Low-Temperature Synthesis of Honeycomb CuP2 @C in Molten ZnCl2 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 °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.