Tailored Surface Structure of LiFePO₄/C Nanofibers by Phosphidation and Their Electrochemical Superiority for Lithium Rechargeable Batteries

We offer a brand new strategy for enhancing Li ion transport at the surface of LiFePO₄/C nanofibers through noble Li ion conducting pathways built along reduced carbon webs by phosphorus. Pristine LiFePO₄/C nanofibers composed of 1-dimensional (1D) LiFePO₄ nanofibers with thick carbon coating layers on the surfaces of the nanofibers were prepared by the electrospinning technique. These dense and thick carbon layers prevented not only electrolyte penetration into the inner LiFePO₄ nanofibers but also facile Li ion transport at the electrode/electrolyte interface. In contrast, the existing strong interactions between the carbon and oxygen atoms on the surface of the pristine LiFePO₄/C nanofibers were weakened or partly broken by the adhesion of phosphorus, thereby improving Li ion migration through the thick carbon layers on the surfaces of the LiFePO₄ nanofibers. As a result, the phosphidated LiFePO₄/C nanofibers have a higher initial discharge capacity and a greatly improved rate capability when compared with pristine LiFePO₄/C nanofibers. Our findings of high Li ion transport induced by phosphidation can be widely applied to other carbon-coated electrode materials