MnO2制备尖晶石LiMn2O4及其电化学性能研究

Preparation and Electrochemical Performance of Spinel LiMn2O4 from Manganese Oxide

摘要:

前驱体MnO2的性质对产物锰酸锂性能影响显著。本文采用液相沉淀法制备不同性质Birnessite型层状MnO2，研究发现，以中性条件制得的MnO2为前驱体，最终产物中存在MnO2杂相且无表面碳包覆，而以酸性条件制得的MnO2为前驱体可以得到碳包覆的纯相尖晶石LiMn2O4。后者在0.2C的充放电倍率下，首次放电比容量为129.7 mAh/g，远高于前者的58.5 mAh/g；在30C的大倍率下，容量高达117.8 mAh/g，经1500次循环后容量保持率约为92%。因此，将液相沉淀法条件优化为酸性得到的LiMn2O4产物表现出优异的大倍率性能和循环稳定性，具有市场应用前景。

关键词:Birnessite型MnO2;尖晶石LiMn2O4;电化学性能;锂离子电池

Abstract:

The property of MnO2 precursor has a great effect on the performance of LiMn2O4 product. In this study, Birnessite-type layered MnO2 was obtained through liquid phase coprecipitation reaction under neutral and acidic conditions. After heat treatment, the final product synthesized from MnO2 under neutral condition possesses the impurity phase MnO2 without any carbon layer, while the product synthesized from MnO2 under acidic condition is proved to be pure spinel LiMn2O4 with a thin carbon layer. The latter carbon-coated LiMn2O4 delivers the initial discharge capacity of 129.7 mAh/g at 0.2C, which is higher than that of the former product with only 58.5 mAh/g; even at higher rate of 30C, the discharge capacity can reach 117.8 mAh/g and retain about 92% capacity after 1500 cycles. The results show that when precursor MnO2 is optimized under acidic condition, the as-synthesized spinel LiMn2O4 can exhibit superior high-rate capability and long-life cycling stability, proving to be a promising cathode material for market applications.

Key words:Birnessite-type layered MnO2; spinel LiMn2O4; electrochemical performance; Li-ion batteries