Activation and Stabilization of Mn‐Based Positive Electrode Materials by Doping Nonmetallic Elements

Abstract

AbstractDisordered rock‐salt (DRS) type active materials are highly significant because of their large reversible capacities, which are due to their unique Li+ diffusion pathway and the redox capabilities of cationic transition metals (TMs) and anionic O ions. Loosely crystalline DRS materials have weak covalent bonds between TMs and O, increasing the O redox contribution and thereby enhancing their capacities. In this study, Mn‐based positive electrode materials with DRS structures are activated and stabilized by mechanochemical doping of nonmetallic elements P and B into interstitial sites. Synthesized Li0.90Mn0.84P0.04O2 (LMPO5) exhibits an initial discharge capacity of 346 mAh g−1 (1050 Wh kg−1) during charging/discharging. Li0.91Mn0.83B0.10O2 (LMBO5) has a moderately expanded lattice size, which facilitates high‐capacity retention during cycling (≈284 mAh g−1 at the 30th cycle). The structural properties of the synthesized active materials are extensively characterized. By introducing nonmetallic elements into the interstitial sites of Mn‐based materials, inexpensive, high‐capacity, and long‐cycling/calendar‐life Co/Ni‐free monometallic positive electrode materials may be further developed.