Boosting anionic redox through lithium doping in P2-layered cathode for high-performance sodium-ion batteries

Anionic chemistry has become a new paradigm for increasing the energy density of rechargeable batteries. Herein to boost the activity of cationic redox in P2-Na0.8Cu0.1Mn0.9O2, a new Li-doped P2-Na0.8Li0.15-Cu0.1Mn0.75O2 cathode is designed, and the electrochemical performances of both materials are systematically investigated. Compared with the undoped sample, P2-Na0.8Li0.15Cu0.1Mn0.75O2 cathode material displays higher reversible capacity, better rate capability and stronger cycling stability. These improvements are supposed to be originated from the positive effect of Li on triggering the anionic redox under high operating voltage, stabilizing the crystal structure as well as facilitating the diffusion of Na+ and electron during the sodiation/desodiation process. This work pursues superior electrochemical performance in P2-layered cathodes through boosting the anionic redox, which probably offers some insights for designing high-performance sodium-ion batteries.