锂离子电池负极材料PAN-ACF/SnO_2的研究

PAN-based Activated Carbon Fiber/SnO_2 Negative Electrodes for Lithium-ion Batteries

以聚丙烯腈基活性碳纤维(PAN-ACF)和SnCl2为原料,采用溶胶-凝胶法制备PAN-ACF/SnO2复合材料并将其用作锂离子电池负极材料。采用X射线衍射仪(XRD)分析材料的组成及晶体结构;用扫描电镜(SEM)观察样品形貌;用热失重分析(TGA)对复合材料中SnO2的含量进行测定;用恒流充放电、交流阻抗(EIS)和循环伏安(CV)对复合材料作为锂离子电池负极材料的电化学性能进行表征。结果表明,SnO2的含量对产物的形貌、结构和电化学性能有重要的影响。所制得的PAN-ACF/SnO2复合材料中SnO2的晶格常数a=0.4739 nm和c=0.3181 nm,为四方金红石结构。PAN-ACF表面在多次充放电过程中未发生明显变化。该复合材料用作锂离子电池负极材料时,在电流密度为50 mA/g的条件下,SnO2含量为41.9%的复合材料首次放电高达1824 mAh/g,20次后容量仍保持在450 mAh/g左右并趋于稳定,呈现出良好的循环性能。

PAN-ACF/SnO2 composites were synthesized by a Sol-Gel method using SnC12 and polyacrylonitrile- based activated carbon fiber （PAN-ACF） as raw materials, and electrochemical performance of the composites as negative electrodes for lithium ion batteries was investigated. The chemical composition and micro-structure of the composites were examined with X-ray diffraction （XRD）. The structure features of PAN-ACF and PAN-ACF/SnO2 composites were analyzed by scanning electron microscope （SEM）. The mass fraction of SnO2 was determined by thermo gravimetric analysis （TGA）. The electrochemical properties of the composites were evaluated by galvanostatic charge-discharge, electrochemical impedance spectrum （EIS） and cyclic voltammetry （CV）. The results indicate that SnO2 mass fraction in the PAN-ACF/SnO2 composites has certain influence on the morphology, structure and electro- chemical performance of the product. The SnO2 in the composites has a tetragonal rutile structure with lattice con- stants ofa = 0.4739 nm and c = 0.3181 nm. There are no obvious changes happened on the surface of PAN-ACF after charging and discharging process. When the composites are used as negative material for lithium ion batteries, the ini- tial discharge capacity of composites with SnO2 mass fraction of 41.9% is up to 1824 mAh/g at current density of 50 mA/g, which remains 450 mAh/g after 20 cycles and tends to be stable, showing a good cycling performance.