Boosting stability of spinel LiMn2O4 cathode materials by creating oxygen vacancies

Abstract

Octahedral spinel lithium manganate dioxide (LiMn2O4, LMO) achieves remarkable electrochemical properties, but manganese dissolution during extended cycling process still cannot be well avoided. Herein, the oxygen vacancies within LiMn2O4 can be effectively modulated by extending the calcination duration. The density functional theory (DFT) calculation and experiments verified that appropriate oxygen vacancies not only promotes the structural stability, but also accelerates the charge transfer to improve the cycle performance under high C rate. Among them, the LMO sintered at 750 °C for 10 h (LMO-10) presented prominent electrochemical performance, delivering 114.58 mAh/g with the capacity retention rate of 95.90 % after 500 cycles at 5C, while the unmodified sample only exhibits 64.46 mAh/g with low retention of 63.75 %. This highly effective and facile approach to manipulate oxygen vacancies of spinel LiMn2O4 would facilitate to develop advanced cathode materials for lithium-ion batteries.