烧结气氛对水热法合成磷酸铁锂材料的影响探究

以抗坏血酸作为还原剂,采用水热法合成了LiFePO4/C复合材料,探究了烧结过程中还原性气氛对材料结构以及电化学性能的影响。制备的材料采用X射线电子衍射(XRD)、扫描电镜(SEM)以及氮气吸脱附测试(BET)来进行表征,并采用循环伏安以及充放电实验来测试材料的锂离子扩散系数和材料容量。结果表明:还原性气氛烧结得到的材料具有更高的容量和更大的锂离子扩散系数,其主要原因在于还原性气氛有利于材料颗粒粒径缩小以及热解炭的形成。采用BET测试表明在含氢气气氛下以及纯氩气气氛下烧结得到的材料的比表面积分别是19.2m2·g-1以及6.6m2·g-1。

Investigation of the reductive atmosphere effects in sintering process on hydrothermally synthesized LiFePO4/C

A hydrothermal method is used to prepare LiFePO4/C composites by using ascorbic acid as carbon resource and the effects of reductive gas in the sintering process on the micro-structural characteristics and electrochemical properties of LiFePO4/C are investigated. The microstructure and morphology of the samples are characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and nitrogen adsorption-desorption method. Cyclic voltammetry （CV） is used to calculate the lithium ion diffusion coefficient and charge/discharge cycling performance to char- acterize their electrochemical properties. Results show that the carbon-coated LiFePO4 sintered in the reductive atmosphere can deliver greater capacity and improve the lithium ion diffusion per- formance. Further tests show that hydrogen in the sintering atmosphere is beneficial to the grain refinement of the end composite and is helpful in producing pyrolyzed carbon. The BET surface area of the LiFePO4/C sintered in the hydrogen-containing gas is 19. 2 m2 · g-l, while it is 6.6 m2 · g-l for the contrast sample.