JPS59154778A - Electrolyte composition - Google Patents

Abstract

PURPOSE:To secure an electrolyte composition for a lithic battery which is made up so as to obtain a sufficient battery characteristic for long hours, by setting those of specified N-substitution oxazolidinon and N,N'-substitution imidasolidinon plus lithium chloride as the main components. CONSTITUTION:N-substitution oxazolidinon and N,N'-substitution imidasolidinon shown in chemical formulas I and II (R1-4 is of H, an alkyl group, a cycloalkyl group and an allyl group while R5-6 is of those of alkyl group, cycloalkyl group and allyl group aforesaid) are mixed with lithium chloride and dissolved whereby made into a conductive electrolyte composition. This electrolyte composition will almost not be chemically changed, meaning that it is always stable in time of charging or discharging so that when being used for a lithic secondary battery, a sufficient battery characteristic can be secured for long hours.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrolyte compositions. More specifically, the present invention relates to an electrolyte composition suitable for lithium batteries.

Batteries using lithium as the negative electrode active material have excellent properties such as high energy density and high discharge voltage, but due to the high reactivity of lithium metal and the high discharge voltage, the electrolyte composition is insufficient. It tends to become unstable, and sufficient battery characteristics may not be obtained. Especially in the case of secondary batteries, the disadvantages become luxurious. For example, when an electrolyte composition in which a lithium salt is dissolved in propylene carbonate, tetrahydrofuran, or the like is used, chemical changes occur during charging and discharging, resulting in deterioration of battery characteristics.

The present inventors have conducted intensive studies aimed at solving these problems, and as a result, have arrived at the present invention. That is, in the present invention, R1+ R2+ R3+ R4 in the general formula and/or c is a hydrogen atom, an alkyl group, a cycloalkyl group, or a')-g. R5 and R6 are an alkyl group, a cycloalkyl group or an aryl group. ) denoted by N −jifi
Substituted oxaoxazolidinone/t f Coba N, N'-substituted imidazolidinone ■ Rahii: l, J thium salt (
8) is an electrolyte composition suitable for lithium batteries.

In general formulas (1) and (2), R1, R2, R3
, R4 include straight or branched alkyl groups having 1 to 1 o carbon atoms, such as methyl group, ethyl group, normal or isopropyl group, normal or isophthyl group, and denyl group. Examples of the cycloalkyl group include a cyclohexyl group and a methylcyclohexyl group. Examples of the aryl group include phenyl group and P-methylphenyl group. R+, R2, R3
, R4, preferred are a hydrogen atom, a methyl group and an ethyl group.

The alkyl group, cycloalkyl group and allyl group for R5 and R6 are "" + R2+ Rs + alkyl group for R4.

Examples include groups similar to cycloalkyl groups and aryl groups. Among R, and R6, methyl and ethyl groups are preferred.

Examples of the N-substituted oxazolidinone represented by the general formula (1) include N-alkyloxazolidinone (N-methyloxazolidinone, N-methyl-4-methyloxazolidinone, N-methyl-5-methyloxazolidinone, N-methyloxazolidinone, ethyloxazolidinone, N-ethyl-4-methyloxazolidinone, N-butyloxazolidinone, etc.), N-cycloalkyloxazolidinone (N-cyclohekyne-4-methyloxazolidinone, etc.), and N-cyclohequine-4-methyloxazolidinone, etc. Aryloxazolidinone (N-phenyloxazolidinone, N-phenyl-4
-methyloxazolidinone). Among these, preferred are N-methyloxazolidinone, N-
They are ethyloxazolidinone, N-methyl-5-methyloxazolidinone and N-ethyl-5-methyloxazolidinone.

As the N,N'-substituted imidazolidinone represented by the general formula (2), N,N'-dialkylimidazolidinone (N
, N'-dimethylimidazolidinone, N,N'-dimethyl-4-methylimidazolidinone, N1N'-dimethyl-44'-dimethylimidazolidinone, N-methyl-N
'-ethylimidazolidinone, N,N'-diethylimidazolidinone, N,N'-dimethyl-4-ethylimidazolidinone), N,N'-syncroalkylimidazolidinone (N,N'- Synchroakilimidazolidinone, etc.) and N,N'-diarylimidazolidinone (N,N'-diphenylimidazolidinone, etc.).

Among these, preferred are N,N'-dimethylimidazolidinone, N-methyl-N'-ethylimidazolidinone, N-methyl-N'-ethylimidazolidinone, N,
N'-dimethyl-4-methylimidazolidinone and N
, N'-dimethyl-4-ethylimidazolidinone.

The compounds represented by formulas (1) and (2) are preferably in liquid form, but solid compounds can also be used as a liquid composition by mixing with liquid compounds.

Other organic solvents used in conventional organic electrolyte type lithium batteries (
Propylene carpone 1~. Esters such as γ-butyrolactone, dimedquinethane.

dimethoxytetrahydrofuran, etc.) can be used in combination. In this case, the star ■ is usually 5% by volume based on the total amount of (a) and other organic solvents.
That's all.

As the lithium salt in the present invention, any lithium salt used in conventional organic solvent type lithium batteries can be used. Examples include lithium perchlorate, lithium borofluoride, lithium arsenic fluoride, lithium phosphorus fluoride, lithium chloroaluminate, and lithium halide, and preferred are lithium perchlorate, lithium borofluoride, and lithium phosphorus fluoride.

The concentration of [F]) in the composition is usually 01 to 5 mol//1. Preferably it is 05 to 3 mol/e.

The method for obtaining an ion conductive composition containing (A) and (J3) is as follows:
) is not particularly limited as long as it is a method of dissolving (I3) in the mixture represented by (1) and (B) is usually mixed and stirred with heating if necessary.

The electrolyte composition of the present invention is an electrolyte composition suitable for lithium batteries, and can be used in the same manner as electrolytes used in ordinary organic electrolyte type lithium batteries.

For example, the electrolytic solution composition of the present invention can be used alone or in the form of a support (fabric, nonwoven fabric, film, etc.) by coating, impregnating or immersing it.

A lithium battery can be constructed using the electrolyte composition of the present invention. In this case, components other than the electrolyte composition can be configured in the same manner as usual. For example, this battery has a positive electrode current collector and a negative electrode current collector, uses a positive electrode active material and a negative electrode active material, and contacts the positive electrode active material and the negative electrode active material with the electrolyte composition of the present invention interposed therebetween. It can be configured as follows.

As the positive electrode or negative electrode current collector, common conductive materials such as stainless steel and carphone can be used. The shape may be a net shape, a plate shape, a rod shape, etc., and a net shape is preferable.

Examples of the negative electrode active material include lithium, alloy C (lithium-aluminum alloy used as a lithium battery body, etc.).

Its shape includes foil, plate, rod, etc., but foil is preferred.

Transition metal oxides (manganese dioxide,
Examples include vanadium pentoxide, molybdenum oxide, copper oxide, etc.), carphone fluoride, and transition metal chalcogen compounds (iron sulfide, titanium sulfide, etc.). The positive electrode active material is generally produced by pressurizing the above positive electrode active material together with powder of synthetic resin (polyethylene, Teflon, polystyrene, etc.) in a mold, sintering,
A molded version is used.

An example of a lithium battery using the electrolyte composition of the present invention will be explained with reference to FIG. In the figure, (1) is the positive electrode can (positive electrode current collector), (2) is the metal net for current collection, and (3) is the positive electrode can (positive electrode current collector).
is a positive electrode active material, (4) is a separator, (5) is a liquid absorbing material, (6) is an L-shaped gasket, (7) is a negative electrode active material,
(8) is a negative polarity net, and (9) is a net made by Kinkuta for TEPCO.

A current collecting metal net (2) is placed on the bottom of the positive electrode can (1), and a molded positive electrode active material (3) is crimped onto the net.

Next, place a porous or mesh-like separator (made of polyethylene, etc.) (4) on the positive electrode active material (3 days), place a synthetic resin absorbent material (5) on the separator (4), and place the liquid absorbent material (5) on the separator (4). After injecting the electrolyte composition of the invention, an L-shaped gasket (6) is inserted along the wall surface of the positive electrode can (1).One side is placed on the liquid-absorbing material (5)-J2 containing and holding it. Then, the open end portion of the positive electrode can (1) is bent inward and sealed.

The electrolytic solution composition of the present invention has high ionic conductivity and is a stable electrolytic solution with almost no chemical changes during charging and discharging. A lithium secondary battery and a secondary battery, especially a secondary battery, using this electrolyte have sufficient battery characteristics for a long time.

A small amount (
When dried so that 2 to 50% by weight of N-substituted oxazolidinone or N,N'-substituted imidazolidinone remains, a solidified electrolyte membrane exhibiting high ionic conductivity is obtained.

A lithium battery can be constructed using this electrolyte membrane. As an example, the basic configuration of this battery is shown in the second example.
As shown in the figure. In the figure, Ql is a positive electrode active material, the cap is a solidified membrane of the electrolyte composition of the present invention, θ is a positive electrode can, α is a metal net for current collection, q4) is a 17-shaped gasket,
α is a negative electrode active material, and OQ is a negative electrode.

The present invention will be further explained below with reference to Examples, Reference Examples, and Reference Comparative Examples, but the present invention is not limited thereto.

Example I Lithium perchlorate was dissolved in N-methyloxazolidinone at a ratio of 1 mol/e to obtain an electrolyte composition of the present invention.

Reference Example Work and Reference Comparative Example 1 5] (L, vanadium, acetylene black, and polyethylene powder were mixed and pressure molded to form a positive electrode active material molded body, which was placed on the bottom of a stainless steel positive electrode can.) Next, a polypropylene separator was mounted on the molded body, and then the electrolyte composition of the present invention of Example 1 was injected and a gasket was inserted.

Thereafter, a stainless steel negative electrode can with lithium foil adhered thereto was placed on a separator, the open end of the positive electrode can was bent inward, and the seal was hermetically sealed with glass to produce a battery.

As a reference comparative example, a battery was similarly prepared using propylene carbonate instead of N-methyloxazolidinone.

Note that both batteries are coin-shaped batteries with a size of 2.5 mm x 28 mmφ.

A charge/discharge n test was performed in which the battery was charged with a constant current of 1 mA until the depth of discharge reached 30%, and the battery was charged by that capacity, and the results are shown in Table 1.
Shown below.

Table 1 Example 2 Adding 0% of lithium borofluoride to N-methyloxazolidinone
The electrolyte composition of the present invention was obtained by dissolving at a rate of 5 mol/e.

Reference Example 2 and Reference Comparative Example 2 A positive electrode made by press-molding a positive electrode active material molded body made by mixing manganese dioxide, acetylene black and polyethylene powder and pressing it onto a stainless steel net, and a positive electrode made by pressing lithium foil into a stainless steel net. The negative electrode prepared in close contact with the container and the electrolyte composition of the present invention of Example 2 were each placed in a glass container and sealed to assemble a battery.

As a reference comparative example, a battery was similarly prepared using propylene carbonate instead of N-methyloxazolidinone.

FIG. 3 shows the voltage characteristics of the battery when charging was performed with a constant current of 0.5 mA. In the figure, I represents the present invention, and II represents the comparative example. Further, FIG. 4 shows the change in internal resistance of the battery when the battery was discharged at a constant current of 0.5 mA until the depth of discharge reached 16% and then charged to that capacity. In the figure, ■ indicates the present invention, and ■ indicates a comparative example.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views. FIG. 3 is a diagram showing the relationship between charging time and battery voltage. FIG. 4 is a diagram showing the relationship between charging time and number of cycles. Patent applicant: Sanyo Chemical Industries, Ltd. Ton 11'￥I1 % to 1 figure Nona 14 Fu 0 no 3 1 song IQ JD 20 Mo scolding officer (It, Ji item + 1 item r t. Buikuru it CI!J)

Claims (1)

[Claims] 1 General formula () % formula % (wherein R1, R2, R3, R4 are 71 (element atoms, alkyl groups, cycloalkyl groups, or aryl groups. R5, R6 are alkyl groups) , cycloalkyl group or aryl group) and/or N,N'-g-substituted imidabridinone/(a)
and (this lithium salt [F]), an electrolyte composition suitable for a lithium battery. 2. The composition according to claim 1, wherein the electrolyte composition 8) is an organic electrolyte composition in which the concentration of 8) is 0.1 to 5 mol/e in the composition.