多孔前驱体渗碳制备LiFePO_4/C

Synthesis of LiFePO_4/C with the carbon-filled porous precursor

用控制结晶法制备了多孔前驱体FePO4.xH2O,将葡萄糖和Li2CO3渗入到前驱体中,然后通过碳热还原反应合成LiFePO4/C。采用XRD、SEM、恒流充放电和交流阻抗等方法对样品进行了研究。反应剩余的碳分布在LiFePO4颗粒的内部及表面,提高了材料的电化学性能。在620℃下合成的LiFePO4/C的0.1C、0.5C和1C首次放电比容量分别为156mAh/g、139 mAh/g和136 mAh/g,循环30次后的容量衰减率仅为0.64%、2.16%和4.41%。该样品虽然含碳9.74%,但振实密度仍有1.20 g/cm3。

Porous precursor FePO4 · xH2O was prepared by the controlled crystallization method. LiFePO4/C was synthesized via carbothermal reduction using the precursors filled with glucose and Li2CO3. XRD, SEM, galvanostatic charge-diseharge and AC impedance methods were used to study the samples. The residual carbon existed inside and the surface of LiFePO4 particles, enhanced its electrochemical performance. The initial specific discharge capacities of LiFePO4/C synthesized at 620 ℃ at 0.1 C, 0.5 C and 1 C were 156 mAh/g, 139 mAh/g and 136 mAh/g, respectively, and the capacity fading rate were only 0.64%, 2.16% and 4.41% after 30 cycles. The sample had a tap density of 1. 20 g/cm^3 though its carbon content was 9.74%.