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Nonaqueous electrolyte solution and lithium secondary battery

A lithium secondary battery and non-aqueous electrolysis technology, applied in the field of non-aqueous electrolytic solutions, to achieve the effects of improving storage characteristics and preventing swelling

Inactive Publication Date: 2007-03-28
UBE IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The object of the present invention is to solve the problems related to non-aqueous electrolytic solutions for lithium secondary batteries

Method used

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  • Nonaqueous electrolyte solution and lithium secondary battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] (preparation of non-aqueous electrolytic solution)

[0057] A non-aqueous solvent of EC:VC:MEC (volume ratio=28:2:70) was prepared. Dissolve LiPF in this solvent 6 , to prepare a 1M non-aqueous electrolytic solution. Add 1% by weight (based on the nonaqueous electrolytic solution) of 2,4-difluoroanisole and 2% by weight (based on the nonaqueous electrolytic solution) of 1-fluoro-4-cyclohexyl in the nonaqueous electrolytic solution benzene. The dynamic viscosity of the electrolytic solution at 25°C is 2.7×10 -6 m 2 / s.

[0058] (preparation of lithium secondary battery and measurement of battery performance)

[0059] 90 wt% LiCoO 2 (positive electrode active material), 5% by weight of acetylene black (conductive material), and 5% by weight of polyvinylidene fluoride (binder). 1-Methyl-2-pyrrolidone was added to the mixture to prepare a slurry. The aluminum foil surface was coated with the slurry. The coated foil is dried and pressure-formed to form the positive...

Embodiment 2

[0065] A 18650 battery was prepared in the same manner as in Example 1, except that 1% by weight (based on the non-aqueous electrolytic solution) of fluorobenzene was used instead of 2,4-difluoroanisole. The performance of the battery after 200 cycles was measured, and the retention value of the discharge capacity relative to the initial discharge capacity (100%) was 82.1%. In the overcharge test, the temperature of the battery surface is not higher than 120°C. Table 1 shows the conditions for preparing the battery and the battery performance of the battery. The dynamic viscosity of the electrolytic solution at 25°C is 2.7×10 -6 m 2 / s.

Embodiment 3

[0067] A non-aqueous solvent EC:VC:MEC:PS (1,3-propane sulfonolactone) (volume ratio=28:2:69:1) was prepared. Dissolve LiPF in this solvent 6 , to prepare a 1M non-aqueous electrolytic solution. To this nonaqueous electrolytic solution were added 1 wt % (based on the nonaqueous electrolytic solution) of fluorobenzene and 2 wt % (based on the nonaqueous electrolytic solution) of 1-fluoro-4-cyclohexylbenzene.

[0068] A 18650 battery was prepared in the same manner as in Example 1, except that the prepared electrolytic solution was used. The performance of the battery after 200 cycles was measured, and the retention value of the discharge capacity relative to the initial discharge capacity (100%) was 82.4%. In the overcharge test, the temperature of the battery surface is not higher than 120°C. Table 1 shows the conditions for preparing the battery and the battery performance of the battery. The dynamic viscosity of the electrolytic solution at 25°C is 2.7×10 -6 m 2 / s.

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Abstract

Disclosed is a lithium secondary battery wherein both overcharge safety and cycle characteristics are improved together. [MEANS FOR SOLVING PROBLEMS] As the nonaqueous electrolyte solution for such a lithium secondary battery, there is used a nonaqueous electrolyte solution obtained by dissolving an electrolyte in a nonaqueous solvent containing plural kinds of cyclic carbonate compounds which electrolyte solution further contains 1-10 mass% of a cyclohexylbenzene compound wherein a halogen atom is bonded to a benzene ring and 0.1-5 mass% of a fluorobenzene compound.

Description

technical field [0001] The present invention relates to a nonaqueous electrolytic solution used in the preparation of a lithium secondary battery with excellent battery performance. More specifically, the battery is improved in overcharge protection, and gas generation due to decomposition is suppressed when the battery is reused or stored at an elevated temperature. The present invention also relates to a lithium secondary battery using the nonaqueous electrolytic solution. Background technique [0002] Recently, lithium secondary batteries have been widely used, for example, as power sources for driving small electronic devices. A lithium secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolytic solution. The positive electrode usually contains lithium composite oxides, such as LiCoO 2 , the negative electrode usually contains carbonaceous materials or metallic lithium. Carbonates such as ethylene carbonate (EC) and dimethyl c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/40H01M6/16H01M10/0525H01M10/0567H01M10/0568H01M10/0569H01M10/36H01M10/42
CPCH01M10/4235Y02E60/122H01M2300/004H01M10/0569H01M10/0568H01M10/0525H01M10/0567Y02E60/10
Inventor 安部浩司
Owner UBE IND LTD