High-temperature high-voltage electrolyte matched with silicon-carbon negative electrode material lithium-ion battery

Abstract

The invention discloses a high-temperature and high-pressure electrolyte matched with a silicon-carbon negative electrode material lithium-ion battery. The electrolyte comprises an electrolyte lithiumsalt, a non-aqueous organic solvent and an additive, the electrolyte lithium salt comprises lithium hexafluorophosphate and lithium difluorosulfate borate, and the additive comprises a negative electrode film-forming additive pentafluorophenyl isocyanate and a positive electrode film-forming additive 4-trimethylsilyl-3-pentene-2-ketone compound. The lithium-ion battery electrolyte provided by theinvention can effectively improve the normal-temperature cycle, high-temperature cycle and high-temperature storage performance of the silicon-carbon battery under high voltage through a synergisticeffect generated by the combined use of the mixed lithium salt and multiple additives.

Description

technical field [0001] The invention belongs to the technical field of electrolyte for lithium-ion power batteries, and in particular relates to a high-temperature and high-pressure electrolyte for lithium-ion batteries matching silicon-carbon negative electrode materials. Background technique [0002] Although commercialized rechargeable Li-ion batteries have been widely used in consumer electronics and have become popular for large-scale applications in electric vehicles and renewable energy storage systems, their energy density still cannot meet the growing demand. The development of next-generation lithium-ion batteries with high energy density can be promoted by adopting advanced electrode materials with higher theoretical specific capacity or higher operating voltage. [0003] Silicon-carbon anode has become the most successful high-capacity anode material due to its high capacity, and its application has become increasingly common. However, the volume expansion of sil...

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Problems solved by technology

[0003] Silicon-carbon anode has become the most successful high-capacity anode material due to its high capacity, and its application has become increasingly common. However, the volume expansion of silicon-carbon anode materials during the lithium intercalation process will not only lead to particle pulverization, Fragmentation will also damage the conductive network of the electrode, and at the same time cause damage to the solid electrolyte interface film (SEI film) on the surface of the negative electrode, causing the fresh electrode surface to be exposed, resulting in the continuous growth of the SEI film and continuous consumption of the battery. Active lithium ions will eventually lead to a sharp decline in battery capacity

In terms of positive electrode materials, by improving LiNi 0.5 co 0.2 mn 0.3 o 2 The charging voltage is used to obtain more specific capacity, which also makes the electrolyte on the surface of the material more easily oxidized, which leads to a rapid increase in the impedance of the lithium-ion battery during cycling and high-temperature storage, seriously affecting the cycle life of the battery and Battery safety performance

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