JP2003040885A - Glycerol dicarbonate derivative, non-aqueous electrolyte solution produced by using the same, polymer electrolyte and cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contribute to the stabilization of the interface between an electrode and an electrolyte, and solve the problems of the lowering of interfacial resistance, by using a glycerol dicarbonate derivative for the production of a non- aqueous electrolyte solution, a polymer electrolyte and a cell. SOLUTION: The glycerol dicarbonate derivative is expressed by formula. A non-aqueous electrolyte solution is obtained by dissolving an electrolyte salt in the glycerol dicarbonate derivative. A polymer electrolyte is obtained by adding an electrolyte salt and the glycerol dicarbonate derivative to a host polymer and a cell produced by using the non-aqueous electrolyte solution or the polymer electrolyte.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a glycerin dicarbonate derivative, a non-aqueous electrolytic solution using the same, a polymer electrolyte and a battery.

[0002]

2. Description of the Related Art In recent years, lithium secondary batteries have been widely used as driving power sources for small electronic devices and the like. A lithium battery is mainly composed of a positive electrode, a non-aqueous electrolyte and a negative electrode. In particular, a lithium secondary battery using a lithium composite oxide such as LiCoO ₂ as a positive electrode and a carbon material or lithium metal as a negative electrode is used. ing. Then, as the electrolytic solution for the lithium secondary battery, carbonates such as ethylene carbonate (EC) and propylene carbonate (PC) are used.

However, there is a demand for a secondary battery having more excellent battery characteristics such as battery cycle characteristics and electric capacity. High-dielectric constant solvents such as EC and PC are used as the non-aqueous solvent used in the electrolytic solution of the lithium secondary battery, but these high-dielectric constant solvents alone have high viscosity and sufficient ionic conductivity. In general, dimethyl carbonate (DM
C), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), and other low-viscosity solvents are mixed in an appropriate mixing ratio to prepare an electrolytic solution so that the highest possible conductivity is obtained.

A non-aqueous electrolytic solution in which an electrolyte is dissolved in the above-mentioned non-aqueous solution is disclosed in which various glycerin carbonate derivatives are added in order to enhance the performance of the non-aqueous electrolytic solution.

For example, Japanese Patent Laid-Open No. 2000-208166 discloses that
There is a disclosure of a lithium secondary battery using a glycerin carbonate derivative obtained from an alkyloxymethyl ether of glycerin such as 4-acetoxymethyl-1,3-dioxolan-2-one and a carbonic acid ester as a non-aqueous electrolyte solvent.

Further, Japanese Patent Laid-Open No. 2000-323170 discloses that
There is a disclosure of a non-aqueous electrolyte solvent for a 4-alkyl-1,3-dioxolan-2-one derivative for a lithium battery. The solvent used here is a solvent obtained by reacting an alkyl glycerin ether and a carbonic acid ester in the presence of an alkali.

By adding these glycerin carbonate derivatives, E having a high dielectric constant but a high viscosity can be obtained.
When used with a solvent such as C or PC, an electrolytic solution for a secondary battery having excellent cycle characteristics and storage characteristics can be obtained.

However, the present situation is that even the non-aqueous electrolyte containing the above compound is not sufficiently effective in reducing the stability and interface resistance at the electrode-electrolyte interface and suppressing the increase over time. .

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. When the synthesis of glycerin dicarbonate derivatives was studied, new substances were obtained. Using this high boiling point glycerin dicarbonate derivative, it is applied to the preparation of non-aqueous electrolytes, polymer electrolytes, and batteries to contribute to the stabilization of the electrode-electrolyte interface and improve the problems such as reduction of interface resistance. This is an issue.

[0010]

The glycerin dicarbonate derivative of the present invention is a compound represented by the following chemical formula 2.

[0011]

[Chemical 2]

(Wherein R represents an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group, an allyl group) The non-aqueous electrolytic solution of the present invention comprises an electrolyte salt and a glycerin dicarbonate derivative represented by the above chemical formula 2. Is dissolved in.

The non-aqueous electrolytic solution of the present invention is obtained by dissolving another non-aqueous solvent and an electrolyte salt in the glycerin dicarbonate derivative represented by the chemical formula (2).

The polymer electrolyte of the present invention is a host polymer to which the glycerin dicarbonate derivative of the above formula 2 and an electrolyte salt are added.

The battery of the present invention uses an electrolytic solution or a polymer electrolyte containing the glycerin dicarbonate derivative represented by the above formula (2).

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A glycerin dicarbonate derivative represented by the chemical formula 2 of the present invention (hereinafter abbreviated as GC-DC)
Is a catalyst such as metallic lithium dissolved in glycerin under an inert gas atmosphere, and then an excess of carbonic acid ester is added and heated at about 120 ° C., so that glycerin undergoes transesterification reaction with carbonic acid ester to form carbonic acid ester. The alcohol constituting the is a substance obtained by distilling and separating 3 mol molecules per 1 mol molecule of glycerin. The reaction process when R is an ethyl group is shown in Chemical formula 3. It should be noted that GC-DC in the chemical formula 3 means GC-DC in the sense of ethyl derivative
It is described as DEC.

[0017]

[Chemical 3]

R in the formula 3 corresponds to an alkyl group or an allyl group of an alcohol constituting the ester group of the carbonic acid ester used in the condensation reaction, and is methyl, ethyl,
Examples thereof include a propyl group, a butyl group, a phenyl group, and a halogenated alkyl group such as a fluoroalkyl group.

It is preferable that the alcohol component of the carbonic acid ester has a boiling point that can be easily removed from the reaction system by distillation when liberated by transesterification.

The product GC-DC is obtained by distilling off the excessively added carbonic acid ester and then distilling under reduced pressure to obtain high-purity GC-DC as a colorless transparent liquid substance having a little viscosity.

The product was confirmed by infrared spectrum (FIG. 1), ¹ H-NMR spectrum (FIG. 2), ¹³ C NMR spectrum (FIG. 3), and elemental analysis when R is ethyl.

The trace amount of unreacted hydroxyl groups remaining in the product can be easily removed by dissolving in a non-aqueous solvent, adding lithium and heating.

The non-aqueous electrolyte of the present invention is the G obtained above.
C-DC can be formed by dissolving various lithium salts. To dissolve the lithium salt, for example, GC-DC and the lithium salt are added to a solvent such as tetrahydrofuran, and the solution is uniformly dissolved by heating at room temperature or heating, and then,
If necessary, the solvent used for mixing is removed by vacuum distillation to obtain a viscous liquid electrolytic solution.

This electrolytic solution exhibits ionic conductivity and exhibits characteristics as an electrolytic solution. For example, an electrolytic solution containing LiPF ₆ as a lithium salt exhibits ionic conductivity, and the ionic conductivity increases as the amount of lithium salt increases.

It is generally known that a high-dielectric constant (high-viscosity) solvent and a low-viscosity (low-dielectric constant) solvent are mixed at an appropriate ratio to obtain an electrolytic solution having a high ionic conductivity.

The GC-DC of the present invention is also DME (1,2-
A non-aqueous electrolyte solution having a higher ionic conductivity can be obtained by mixing another non-aqueous solvent such as dimethoxyethane).

Other non-aqueous solvents that can be used with GC-DC include, for example, dimethyl carbonate (DM
C), chain carbonates such as methyl ethyl carbonate (MEC) and diethyl carbonate (DEC), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2- Examples thereof include ethers such as diethoxyethane and 1,2-dibutoxyethane, lactones such as γ-butyrolactone, nitriles such as acetonitrile, esters such as methyl propionate, and amides such as dimethylformamide. These may be used alone or in combination of two or more to increase the ionic conductivity.

These electrolytes are usually used after being dissolved at a concentration of 0.1 to 3M, preferably 0.5 to 1.5M.

In the polymer electrolyte of the present invention, a polymer corresponding to a host polymer, a lithium salt and GC-DC are dissolved in, for example, acetonitrile, and the solvent is removed under reduced pressure to form a solid electrolyte. it can.

As the host polymer, for example, polymethylmethacrylate (PMMA), polyethylene oxide (PEO) or the like is used, and a lithium salt and GC-DC are mixed to form a polymer electrolyte. Moreover, it is also possible to mix other non-aqueous solvent as needed.

Examples of lithium salts that can be used include:
LiPF ₆ , LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ , Li
Examples include N (SO ₂ C ₂ F ₅ ) ₂ and LiC (SO ₂ CF ₃ ) ₃ . These electrolytes may be used alone,
You may use it in combination of 2 or more types.

In a polymer electrolyte containing PEO, a lithium salt and GC-DC, GC-DC acts as a safe plasticizer having a high boiling point to improve the mobility of the ether chain of PEO and enhance the ionic conductivity. Conceivable.

The battery prepared by using the above-mentioned polymer electrolyte can reduce the positive electrode interfacial resistance. This forms a passive phase between the negative electrode and the positive electrode, and the electrolyte-positive electrode interface resistance is greatly reduced. It is considered that this is because the microscopic adhesion of the electrode-electrolyte is improved and the interface state of the positive electrode active material-PEO portion in the electrode is improved.

It is considered that the electrochemical stability of the electrolytic solution containing GC-DC is higher than that of the electrolytic solution containing PC and has a wider potential window.

The electrolytic solution of the present invention is used as a constituent member of a lithium secondary battery. The constituent members other than the electrolytic solution that constitute the secondary battery are not particularly limited, and various conventionally used constituent members can be used. For example, as the positive electrode active material, at least one selected from the group consisting of cobalt, manganese, nickel, chromium, iron and vanadium.
A complex oxide of a type of metal and lithium is used. As such a composite metal oxide, for example, LiCo
O ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiPF ₆ , LiT
Rif, LiTFSI, etc. are mentioned.

For the positive electrode, the positive electrode active material was kneaded with a conductive agent such as acetylene black or carbon black and a binder such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) to prepare a positive electrode mixture. After that, this positive electrode material is applied to a foil or lath plate made of aluminum or stainless steel as a current collector, dried, pressure-molded,
It is produced by heat treatment under vacuum at a temperature of about 50 ° C. to 250 ° C. for about 2 hours.

As the negative electrode active material, lithium metal, lithium alloy, graphite which is a carbon material capable of absorbing and releasing lithium, and the like are used. In addition, powdered materials such as carbon materials are ethylene propylene diene polymer (E
PDM), polytetrafluoroethylene (PTFE),
It is kneaded with a binder such as polyvinylidene fluoride (PVDF) and used as a negative electrode mixture.

The structure of the secondary battery is not particularly limited, and a coin-type battery having a positive electrode, a negative electrode, and a single-layer or multi-layer separator, a cylindrical battery having a positive-negative electrode and a roll-shaped separator, and a square battery. For example, a type battery or the like can be given. As the separator, a known polyolefin microporous film, woven fabric, non-woven fabric, or the like can be used.

[0039]

EXAMPLES The present invention will be specifically described below based on examples.

4- (ethoxycarbonyloxymethyl)
Synthesis of -1,3-dioxolan-2-one (GE-DEC) A small piece of lithium metal was placed in a 300 ml three-necked flask under an argon atmosphere, and glycerin (18.756 g,
0.204 mol) was added and the mixture was stirred at room temperature for 12 hours to dissolve lithium metal. The undissolved lithium metal was removed from the system. Next, a Dean-Stark tube and a bulb cooling tube were connected to the three-necked flask, an excess amount of diethyl carbonate was added, and the mixture was heated and stirred in an oil bath at 120 ° C. for 3 hours to distill off the produced ethanol. Then heat (12
The reaction was completed by stirring for 24 hours. After completion of the reaction, unreacted diethyl carbonate was distilled off under reduced pressure (room temperature, 0.1 mmHg).

The above residue was dissolved in 40 ml of ethyl acetate and the ethyl acetate solution was added to 4 ml of 10 ml of slightly acidified water.
The lithium salt and unreacted glycerin were removed by washing twice. Then, the ethyl acetate solution was dried overnight with magnesium sulfate, the solvent ethyl acetate was distilled off, and the residue was distilled under reduced pressure (129-130 ° C, 0.045 mmHg) to give a colorless transparent slightly viscous liquid. Obtained (18.819 g, yield 52.
Five%).

(Treatment of residual OH groups in GC-DEC with lithium metal) GC-DEC (18.
283 g) and small pieces of lithium metal were transferred to a 100 ml two-necked flask. Add this mixture to an oil bath at 40
The mixture was stirred for 12 hours while maintaining the temperature at 0 ° C. At the time of stirring, the reaction between the OH group and lithium metal was promoted by applying ultrasonic waves several times for 5 minutes. After completion of stirring, lithium metal was removed from the system, and vacuum distillation (130 to 134 ° C., 0.06 mmHg) was performed to obtain a colorless transparent liquid (14.688 g, yield 80.3%).

The product (GC-DEC) is about 0.05 m
It had a very high boiling point of mHg and 130 ° C. The product was confirmed to have a cyclic carbonate and an acyclic carbonate structure by infrared spectrum and NMR elemental analysis.

[0044]

[Chemical 4]

The numbering for determining the position of the atom in the spectrum is added to the formula (4).

FT-IR (Fig. 1), 2990 cm^-1(C
H₃), 1800 cm^-1(²C = on the O ring), 1750 cm ^-1(⁸C = O
(On the chain), 772 cm^-1, 712 cm^-1.

¹ H-NMR (FIG. 2) 1.25 to 1.41 (t, 3
H-CH ₃ ), 4.13 to 4.67 (m, 2HC ⁴ H ₂ , m, 2HC ¹⁰ H ₂ , m, 2HC ⁶ H ₂ ),
4.82 to 5.06 (m, 1HC ⁵ H), ¹³ C-NMR (Fig. 3) 14.0 (C
¹¹ ), 64.3 (C ¹⁰ ), 66.0 (C ⁵ ), 66.7 (C ⁴ ), 74.2 (C ⁶ ), 154.3, 15
The measurement result of 4.7 (C ² , C ⁸ ) is shown.

The result of elemental analysis of this product is carbon 44.
It was 23% (calculated value 44.22%) and hydrogen 5.21% (calculated value 5.3%).

Thermal properties (melting point) of the product GC-DEC
Was measured using differential thermal analysis (DSC). The results of comparison of the measurement results with PC and EC are shown in Table 1 and FIG.

[0050]

[Table 1]

According to the graph of DSC, a peak showing the melting point of GC-DEC is seen around -46 ° C. This value was almost the same as that of PC, which is a general cyclic ester carbonate, and it was found that it does not become a solid around room temperature like EC. The boiling point was 129 to 130 ° C. (0.045 mmHg).
This value is about 380 ° C. when converted to 760 mmHg, which indicates that it has a high boiling point and low flammability.

(Preparation of LiPF ₆ / GE-DEC electrolyte) LiPF ₆ (0.112 g, 0.732 mmol) and GC-DEC
(0.3813 g, 2.165 mmol) was weighed into a 50 ml two-necked flask and dissolved in 20 ml of tetrahydrofuran. After stirring this mixed solution for 6 hours, tetrahydrofuran was distilled off under reduced pressure at room temperature. A white brittle solid was obtained (0.4810 g,
Yield 97.5%).

Various electrolytes having different lithium salt concentrations were prepared by the above-mentioned method and subjected to measurement of ionic conductivity.

(Measurement of Ionic Conductivity of LiPF ₆ / GC-DEC Electrolyte) The ionic conductivity and mechanical properties at each lithium salt concentration are shown in Table 2. The relationship between ionic conductivity and lithium salt concentration is shown in FIG.

[0055]

[Table 2]

At the lithium salt concentration m = 1.47 shown in Table 2, the electrolyte was a uniform brittle solid, but at a lithium salt concentration higher than that, phase separation occurred between the liquid phase and the solid phase, and the uniform electrolyte was obtained. Couldn't get But,
At a lithium salt concentration lower than that, a uniform liquid electrolyte was obtained.

As shown in FIG. 5, the ionic conductivity is LiPF.
_It increased when the concentration of ₆ increased, then decreased and increased again. The ionic conductivity was lower than that of the non-polar organic solvent generally used for lithium ion batteries. It is considered that the initial increase in the ionic conductivity of GC-DEC is due to the increase in the number of carriers in the electrolyte. It is considered that the subsequent decrease in ionic conductivity is due to a decrease in carrier mobility due to an increase in the viscosity of the electrolyte and a decrease in the number of carriers due to a solvent-ion or ion-ion interaction. Although the ionic conductivity is rising again, it is considered to be due to the increase of carrier ions due to the formation of highly associated bodies or the phase separation of the electrolyte.

(GC-DEC / DME / LiPF ₆ Electrolyte) Generally, a high dielectric constant (high viscosity) solvent and a low viscosity (low dielectric constant) solvent are mixed at an appropriate ratio to obtain an electrolyte having a high ionic conductivity. It is known to be obtained. So G
DME which is a typical aprotic solvent for C-DEC
(εr = 7.2 η0 = 0.46) is mixed, and GC-DEC / DME /
A LiPF ₆ electrolytic solution was prepared and evaluated. The lithium salt concentration in the electrolytic solution was fixed at 0.5M. The measurement results of the mixing ratio and the ionic conductivity are shown in FIG.

As shown in FIG. 6, as the amount of DME mixed was increased, the ion conductivity increased by two orders of magnitude. This is GC-DE
It is considered that the viscosity of C was so high that the viscosity was appropriately reduced by DME. GC-DEC: DME = 2
Highest ionic conductivity 1.0x1 at a ratio of 0: 80% by volume
Although 0 ^-2 S / cm was obtained, LiPF ₆ seems to be easily dissociated even in DME because of its high dissociation property. Further, it was found that the electrolyte mixed with PC, which is said to have a slightly high viscosity, reached the order of 10 ^{−3 as} a result of measurement, and it can be presumed that if the viscosity can be improved, the conductivity will be higher because the dielectric constant will be high. (Preparation of PEO-based solid polymer electrolyte) PEO (polyethylene oxide), LiTrif, L as lithium salt
iTFSI was used. For the preparation of the electrolyte, use GC-DEC 5
Transferred to a 0 ml two-necked flask and dissolved in acetonitrile by stirring. After removing acetonitrile by heating, a white solid was obtained by drying under reduced pressure. Here, the lithium salt concentration in the electrolyte is O / Li (PE
The ratio of oxygen to lithium in O) was set to 20. (PMMA Polymer Gel Electrolyte Containing GC-DEC) A polymer electrolyte was prepared using the synthesized GC-DEC.
PMMA (polymethylmethacrylate) was used as the host polymer, LiPF ₆ was used as the salt, and the composition was PMMA (2
0 wt%) / GC-DEC (75 wt%) / LiPF ₆
(5% by weight). The mechanical properties are slightly soft and it seems that the mechanical properties become better with a little more PMMA. Ionic conductivity is 1.2 × 10 ^-5 S at room temperature
Although it was not so high as / cm, if the GC-DEC / PC mixed electrolyte is used, an increase in ionic conductivity of one digit or more can be expected. (Ionic conductivity of PEO ₂₀ LiTrif / GC-DEC polymer electrolyte) GC-DEC for PEO polymer electrolyte
Was added and the effect on ionic conductivity was investigated. Here, LiTrif was used as the lithium salt, and the lithium salt concentration was fixed at O / Li = 20. The temperature dependence of ionic conductivity is shown in Table 3 and FIG.

[0060]

[Table 3]

GC-DE as shown in Table 3 and FIG.
An increase in ionic conductivity of about one digit was observed by adding 10% by weight of C. It is considered that this is because GC-DEC worked as a plasticizer in the electrolyte and improved the mobility of the ether chain of PEO. It is considered that the amount of GC-DEC added is increased in order to further improve the ionic conductivity, but in PEO, GC-DE is added in the matrix.
It is difficult to hold C at about 10% or more, and C oozes out on the surface of the electrolyte. The same can be said for other cyclic carbonate ester solvents. (Ionic conductivity of PEO ₂₀ LiTFSI / GC-DEC type polymer electrolyte) GC-DEC for PEO type polymer electrolyte
Was added and the effect on ionic conductivity was investigated. Here, LiTFSI is used as the lithium salt, and the lithium salt concentration is O /
It was fixed at Li = 20. The temperature dependence of ionic conductivity is shown in Table 4 and FIG.

[0062]

[Table 4]

10% by weight as shown in Table 4 and FIG.
The ionic conductivity was increased by adding GC-DEC in the same manner as in the case of using LiTrif as the lithium salt. This effect was more obvious (about one digit) in the temperature range lower than the melting point of PEO crystals. This is LiTri
It is considered that GC-DEC acts as a plasticizer in the electrolyte as in the case of the f type, and improves the mobility of the ether chain. Further, as in the case of the LiTrif system, G of 10 wt% or more
C-DEC is difficult to keep in the electrolyte. Therefore, if a PEO-based polymer having a crosslinked structure is used,
It is believed that the solvent retention in the electrolyte can be increased. (GC-DEC in PEO-based electrolyte / Li interface resistance
Effect) The composition of the electrolyte used for the interface resistance measurement is shown in Table 5. The time dependence of the electrolyte / Li interface resistance is shown in FIG.

[0064]

[Table 5]

As shown in Table 5, by adding a small amount of GC-DEC to the positive electrode using PEO as a binder in the electrolyte, the initial interface resistance does not include GC-DEC as shown in FIG. It decreased compared to the one. It is considered that this is because the adhesion between the electrode and the electrolyte was improved, and the state of the interface between the positive electrode active material and the PEO portion in the electrode was improved.

It has been generally reported that a passive phase containing a substance such as LiCO ₃ is formed between a carbonate ester solvent and a negative electrode or a positive electrode, and it is possible that the same passive phase was formed in GC-DEC. Can be considered.

(Effect of CD-DEC on PEO Electrolyte / Li Interface Resistance) The composition of the electrolyte used for the interface resistance measurement is shown in Table 6.

[0068]

[Table 6]

FIG. 1 shows the time dependence of the electrolyte / Li interface.
It was shown at 0.

Addition of GC-DEC into the electrolyte reduced the initial interfacial resistance. This is considered to improve the electrode-electrolyte contact property. Used GC-DEC
Was compared with untreated, LiAlH ₄ treated, and Li treated.

As shown in FIG. 10, the interface resistance is about 50.
After a lapse of time, it showed a sharp rise. It is considered that this is because unreacted OH groups in GC-DEC reacted with lithium to form a Li salt on the surface, and this Li salt acted as a decomposition catalyst of GC-DEC. In the GC-DEC used for this measurement, OH groups could not be confirmed by infrared spectrum (IR) measurement. But from this result, IR
It is considered that there is an OH group which is not detected in the above, and it affects the interface resistance. So O in GC-DEC
Attempts were made to treat the H group by reaction with liAlH ₄ or Li. As a result, the abrupt increase in interfacial resistance becomes slower than that before the treatment, and it is considered that lithium metal is more effective in the effect of the OH treatment.

(Polymer electrolyte containing GC-DEC / Li
Co _0.2 Ni _0.8 O ₂ Electrode Interface Resistance) The nature of the electrolyte / electrode interface has a great influence on the battery performance. So L
iCo _0.2 Ni _0.8 O ₂ electrode / PEO ₂₀ Li (CF ₃ S
The influence of CD-DEC was examined on the O ₂ ) ₂ N interface.

P which is often used as a polymer electrolyte
10 wt% BaTiO _{3 in} EO ₂₀ Li (CF ₃ SO ₂ ) ₂ N
Was added to prepare a membrane.

An electrode film containing GC-DEC and an electrode film containing no GC-CED for comparison were prepared with the following compositions.

System containing GC-DEC: PEO₂₀Li (C
F₃SO₂)₂N (33%), acetylene black (A
B) (9%), LiCo_0.2Ni_0.8O₂(54%), G
C-DEC (3%) / PEO₂₀LiTFSI + 10% B
aTiO₃/ PEO₂₀LiTFSI (33%), acetyl
Renblack (AB) (9%), LiCo_0.2Ni_0.8O
₂(54%), GC-DEC (3%) System without GC-DEC: PEO₂₀Li (CF₃S
O₂)₂N (33%), acetylene black (AB) (9
%), LiCo_0.2Ni_0.8O₂(54%) / PEO₂₀L
iTFSI + 10% BaTiO₃/ PEO₂₀LiTFS
I (33%), acetylene black (AB) (9%),
LiCo_0.2Ni_0.8O₂(54%) / PEO₂₀LiTF
SI The polymer electrolyte membrane is sandwiched between the electrode membranes as shown in FIG.
Then, measure the interfacial resistance by AC impedance method
It was

As shown in FIG. 12, a change in the plot of AC impedance was observed with time. The high frequency intersection of the plot of AC impedance indicates the resistance of the polyelectrolyte. One small semicircle also appeared on the medium frequency side. Figure 1 shows the time-dependent change in resistance due to a semicircle at high and medium frequencies.
Shown in 3.

As shown in FIG. 12, as the time increases, the resistance of the polymer electrolyte decreases (a). This is GC-D
It is considered that EC is diffused into the electrolyte layer and the resistance of the electrolyte layer is reduced (the ionic conductivity is increased). Further, as shown in (b), the resistance of the polymer electrolyte decreases as the time increases. It is considered that this is because the electrolyte takes up GC-DEC.

The resistance due to the high-medium frequency semicircle in FIG. 13 is considered to be because the addition of GC-DEC forms a passive film at the electrode / electrolyte interface and stabilizes the interface.

(Electrochemical Stability of Electrolyte Containing GC-DEC) Using cyclic voltammetry (CV),
The electrochemical stability of GC-DEC was measured. LiTrif is used as the lithium salt, 0.5MP for comparison
C-LiTrif, 0.5M GC-DEC-LiTri
The measurement was performed for f. Figure 1 shows the cathode side of the measurement results.
4 shows.

From FIG. 15, there is a peak which is considered to be the oxidation of the electrolyte. Dissolution of lithium metal and stripping were confirmed in the vicinity of +3.0 V in both electrolytes. Therefore, when comparing the two electrolytes, it was found that
0.5M L for 5M LiTrif-GC-DEC
It can be seen that it has a wider potential window than iTrif-PC. This is considered to be due to the difference in potential window between PC and GC-DEC.

[0081]

INDUSTRIAL APPLICABILITY The GC-DEC of the present invention is a novel aprotic solvent and can be added as a non-aqueous electrolyte to a high-viscosity solvent used in an electrolytic solution for a battery or the like to reduce the viscosity. High boiling point and low flammability compared to EC, PC, etc.

When it is used as a non-aqueous electrolytic solution or a polymer electrolyte, an electrolytic solution or electrolyte having a practical level of ionic conductivity can be obtained due to the high dielectric constant of GC-DEC.

When used as a battery, especially in a polymer battery, it not only improves the ionic conductivity as a safe high boiling point plasticizer but also contributes to the stabilization of the electrode-electrolyte interface, reducing the interface resistance and increasing with time. The effect of suppressing is obtained.

[Brief description of drawings]

FIG. 1 shows an infrared spectrum of GC-DEC.

FIG. 2 is a ¹ H-NMR spectrum of GC-DEC.

FIG. 3 is a ¹³ C-NMR spectrum of GC-DEC.

FIG. 4 is a chart of DSC measurement on GC-DEC.

FIG. 5 is a graph showing the relationship between the ion concentration and the electrolyte concentration of LiPF ₆ / GC-DEC electrolyte.

FIG. 6D of GC-DEC / DME / LiPF ₆ electrolyte
It is a graph of the ionic conductivity when the amount of ME added is changed.

FIG. 7 is a graph of temperature change of ionic conductivity of GC-DEC / PEO / LiTrif electrolyte.

FIG. 8 is a graph of temperature change of ionic conductivity of GC-DEC / PEOE / LiTFSI electrolyte.

FIG. 9 shows the GC-in the Li interface resistance of PEO-based electrolyte.
It is a graph which shows the addition effect of DEC.

FIG. 10 is a graph showing a change over time in interfacial resistance by measuring AC impedance.

FIG. 11 is a diagram showing a configuration of a membrane measured by sandwiching a polymer electrolyte membrane used for AC impedance measurement with electrode membranes.

FIG. 12 is a graph showing a result of measurement of AC impedance.
Indicates that GC-DEC is not included, and b indicates that GC-DEC is included.

FIG. 13 is a graph showing the change with time in resistance due to a semicircle at high and medium frequencies in the measurement of AC impedance.

FIG. 14 is a graph showing the electrochemical stability of an electrolytic solution containing GC-DEC.

Continued front page    (72) Inventor Mary Ammeter             1873-4 Tomitsukacho, Hamamatsu City, Shizuoka Prefecture             Tomitsuka 204 F-term (reference) 5G301 CA16 CA30 CD01                 5H029 AJ04 AJ05 AJ06 AK03 AL07                       AL12 AM03 AM04 AM05 AM07                       AM16 CJ08 DJ09 HJ02

Claims (5)

[Claims] 1. A glycerin dicarbonate derivative represented by the following general formula. [Chemical 1] (In the formula, R represents an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group, or an allyl group) 2. A non-aqueous electrolytic solution in which an electrolyte salt is dissolved in the glycerin dicarbonate derivative of the above chemical formula 1. 3. A non-aqueous electrolytic solution in which another non-aqueous solvent and an electrolyte salt are dissolved in the glycerin dicarbonate derivative of the above chemical formula 1. 4. A polymer electrolyte obtained by adding a glycerin dicarbonate derivative represented by the above chemical formula 1 and an electrolyte salt to a host polymer. 5. A battery using an electrolytic solution or a polymer electrolyte containing the glycerin dicarbonate derivative represented by the chemical formula 1 above.