Electrolyte regulating and interface engineering for high voltage LiCoO2 lithium metal batteries

Abstract

To achieve higher energy density of lithium ion batteries (LIBs), researchers are developing a new generation of high-voltage (≥4.5 V) LiCoO2 (LCO). Increasing the voltage is accompanied by the decomposition of the electrolyte, successive irreversible phase transitions, and dissolution of transition metals, etc., which are largely benefit from detrimental cathode-electrolyte interface reactions. Here, we construct a stable N, S-rich electrode/electrolyte interphase on both Li anode as well as LCO cathode to solve the above problems through the electrolyte design with the dual additives of acrylonitrile and phenyl vinyl sulfone. Specifically, the uniform N, S-rich cathode/electrolyte interphase (CEI) separates the electrolyte and LCO, and reduces the catalytic decomposition of the electrolyte by Co4+. Moreover, phenyl vinyl sulfone has an excellent compatibility with the Li metal anode due to the in-situ formed LiF-rich solid electrolyte interphase (SEI). With the modification of dual-additives, the LCO lithium metal battery exhibits high-capacity retention about 80 % over 1000 cycles at upper cut-off voltage of 4.5 V and 76 % over 300 cycles at 4.6 V.