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 poten...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.展开更多
基金financially supported by National Key Research and Development Program of China(2024YFE0213000)National Natural Science Foundation of China(No.U22A20438)+1 种基金Hubei Natural Science Foundation(2023BAB036,2024BAB103)the Key Research and Development Program of Ningxia Hui Autonomous Region(2024BEE02002).
文摘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.
