新型锂离子电池正极材料Li_(0.86)V_(0.8)O_2的水热合成及性质

Hydrothermal Synthesis and Properties of New CathodeMaterial Li_(0.86)V_(0.8)O_2

采用两步反应制备了新型锂离子电池正极材料Li0.86V0.8O2.该材料具有六方层状结构,空间群为R3m.研究了在水热条件下溶液的碱度对于钒酸锂盐形成的影响,在低碱度的条件下,前驱体V2O3和L iOH.H2O并未发生反应,只有在碱度达到2.5 mol/L时,才能形成单相的Li0.86V0.8O2材料.X射线光电子能谱分析发现,V2p的结合能位于516.4和523.1 eV,分别对应于四价钒离子的V2p3/2和V2p1/2,这说明在Li0.86V0.8O2中V离子主要价位为+4价.在电流密度为7.4 mA/g的充放电中,L i0.86V0.8O2初始充电容量达到163 mA.h/g,首次放电容量也能达到113 mA.h/g,20次循环后放电容量仍然可以达到80 mA.h/g,表现出较好的循环性能.

The new cathode material Li0. 86V0. 8O2 was synthesized by two-steps reaction. The material crystallizes in the layered rhombohedral structure with space group R3m The mechanism of phase evolution was studied in different alkalinity under hydrothermal condition. It is found that the hydrothermal reaction does not work in low LiOH · H2O concentration. The single phase material of Li0. 86V0. 8O2 can only be obtained in the concentration of 2. 5 mol/L. Through X-ray photoemission spectrum, the binding of 516. 4 and 523.1 eV can be attributed to the V4＋ and 4 ＋ 2p3/2 V^4＋2p1/2 , which confirm the quadrivalent state of V ion in Lio. 86Vo. 802. With a current density of 7.4 mA/g, the charge capacity of Li0.86V0.8O2 is 163 mA · h/g in the first cycle, and the first discharge capacity of the materials is 113 mA · h/g. After 20th cycles, the discharge capacity is still 80 mA · h/g, which shows good electrochemicalstability.