Ultrafast Non‐Equilibrium Phase Transition Induced Twin Boundaries of Spinel Lithium Manganate

Abstract Defect engineering is demonstrated to be an important factor in enhancing the electrochemical performance of lithium‐ion batteries by improving structural stability and ion diffusion. However, conventional synthetic methods have long and complicated processes, making it challenging to effectively and easily introduce defects into electrode materials. In this work, a high‐temperature shock technique (HTS) with an ultrafast heating and cooling process that can quickly introduce twin boundaries (TBs) into phase‐pure spinel LiMn₂O₄ in seconds is reported. Various ex situ techniques reveal the crystallization mechanism of LiMn₂O₄ during ultrafast synthesis. LiMn₂O₄ with TBs exhibits a higher rate performance than that obtained from the traditional method. Additionally, alien elements can be evenly incorporated into LiMn₂O₄ in seconds, resulting in excellent cycling performance. For instance, 2% Ni‐doped LiMn₂O₄ shows an initial capacity of 121 mAh g⁻¹ and retention of 86.5% after 500 cycles at 1 C.