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

TL;DR

A new hybrid material with hexagonal crystal structure and carbon shells is developed for better lithium-ion battery anodes.

Contribution

A novel Mn5.64P3-C hybrid with hexagonal crystal structure and N/P-doped carbon shells is synthesized for improved LIB anode performance.

Findings

Mn5.64P3-C exhibits 160 mAh g−1 reversible capacity after 3000 cycles at 0.5 A g−1.

N/P-doped carbon shells act as a buffer matrix to preserve active material during cycling.

Hexagonal Mn5.64P3 transforms into amorphous LixMnyPz during initial charge/discharge.

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 (Mn5.64P3) particles with hexagonal crystal structure embedded into nitrogen/phosphorus (N/P) co-doped carbon shells (Mn5.64P3-C) are successfully prepared by the self-template and recrystallization–self-assembly method. The electrochemical properties of as-synthesized Mn5.64P3-C as anode materials for LIBs are systematically investigated. The XRD and HRTEM combined with SAED indicate that the prepared Mn5.64P3-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 Mn5.64P3-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 Mn5.64P3 could be transformed to the amorphous LixMnyPz. 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 Mn5.64P3 active material during cycling. The Mn5.64P3 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.

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