Band Structure Engineering Promotes Anionic Redox Reversibility of Cobalt ‐Free Li‐Rich Layered Oxides Cathodes

The incorporation of Mo with high d state orbit and Cl with low electronegativity for Co-free Li1.16Mn0.56Ni0.28O2 cathodes can narrow the band energy gap between bonding and antibonding bands via increasing the filled lower-Hubbard band (LHB) and decreasing the non-bonding O 2p energy bands, promoting the anionic redox reversibility and structural stability. AbstractLi-rich layered oxides cathodes (LLOs) have prevailed as the promising high-energy-density cathode materials due to their distinctive anionic redox chemistry. However, uncontrollable anionic redox process usually leads to structural deterioration and electrochemical degradation. Herein, a Mo/Cl co-doping strategy is proposed to regulate the relative position of energy band for modulating the anionic redox chemistry and strengthening the structural stability of Co-free Li1.16Mn0.56Ni0.28O2 cathodes. The incorporation of Mo with high d state orbit and Cl with low electronegativity can narrow the band energy gap between bonding and antibonding bands via increasing the filled lower-Hubbard band (LHB) and decreasing the non-bonding O 2p energy bands, promoting the anionic redox reversibility. In addition, strong covalent Mo ─O and Mn─Cl bonding further increases the covalency of Mn─O band to further stabilize the O2n − species and enhance the reversible distortion of MnO6 octahedron. The strengthening electronic conductivity, together with the epitaxial structure Li2MoO4 facilitates the fast Li+ kinetics. As a...
Source: Small - Category: Nanotechnology Authors: Tags: Research Article Source Type: research