Controllable synthesis of high-performance LiMnPO4 nanocrystals by a facile one-spot solvothermal process

Abstract

Olivine-type LiMnPO₄ has been considered as a promising cathode material for the next-generation high-power lithium ion batteries. Preparing high-performance LiMnPO₄ cathodes by a simple approach has been a subject of much scientific inquiry for several years. Here, we report a simple solvothermal synthesis of LiMnPO₄ nanocrystals using LiOH·H₂O, H₃PO₄ and MnSO₄·H₂O as the precursors and ethylene glycol as the reaction medium. We found that the ratio of the starting materials exerts a significant influence on the morphology, size and crystal orientation of LiMnPO₄ nanocrystals. We confirmed the critical role of H⁺ concentration in altering the crystallization characteristics of LiMnPO₄. The results showed that after carbon coating, the plate-like LiMnPO₄, which was synthesized from the precursor with a LiOH/H₃PO₄/MnSO₄ ratio of 3 : 1.1 : 1, exhibited the best electrochemical performance, yielding a discharge capacity of 108.2 mA h g⁻¹ at 10 C and maintaining a discharge capacity of 133.5 mA h g⁻¹ after 100 cycles at 0.5 C. This simple, one-spot solvothermal preparation method sheds light on the synthesis of high-performance LiMnPO₄ cathode material.