Polyhedron structured sphere-like lithium manganese oxide (LiMninf2/infOinf4/inf) is successfully synthesized from β-MnOinf2/inf nanorod precursor via a solid state reaction at a temperature of 800 °C. For comparison, LiMninf2/infOinf4/inf materials with nanorod and octahedron structures are also obtained from β-MnOinf2/inf nanorod precursor at temperatures of 700 °C and 900 °C, respectively. The galvanostatic charge-discharge result shows that the polyhedron sphere-like LiMninf2/infOinf4/inf 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 °C and 81% at 55 °C. This is attributed to that the polyhedron sphere-like spinel LiMninf2/infOinf4/inf 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 LiMninf2/infOinf4/inf sample has the lowest BET surface area, largest diffusion coefficient of Lisup+/sup and least charge transfer resistance. This study provides an insight into the capacity fading of LiMninf2/infOinf4/inf electrodes and the polyhedron structured sphere-like LiMninf2/infOinf4/inf can be a promising material for lithium ion batteries.
Date de publication
Journal of Alloys and Compounds632 (30 janvier 2015) : 222–228.