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.

Lithium difluoro(oxalate)borate for robust passivation of LiNi0.5Mn1.5O4 in lithium-ion batteries

“…Whereas surface analysis of the composite electrode with the surface derived film is complex owing to interferences from the conducting agent and binder that complicate interpretation of the spectra for the surface derived film from the electrolyte, Au electrodes with only the active material embedded are greatly beneficial for evaluation of the surface film without interferences from the other components in the electrode [3,33]. The C 1s spectra presented in Fig.…”

“…Numerous recent investigations have focused on the development of high energy density LIBs to meet the demands of emerging applications such as electric vehicles (EVs) and energy storage system (ESS) to achieve LIBs with high standard energy density [3][4][5][6][7]. Various types of anode materials such as Si, Sn, and metal oxides that exhibit high energy density due to electrochemical accommodation of numerous lithium ions have been used for overcoming the energy density deficiency of LIBs [8][9][10][11][12].…”

Thin‐Layer Chemical Modulations by a Combined Selective Proton Pump and pH Probe for Direct Alkalinity Detection

“…The thin layer confinement of liquids has recently attracted the attention of diverse chemical domains that include energy storage, [1] engineered microfluidics, [2] separation techniques, [3] material science, [4] and fundamental as well as applied electrochemistry. [5] On the one hand, major uses of thinlayer solutions or other thin-layer materials (i.e., insulators, conductive materials,m embranes,e tc.)…”

A polymerized C60 coating enhancing interfacial stability at three-dimensional LiCoO2 in high-potential regime

“…The Coulombic efficiency (CE) of C 60 @3D HT-LCO exhibits the highest value (94%), followed by 3D HT-LCO (92%) and bare HT-LCO (88%). A higher CE value indicates a lower irreversible capacity loss, which is mainly attributed to the suppression of reversible ion loss from side reactions due to electrolyte decomposition during charge (up to 4.5 V) or interfacial kinetic issues resulting from the discharge procedure [30,31]. In addition, we observe that the C 60 @3D HT-LCO present a lower overpotential, announcing a smaller internal resistance of the cell.…”