Anisotropy of electronic and ionic transport in LiFePO4 single crystals

A material of key relevance as a cathode in rechargeable lithium batteries is LiFePO4, whose major shortcoming lies in its sluggish mass and charge transport, the overcoming of which requires a precise knowledge of transport properties, as of yet unavoidable. The present work aims at filling this gap. We report here a clear experimental investigation of electronic and ionic conduction as well as chemical diffusion for Li (D-Li(delta)) in LiFePO4 single crystals. We show that the electronic conductivity, ionic conductivity, and chemical diffusivity of Li are essentially two-dimensional (b-c plane) in our single crystals. The ionic conductivities along all three axes are found to be much smaller than the electronic conductivities. Present results on LiFePO4 are crucial for systematic optimization of its performance in Li-batteries in terms of doping or microstructural design. (c) 2006 The Electrochemical Society.