Use of Ethylene Carbonate Free Ester Solvent Systems with Alternative Lithium Salts for Improved Low-Temperature Performance in NCM622∣∣ Graphite Li-ion Batteries. Issue 11 (1st November 2022)

• Record Type: Journal Article
• Authors: Rodrigo, Nuwanthi D.; Jayawardana, Chamithri; Rynearson, Leah; Hu, Enyuan; Yang, Xiao-Qing; Lucht, Brett L.
• Is Part Of: Journal of the Electrochemical Society. Volume 169:Issue 11(2022)
• Publication Date: 2022-11-01
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ac9d0a
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : An investigation of alternative lithium salts, lithium tetrafluoroborate (LiBF4 ), lithium difluoro(oxalato)borate (LiDFOB) and lithium hexafluorophosphate (LiPF6 ), in novel ester-based (methyl acetate/fluoroethylene carbonate- MA/FEC or methyl propionate/fluoroethylene carbonate- MP/FEC) electrolyte formulations has been conducted in LiNi0.6 Co0.2 Mn0.2 O2 (NCM622)/graphite cells to improve low temperature cycling performance of lithium ion batteries at −20 °C. Improved low temperature performance was observed with all the lithium salts in MA/FEC electrolyte while comparable room temperature (25 °C) capacities were observed with LiPF6 salt only. Detailed ex-situ analysis of surface films generated with LiBF4, LiDFOB and LiPF6 in ester-based electrolytes reveals that the solid electrolyte interphase (SEI) is predominately composed of lithium salt decompaction products and addition of 10% FEC (by volume%) may not be sufficient at forming a protective SEI.