JPH02207460A - Fully solid state lithium battery - Google Patents

Abstract

PURPOSE:To increase the safety of a battery by using a solid electrolyte prepared by dissolving a lithium salt in a specific organic compound or its mixture. CONSTITUTION:A fully solid state lithium battery is manufactured by combining a positive active material and a negative active material with a solid electrolyte prepared by dissolving a lithium salt in oligoethyleneoxy polyphosphazene having allyl groups formed by randomly arranging segments represented by formulas I, II, III. A battery having low charge-discharge loss, no leakage, and no ignition can be obtained. In the formulas, R shows methyl, ethyl, or propyl group alone, or its mixture, n and k are the mean repeating number of ethyleneoxy units, 0<=n<=15, 0<=k<=5 and 1, m, n are zero or a positive integer of 3 <=1+m+n<=200000, nnot equal to 0.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to high energy density all-solid-state lithium primary and secondary batteries.

(Technology based in the United States) Much research has been conducted on high-energy density batteries that use conventional lithium as the negative electrode active material. In particular, primary lithium batteries are already commercially available, and the demand for them is only increasing. Lithium primary batteries using manganese dioxide as a positive electrode active material and lithium primary batteries using manganese dioxide as a positive electrode active material are well known.

Furthermore, active research has been conducted recently on rechargeable and dischargeable lithium secondary batteries, and numerous proposals have been made regarding battery constituent members and battery configurations.

For example, V6O13, MoS2 as a positive electrode active material
, TiS2, Cr30a, M n 02, etc. are used,
A lithium secondary battery using lithium, a lithium-aluminum alloy, or the like as a negative electrode active material has been proposed.

However, the problems with these lithium batteries from the beginning have not yet been resolved.The first problem is that an electrolyte material that can move lithium ions for an electrochemical reaction with the positive electrode active material or negative electrode active material Examples include propylene carbonate, tetrahydrofuran, 2-methyltetrahydro-7rane, dioxolene, 7-cetonitrile, formamide, ethylene carbonate), 1,2-nometochineecune, dimethylformamide, dichloromethane,
LiClo, , LiBF, %LiAs in one or more aprotic organic solvents such as trimethyl sulfoxide.
F s, L: AlC1,, L i P F ! Electrolytes in which lithium salts such as E.g. There is a risk of malfunction and WK cracking due to overcharging.

The second problem is that due to repeated charging and discharging in the secondary battery, convection of the electrolyte that occurs on the lithium negative electrode
The problem is that it promotes the growth of Li dendrite crystals and eventually comes into contact with the positive electrode and short-circuits.

These two major problems stem from the fact that the electrolyte is a flammable liquid. In order to solve this problem, lithium batteries using solid electrolytes are being studied.
For example, 1 Fuji [52nd New Materials Research Conference Lecture Review]
(December 8, 1983)
i, using a PO-based solid electrolyte, the positive electrode is T is 2
9%, thin all-solid lithium 2 with lithium film as negative electrode
We are proposing the next battery. However, this product has a small capacity and poor battery characteristics at low temperatures, so it has not been put into practical use, and P.M. Plonsky et al.

Cal Society Volume 106 e 6854 pages 198
4th year (P.

M, Blonsky et ale J, Am+C
hew, Soc, t106, 6854. 1984
) describes that polyphos-77zene is useful as an electrolyte for electrochemical cells. However, they are 30
It only shows AC conductivity data in the range of 97°C to 97°C, and does not solve the problem.

(Problems to be Solved by the Invention) An object of the present invention is to improve the above-mentioned problems and provide all-solid-state lithium primary and secondary batteries that are small, lightweight, have a large charge/discharge capacity, and have excellent battery characteristics. It's about doing.

(Means for solving problems) The present invention relates to a positive electrode active material, a negative electrode active material, and the following formula (■).

An all-solid-state lithium battery comprising an oligoethyleneoxypolyphosphazene or a mixture thereof having an allyl group in which segments represented by (U) and (I[I) are arbitrarily arranged, and a solid electrolyte in which a lithium salt is dissolved. .

0(CH2CH20)hCHzCH=CH2L) (to 1-12CF12 (J)h CM2 city
= siM20(CH,CH20)kR0(CH,CH,0)hCH,CH=CH.

(However, R represents a single or mixed methyl, ethyl, or propyl group, h and k mean the average repeating number of ethyleneoxy units, and O≦h≦15.
It takes a real value in the range of 0≦≦15, and 1
, lit n takes 0 or a positive integer value in the range of 3≦lToso+n≦200000, and is n-1. ) In the all-solid-state lithium battery of the present invention, an oligoethyleneoxypolyphosphazene compound, which has greatly improved ionic conductivity and is neither flammable nor ignitable, is used as the solid electrolyte. Furthermore, when using a known positive electrode active material, in order to improve the interfacial adhesion with the present solid electrolyte and improve the positive electrode performance, (V 205) l-X * (A)
Hydrated sol of x (where A is a metal or metalloid oxide, O≦
x≦0.6) can also be mixed. We have discovered that by combining a known negative electrode active material with the improved solid electrolyte and positive electrode active material described above, it is possible to obtain characteristics superior to those of lithium batteries made in the United States, and to construct an all-solid-state film lithium battery. .

As the positive electrode active material used in the present invention, MnO2, graphite, graphite fluoride, etc. are used for lithium primary batteries.
Also, for lithium secondary batteries, MnO2, (Li20)
Manganese oxides such as x・(MnO2)+-x (0<x≦0゜6), MoS2, Mo53, TiS
2. Transition metal compounds such as V, S, etc., ■20
1, V s O. , amorphous 'fJ V 20 s P
A cathode active material based on a nanonumerary oxide such as tOs, or an organic polymer type such as polyaniline is used. Generally, using these positive electrode active materials, to form a positive electrode, a conductive powder such as acetylene black, Ketchien black, or graphite is mixed, and a binder powder such as polytetrafluoroethylene, polyethylene, or polystyrene is further mixed. is added as required, and this mixture is cross-wired and formed into pellets or sheets of a predetermined thickness, which can be attached to a wire mesh made of stainless steel, nickel, etc. to form a positive electrode. Although the goals of the present invention can be fully achieved using the cathode material formed in this way, the following method is recommended for forming the cathode material for constructing an all-solid-state film lithium battery. The method is effective.

That is, the known positive electrode active material d(V 205)l−X +
(A) Add and mix the hydrated sol solution of x. Here O<x
≦0.6. Further, A is an oxide of a metal or a metalloid, and specific examples include M o O3, WO2, C'01, Ti
Examples include e, , Gem2, Sin, , B 120-1Te02, and the like. This sol has a layered structure■
The 20° fibrils form a fiber bundle, and the fibers have a structure in which they are dispersed in a network, and the dest oxide (A) is present in the network space or between the eyebrows, or as an intercalate. Therefore, the dried form of this sol has high electron conductivity in the direction of the fibers, and also has high material stability due to the hybridization of fibrous molecules (V20s) and granular molecules (A). VzOsL-X・(A
) There is no particular restriction on the weight mixing ratio with x, but 1:0,
An I range of 0.02 to 0.02:1 is preferable, and by controlling the amount of water in this positive electrode mixture, a coated positive electrode material,
It is possible to process a sheet-like positive electrode material by roll position molding, a substrate-adhesive positive electrode material by press molding, etc.

In addition, the positive electrode material obtained by adding and mixing the allyl group-containing oligoethyleneoxypolyphosphazene compound used in the present invention to the positive electrode active material has a large amount of lithium ions doped into the positive electrode active material. Above, there is no particular restriction on the weight mixing ratio of the positive electrode active material and the oligoethyleneoxypolyphosphazene compound, which increases the stability of the interface between the solid electrolyte layer and the positive electrode layer, but it is preferably from 1:0.005 to 1:0.9. A range is preferred.

In this case as well, by controlling the amount of the polyphos-77zene compound added, it is possible to process the material into coated cathode materials, sheet-like cathode materials, substrate-adhesive cathode materials, and the like.

Here, the method for synthesizing the hydrated sol of (V205L-X/(A)x is to mix V20s and other oxides to be added in a predetermined ratio, melt the resulting mixture, is blown onto the surface of a metal roll spinning at high speed, and is rapidly cooled and solidified. This solidified material has an amorphous structure. By dissolving 7 moles of this human body in water, A hydrated sol solution can be obtained.Also, as another method, it can also be prepared by mixing a predetermined amount of alkoxides of V and Ol and alkoxides of (A) oxide and hydrolyzing the mixture.Furthermore, it can be prepared by an ion exchange method or a composition melt. It is also possible to prepare a desired sol by blowing directly into water.

The negative electrode active material used in the present invention is lithium or a lithium alloy, and a wood alloy can also be used. When these are used as negative electrode materials, they are processed into sheets or films, or used in the form of sheets crimped onto nickel or stainless steel plates. Alternatively, a thin film of a negative electrode active material formed on a nickel or stainless steel plate by a PVD method such as a vacuum evaporation method or a sputtering method or a CVD method can be used.

In the present invention, as the electrolyte, the above formulas (I) and (■) are used.

(I[[) A lithium salt dissolved in oligoethyleneoxypolyphosphazene having allyl groups in which segments are arbitrarily arranged or a mixture thereof is used. This polymer is a polymer in which oligoethyleneoxy groups and allyl groups are arranged in an inorganic polymer skeleton with a phosphonitrile main chain, and is soft and water-soluble.
C4'OLiBF, , LiAsF, , L: AlC1,
It has the ability to dissolve lithium salts required as electrolytes for lithium ion conduction, such as , LiPF5, etc. or,
By introducing an allyl group to the end of the side chain, the end of the side chain can be crosslinked, and the membrane shape can be excellently maintained without losing the characteristics of the skeleton and the flI chain. These characteristics are suitable for solving the problems of lithium batteries mentioned above.

Formula (1) used in the present invention, ([[), (
Oligoethyleneoxypolyphosphazene in which the segment represented by Ill) has an arbitrarily arranged allyl group is
It is synthesized as follows. That is, by reacting a dichlorophosphonitrile polymer obtained by ring-opening polymerization of hexachlorotriphosphonitrile with a predetermined amount of an alkali metal alcoholade of oligoethylene glycol monoalkyl ether and oligoethylene glycol monoallyl ether, which had been prepared in advance. The reaction that can produce 9I can be carried out by mixing the components at about 40°C or less using a common organic solvent such as tetrahydrofane (THF), diglyme, etc., and then heating and refluxing for several hours. The alkali metals include sodium,
Lithium or the like can be suitably used.

When using this polymer as an electrolyte, a solvent solution of a lithium salt is added to a solution in which the polymer is dissolved in the following solvent, and after uniformly dissolving the polymer, it can be used by forming a film. Further, depending on the purpose of use, compositing may be performed by treatment such as heating, ultrasonic irradiation, ultraviolet irradiation, etc. before or after film formation.

Examples of solvents include ethers such as THF, dioxane, nomethoxyethane, a7tone, methyl ethyl ketone (
Examples include ketones such as MEK), furfurs such as methanol and ethanol, acetonitrile, and propylene carbonate.

It seems that the allyl group that the polymer used in the present invention has in its molecule acts effectively in the conjugation process. In other words, although the details are unknown,
It is thought that the coupling between the allyl groups and the reaction or interaction between the allyl groups and the added salt establishes and maintains a form convenient for use as a battery electrolyte.

Lithium salts used in the present invention include LiCtO,
, LiAIC/-1LiBF-5LiCZ%LiPF6
, LiAsF, CF 2 SOs Li, etc., are preferably used. In addition, a separator membrane such as a nonwoven fabric or a porous membrane may be installed as necessary depending on the battery configuration.

A method for manufacturing a battery is, for example, by applying a positive electrode active material to a predetermined stainless steel plate, drying it, applying a solution of a solid electrolyte prepared in advance onto the surface of the positive electrode material, removing the solvent, and forming a film. It is obtained by vacuum-sealing a separately prepared sheet of negative electrode active material in an inert gas atmosphere or dry air using a stainless steel plate and a sealing material.

An example of an all-solid-state lithium battery of the present invention made using the above-mentioned members is shown in FIG. 1. This battery shows an example of an all-solid-state film battery, and the application form and configuration are Needless to say, the invention is not limited to this, and can also be applied to button-type, Schilling-type, etc. batteries.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

Note that the battery preparation and measurements were performed in an argon atmosphere.

Example 1 (1) Preparation of positive electrode body Positive electrode active material M n 02, (LnO)o, +(MnO
z) o, *, (Li20). ,,(MnO,),,,,
MOS,, TiS2, ■201, ■, 0°, amorphous (V
20s). 0. ,・(P2O3). ,. 1. Graphite and fluorinated graphite are manufactured by Rare Metallic Co., Ltd. with a purity of 99.9%, and the binary oxide composition is mixed at a predetermined ratio, heated to form a solid solution, and then ground again. did. Also, amorphous (V 20 s) o, ms ” (P x
o s) o, oslt V 2o, and t/P t
A predetermined amount of Os is mixed, heated to form a melt, and the resulting composition melt is blown out onto the surface of a roll that is being softened at high speed.
The sample was rapidly cooled at a rate of 10'°C/sec to obtain an amorphous sample. For evaluation of amorphization, a Barlow pattern with no diffraction peak was confirmed by X-ray diffraction.

Further, polyaniline was electrolytically polymerized and precipitated on a stainless steel plate to form a polyaniline positive electrode II (thickness: 100 μm). The positive electrode active material prepared in this manner was placed in a mortar to have a uniform particle size. Acetylene plaque was used as a conductive material, and polytetrafluoroethylene was used as a molding binder. They were mixed with a positive electrode active material at a ratio of 5:25 to 0, respectively, and sheet molding was performed using a roll press. A positive electrode material was punched out from this sheet to a predetermined size. Here, the dimensions of the positive electrode material are (width) 55-1 x (length) 90-
The thickness is 0.5 mm. Stainless steel plate that serves as current collector and casing material (width) 60m*X (length) 100mm
The positive electrode material was molded onto a X (thickness) 50μ ring.

(Z) Preparation of negative electrode body (width) 60 ma x (length) 100 mm x (thickness jL) 5
0/j mf) A lithium metal tube, lithium-aluminum alloy (1/1) foil, or Li (Pb
-Cd.In) alloy (1/1) whistle, a so-called Li-wood alloy, was crimped to form a negative electrode body.

(3) Preparation of electrolyte (HP to (CHzCHzO)tcHtcH= C1
(21°-53(0(CHzCllzO)ycHsl+
, nt) Phos7 with an average molecular weight of about 260,000, denoted by n
7 Zenbori V-101r and LiC! ! 041g in THF
It was dissolved in 189 g to form a homogeneous solution at room temperature.

(4) Battery assembly Figure 1 is a schematic cross-sectional view of a sheet-type battery, which is an example of the battery according to the present invention, and the external dimensions are 60+am x 10
It is made to fit a business card size of 0mm, and the thickness is approximately 1mm.
- In the figure, 1 is the positive electrode material, 2 is the negative electrode material,
3 is a phos7 azene polymer film in which LiC10 is dissolved,
4 is a stainless steel plate, and 5 is a sealing material. In assembling the battery, the above electrolyte solution was applied onto the above positive electrode body, THF was removed, and then the negative electrode material was bonded together via a sealing material and vacuum sealed to complete the battery.

For comparison, 1 m of Li C104 was added to a 1:1 mixture of propylene carbonate and dimethoxyethane as an electrolyte.
Comparative Examples 1 and 2 were produced in the same manner as in the Example except that the battery was dissolved in OL/Z and impregnated into a polypropylene cloth.

(5) Measurement of charging and discharging characteristics of batteries These batteries were charged and discharged at a constant current of 0.5 A between 4V and 2■ as secondary batteries, and the capacity retention rate of the batteries in each cycle was (Initial discharge capacity is 100
%) was measured. The results are shown in Table 1.

Example 2 Positive electrode active material (V 205L-X ・(A )x ・n
Applying a wet product from a liquid product obtained by mixing an H20 sol solution or an oligoethyleneoxypolyphosphazene compound having an allyl group according to each condition and purpose.
A thin film positive electrode material by drying method and a sheet positive electrode material by roll press molding method are further processed into positive electrode materials, etc., which are individually crimped by press molding method on the current collector plate of battery 1, respectively, as positive electrode materials, and Phos77 Zenvolimer was used as a compound with an average molecular weight of about 320,000 (NPiO(C2CH20), CH2CH=C
11□10. +4io(CIlzCH20)tcHsl
A battery was assembled in the same manner as in the example except that the battery was used as shown in +1s). These batteries were charged and discharged (0.5 mA constant current) in the dark at 4 V and 2 V, and the average discharge amount up to 300 cycles was measured. The results are shown in Table #S2.

To prepare the hydrated sol solution of the additive (VzOs)+-x・(A)× in the table, the amorphous (V2O5)I-X・(A)x was prepared by the liquid m quenching method described above. This amorphous body was dispersed and dissolved in water to prepare a hydrated sol solution of (V 20 s) + - x (A) ×. A in the formula 0 represents a metal oxide or a metalloid oxide, - Using Gem2, Sin, as an example, V2O5, (V 2os) o, * ・(GeO2)
0.1, (V2O5). ,,・(S io 2). 0.
Each aquarium sol was manufactured by ill. Figure 2 shows (V 20
s) O, s - (GeO2) a, X#a diffractogram of a dry hydrated sol, showing V2O5 and (V 205)6
．． 4-(Sio z)o*1l-) Itemo #2 It was the same as in Figure 2.

(Effects of the Invention) According to the present invention, an all-solid-state lithium battery with less charge/discharge loss, no leakage, and no risk of ignition or ignition can be obtained. Although the lithium battery of the present invention has been evaluated for its physical properties as a rechargeable and dischargeable secondary battery, it can of course be used as a primary battery. Further, according to the present invention, since the battery member can be made very thin, an all-solid-state film-like lithium battery can be obtained, and its applications can be expanded widely.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view of a sheet type battery which is an example of a battery according to the present invention. , 4 is a stainless steel plate serving as an electrode/cover material, and 5 is a sealing material. Figure 2 shows additive substances (Vz
The X-ray diffraction pattern of the dried hydrated sol of Oi)o,s·(GeOz)o,+ shows that this compound has a layered structure. (The above) Applicant Otsuka Chemical Co., Ltd. Agent Patent attorney 1) Iwao Mura 2nd 2θ (deg,) CUKa

Claims (10)

[Claims] (1) Positive electrode active material, negative electrode active material and the following formulas (I), (II
An all-solid-state lithium battery comprising an oligoethyleneoxypolyphosphazene having an allyl group in which the segments shown in ) and (III) are arbitrarily arranged, or a mixture thereof, and a solid electrolyte in which a lithium salt is dissolved. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (III) (However, R is a methyl, ethyl, propyl group h and k mean the average repeating number of ethyleneoxy units, 0≦h≦15, respectively.
It takes a real value in the range 0≦k≦15, and l
, m, and n take 0 or positive integer values in the range of 3≦l+m+n≦200000, and n≠0. ) (2) The positive electrode active material is MnO_2, LiMn_2O_4 or (Li_2O)x・(MnO_2)_1-x (0<x
≦0.6), and the negative electrode active material is lithium or a lithium alloy. (3) the positive electrode active material is MoS_2 or TiS_2,
Claim 1 wherein the negative electrode active material is lithium or a lithium alloy.
All-solid-state lithium battery described. (4) The all-solid-state lithium battery according to claim 1, wherein the positive electrode active material is a polyaniline compound, and the negative electrode active material is lithium or a lithium alloy. (5) The positive electrode active material is V_2O_5, V_6O_1_3 or amorphous (V_2O_5)_1-y・(P_2O_5)
The all-solid-state lithium battery according to claim 1, wherein y (0≦y<0.1) and the negative electrode active material is lithium or a lithium alloy. (6) The all-solid-state lithium battery according to claim 1, wherein the positive electrode active material is graphite or fluorinated graphite, and the negative electrode active material is lithium, a lithium alloy, or a wood alloy. (7) The positive electrode active material according to any one of claims 2 to 6 (
V_2O_5)_1-x・(A) A thin film-like positive electrode material formed by coating and drying a liquid obtained by mixing the hydrated sol of x, and a negative electrode active material made of lithium, lithium alloy or wood alloy. The all-solid-state lithium battery according to claim 1, which uses a substance. (However, A is a metal oxide or a metalloid oxide, 0≦x≦0
．． It is 6. ) (8) Positive electrode active material and (V_2O_5)_1-x・(A)
The all-solid-state lithium battery according to claim 1, wherein the weight mixing ratio of x is in the range of 1:0.02 to 0.02:1. (9) The positive electrode active material according to any one of claims 2 to 6,
A positive electrode material obtained by mixing the oligoethyleneoxypolyphosphazene having an allyl group according to claim 1 and press-molding the mixture, and a negative electrode active material comprising lithium, a lithium alloy, or a wood alloy. Solid-state lithium battery. (10) The weight mixing ratio of the positive electrode active material and oligoethyleneoxypolyphosphazene having an allyl group is 1:0.00.
The all-solid-state lithium battery according to claim 9, wherein the ratio is 5 to 1:0.9.