High-Rate Charge/Discharge Properties of Li Ion Secondary Battery Using V{sub}2O{sub}5/Carbon Composite Electrodes with Carbon Fiber

摘要

The charge/discharge properties of V{sub}2O{sub}5/carbon composites with controlled microstructures were investigated to achieve a high-rate lithium electrode performance. Composite electrodes were synthesized by mixing a V{sub}2O{sub}5 sol, carbon and a surfactant, followed by drying. V{sub}2O{sub}5/AB (acetylene black) and V{sub}2O{sub}5/VGCF (vapor-grown carbon fiber) composite electrodes showed high-rate charge/discharge properties only when they had very high carbon contents. V{sub}2O{sub}5/ (AB and VGCF) composite electrodes with controlled microstructures exhibited a discharge capacity of 245 mA·h·g{sup}(-1) at a high current density of 40 A·g{sup}(-1), which was approximately 70% of that at a low current density of 100 mA·g{sup}(-1). The improvement in the high-rate charge/discharge properties was attributed to the short lithium ion diffusion distance, large reaction area and high electronic conductivity of those composite electrodes.