Li–S Chemistry of Manganese Phosphides Nanoparticles With Optimized Phase

Abstract

Abstract The targeted synthesis of manganese phosphides with target phase remains a huge challenge because of their various stoichiometries and phase‐dependent physicochemical properties. In this study, phosphorus‐rich MnP, manganese‐rich Mn2P, and their heterostructure MnP–Mn2P nanoparticles evenly dispersed on porous carbon are accurately synthesized by a convenient one‐pot heat treatment of phosphate resin combined with Mn2+. Moreover, their electrochemical properties are systematically investigated as sulfur hosts in lithium–sulfur batteries. Density functional theory calculations demonstrate the superior adsorption, catalysis capabilities, and electrical conductivity of MnP–Mn2P/C, compared with MnP/C and Mn2P/C. The MnP–Mn2P/C@S exhibits an excellent capacity of 763.3 mAh g−1 at 5 C with a capacity decay rate of only 0.013% after 2000 cycles. A phase evolution product (MnS) of MnP–Mn2P/C@S is detected during the catalysis of MnP–Mn2P/C with polysulfides redox through in situ X‐ray diffraction and Raman spectroscopy. At a sulfur loading of up to 8 mg cm−2, the MnP–Mn2P/C@S achieves an area capacity of 6.4 mAh cm−2 at 0.2 C. A pouch cell with the MnP–Mn2P/C@S cathode exhibits an initial energy density of 360 Wh kg−1.

Keywords

• heterostructure
• lithium–sulfur batteries
• manganese phosphide
• phase evolution
• porous carbon