\u3cem\u3eAb initio\u3c/em\u3e Investigations on Metal Ion Pre-Intercalation Strategy of Layered V\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e5\u3c/sub\u3e Cathode for Magnesium-Ion Batteries

Metal ions pre-intercalated layered structure materials are considered as potential high performance cathodes for Mg-ion batteries (MIBs). Herein, metal ions pre-intercalation strategy of layered cathode for MIBs by using Li, Na, Al pre-intercalated V2O5 cathode as a carrier has been investigated and proposed based on first principle calculations. The pre-intercalation process is energetically favorable and metal ion pre-intercalation improves the electronic conductivity of V2O5. The bondings of Li-V2O5, Na-V2O5 and Al-V2O5 all exhibit ionic characters, and the interaction between Al ion and V2O5 is the strongest. The interlayer distance expansion of Na pre-intercalated V2O5 is more trivial than that of Li, Al pre-intercalated V2O5. The open circuit voltage of the V2O5 cathode is dropped by pre-intercalated metal ions, and the voltage of Li and Na pre-intercalated V2O5 is higher than that of Al pre-intercalated V2O5. The diffusion barriers of Mg in the V2O5 matrix are reduced by pre-intercalation. Overall, metal ion pre-intercalation with a large atomic radius and small atomic charges holds great potentials to expand interlayer distance, enhance electronic conductivity, maintain high discharge voltage and improve diffusion ability of layered cathode. We hope our work could provide a significant guidance to the practical design of layered cathodes for MIBs