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-AlCl3) has been developed to synthesize peapod-like CoP@C nanostructures by using low-toxicity industrial PCl3 as the phosphorus source and Mg as the reductant at 250 degrees C. Importantly, high efficiency of the phosphorous source is achieved since only stoichiometric PCl3 is required to complete the reaction. The molten NaCl-KCl-AlCl3 not only provides a liquid environment but also participates in the electron transport by the reversible conversion of the Al3+/Al redox couple. The obtained 0D-in-1D peapod CoP@C structure exhibits excellent lithium storage performance, delivering a superiorly stable capacity of 500mAhg(-1) after 800 cycles at a high current of 1.0Ag(-1).