Fabrication and electrochemical properties of 3D nano-network LiFePO4@multiwalled carbon nanotube composite using risedronic acid as the phosphorus source

摘要

LiFePO4@multiwalled carbon nanotubes（LFP@MWCNTs） nanocomposite has been fabricated using risedronic acid（RDA） as a new eco-friendly phosphorus source. Microscopic, spectroscopic, and electrochemical characterization demonstrate that the MWCNTs are in the form of coiled and cross-linking nanoribbon, which wrapped and encrusted around LiFePO4 particles to form a three-dimensional（3D） nano-network composite.This microstructure of 3D nano-network is obtained due to the reactions between RDA’s special functional groups with Fe2+ and C-OH,-C=O or-COOH on the surface of the functionalized MWCNTs. The results also show that the particle size of the fabricated LiFePO4@MWCNTs composite is below 300 nm with the pure crystal of olivine. This nanocomposite indicates an enhanced reversible capacity of 162.2 mAh g-1 at 0.2C, and high capacity retention of 76.5% even at 10C after the 800 th cycles. The electric conductivity and Li+ diffusion coefficient(DLi+) of the LiFePO4@MWCNTs are 3.79 × 10-2S cm-1 and 4.46 × 10-11 cm~2s-1, respectively.These improved electrochemical parameters can be attributed to the nano-sized effect of particles, MWCNTs’ wrapping effect and 3D nano-network microstructure of the LFP@MWCNTs resulted from using RDA as a new phosphorus source.