Energy Storage Science and Technology ›› 2024, Vol. 13 ›› Issue (7): 2171-2180.doi: 10.19799/j.cnki.2095-4239.2024.0374

• Special Issue on Low Temperature Batteries • Previous Articles     Next Articles

Controlling electrolyte solvent components to enhance cycle life of LCO/C low-temperature 18650 batteries

Guangyu CHENG1(), Xinwei LIU2, Shuo LIU1, Haitao GU1, Ke WANG1   

  1. 1.State Key Laboratory of Space Power Sources, Shanghai Institute of Space Power-Sources, Shanghai 200245, China
    2.Shanghai Aerospace Power Technology Co. Ltd. , Shanghai 201112, China
  • Received:2024-05-06 Revised:2024-05-31 Online:2024-07-28 Published:2024-07-23
  • Contact: Guangyu CHENG E-mail:chengguangyu12@126.com

Abstract:

The cycle life of low-temperature 18650 batteries has always been a key factor that limited their development. To achieve a balance between a long cycle life and low-temperature performance, the effects of different electrolytes on rate performance, high- and low-temperature discharge performance, charge retention capacity, cycle life, low-temperature cycle performance, and EIS were compared and analyzed by adjusting the components of the electrolyte solvent. The results demonstrated that the design of the electrolyte composition had a significant impact on the performance of the battery. By partially replacing the carbonate esters and the short-chain carboxylic esters with long, linear carboxylic esters having a low melting point, impressive low-temperature performance as well as high-temperature stability were achieved, which illustrated that EP and PP play an important role in the cyclic stability of the LCO/C electrode system. The solvent component EC+EP+PP (mass ratio 2∶5∶3) exhibited the best comprehensive performance. The developed LTB battery maintained a discharge capacity retention of 99.86% at 5C and a discharge capacity retention of 92.84% at -40 ℃ and 1C. After 1000 cycles, the low-temperature discharge capacity at -40 ℃ and 1C was still 90% of the initial low-temperature discharge capacity. At room temperature, the cycling retention rate reached 85% after 1500 cycles; at a low temperature of -10 ℃, the cycling retention rate was 82.4% after 500 cycles.

Key words: low-temperature, 18650 battery, electrolyte, cycle life, lithium-ion battery

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