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Electrolyte and lithium-ion secondary battery

A technology of electrolyte and electrolyte salt, applied in secondary batteries, circuits, electrical components, etc., can solve the problems of lower cycle performance of lithium ion secondary batteries, and achieve the effect of good normal temperature cycle performance and good low temperature discharge capacity

Active Publication Date: 2010-09-01
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problem in the prior art that propylene carbonate (PC) is used in the electrolyte of lithium ion secondary batteries containing ethylene carbonate (EC), the cycle performance of lithium ion secondary batteries decreases, the invention provides firstly An electrolyte solution for a lithium-ion secondary battery, comprising a mixed solvent and an electrolyte salt, the mixed solvent including ethylene carbonate, propylene carbonate, a low-viscosity organic solvent with a viscosity not greater than 1mPa·s at normal temperature, and the formula (1) Silicone:

Method used

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Examples

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preparation example Construction

[0035] According to the preparation method of the non-aqueous electrolytic solution of the present invention: the siloxane of ethylene carbonate, propylene carbonate, the low-viscosity organic solvent whose viscosity is not greater than 1mPa·s at normal temperature, the siloxane of formula (1) is mixed according to the ratio of the present invention Mix in a dry environment to form a mixed solvent, then add the electrolyte salt into the above mixed solvent, heat and stir to completely dissolve the electrolyte salt, and prepare the non-aqueous electrolyte solution according to the present invention. The purpose of heating the mixed solvent is to quickly and completely dissolve the electrolyte salt, and has little effect on the non-aqueous electrolyte itself, as long as the electrolyte salt can be completely dissolved.

[0036] A lithium ion secondary battery according to the present invention comprises a battery casing, an electrode group and an electrolyte, the electrode group ...

Embodiment 1

[0041] Select the siloxane of structural formula (a) for use:

[0042]

[0043] 1. Electrolyte Preparation

[0044] Weigh 30 grams of EC, 20 grams of PC, 50 grams of DEC, and 10 grams of siloxane of the above formula (a), mix the above four substances evenly, and then add LiPF 6 Make the concentration reach 1mol / L, heat and stir at 50°C to make LiPF 6 Dissolve completely to obtain an electrolyte solution. The siloxane of the above formula (a) accounts for 9.1 wt% of the mixed solvent.

[0045] 2. Preparation of Cathode

[0046] Weigh 92 grams of LiFePO 4, 4 grams of carbon black and 4 grams of polyvinylidene fluoride (PVDF), the above three kinds of materials were dissolved in 100g N-N dimethylpyrrolidone (NMP), fully stirred and mixed evenly to make positive electrode slurry. The positive electrode slurry was evenly coated on an aluminum foil with width×thickness=200mm×16mm by a pulper. Then put the aluminum foil coated with the positive electrode slurry into a vacuu...

Embodiment 2～6

[0061] According to the method of Example 1, the difference is the selection and content of each component in the mixed solvent, as shown in Table 3 below.

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Abstract

The invention provides an electrolyte, which comprises a mixed solvent and an electrolytic salt. The mixed solvent comprises ethylene carbonate, propylene carbonate, low-viscosity organic solvent with a viscosity of no less than 1mPa.S at normal temperature and siloxane of the formula (1): C(R1R2)=C(R3)-Si-[O-(CH2)n-O-C(R4R5R6)]3(1), wherein R1 to R6 may be hydrogen, halogen, alkyl having 1 to 5 carbon atoms or halogenated alkyl having 1 to 5 carbon atoms independently; n is more than or equal to 1 and less than or equal to 10; the siloxane in the formula (1) is no more than 35 percent based on the weight of mixed solvent; and the total weight of the ethylene carbonate and propylene carbonate is 30 to 50 percent based on the weight of the mixed solvent. A secondary battery adopting the electrolyte of the invention better solves the shortcoming of poor low-temperature performance which happens when the electrolyte contains the propylene carbonate.

Description

technical field [0001] The invention relates to an electrolytic solution and a lithium ion secondary battery using the electrolytic solution. Background technique [0002] It is theoretically believed that propylene carbonate (PC) can effectively inhibit the crystallization of ethylene carbonate (EC) at low temperature, which is helpful to improve the low-temperature performance of lithium-ion secondary batteries. But in fact, if PC is used in lithium-ion secondary batteries, since it cannot form a solid electrolyte interface (solid electrolyte interface, SEI) film on the graphite negative electrode before Li+ intercalation, it will co-embed the graphite structure with Li+, And the reduction and decomposition reaction occurs to destroy the graphite structure, resulting in the performance of the lithium-ion secondary battery, especially the normal temperature cycle performance and low temperature discharge capacity. Contents of the invention [0003] In order to solve the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/40C07F7/18
Inventor 刘国刚江文锋
Owner BYD CO LTD
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