High-voltage rate electrolyte with high-and-low temperature performance and lithium ion battery using electrolyte

Abstract

The invention discloses a high-voltage rate electrolyte with high-and-low temperature performance and a lithium ion battery using the electrolyte. The electrolyte comprises a non-aqueous solvent, a lithium salt dissolved in the non-aqueous solvent and additives, wherein the non-aqueous solvent comprises propylene carbonate (PC) and linear carboxylic ester; and the additives comprise citraconic anhydride, lithium difluorophosphate (LiPO<2>F<2>), fluoroethylene carbonate, ethylene sulfate and 1, 2-di(2-cyanoethoxyl)ethane. By applying the synergistic effect generated by the solvent system and the additive optimization combination to the lithium ion battery, excellent cycle life, low-temperature discharge characteristic and high-temperature storage characteristic of the battery still can be maintained at high-voltage rate.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery preparation, in particular to a high-voltage rate electrolyte solution with both high and low temperature performance and a lithium-ion battery using the electrolyte solution. Background technique [0002] Lithium-ion battery is the most competitive battery of the new generation. It has the advantages of high working voltage, large specific capacity, long cycle life, no memory effect and environmental friendliness. It is widely used in digital, energy storage, power and military aerospace, etc. field. In recent years, lithium-ion batteries have achieved great success in the field of high-energy batteries, but consumers can still have batteries with comprehensive performance that meet high-low temperature, high-voltage rate, and this depends on the research on new electrolyte systems and additives and development. [0003] The high and low temperature performance of lithium-ion batter...

AI Technical Summary

Problems solved by technology

[0003] The high and low temperature performance of lithium-ion batteries is mainly affected by the following factors: (1) In high temperature and high voltage, the dissolution of positive metal ions intensifies the catalytic decomposition of the electrolyte, and the decomposition gas products directly lead to battery thickness expansion, solid The product is deposited on the interface of positive and negative electrodes, which increases the internal resistance of the battery and reduces the retention rate of capacity; (2), LiPF in the electrolyte 6 It is easy to decompose at high temperature, producing HF and PF 5

Among them, HF will corrode the positive electrode, leading to the dissolution of metal ions, thereby destroying the structure of the positive electrode material, resulting in capacity loss; (3), under high voltage, the electrolyte is easily oxidized at the positive electrode, causing the metal ions of the positive electrode active material to be easily reduced. Dissolution into the electrolyte, thereby destroying the structure of the positive electrode material, resulting in capacity loss (4) The SEI film formed when the battery is charged for the first time decomposes under high temperature conditions, and the metal ions dissolved into the electrolyte can easily pass through the SEI to reach the negative electrode to obtain electrons However, it is reduced to a single metal substance, which destroys the structure of the SEI and leads to a sharp decline in battery performance, increasing negative electrode impedance, increasing battery self-discharge, increasing irreversible capacity, and deteriorating performance cycles; (5), lithium-ion battery electrolyte solvent combination , Solvent freezing point, solvent low-temperature viscosity, will directly determine the performance of lithium-ion battery ions at low temperature; (6), the resistance value of the interfacial film formed by the decomposition of lithium-ion battery electrolyte additives has a great impact on the low-temperature performance of the battery and the conductivity of the new lithium salt. rate or the migration ability of lithium ions at low temperature will be greatly affected

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