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

The surface of LiFePO4/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 LiFePO4/C are investigated systematically by the charge/discharge testing, cyclic voltammograms and AC impedance spectroscopy, respectively. In comparison with the pristine LiFePO4/C, the Sn-coated LiFePO4/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 LiFePO4/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 LiFePO4 in the LiFF6 based electrolyte. (C) 2012 Elsevier B.V. All rights reserved.