摘要
Elevating the upper cutoff voltage to 4.6 V could effec-tively increase the reversible capacity ofLiCoO_(2)(LCO)cathode,whereas the irreversible structural transition,unstable electrode/electrolyte interface and potentially induced safety hazards severely hinder its industrial application.Building a robust cathode/electrolyte interface film by electrolyte engineer-ing is one of the efficient approaches to boost the performance of high-voltage LCO(HV-LCO);however,the elusive interfacial chemistry poses substantial challenges to the rational design of highly compatible electrolytes.Herein,we propose a novel electrolyte design strategy and screen proper solvents based on two factors:highest occupied molecular orbital energy level and LCO absorption energy.Tris(2,2,2-trifluoroethyl)phosphate is determined as the optimal solvent,whose low defluorination energy barrier significantly promotes the construction of LiF-rich cathode/electrolyte interface layer on the surface of LCO,thereby eventually suppresses the phase transition and enhancesLi+diffusion kinetics.The rationally designed electrolyte endows graphite||HV-LCO pouch cells with long cycle life(85.3%capacity retention after 700 cycles),wide-temperature adaptability(-60–80℃)and high safety(pass nail penetration).This work provides new insights into the electrolyte screening and rational design to constructing stable interface for high-energy lithium-ion batteries.
基金
financially supported by National Key Research and Development Program of China(2024YFE0213000)
National Natural Science Foundation of China(No.U22A20438)
Hubei Natural Science Foundation(2023BAB036,2024BAB103)
the Key Research and Development Program of Ningxia Hui Autonomous Region(2024BEE02002).
