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

Abstract LiFePO 4 @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 LiFePO 4 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 Fe 2+ 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 LiFePO 4 @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 0.2 C, and high capacity retention of 76.5% even at 10 C after the 800th cycles. The electric conductivity and Li + diffusion coefficient (D Li + ) of the LiFePO 4 @MWCNTs are 3.79 × 10 −2  S cm −1 and 4.46 × 10 −11  cm 2  s −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.