High performance LiMnPO4/C prepared by a crystallite size control method

Abstract

A carbon matrix, for restricting growth of LiMnPO₄ crystallites, is built on the small Li₃PO₄ crystallites precipitated from aqueous solutions, by the pyrolysis of sucrose. LiMnPO₄ is prepared using the carbon coated Li₃PO₄ as one of the reactants (the other reactant is MnSO₄) and the nuclei by a solvothermal method. Smaller-crystallite-size (8–12 nm) LiMnPO₄ is successfully obtained on the carbon matrix by a crystallite size control method. The as-prepared LiMnPO₄/C sample presents the desired electrochemical performance, including higher discharge potential plateau, larger discharge capacity, excellent high-rate capability, and good cycle stability. It is also confirmed that the smaller LiMnPO₄ crystallites on the carbon matrix are beneficial for shortening the lithium ion diffusion path and increasing the electrical conductivity of the LiMnPO₄/C sample, contributing to an improvement in electrochemical performance. The methodology described in this work could be helpful in the development of LiMnPO₄/C cathode materials for lithium ion batteries with high energy density.