Surface control and multi-composite cathodes
We report recent progress in surface control of cathode element particles. Re-crystallization of the surface layer can be obtained not only in olivines, but also in lamellar compounds, which results in an increase of the electrochemical properties. In addition, we take benefit of the stability of LiFePO4 and the fact that it does not need protection against overcharge, by synthesizing multi-component particles formed by a core particle with higher working potential like LiMnPO4 (4-V cell) and even LiMn1.5Ni0.5O4 (5-V cell) surrounded by LiFePO4 coated with carbon to the particles with LiFePO4. The remarkable improvement of the electrochemical properties obtained in this process gives evidence that the synthesis of such multi-component composites are promising to improve the energy density and high-rate performance of Li-ion batteries in the near future.