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Improving Stability of LiCoO 2 Cathode by Using Lithium Bis(Trifluoroborane)‐5‐Cyano‐2‐(Trifluoromethyl) Benzimidazolide as Additive
Author(s) -
Admas Teshager Minbale,
Yang ShengChiang,
Hwang BingJoe,
Lin Shawn D.
Publication year - 2019
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201901686
Subject(s) - electrolyte , dielectric spectroscopy , lithium (medication) , cyclic voltammetry , cathode , electrochemistry , decomposition , trifluoromethyl , chemistry , fourier transform infrared spectroscopy , salt (chemistry) , chemical engineering , materials science , electrode , inorganic chemistry , organic chemistry , medicine , alkyl , engineering , endocrinology
LiCoO 2 is an important cathode material of commercial lithium‐ion batteries (LIBs) and therefore, improving the stability when LiCoO 2 cathode is overcharged can have an immediate impact on commercial LIBs. A novel Li salt, lithium 5‐cyano‐bis(trifluoroborane)‐2‐(trifluoromethyl) benzimidazolide (Li[CBTBI]) is evidenced in this study as an effective additive for improving the electrode/electrolyte interface of LiCoO 2 at high voltage operation condition. The presence of 2 % additive in commercial 1 M LiPF 6 /EC+DEC lead to the formation of stable interface of LiCoO 2 through cycles to 4.5 V, as demonstrated in cyclic voltammetry (CV). Electrochemical impedance spectroscopy (EIS) indicates a low‐impedance of the formed interface in the presence of the additive. Cyclability test also shows an improved stability in overcharging potential window by the presence of 2 % additive. In situ diffuse reflectance infrared Fourier‐transformed spectroscopy (DRIFTS) confirms the suppression of LiPF 6 decomposition, delay of onset potential of solid electrolyte interphase (SEI) formation, and thin SEI comparing to that without the additive. The possible reasons of the advantageous effect of using Li salt additives are discussed.