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.