Anisotropy of Electronic and Ionic Transport in LiFePO4 Single Crystals

A material of key relevance as a cathode in rechargeable lithium batteries is LiFePO 4 , 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 δ Li ) in LiFePO 4 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 LiFePO 4 are crucial for systematic optimization of its performance in Li-batteries in terms of doping or microstructural design.

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