Tuning the phase evolution pathway of LiNi0.5Mn1.5O4 synthesis from binary intermediates to ternary intermediates with thermal regulating agent

Transition metal cation ordering is essential for controlling the electrochemical performance of cubic spinel LiNi0.5Mn1.5O4 (LNMO), which is conventionally adjusted by optimizing the high temperature sintering and annealing procedures. In this present work, multiple characterization techniques, including 6,7Li NMR, XRD and HRTEM, have been combined to trace the phase transformation and morphology evolution during synthesis. It has been illustrated that simultaneous formation of LiMn2O4 (LMO) and LiNiO2 (LNO) binary oxides and their conversion into highly reactive LixNi(y)(3+)Mn(z)(3.5+)O ternary intermediate is a thermal dynamically difficult but crucial step in the synthesis of LNMO ternary oxide. A new strategy of modifying the intermediates formation pathway from binary mode to ternary mode using thermal regulating agent has been adopted. LNMO synthesized with thermal regulating agent exhibits supreme rate capability, long-cycling performance (even at elevated temperature) and excellent capacity efficiency. At a high rate of 100 C, the assembled battery delivers a discharge capacity of 99 mAh g(-1). This study provides a way to control the formation pathway of complex oxides using thermal regulating agent. (c) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

In this study, multiple characterization techniques were used to trace the phase transformation and morphology evolution during the synthesis of LNMO, showing that using a thermal regulating agent to modify the formation pathway of intermediates can enhance the performance of LNMO with superior rate capability and long cycling performance.