Optimizing LiFePO4@C Core–Shell Structures via the 3-Aminophenol–Formaldehyde Polymerization for Improved Battery Performance

Polyanion-type cathode materials are well-known for their low electronic conductivity; accordingly, the addition of conductive carbon in the cathode materials becomes an indispensable step for their application in lithium ion batteries. To maximize the contribution of carbon, a core–shell structure with a full coverage of carbon should be favorable due to an improved electronic contact between different particles. Here, we report the formation of a uniform carbon nanoshell on a typical cathode material, LiFePO4, with the shell thickness precisely defined via the 3-aminophenol–formaldehyde polymerization process. In addition to the higher discharge capacity and the improved rate capability as expected from the carbon nanoshell, we identified that the core–shell configuration could lead to a much safer cathode material as revealed by the obviously reduced iron dissolution, much less heat released during the cycling, and better cyclability at high temperature.