Silane additive composition, electrolyte containing same and lithium ion battery

Abstract

The invention discloses a silane additive composition containing a carbon-carbon triple bond, an electrolyte containing the composition and a lithium ion battery, the composition comprises: a silane additive used for inhibiting gas production of a cell and accounting for 0.01-10.0% of the total mass of the electrolyte; and a fluorine-containing lithium salt additive which is used for improving the initial impedance of the battery cell and inhibiting the continuous increase of the impedance in the cyclic process, and accounts for 0.1-10.0% of the total mass of the electrolyte. The composition disclosed by the invention has the advantages of improving the high-temperature storage performance, high-temperature cycle performance, rate capability and low-temperature performance of the battery at the same time.

Description

technical field [0001] The invention relates to a lithium ion battery electrolyte, in particular to a composition of a carbon-carbon triple bond-containing silane additive and a fluorine-containing lithium salt additive, an electrolyte containing the composition, and a lithium ion battery. Background technique [0002] High energy density is the development trend of lithium batteries. The commonly used ways to improve it include increasing the working voltage or increasing the nickel content in the positive electrode material, but both of these methods will pose new challenges to the cycle performance and safety performance of the battery cell. Therefore, the high-temperature cycle performance and high-temperature storage stability of batteries have attracted much attention. [0003] In order to improve the high-temperature storage performance of lithium-ion batteries, vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propane sultone (PS), 1,3 - Propyl sulfonate ...

AI Technical Summary

Problems solved by technology

[0004] However, these additives have disadvantages. In a high-voltage battery system, VEC or VC has a large volume expansion (gas production) after high-temperature storage, and the effect of inhibiting the growth rate of cell impedance is also poor; PS, PST and other sulfonate esters The additive has a significant effect of inhibiting the gas production of the battery cell, but its initial impedance and impedance growth rate are high, which is unfavorable to the low-temperature performance and rate performance of the battery. More importantly, PS is a carcinogen and has been included in Reach control List of substances whose use is increasingly restricted

Homologs or structural analogs such as PST or 1,4-butane sultone (BS) have similar risks and are not recommended

Although TMSB can improve the high-temperature performance of the high-nickel material system, its effect of suppressing the gas production of the cell is insufficient, and the effect of suppressing the increase of impedance is not good.

[0005] Generally speaking, the existing high-temperature performance-improving additives not only need to improve the high-temperature storage performance, but most of the interface protective films have high impedance and fast growth rate of impedance, which deteriorates the rate performance, low-temperature performance and long-term cycle stability of the battery.

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