锂离子电池负极材料PAN-ACF/SnO2的研究

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-based Activated Carbon Fiber/SnO2 Negative Electrodes for Lithium-ion Batteries

PAN-ACF/SnO₂ composites were synthesized by a Sol-Gel method using SnCl₂ 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 electrochemical performance of the product. The SnO₂ in the composites has a tetragonal rutile structure with lattice constants of a = 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 initial 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.