Low-temperature synthesis of honeycomb CuP2@C in ZnCl2 molten salt for high-performance lithium ion batteries.

Phosphorus-rich metal phosphides have very high lithium storage capacities, but they are difficult to prepare. A low-temperature phosphorization method based on Mg reducing PCl3 in ZnCl2 molten salt at 300 degrees C is developed to synthesize phosphorus-rich CuP2@C from a Cu-MOF derived Cu@C composite. Abnormal oxidation of Cu by Zn2+ in the molten salt is observed, which leads to the porous honeycomb nanostructure and homogeneously distributed ultrafine CuP2 nanocrystals. The honeycomb CuP2@C exhibits excellent lithium storage performance with high reversible capacity (1146 mAh g(-1) at 0.2 A g(-1)) and superior cycling stability (720 mAh g(-1) after 600 cycles at 1.0 A g(-1)), showing the promising application of P-rich metal phosphides in lithium ion batteries.