Low-temperature type carbonic ester lithium battery electrolyte

Abstract

The invention discloses a low-temperature type carbonic ester lithium battery electrolyte. The electrolyte mainly comprises the following components: ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate and propylene carbonate as solvents, lithium hexafluorophosphate and a low temperature additive. The four carbonic ester solvents are in the following weight ratio: EC: DMC: EMC: PC=2:3:5:1; the components are prepared into an 1 mol / L electrolyte containing LiPF6, four carbonic ester solvents, the low temperature additive; and the low temperature additive is one selected from polydimethylsiloxane, 1,3- propane sultone, and vinylene carbonate, or a combination thereof. According to the invention, optimization of composition of the carbonic ester solvents and addition of the low temperature additive are employed to increase solubility, degree of dissociation and conductivity of the electrolyte, improve structure of a solid phase interfacial film (SEI membrane) of the lithium ion battery cathode, the integral stability of the battery and battery cycling and prolong usage life. Especially, the invention provides a mainstream electrolyte for lithium ion power batteries used in a lowest temperature of -50 DEG C in most regions in northern China.

Description

technical field [0001] The invention belongs to the lithium battery electrolyte in the technical field of electrochemical materials, in particular to a low-temperature carbonate lithium battery electrolyte which uses carbonate organic matter as a solvent and improves the low-temperature performance of the electrolyte. Background technique [0002] As the marketization of lithium-ion batteries continues to deepen, people's expectations for battery performance are getting higher and higher. At present, it is difficult for commercial lithium-ion batteries to meet the needs of important fields such as electric vehicles, aerospace technology and military affairs. One of the main reasons is that the performance of batteries is not good at high and low temperatures. Key issues of concern to researchers. Starting from the electrolyte to improve the temperature performance has been proved to be a feasible technical approach, because as an ionic conductor that plays a conductive role...

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Problems solved by technology

[0003] Some research results show that: lithium iron phosphate batteries will affect the charge and discharge performance of batteries under low temperature conditions due to the low ionic conductivity of lithium iron phosphate materials; in recent years, the limit value of climate change has continuously refreshed historical records, especially in the north The temperature in winter is low, and the battery cannot fully discharge the power during use at low temperature, which affects the efficiency of the battery. In response to this shortcoming, some material manufacturers and research institutions try to increase the specific surface area by preparing nano-sized particles, surface coating modification, etc. However, the low-temperature performance of lithium iron phosphate lithium-ion batteries has not been completely solved.

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