Li3V2（PO4）3/C材料合成中碳源含量优化

通过固相法和溶胶-凝胶法合成不同碳含量的磷酸钒锂/C正极材料,研究了作为碳源的蔗糖和柠檬酸添加量对产物电化学性能的影响.实验发现,在固相合成方法中,添加量高于10.5％（质量百分数）时进一步增加蔗糖添加量后产物放电容量变化不明显.但是在溶胶-凝胶合成方法中,柠檬酸的添加量存在最佳值,高于或者低于此最佳数值都会引起产物容量的降低,这是与固相合成技术的一个明显不同之处.另一点不同之处在于对于溶胶凝胶合成的样品,最佳添加量与产物的工作电流有关.本实验条件下,在0.2C倍率以下柠檬酸与氢氧化锂最佳比值为1∶3,但是在放电倍率高于0.5C时最佳比值为1∶2.

The optimized content of the carbon source in synthesis of Li3V2(PO4)3/C

The Li3V2 （PO4）3 with different contents of carbon positive electrode materials have been synthesized via solid-state method and sol-gel one. The effect of sucrose and citric acid as carbon sources on the electrochemical properties has been investigated. It was found that in the solid-state synthesis method when the content of the sucrose is more than 10.5wt. %, the further increase in the sucrose content can not increase the electrode properties. For the sol-gel synthesis technology, there exists an optimum content of citric acid. In addition, or the sol-gel synthesis technology, the optimum content depends on the operation mode, i. e. , working current density. The ratio of carbon source vs. Li source in the precursor has been also studied. In our experimen- tal condition, in lower rate than 0.2C, the optimum ration of citric acid vs. LiOH is 1 ~ 3, but in higher rate than 0.5C, the optimum ratio is 1 ： 2.