JPS59108277A - Organic electrolytic battery - Google Patents

Abstract

PURPOSE:To perform the deterioration of discharge capacity, generation of gas, and increase in internal resistance through impurities and obtain an electrolyte for an organic electrolytic battery by using the adduct consisting of lithium salt of phosphorus, antimony, arsenic, or boron and a specific amine compound as the solute. CONSTITUTION:The adduct consisting of a compound represented by a general expression ( I ) and an amine compound represented by a general expression (II) is formed in ethylene glycol ether, and the dissolution of a compound represented by the general expression ( I ) into ethylene glycol ether and such is performed under the heating conditions at 50 to 80 deg.C. When an amine compound represented by the general expression (II) is added to the heated solution by three times mol or more, the adduct consisting of the compound represented by the general expression ( I ) and the amine compound represented by the general expression (II) is deposited without being cooled. A concrete example of the compound represented by the general expression ( I ) is LiPF6, LiSbF6, LiAsF6, and LiBF4. In addition, for example, N,N,N',N'-tetramethylethylendiamine, N,N,N',N'-tetramethylebutanediamine, and such are recommended as the amine compound represented by the general expression (II). Besides, for example, propylenecarbonate, gamma-butyrolactone, tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolan, and such are used as the electrolytic solvent.

Description

[Detailed description of the invention] The present invention relates to organic electrolyte batteries.

Recently, as an electrolyte for organic electrolyte batteries, the general formula () % formula % () (where X is phosphorus, antimony, arsenic or boron; The compound represented by 4) for boron is attracting much attention because it has good solubility in organic solvents, high conductivity, and is safer than perchloric acid-based compounds.

However, generally available commercially available products are manufactured using the following manufacturing method:
Depending on the battery, however, it contains a considerable amount of impurities, and these impurities react with the active material within the battery, causing a decrease in discharge capacity, gas generation, and an increase in internal resistance.

Therefore, the present inventors dissolved the compound represented by general formula (I) in ethylene glycol ether, and dissolved Yj5
After removing impurities insoluble in ethylene glycol ether, the filtrate is cooled to precipitate the compound represented by general formula (1) as a solvate of ethylene glycol ether, and the resulting precipitate is evaporated under reduced pressure. It was discovered that it could be purified by heating at a lower temperature to remove solvated ethylene glycol ether, and a patent application has already been filed for this.

However, in the above purification method, the filtrate is cooled and the general formula (■)
In order to precipitate the ethylene glycol ether solvate of the compound represented by formula (I), impurities dissolved in the filtrate may be accompanied by the solvate of the compound represented by formula (I) and ethylene glycol ether. Therefore, the inventors conducted further research and found that the general formula C
The compound represented by I) is dissolved in ethylene glycol ether and filtered to remove impurities insoluble in ethylene glycol ether. , R2, R3 and R4 are alkyl groups having 1 to 4 carbon atoms, and m is an integer of 2 to 4) at a molar ratio of 8 times or more to the compound represented by general formula (I). It has been found that when added, an adduct of the compound represented by the general formula (1) and the amine compound represented by the general formula @) is precipitated from a hot ethylene glycol ether solution without requiring cooling. And its general formula (
■) The adduct of the compound represented by formula (I) and the amine compound represented by general formula (I[) is prepared under reduced pressure under heating to form the general formula (II).
When the molar ratio of the amine compound represented by is less than 3 times, preferably 0.3 to 1.5 times, addition of the compound represented by the general formula (I) and the amine compound represented by the general formula (for each general formula) substances as solutes in the electrolyte in organic electrolyte batteries.
■We discovered Kokichi that can be used and completed the present invention.

An adduct with a molar ratio of 1:3 or more between the compound represented by the general formula (I) and the amine compound represented by the general formula (I[) obtained by the above method is precipitated from a hot ethylene glycol ether solution. The adduct is heated and depressurized to reduce the molar ratio of the amine compound represented by the general formula (■) to 3. When applied to batteries, those with less than 100% are stabilized by the added amine compound, and are more stable than the pure compound represented by the general formula (■), and are not subject to decomposition due to heat.

In addition, the compound represented by the general formula (I) and the amine compound represented by the general formula (I[) are considered to be added in the form shown below, to exemplify typical examples thereof.

Specific examples of compounds represented by the general formula (■) used in the present invention HLiPF6, LiSbF6, LiAsF6, #
LiBp4, and amine compounds represented by the general formula ・(■) include, for example, N, N, N', N/
-tetramethylethylenediamine, N, N, N',
N'-tetraethylethylenediamine, N, N, Nz
NC-tetramethylpropanediamine, N, N, NzN
-1-tetramethylbutanediamine and the like are preferably used.

A compound represented by the general formula CI) as described above and a compound represented by the general formula (CI)
The adduct with the amine compound represented by II) is formed in ethylene glycol ether, and examples of the ethylene glycol ether include ethylene glycol dimethyl ether (i.e., 1,2-dimethoxyethane), ethylene glycol diethyl ether. , ethylene glycol dibutyl ether, etc. are used. -Also, diethyl ether, water, etc. can be used instead of ethylene glycol ether.

-He The compound represented by the formula (I) is dissolved in ethylene glycol ether etc. under heating at 50 to 80°C, and the amine compound represented by the general formula) is dissolved in the heated solution by 3 times the mole or more. When added, an adduct of the compound represented by the general formula (I) and the amine compound represented by the general formula @) is precipitated without cooling.

The amine compound represented by the general formula (II) can be partially removed from the adduct by heating under reduced pressure or by exposing it to a stream of an inert gas such as nitrogen or argon at room temperature. It will be done.

In the case of vacuum drying, what about temperature? ]-0~20℃, 0.1
It is preferable to reduce the pressure to about 10πMHz.

Examples of electrolyte solvents include propylene carbonate, γ
- A single solvent or a mixed solvent of two or more of butyrolactone, tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolane, etc. is used, and the compound represented by the general formula (I) and the general formula The adduct with the amine compound represented by (II) is usually 1.0 to 30 mol/l.
(However, as a compound represented by general formula (I)) An electrolytic solution is prepared by dissolving it.

Examples of light metals used as negative electrode active materials in the present invention include lithium, lithium alloys, sodium, magnesium, aluminum, etc., and examples of positive electrode active materials include titanium disulfide, iron sulfide, steel oxide, manganese dioxide, carbon fluoride, etc. is used.

Next, the present invention will be explained with reference to 8 examples and examples.

Reference example Commercially available LiPF6 (purity: 98) 20 (Hl at 70°
ethylene glycol dimethyl ether heated to C,
000mlK was added little by little over 1 hour, and after the addition, stirring was continued for 1 hour while maintaining the temperature at 70°C.

The obtained solution was filtered through a glass filter while maintaining the temperature at around 70'C, and the filtrate K 4609 NI N, N;
N'-7-tramethylethylenediamine (hereinafter referred to as TM
Gradually add EDA) to form a white precipitate,
It was separated by furnace using a glass filter. The resulting precipitate was washed several times with 300 mft of hot ethylene glycol dimethyl ether on a glass filter. The amount of precipitate obtained was 600y, which was determined by thermogravimetry analysis (TMEDA).
3L! It was confirmed to be PF6.

The obtained (TMEDA) 3LIPF6 was dried at room temperature under an argon gas stream to obtain (TMEDA) 1.3LiPF.
I got 6.

Table 1 shows the results of examining the pH of the purified 1PF6 obtained above, LIPF6 purified as a solvate of ethylene glycol dimethyl ether, and phase LiPF6.

Table 1 L purified by addition of KTMEDA as shown in Table 1
iPF6 has a high pH, and acidic impurities such as hydrogen fluoride contained in crude LiPF6 are sufficiently neutralized.

(TMEDA)3LiPF6 obtained according to the reference example was heated at 5°C.
The pressure was reduced to 11% Hg and the molar ratio of TMEDA was set to 0.5 mol (TMEDA) (1,5L 1PF6 to 4-
Prepare an electrolytic solution by dissolving 1.5 mol/l of methyl-1,3-dioxolane and 1,2-dimethoxyethane in a mixed solvent with a ratio of 7=3. Battery A uses titanium disulfide as a negative electrode active material and titanium disulfide as a positive electrode active material.
was manufactured.

For comparison, an electrolytic solution was prepared by dissolving 1.5 mol/l of ethylene glycol dimethyl ether-solvated (DME)3LiP F6 in the same mixed solvent as above, and using this electrolytic solution, the above A battery B similar to the above was manufactured.

Initial internal resistance of batteries A and B as above and 6
The internal resistance was measured after storage at 0°C for 10 days. The results are shown in Table 2.

%2 table Patent applicant: Hitachi Maxell, Ltd.

Claims (1)

[Claims] 1. In a battery having a negative electrode and a positive electrode made of a light metal such as lithium, and an organic electrolyte, the solute of the electrolyte has a general formula (
I) LiXFn (■) (wherein, X is phosphorus, antimony, arsenic, or boron; n is 6 when X is phosphorus, antimony, or arsenic;
is 4 when is boron) and less than 3 mol of the compound represented by the general formula (I) R1R2N-+CH2N R2H,4(
II) (wherein R1, R2, R6 and R4 have 1 carbon number
An organic electrolyte battery characterized in that an adduct with an amine compound represented by an alkyl group of -4 and m is an integer of 2 to 4 is used.