Twin boundaries induced by high-temperature shock boost the structural stability of Li-rich layered-oxide

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 continuous structural transformation during cycling. Defect engineering can effectively tune the electronic and crystal structures of nanomaterials and improve the electrochemical performance of cathode materials. To date, it is challenging to introduce dense defects into the materials synthesized via 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 with the processes of rapid heating and cooling, is reported to introduce twin boundaries (TBs) into Li_1.2Ni_0.13Co_0.13Mn_0.54O₂. 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, Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ prepared via the HTS method exhibits a superior reversible capacity of 278 mA h g⁻¹ at 0.1C, a high initial coulombic efficiency of 81%, and a capacity retention of 89.4% after 100 cycles at 0.5C. This work exerts profound implications on understanding defect engineering for modulating the structure and electrochemical performance of materials.