Facile synthesis of spinel LiMn2O4 cathode material from nanoscale Mn3O4 for lithium-ion batteries

Abstract

Mn₃O₄ nanoparticles synthesized form the room-temperature solid-state reactions between hydrated manganese salts and alkalis were explored as the starting material for preparing spinel LiMn₂O₄. Sintering temperature and lithium excess were tuned to obtain LiMn₂O₄ with optimal electrochemical performance and their effects were investigated. The results show that pure and highly crystalline LiMn₂O₄ was obtained, and the electrochemical performance is strongly affected by Mn valence, point defect and order of crystal structure as well as the particle size, which are highly dependent on sintering temperature and lithium excess. The LiMn₂O₄ with well crystalline order and competitive electrochemical performance can be readily synthesized at a moderate sintering temperature of 750 °C without excess lithium, which delivered an initial discharge capacity of 129.3 mAh/g at 0.2 C with the initial coulombic efficiency of 93.43 % and kept a capacity retention of 90.9 % after 100 cycles. Thus, nanoscale Mn₃O₄ is proved to be a promising starting material for the preparation of high quality LiMn₂O₄.