Carbon-coated LiFePO4-carbon nanotube electrodes for high-rate Li-ion battery

Olivine LiFePO4 (LFP) is a promising cathode material for high-rated lithium-ion batteries. However, olivine faced a severe disadvantage of low conductivity and sluggish transportation of Li+ ions, which slows down the chemical reactions and thus the retention capacity of battery. Therefore, in this work, nanocomposite LiFePO4/carbon was synthesized by a hydrothermal route. A mixing of carbon nanotubes (CNTs) on the composite electrode was investigated to enhance the electrochemical performance of nanocomposite LiFePO4/C. The XRD pattern and XPS spectrum showed a high crystallite of olivine phase and a successful coating of carbon onto the surface of olivine. Electrochemical properties were evaluated by cyclic voltammetry (CV) and cyclability test. Lithium diffusion coefficients (D (Li)) were determined by the evolution of reduction peak on CV curves. An increase of D (Li) was observed with the increase of CNT amount in electrode composite. Practically, the composite electrode LFP/C/10%CNTs exhibited an excellent performance in cycling test and rate capability; a retention capacity of 98% was observed after 200 cycles.