Improved cyclic stability of layered lithium cobalt oxide at high potential via cathode electrolyte interphase formed by 4-(trifluoromethyl) benzonitrile. (1st December 2015)

• Record Type: Journal Article
• Authors: Wang, Xianshu; Liao, Xiaolin; Huang, Wenna; Xing, Lidan; Liao, Youhao; Huang, Qiming; Xu, Mengqing; Li, Weishan
• Is Part Of: Electrochimica acta. Volume 184(2015)
• Page Start: 94
• Page End: 101
• Publication Date: 2015-12-01
• Subjects: 4-(trifluoromethyl) benzonitrile -- electrolyte additive -- cathode electrolyte interphase -- lithium cobalt oxide -- cyclic stability; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2015.10.022
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: 4-TB is an effective electrolyte additive for improving the cyclic stability of LiCoO2 under 4.5 V. 4-TB combines with Co(IV) and is oxidized preferentially forming CEI film on LiCoO2 . CEI protects LiCoO2 from structural destruction and suppresses electrolyte decomposition. Abstract: The cyclic stability of LiCoO2 as cathode of lithium ion battery under 4.5 V is improved by using 4-(trifluoromethyl) benzonitrile (4-TB) as an electrolyte additive. In a standard (STD) electrolyte (1.0 mol/L LiPF6 in EC/EMC/DMC, 1/1/1 by volume) containing 0.5 wt.% 4-TB, LiCoO2 exhibits an improved cyclic stability when the end-off charge potential is increased to 4.5 V. The characterizations, from XRD, ICP, SEM, FTIR, and XPS, demonstrate that a cathode electrolyte interphase (CEI) film is formed on LiCoO2 from 4-TB, which suppresses the successive decomposition of STD electrolyte and prevents LiCoO2 from crystal destruction. Theoretical calculations confirm that 4-TB is adsorbed and oxidized on LiCoO2 preferentially to the carbonates in electrolyte, forming the protective CEI film.