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

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 elec-trolyte, 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 elec-trolyte 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.