High-Voltage Layered Ternary Oxide Cathode Materials:Failure Mechanisms and Modification Methods

Due to the large reversible capacity,high operating voltage and low cost,layered ternaryoxide cathode materials LiNixCoyAl-x-yO2(NCA)and LiNixCoyMn1-x-yO2(NCM)are considered asthe most potential candidate materials for lithium-ion batteries(LIBs)used in(hybrid)electricvehicles(EVs).However,next-generation long-range EVs require a high specific capacity(around 203 mAh·g^-1at 3.7V)at the cathode active material level,which is not provided withcurrent commercially layered ternary oxide cathodes.Increasing the operating voltage is aneffective method to improve the specific capacity of the cathode and the energy density of the battery,but the high operating voltage also causes a lot of problems,such as cation mix-ing and phase transformation,electrolyte decomposition,transition metal dissolution andmicrocracks.So far,researchers have carried out a lot of works to solve these issues.Surfacecoating,element doping and the design of electrolytes have been proved to be effective solu-tions.In this review,the failure mechanisms and modification methods of high-voltage lay-ered ternary oxide cathode materials are summarized,which could provide valuable infor-mation to the research of high-voltage layered ternary oxide cathode materials in basic sci-ence and industrial production.