Ultrathin carbon nanopainting of LiFePO₄ by oxidative surface polymerization of dopamine

The common strategy to address the low electronic conductivity of LiFePO₄ is to downsize LiFePO₄ and to coat the nanocrystal with conductive carbon film. The major issues with existing carbon coating techniques are thickness and quality control. This paper reports a facile carbon coating method which can provide ultrathin, uniform and fully encapsulating carbon coating on LiFePO₄. This coating method capitalizes on the redox chemistry of surface Fe³⁺ on solvothermally synthesized LiFePO₄ nanocrystal, to deposit uniform thin films of polydopamine films. The polymer film is easily carbonized into ultrathin carbon film. The carbon coated LiFePO₄ exhibits very high rate performance (143 mAh g^-1 at current density of 1700 mA g^-1) with excellent capacity retention.