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

• Published in: Carbon Letters 2024, 34(8), 15, pp.2113-2125
• Main Authors: Kim, Chan-Gyo, Jekal, Suk, Kim, Jiwon, Kim, Ha-Yeong, Park, Gyu-Sik, Ra, Yoon-Ho, Noh, Jungchul, Yoon, Chang-Min
• Format: Article
• Language: English
• Subjects: Acetic acid; Aluminum; Anodes; Carbon; Characterization and Evaluation of Materials; Chemistry and Materials Science; Conductivity; Decomposition; Decomposition reactions; Electrochemical analysis; Electrochemistry; Electrolytes; Electrolytic cells; Energy storage; Esters; Ethyl acetate; Ethyl propionate; Graphite; Lithium; Lithium compounds; Lithium-ion batteries; Low temperature; Materials Engineering; Materials Science; Methyl acetate; Molten salt electrolytes; Nanotechnology; Original Article; Performance degradation; Propionic acid; Scanning electron microscopy; Solid electrolytes; Solvents; Spectrum analysis; Synergistic effect; Temperature; Transmission electron microscopy; Viscosity; 자연과학일반
• ISSN: 1976-4251; 2233-4998
• DOI: 10.1007/s42823-024-00749-7

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 LiPF 6 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 LiCoO 2 /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 LiCoO 2 /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. Graphical abstract