Enhanced electrochemical performances of LiFePO4/C by surface modification with Sn nanoparticles

Abstract The surface of LiFePO 4 /C cathode material is coated with nano-sized Sn via a simple electroless deposition (ED) process, and the effects of the Sn-coating on the electrochemical performances of LiFePO 4 /C are investigated systematically by the charge/discharge testing, cyclic voltammograms and AC impedance spectroscopy, respectively. In comparison with the pristine LiFePO 4 /C, the Sn-coated LiFePO 4 /C exhibits higher capacity, better cyclability and higher rate capability in a wide operation temperature range. An analysis of the electrochemical measurements reveals that Sn-coated LiFePO 4 /C has good electric contact among particles, much lower charge-transfer resistances and higher lithium diffusion rate, especially at low temperature. In addition, the Sn-coating layer protects the active materials from chemical attack by HF and thus suppresses the dissolution of Fe from LiFePO 4 in the LiPF 6 based electrolyte.