Polyanion-Type Cathode Materials for Li-Ion Batteries

Polyanion-type materials are considered as one of the most promising cathode materials for power batteries due to the good safety, low cost and environmental benign of the materials. However, the commercial application of this kind of material is hindered by the poor rate capability and low-temperature performance caused by the low electronic and ionic conductivity of the materials. Recently, the electrochemical performances of the materials have been improved to a certain extend by coating the material particles with carbon or conductive polymer, doping the compounds with foreign metal ions, and preparing the nano-structured materials. And the commercial applications of LiFePO4 in power batteries have been successfully achieved. In this paper, the recent progress on the polyanion-type cathode materials, including silicates and sulfates which have become the research focus again, are reviewed. The crystal structure, synthesis and modification process, electrochemical characteristics, safety of the material, as well as the technical bottlenecks in the actual applications are discussed. The possible approaches to improve the output performance of the materials and the development trends of the polyanion-type cathode materials are also discussed and prospected.