Design and Synthesis of In Situ VGCFs Improved LiFePO 4 Composite Cathode Materials

Abstract

One of the most important factors which currently limit the application of LiFePO4 cathode material in lithium-ion batteries is its low electronic conductivity. In order to enhance the electronic conductivity of LiFePO4 cathode material, in situ vapor-grown carbon fibers (VGCFs) improved LiFePO4 composite cathode materials were designed and synthesized in one step by microwave pyrolysis chemical vapor deposition (MCVD). The phase, microstructure and electrochemical performances of the composite cathode materials were investigated. Results show that network-like VGCFs formed during the MCVD process generally grow with an in situ growth mode on the graphite particles, which is extremely beneficial to improve the electronic conductivity of the composite cathode materials. The initial discharge capacity of the composite cathode materials, compared with the cathodes without in situ network-like VGCFs, increases from 109 mAhg-1 to 144 mAhg-1 at 0.5C rate, and the total electric resistance corresponding to the electron jumping varies from 538 Ω to 66 Ω.