Twin Boundary Induced by High Temperature Shock Boosts Li-rich Layered-oxide Structural Stability

Abstract

Li-rich cathode materials are one of the most potential candidates for next-generation Li-ion batteries. However, they suffer from severe capacity degradation because of cracks and the continuous structural transformation during cycling. Defect engineering can effectively tune the electronic and crystal structure of nanomaterials and improve the electrochemical performance of cathode materials. Up to now, it is challenging to introduce dense defects into the materials synthesized by conventional tube furnace calcination due to the thermodynamic and kinetic equilibrium. In this work, a non-equilibrium high temperature shock (HTS) strategy with ultra-fast cooling, accompanied by the processes of rapid heating and cooling, is reported to introduce the twin boundaries (TBs) into the Li1.2Ni0.13Co0.13Mn0.54O2. The rock-salt phase along the TBs acts as a rigid framework that mitigates the inherent phase transformation of Li-rich layered-oxide materials during cycling. Benefiting from the unique structure, Li1.2Ni0.13Co0.13Mn0.54O2 prepared by HTS method exhibits a superior reversible capacity of 278 mAh g-1 at 0.1 C, a high initial Coulombic efficiency of 81%, and capacity retention of 89.4% after 100 cycles at 0.5 C. This work exerts profound implications on understanding defect engineering for modulating structure and electrochemical performance of materials.