混合溶剂沉淀法合成锂离子电池负极材料MnC_(2)O_(4)

Mixed solvent precipitation synthesis of MnC_(2)O_(4) as an anode material for lithium-ion batteries

在N,N二甲基乙酰胺(DMAc)水混合溶剂中用沉淀法合成锂离子电池负极材料MnC_(2)O_(4),利用X射线粉末衍射技术(XRD)、扫描电子显微镜(SEM)、恒流充放电测试和电化学阻抗谱研究反应时间对材料结构、形貌和电化学性能的影响。结果表明:不同反应时间下制备的前驱体为柱状正交结构γ-MnC_(2)O_(4)·2H_(2)O,脱水后转变为介孔柱状正交结构β-MnC_(2)O_(4)。随着反应时间的延长,MnC_(2)O_(4)的粒径增大,比表面积先增大后减小。反应时间为24 h下合成柱状介孔MnC_(2)O_(4)颗粒的比表面为10.369 m 2/g,平均孔径约为16 nm,在1、4 A/g下循环150次后的放电比容量分别为998、822 mAh/g,显示出较好的电化学性能。

Manganese oxalate(MnC_(2)O_(4))was prepared in the N,N dimethylacetamide(DMAc)water mixed solvent by precipitation method.The effects of the reaction time on the structure,morphology and electrochemical performance were investigated by X-ray powder diffraction(XRD)scanning electron microscope(SEM),constant current charge/discharge test,and electrochemical impedance spectroscopy.The precursor prepared under different reaction time is columnarγ-MnC_(2)O_(4)·2H_(2)O with orthorhombic structure,which can transform into mesoporous columnarβ-MnC_(2)O_(4) with orthorhombic structure after dehydration.When the reaction time increases,the particle size of the prepared MnC_(2)O_(4) tends to increase,while the specific surface area first increases and then decreases.The mesoporous columnar MnC_(2)O_(4) prepared under the reaction time of 24 h has a specific surface area of 10.369 m 2/g and an average pore size~16 nm.This mesoporous sample deliveres a capacity of 998,822 mAh/g after 150 cycles at the current density of 1 A/g and 4 A/g,respectively,exhibiting good electrochemical performance.