Résumé
MnP4 has already been identified as a promising negative electrode for Li-ion batteries. Despite its interesting theoretical capacity, well above that of graphite, this material was not studied further due to its poor cyclability. MnP4 was here prepared by ball milling and used as an active negative electrode material in optimised electrode formulation. This ball milled MnP4 optimised electrode shows improving cycling performance, with a stable specific capacity of 600 mAh g−1 over 60 cycles. The combination of operando X-ray diffraction, Mn K-edge X-ray absorption spectroscopy, and 31P and 7Li NMR analyses reveals a two-step reversible mechanism: Li insertion in MnP4 forming amorphous “LixMnP4” which is converted into Li3P and Mn metal at low potential. Unlike in previous studies related to MnP4, the MnP4 CMC-based electrode shows neither crystalline Li7MnP4 formation at mid discharge, nor MnP4 reformation upon charge. This modified reaction pathway appears to be beneficial for long-term capacity retention.