Synthesis and electrochemical properties of high performance polyhedron sphere like lithium manganese oxide for lithium ion batteries

Polyhedron structured sphere-like lithium manganese oxide (LiMn2O4) is successfully synthesized from beta-MnO2 nanorod precursor via a solid state reaction at a temperature of 800 degrees C. For comparison, LiMn2O4 materials with nanorod and octahedron structures are also obtained from beta-MnO2 nanorod precursor at temperatures of 700 degrees C and 900 degrees C, respectively. The galvanostatic charge-discharge result shows that the polyhedron sphere-like LiMn2O4 sample exhibits the best electrochemical performance at high rate and high temperature. After 100 cycles at 5 C, this electrode is able to maintain 94% of its capacity at 25 degrees C and 81% at 55 degrees C. This is attributed to that the polyhedron sphere-like spinel LiMn2O4 can suppress the dissolution of manganese ions. Based on Brunauer Emmett Teller (BET), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the polyhedron sphere-like LiMn2O4 sample has the lowest BET surface area, largest diffusion coefficient of Li+ and least charge transfer resistance. This study provides an insight into the capacity fading of LiMn2O4 electrodes and the polyhedron structured sphere-like LiMn2O4 can be a promising material for lithium ion batteries. (C) 2015 Elsevier B.V. All rights reserved.