碳包覆锂锰钒氧纳米材料的制备及其电化学性能

Synthesis and Electrochemical Performance of Carbon-coated LiMnVO4 Nanomaterials

摘要:

以醋酸锂、醋酸锰、五氧化二钒、过氧化氢为原料，葡萄糖作碳源，采用溶胶-凝胶法结合水热合成技术制备了不同碳质量分数的碳包覆锂锰钒氧纳米材料LiMnVO4/C。利用SEM、TEM、XRD、Raman、EDS、TG对其形貌和结构进行了表征。结果表明，所制备的纳米材料呈立方晶系结构，经碳包覆后的复合纳米材料的纳米颗粒分散性较好。电化学测试结果证实，在相同的测试条件下，碳质量分数为0%、5%、10%和15%的碳包覆锂锰钒氧纳米材料的首次可逆比容量分别为682、686、696和580 mAh/g，60次循环后的可逆比容量分别为226、336、513和440 mAh/g。因此，碳质量分数为10%的碳包覆锂锰钒氧纳米材料具有较好的循环稳定性和较高的可逆比容量，这主要归因于合适的碳包覆量不仅能提高纳米电极材料的界面稳定性，抑制晶粒的长大和团聚，而且能改善复合电极材料的电子导电性。

Abstract:

Carbon-coated LiMnVO4 nanomaterials with different carbon mass fraction were synthesized by a combined sol-gel reaction and hydrothermal process, using LiAc•2H2O, Mn(Ac)2•4H2O, V2O5 and H2O2 as raw materials and glucose as carbon source. The morphology and structure were characterized by SEM、TEM、XRD、Raman、EDS、TG. The results indicated that the as-prepared samples presented cubic crystal structure, and had good dispersibility after carbon coated. Electrochemical measurement results confirmed that carbon-coated LiMnVO4 nanomaterials with different carbon mass fraction (0%, 5%, 10% and 15%) as anode materials for LIBs delivered initial reversible capacities of 682, 686, 696 and 580 mAh/g under the same conditions, remained 226, 336, 513 and 440 mAh/g after 60 cycles. Hence, carbon-coated LiMnVO4 nanomaterials with 10% carbon mass fraction have better cycling stability and higher reversible capacity than others．The appropriate carbon mass fraction not only increases the interface stability of nanomaterials, inhibits the growth and agglomeration of grains, but also improves the electronic conductivity of composite electrode materials.