不同碳源对Li_3V_2(PO_4)_3/C复合正极材料性能的影响

以甲基纤维素、壳聚糖及葡萄糖分别作为碳源,应用碳热还原法合成正极Li3V2(PO4)3/C复合材料.XRD、SEM等方法分析、表征材料的结构、形貌和电化学性能.结果表明,碳源的选择对产物的比容量、循环寿命和倍率性能等均有较大的影响.以甲基纤维素为碳源制备的单斜Li3V2(PO4)3正极材料具有较好的电化学性能,在3.0～4.5V,0.2C倍率下,其初始容量为130.6mAh·g-1,30次循环后放电比容量仍可达到108mAh·g-1.

Effects of Different Carbon Sources on Performance of Li_3V_2(PO_4)_3/C Composite Cathode Materials

The monoclinic Li3V2(PO4)3 cathode materials were prepared by carbothermal reduction method,with methyl cellulose,chitosan(crab shells) or glucose anhydrous as carbon sources,respectively.The crystal structures,morphologies and the electrochemical performances were characterized by XRD,SEM and electrochemical measurement.The XRD patterns show that the samples obtained at 800 ℃ for 6 h have a pure monoclinic structure,which indicates that the carbon exists in amorphous phase.Electrochemical measurements show that the difference of carbon sources has a significant influence on the electrochemical properties of the materials.The Li3V2(PO4)3 /C with methyl cellulose as the reduction agent has the best electrochemical performance.In the voltage range of 3.0 ～ 4.5 V and at 0.2 C(1 C = 140 mAh·g-1),the initial discharge specific capacity reached 130.6 mAh·g-1,and maintained 108 mAh·g-1 after 30 cycles,even after 50 cycles at 1 C,the specific capacity were still more than 90 mAh·g-1.