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Ester-based electrolytes for graphite solid electrolyte interface layer stabilization and low-temperature performance in lithium-ion batteries

  • Carbon Letters
  • Abbr : Carbon Lett.
  • 2024, 34(8), pp.2113-2125
  • DOI : 10.1007/s42823-024-00749-7
  • Publisher : Korean Carbon Society
  • Research Area : Natural Science > Natural Science General > Other Natural Sciences General
  • Received : April 23, 2024
  • Accepted : May 12, 2024
  • Published : December 5, 2024

Kim Chan-Gyo 1 Jekal Suk 2 Kim Jiwon 1 Kim Ha-Yeong 1 Park Gyu-Sik 1 Ra Yoon-Ho 1 Noh Jungchul 3 Yoon Chang-Min 1

1한밭대학교
2국립한밭대학교
3University of Texas at Austin

Accredited

ABSTRACT

In this study, ester co-solvents and fluoroethylene carbonate (FEC) were used as low-temperature electrolyte additives to improve the formation of the solid electrolyte interface (SEI) on graphite anodes in lithium-ion batteries (LIBs). Four ester co-solvents, namely methyl acetate (MA), ethyl acetate, methyl propionate, and ethyl propionate, were mixed with 1.0 M LiPF6 ethylene carbonate:diethyl carbonate:dimethyl carbonate (1:1:1 by vol%) as the base electrolyte (BE). Different concentrations were used to compare the electrochemical performance of the LiCoO2/graphite full cells. Among various ester co-solvents, the cell employing BE mixed with 30 vol% MA (BE/MA30) achieved the highest discharge capacity at − 20 °C. In contrast, mixing esters with low-molecular-weight degraded the cell performance owing to the unstable SEI formation on the graphite anodes. Therefore, FEC was added to BE/MA30 (BE/MA30-FEC5) to form a stable SEI layer on the graphite anode surface. The LiCoO2/graphite cell using BE/MA30-FEC5 exhibited an excellent capacity of 127.3 mAh g−1 at − 20 °C with a capacity retention of 80.6% after 100 cycles owing to the synergistic effect of MA and formation of a stable and uniform inorganic SEI layer by FEC decomposition reaction. The low-temperature electrolyte designed in this study may provide new guidelines for resolving low-temperature issues related to LIBs, graphite anodes, and SEI layers.

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