 hours at 1150 ° C for 12 hours.

The calcined product was crushed and press-molded under a pressure of 130 MPa to obtain pellets having a diameter of 10 mm and a thickness of 1 to 3 mm. The pellets were calcined in air for 6 hours at 1350 ° C. and allowed to cool to room temperature.

(Chemical composition). The molar ratio of each metal in the sample was measured by the inductively coupled plasma spectroscopy (ICP) by the external standard method. As a result, the molar ratio of each metal was Li: La: Ti = 0.34: 0.51: 1. Therefore, the composition formula of the above sample is Li _0.34 La _0.51 TiO _2.94.
Met. However, the amount of oxygen was determined from the principle of electrical neutrality.

The target composition in this experiment is Li _0.5 La.
It was _0.5 TiO ₃ . Therefore, during the high temperature treatment, part of the lithium has evaporated. As a result,
Only 85% of A site is filled, and there is a vacancy.

(Crystal structure of sample). The crystal phase was identified and the lattice constant was measured by a powder X-ray diffraction method using CuKα radiation. As a result, it was confirmed that it had a cubic perovskite structure. From the analysis of the crystal structure, La ³⁺ and TiO ₆ octahedron form a solid frame,
It is considered that lithium ions are statistically dispersed in the A sites other than the A sites occupied by La ³⁺ . In addition, it was also confirmed that in this perovskite structure, an extremely large number of equivalent sites suitable for accommodating lithium ions were present.

Therefore, at the A site in the perovskite structure, a large number of equivalent sites suitable for accommodating lithium ions are present between the sites occupied by La ³⁺ , and a suitable number of vacancies are present. It is considered that the lithium ions of the above move sequentially.

(Relative density and electronic conductivity). The relative density of the above samples was greater than 90%. The electronic conductivity (at room temperature) of this sample was measured by a direct current polarization method using two silver paste electrodes, and was found to be 1 × 10 ⁻⁸ S at room temperature.
It was smaller than / cm.

(Production of mixed conductor by reaction of sample with lithium). When the above sample is sandwiched between lithium metals in an Ar atmosphere at room temperature, the total conductivity is initially 2 to 4 × 10.
It was ^-5 S / cm (DC method). This is 1x after 3 days
It reached 10 ^-2 S / cm. During this period, the above perovskite structure easily reacted with lithium metal, and the color of the sample changed from ivory to blue-black. It is considered that this is because lithium entered the above-mentioned vacancies of the perovskite structure and reduced tetravalent titanium ions, and as a result, electron carriers increased and electron conductivity increased.

However, even after the reaction, the increase in lithium content was not detected by ICP, so the increase in lithium was extremely small. Further, in air, the electron conductivity of the sample after the reaction became lower with time, and the color gradually faded. This is because the titanium ion (Ti ³⁺ ) was re-oxidized by the oxygen that entered the vacancy of the oxygen atom.

As described above, the lithium ion conductor of the present invention chemically reacts with lithium to increase the electron conductivity and becomes a mixed conductor. Therefore, it is necessary to prevent the lithium ion conductor of the present invention from coming into direct contact with lithium metal in the lithium solid electrolyte battery.

(Measurement of lithium ion conductivity). The lithium ion conductivity of the above sample at room temperature in an argon atmosphere was measured by the direct current method.

However, as described above, this sample easily reacts with lithium metal. Therefore, as shown in FIG. 1, porous polypropylene films 2 were attached to both surfaces of the pellet (Sample 1). This polypropylene film 2 has 1
It is impregnated with a propylene carbonate solution containing M LiClO ₄ . Then, each polypropylene film 2
The lithium electrode film 3 was attached to the surface of the. The polypropylene film 2 prevents the sample 1 from coming into contact with lithium metal.

The resistance value of this polypropylene film 2 is small and can be ignored. Using this assembly, the ionic conductivity was measured by the direct current method. As a result, the color of Sample 1 did not change, and the electronic conductivity also did not change.

At room temperature, the equilibrium conductivity values corresponding to the lithium ion conductivity of the samples having different thicknesses were measured by the direct current method and found to be 2 × 10 ^-5 S / cm. These values are in agreement with the initial values measured by the direct current method by directly contacting the sample with lithium metal.

The lithium ion conductivity of the above sample was measured by the AC impedance method at 5 Hz to 13 MHz.
Was measured in a temperature range of 200 K to 700 K over a frequency range of. A gold electrode was used for the measurement. It was found that the conductivity measured by the AC impedance method can be divided into contributions from bulk crystals and contributions from grain boundaries. FIG. 2 is a model of an equivalent circuit corresponding to a bulk crystal and a grain boundary. Here, R _b represents the resistance of the bulk crystal, C _b represents the capacitance of the bulk crystal, R _gb represents the resistance of a grain boundary, and C _gb represents the capacitance of the grain boundary.

The bulk crystal and grain boundary region key at 300 K
The capacity is 100 pF and 10 nF, respectively.
It is an order. The conductivity in bulk crystals is σ _bulk=
1 x 10^-3S / cm, conductivity at the grain boundary is σ_gb= 7.
5 x 10^-FiveS / cm. Measured by AC impedance method
The total conductivity at 300K is 7 × 10^-FiveS / cm.
This value matches the value measured at room temperature by the DC method.

Since the electronic conductivity of the above sample measured by the direct current method is less than 1 × 10 ^-8 S / cm, the transport number of ions exceeds 1000 times the transport number of electrons.

FIG. 3 is a graph showing the temperature dependence of the ionic conductivity of the sample in the Arrhenius plot. Above room temperature, the activation energy of the bulk crystal part is
It decreases with increasing temperature. The activation energy calculated using this data is 0.15 eV above 400 K.
And 0.40 eV at 400 K or less. This phenomenon is
It can be attributed to some phase transition. The activation energy of the grain boundary portion is constant at 0.42 eV.

Table 1 shows the relationship between the ionic conductivity σ _bulk corresponding to the bulk crystal part, the ionic conductivity σ _gb corresponding to the grain boundary part, the total conductivity σ _total and the temperature. This corresponds to a part of FIG. 200K, 70
In the case of 0K, since σgb and σbulk cannot be distinguished, only the value of σtotal is shown.

[0045]

[Table 1]

Furthermore, the system of La _{2 / 3-m} Li _3m Ti0 ₃ and (La _{2 / 3-m}
Li _3m ) (Mg _0.5 W _0.5 ) O ₃ and lithium ion conductivity were measured. (Production of sample)

La₂O₃(4N purity), Li₂CO₃(3N or 4
N purity), TiO₂(3N purity), MgO (4N purity) and
WO₃(5N purity) was used as the starting material. La ₂O₃Over
The amount of metal in MgO and MgO was determined by quantitative analysis using EDTA.
Therefore, it was measured. These starting materials in ethanol
I stirred it. Stoichiometric mixture of powders, some intermediate
While crushing, calcine in air at 800 ° C for 4 hours,
It was calcined at 1150 ° C to 1200 ° C for 6 to 12 hours.

The calcined product was crushed and pressed under a pressure of 130 MPa to obtain pellets having a diameter of 10 mm and a thickness of 3 mm. This pellet in air for 3 to 10 hours, 1350
Baking was performed at ℃ to 1400 ℃, and cooled to room temperature.

(Crystal structure of sample) The crystal phase was identified and the lattice constant was measured by the powder X-ray diffraction method using CuKα radiation. At this time, an Rigaku or Mac Science X-ray diffractometer equipped with a graphite monochromator was used. Silicon powder (5N) was used as an internal standard for the sample when measuring the lattice constant.

(Chemical composition) The molar ratio of each metal in the above sample was measured by the inductively coupled plasma spectroscopy (ICP) by the external standard method. The sample for analysis was manufactured as follows. A small amount of sample (about 10 mg) and 1 ml of concentrated hydrochloric acid (35% by weight) were enclosed in a Pyrex glass tube and kept at about 130 ° C for 1 to 3 hours to dissolve.

(Measurement of Lithium Ion Conductivity) The lithium ion conductivity for a sample having a gold or silver paste electrode was measured from 5 Hz to 13 Hz by an AC impedance method using a YHP4192 impedance analyzer.
It was measured over the frequency range of Hz. The ionic conductivity at room temperature in an argon atmosphere was also measured by the direct current method.

The sample reacts readily with lithium metal. Therefore, as shown in FIG. 1, porous polypropylene films 2 were attached to both surfaces of the pellet (sample) 1. This polypropylene film 2 is impregnated with a propylene carbonate solution containing 1M LiClO ₄ .

Next, the lithium electrode film 3 was attached to the surface of the polypropylene film 2. The polypropylene film 2 prevents the sample 1 from coming into contact with lithium metal. The resistance value of this polypropylene film 2 is small,
Can be ignored. Using this assembly, the ionic conductivity was measured by the direct current method. The same cell was used for the AC impedance method to check the ionic conductivity at room temperature obtained by the DC method and the AC method described above.

(Test Results for the System of La _{2 / 3-m} Li _3m Ti 0 ₃ ) The structural units of these compounds have two subcells caused by the A-site deficient arrangement order along the C axis. . In this study, the inventor investigated not only ionic conductivity, but also chemical composition, especially with respect to lithium content. Table 2 shows the results of the chemical analysis, the amount of A site deficiency, the ionic conductivity at 300 K, and the activation energy. However, the A site deficiency is 1- (Analysis value of La)-(Analysis value of Li). The activation energy value was calculated using the data at 250K-400K.

[0055]

[Table 2] Composition of starting materials Bulk activation at A site 300K (Analysis data) Ionic conductivity energy (/ Scm ¹ ) (eV) La _0.5 Li _0.5 TiO ₃ (La _0.51 Li _0.34 TiO _2.94 ) 0 .15 1.0 × 10 ^-3 0.38 La _0.55 Li _0.35 TiO ₃ (La _0.57 Li _0.26 TiO _2.99 ) 0.17 1.0 × 10 ^-3 0.34 La _0.6 Li _0.2 TiO ₃ (La _0.62 Li _0.16 TiO _3.01 ) 0.22 6.3 × 10 ^-4 0.33 La _0.63 Li _0.1 TiO ₃ (La _0.64 Li _0.067 TiO _2.99 ) 0.29 7.9 × 10 ^-5 0.36

FIG. 4 shows the temperature dependence of the ionic conductivity of the bulk portion from the sample, that is, the Arrhenius plot. The activation energy decreases as this temperature increases, and the conductivity value appears to approach a composition-independent saturation value at high temperature.

This can be caused by thermal disturbances due to lattice vibrations at high temperatures. In such a high temperature region, lithium ions jump and easily move in a narrow range, but on the other hand, the probability of lithium ions colliding with each other also increases, and this collision reduces the mobility of lithium ions. The activation energy obtained from this data is 25
It is almost the same between 0K and 500K, and is 0.33 to 0.38 eV as shown in Table 2.

FIG. 5 shows the ionic conductivity of the bulk part at 300 K as a function of Li content obtained from ICP analysis. This ionic conductivity increased as the Li content increased or the La content decreased. However, this conductivity is approaching saturation.

This tendency can be estimated as follows. That is, the amount of Li is 3 m, the amount of La is 2 / 3-m, and the amount of voids in the defective portion at the A site is 1 / 3-2 m due to the principle of electrical neutrality. Since lithium ions are considered to move only in the voids of the A site, the mobility of lithium ions is considered to be proportional to the value obtained by multiplying the amount of lithium by the amount of voids, that is, the square of m.

Actually, the lithium substitution amount of 3 m is 0.31
, The maximum lithium ion conductivity σ = 1.02 ×
10 ⁻³ Scm ⁻¹ was obtained. Also, 3m = 0.26 ~
The lithium ion conductivity is remarkably high in the range of 0.34.

(Results for System of (La _{2 / 3-m} Li _3m ) (Mg _0.5 W _0.5 ) O ₃ ) The present inventor has lithium ion conductivity and is chemically stable to lithium metal. We searched for new perovskite compounds. The above-mentioned La _{2 / 3-m} Li _3m TiO ₃ -based compound easily reacts with lithium metal and has relatively high electron conductivity (10 ⁻² Scm ⁻¹ at room temperature).

Here, the present inventor has (La _{2 / 3-m} Li _3m )
Compounds of the (Mg _0.5 W _0.5 ) O ₃ series were tested. La _2/3 (Mg _0.5 W) of the perovskite structure, which is the mother compound of this system compound
_0.5 ) O ₃ is a known compound and has been synthesized (Torii
Chem. Lett. 1979, 1215). According to the analysis of the author of this document, Mg ^{2 +} and W ^{6 +} are arranged in a rock-salt-like manner within this B site, while La ^{3 +} and vacancies within the A site are layered along the c-axis. It is arranged in a state.

Based on such an order of each component ion in La _2/3 (Mg _0.5 W _0.5 ) O ₃ , the following thought was reached. That is, the compound of the system of (La _{2 / 3-m} Li _3m ) (Mg _0.5 W _0.5 ) O ₃ is chemically stable against lithium, and it is not inferior to exerting electron conductivity. I thought and proved.

According to the procedure described above, (La _{2 / 3-m} Li _3m )
(Mg _0.5 W _0.5 ) O ₃ , 3 m = 0.1, 0.2, 0.
Attempts were made to synthesize compositions of 35 and 0.5. (La _0.63 L
i _0.1 ) (Mg _0.5 W _0.5 ) O ₃ was obtained as a single phase. Compounds of other compositions were also obtained as a nearly single phase, but a small amount of impurity phase was also seen. (La _0.63 Li _0.1 ) (Mg _0.5 W _0.5 ) O
₃ has the same structure as that of La _2/3 (Mg _0.5 W _0.5 ) O ₃ . This orthorhombic lattice constant is a = 7.8075,
b = 7.8349 and c = 2 × 7.9145.

This compound is more stable to lithium metal than the La _{2 / 3-m} Li _3m TiO ₃ system. When it reacts with lithium metal, it has an electron conductivity of 10 ⁻⁵ Scm at room temperature. The ionic conductivity of this sample was measured by the direct current method as described above to be 1 × 10 ⁻⁶ Scm at 290K.
Met. FIG. 6 shows an impedance plot at 290K. Moreover, the complex impedance measurement using the gold paste electrode was also performed.

In the case of the gold paste electrode, one large semicircle (C = 50 pF) can be seen. On the other hand, in the case of a lithium electrode, two semicircles can be seen. As described above, using a lithium electrode and a gold paste electrode, the total conductivity (σ =
1 × 10 ⁻⁶ Scm) is in agreement with the total conductivity measured by the direct current method.

In FIG. 6, when a lithium electrode is used, one semicircle on the left side (C = 60 pF)
Is believed to be due to the bulk portion of ionic conductivity. In FIG. 6, when a lithium electrode is used, the other semi-circle on the right side (C = 150 pF)
Is considered to be caused by the grain boundary portion of ionic conductivity. In the bulk part, σ = 3 × 10 ⁻⁶ , and in the grain boundary, σ = 3 × 10 ⁻⁶ Scm ⁻¹ . In the case of gold electrodes, a large semicircle is responsible for the total conductivity.

FIG. 7 shows the temperature dependence of the total conductivity of the sample,
Shown in the Arrhenius plot. The activation energy calculated from FIG. 7 is 0.39 eV.

A sample consisting of (La _0.6 Li _0.2 ) (Mg _0.5 W _0.5 ) O ₃ was prepared. When the lithium ion conductivity σ total was measured by the AC impedance method using a gold electrode, it was 7 × 1.
It was 0 ^-6 S / cm (290K). Further, when the lithium ion conductivity was measured by the DC method in the same manner as in the above Example, it was 6 × 10 ⁻⁶ S / cm (290K).

Since the compound of the (La _{2 / 3-m} Li _3m ) (Mg _0.5 W _0.5 ) O ₃ system does not easily react with lithium as described above, lithium metal or lithium alloy is used as the negative electrode active material. Then, even if this is brought into contact with the lithium ion conductive partition, a lithium solid electrolyte battery can be satisfactorily prepared.

FIG. 8 is a schematic diagram showing the lithium solid electrolyte battery of the present invention. The partition wall 5 made of the lithium ion conductor is sandwiched between the non-metal positive electrode active material 6 and the non-metal negative electrode active material 7. During discharge, the negative electrode active material 7
Lithium ions are emitted from the cell as indicated by arrow A, and electrons are emitted to the external circuit to the opposite side. Positive electrode active material 6
Accept the lithium ions that have conducted through the partition walls 5. Electrons flow into the positive electrode active material 6, and a current flows in the direction of arrow D. In FIG. 8, 8A and 8B are switches, 9 is a DC power source, and 10 is a load.

At the time of charging, lithium ions are emitted from the positive electrode active material 6 as shown by arrow B, and electrons are emitted to the opposite side to the external circuit. The negative electrode active material 7 receives the lithium ions that have conducted through the partition walls 5. Electrons flow into the positive electrode active material 6, and current flows in the direction of arrow C.

As the positive electrode active material 6, various materials that can be doped with lithium ions and dedoped can be used. For example, lithium-containing composite oxides such as LiCoO ₂ represented by the general formulas Li _x CoO ₂ and Li _x NiO ₂ , lithium-cobalt-nickel composite oxide, LiM
Lithium-manganese composite oxide such as nO ₄ , V ₂ O
₅ , vanadium oxide, fluorinated graphite, MnO ₂ ,
Polyacetylene, polyparaphenylene, polypyrrole,
Examples thereof include polythiophene and polyaniline.

Examples of the negative electrode active material 7 include lithium ion-doped carbonaceous materials such as coke, carbon materials such as graphite, and conductive polymers such as polyacetylene.

Chalcogenides such as sulfides of titanium, tantalum and molybdenum can be used for both the positive electrode active material and the negative electrode active material depending on the combination with the paired electrode materials.

FIG. 9 is a schematic diagram showing the lithium solid electrolyte battery of the present invention. The positive electrode active material 6 is in contact with one of the partition walls 5 made of the lithium ion conductor. The negative electrode active material 11 is made of lithium metal or lithium alloy.
A reaction prevention film 12 is sandwiched between the negative electrode active material 11 and the partition wall 5.

Examples of the lithium alloy include Li / wood metal alloys and Li / Al alloys. As the reaction preventing film 12, an organic polymer compound film containing a lithium salt (so-called polymer solid electrolyte) is preferable. Also, a carbonaceous material such as coke or a thin film of a carbon material such as graphite can be used. Examples of the lithium salt of the polymer solid electrolyte include LiClO ₄ and LiCF ₃ SO _3. Examples of the polymer compound include polyethylene oxide, polypropylene oxide, poly (methoxyethoxyethoxide phosphazene), methylsiloxane-ethylene oxide copolymer. Examples thereof include coalesce, poly (methyl methacrylate), poly (vinylidene fluoride), and the like. As an additive, poly (ethylene glycol), propylene carbonate or the like may be added.

[0078] Further, the partition wall, having a perovskite structure _{(D y Li x) (Mg} 0.5 W 0 .5) O 3 (D is a trivalent metal atom .0 <x ≦ 1 / 2,1 / 2 ≦ y ≦ 2/3, 1/2 <
x + y ≦ 1, 1.6 ≦ x + 3y ≦ 2.2) in the lithium battery of FIG.
As the above, the above-mentioned lithium metal or lithium alloy can be used.

The battery of the present invention schematically shown in FIGS. 8 and 9 does not contain an electrolytic solution, unlike a general commercial lithium battery. Therefore, batteries of various shapes can be formed. Moreover, the above-mentioned lithium ion conductor (perovskite structure) can be manufactured by a usual ceramics manufacturing technique, and there is no particular restriction on the shape. Therefore, a flat battery having a single layer structure, a flat battery having a multilayer structure, a cylindrical battery having an inside-out structure, a cylindrical battery having a spiral structure, a prismatic battery, a coin battery and the like can be manufactured. Further, it is stable even at high temperature, and the battery can be operated at high temperature.

10 and 11 schematically show design examples of each element of the battery. FIG. 10 shows a battery element having a laminated structure, which includes a flat plate-shaped negative electrode active material 7A, a partition wall 5A, a flat plate-shaped positive electrode active material 6A, and a flat plate-shaped current collector 13A. Figure 1
It is also possible to stack a large number of repeating units represented by 0 to form an assembled battery.

FIG. 11 shows a roll type battery element. The thin film negative electrode active material 7B, the partition wall 5B, the positive electrode active material 6B, the current collector 13B, and the insulator 14 are wound.

[0082]

As described above, according to the lithium solid electrolyte battery of the present invention, it is possible to obtain a high-power battery and a battery that operates stably in the air. .

Furthermore, in the present invention, since the non-metal substance capable of releasing lithium ions is used as the negative electrode active material, the reaction between the lithium ion conductor having the perovskite structure and the lithium metal does not occur. Alternatively, when lithium or a lithium alloy is used as the negative electrode active material, a reaction prevention film is sandwiched between the negative electrode active material and the partition wall to prevent contact between the two.

Further, it has a perovskite structure (D _y
It was further found that the partition wall made of Li _x ) (Mg _0.5 W _0.5 ) O ₃ is difficult to react with lithium metal or lithium alloy. Therefore, in this case, by using lithium metal or lithium alloy as the negative electrode active material, a good battery can be prepared.

[Brief description of drawings]

FIG. 1 is a schematic view showing a holding state of a sample (pellet) 1 made of a lithium ion conductor of the present invention when the ionic conductivity is measured by an AC impedance method.

FIG. 2 is an equivalent circuit diagram for showing contributions of a bulk crystal part and a grain boundary part in the lithium ion conductor of the present invention.

FIG. 3 is a graph showing the temperature dependence of each ionic conductivity of a bulk crystal part and a grain boundary part.

FIG. 4 is a graph showing temperature dependence of ionic conductivity σ of a bulk portion from each sample, that is, an Arrhenius plot.

FIG. 5 is a graph showing ionic conductivity of the bulk portion at 300 K as a function of Li content obtained from ICP analysis.

FIG. 6 is a graph showing an impedance plot at 290K.

FIG. 7 is a graph showing the temperature dependence of the total conductivity of a sample made of (La _0.63 Li _0.1 ) (Mg _0.5 W _0.5 ) O ₃ in an Arrhenius plot.

FIG. 8 is a schematic diagram showing a lithium solid electrolyte battery of the present invention.

FIG. 9 is a schematic view showing a lithium solid electrolyte battery of the present invention.

FIG. 10 is a perspective view schematically showing a design example of the shape of each battery element.

FIG. 11 is a perspective view schematically showing a design example of the shape of each battery element.

[Explanation of symbols]

1 sample 2 porous polypropylene membrane 5, 5A,
5B Partition wall made of lithium ion conductor 6, 6A,
6B Positive electrode active material 7, 7A, 7B Non-metal negative electrode active material (or negative electrode active material made of lithium metal or lithium alloy) 11 Negative electrode active material made of lithium metal or lithium alloy 12 Reaction preventive film

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Mitsuru Ito 33-7 Sakuradai, Midori-ku, Yokohama-shi, Kanagawa 1-11 Sakuradai Court Village (72) Inventor Tetsuro Nakamura 2-41-21 Fujigaoka, Midori-ku, Yokohama-shi, Kanagawa Gaoka Residence 403

Claims (3)

[Claims] 1. A lithium ion conductor composed of a complex oxide having a perovskite structure, wherein at least half of the A sites of the perovskite structure are composed of a lithium ion conductor occupied by lithium and a trivalent metal atom. A lithium solid electrolyte battery comprising: a partition wall; a non-metal positive electrode active material capable of receiving lithium ions; and a non-metal negative electrode active material capable of releasing lithium ions. 2. A lithium ion conductor composed of a composite oxide having a perovskite structure, wherein at least half of the A sites of the perovskite structure are composed of a lithium ion conductor occupied by lithium and a trivalent metal atom. A partition wall; a non-metal positive electrode active material capable of receiving lithium ions; a negative electrode active material made of lithium metal or a lithium alloy; and a reaction preventive film sandwiched between the negative electrode active material and the partition wall. , Lithium solid electrolyte batteries. 3. Having a perovskite structure (D _y Li _x ).
(Mg _0.5 W _0.5 ) O ₃ (D is a trivalent metal atom. 0 <x ≦
1/2, 1/2 ≤ y ≤ 2/3, 1/2 <x + y ≤ 1, 1.
6 ≦ x + 3y ≦ 2.2), a partition wall; a non-metal positive electrode active material capable of receiving lithium ions; and a negative electrode active material made of lithium metal or a lithium alloy,
Lithium solid electrolyte battery.