A Novel N/P-Doped Carbon Shells/Mn5.64P3 with Hexagonal Crystal Structure Hybrid as a Prospective Anode for Lithium-Ion Batteries.

Abstract

The tailored crystalline configuration coupled with submicron particles would be conducive to superior ionic conductivity, which could further improve the cycle life of lithium-ion batteries (LIBs). Here, manganese phosphide (Mn_5.64P₃) particles with hexagonal crystal structure embedded into nitrogen/phosphorus (N/P) co-doped carbon shells (Mn_5.64P₃-C) are successfully prepared by the self-template and recrystallization-self-assembly method. The electrochemical properties of as-synthesized Mn_5.64P₃-C as anode materials for LIBs are systematically investigated. The XRD and HRTEM combined with SAED indicate that the prepared Mn_5.64P₃-C hybrid with the ratio of 1:10 of Mn:C present a hexagonal crystal structure covered with a carbon layer. During charging/discharging at the current density of 0.5 A g^-1, the Mn_5.64P₃-C electrode exhibits the reversible capacity of 160 mAh g^-1 after 3000 cycles with high-capacity retention. The ex-situ XRD of initial discharge/charge process at different voltages implies that the Mn_5.64P₃ could be transformed to the amorphous Li_xMn_yP_z. The N/P co-doped carbon shells can provide high specific area for electrolyte infiltration, and act as the buffer matrix to suppress the loss of the Mn_5.64P₃ active material during cycling. The Mn_5.64P₃ with the hexagonal crystal structure and N/P co-doped carbon shells could promote the further optimization and development of manganese phosphide for high-performance LIBs.