A Peapod-like CoP@C Nanostructure from Phosphorization in a Low-Temperature Molten Salt for High-Performance Lithium-Ion Batteries.

A mild phosphorization process in low-temperature molten salt (NaCl-KCl-AlCl ) has been developed to synthesize peapod-like CoP@C nanostructures by using low-toxicity industrial PCl as the phosphorus source and Mg as the reductant at 250 °C. Importantly, high efficiency of the phosphorous source is achieved since only stoichiometric PCl is required to complete the reaction. The molten NaCl-KCl-AlCl not only provides a liquid environment but also participates in the electron transport by the reversible conversion of the Al /Al redox couple. The obtained 0D-in-1D peapod CoP@C structure exhibits excellent lithium storage performance, delivering a superiorly stable capacity of 500 mAh g after 800 cycles at a high current of 1.0 A g .