Enhanced electrochemical properties of LiFePO4 cathode for Li-ion batteries with amorphous NiP coating

Here we show that the intrinsic low electrical conductivity of LiFePO4 which seriously hinders the application of LiFePO4 for Li-ion batteries is overcome with conductive metallic NiP nano-coating. High resolution transmission electron microscopy image reveals that the NiP coating is a nanoscale amorphous layer, which was deposited on the LiFePO4 particles to form a so-called core/shell structure via electroless plating at room temperature. The electrochemical performances of NiP coated LiFePO4 show that both of the rate performance and cycleability of LiFePO4 against graphite anode are improved by the NiP coating. Analysis of electrochemical impedance spectra of the LiFePO4/graphite cells demonstrates that the NiP coating decreases both of the surface film resistance and charge transfer resistance. The dissolution of Fe from LiFePO4 in the LiPF6 based electrolyte is remarkably suppressed by the protective NiP coating. (C) 2010 Elsevier B.V. All rights reserved.