title: Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries.
abstract: Room-temperature ionic liquid (RTIL) electrolytes have attracted much attention for use in advanced, safe lithium-ion batteries (LIB) owing to their nonvolatility, high conductivity, and great thermal stability. However, LIBs containing RTIL-electrolytes exhibit poor cyclability because electrochemical side reactions cause problematic surface failures of the cathode. Here, we demonstrate that a thin, homogeneous surface film, which is electrochemically generated on LiCoO2 from an RTIL-electrolyte containing an unsaturated substituent on the cation (1-allyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, AMPip-TFSI), can avert undesired side reactions. The derived surface film comprised of a high amount of organic species from the RTIL cations homogenously covered LiCoO2 with a <25 nm layer and helped suppress unfavorable thermal reactions as well as electrochemical side reactions. The superior performance of the cell containing the AMPip-TFSI electrolyte was further elucidated by surface, electrochemical, and thermal analyses.
authors.affiliation: 1] Department of Chemical and Biological Engineering, Seoul National University, Seoul 151-744 Korea [2] Department of Energy and Chemical Engineering, Incheon National University, Incheon 406-840 [3].
authors.forename: Junyoung
authors.initials: J
authors.lastname: Mun
authors.affiliation: 1] Department of Chemical and Biological Engineering, Seoul National University, Seoul 151-744 Korea [2] Advanced Batteries Research Center, Korea Electronics Technology Institute (KETI), Gyunggi-do 463-816, Korea [3].
authors.forename: Taeeun
authors.initials: T
authors.lastname: Yim
authors.affiliation: School of Green Energy, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea.
authors.forename: Jang Hoon
authors.initials: JH
authors.lastname: Park
authors.affiliation: Graduate School of Knowledge-based Technology, Korea Polytechnic University, Korea.
authors.forename: Ji Heon
authors.initials: JH
authors.lastname: Ryu
authors.affiliation: School of Green Energy, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea.
authors.forename: Sang Young
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Chemical and Biological Engineering, Seoul National University, Seoul 151-744 Korea.
authors.forename: Young Gyu
authors.initials: YG
authors.lastname: Kim
authors.affiliation: Department of Chemical and Biological Engineering, Seoul National University, Seoul 151-744 Korea.
authors.forename: Seung M
authors.initials: SM
authors.lastname: Oh