Toward an understanding of bimetallic MXene solid-solution in binder-free electrocatalyst cathode for advanced Li-CO${}_2$ batteries

Li-CO${}_2$ batteries have received extensive attention due to their high energy storage capacity and utilization of CO${}_2$ resources. Herein, bimetallic MXene solid-solution TiVC is prepared and combined with highly conductive graphene for the construction of binder-free electrocatalyst cathodes for Li-CO${}_2$ batteries. Considering the electronic structure, the unique synergy effect between Ti and V in TiVC enhances the interfacial chemical bonding ability, facilitates sufficient exposure of active sites and promotes catalytic interfacial structural reformation, thereby promoting the reversible formation and decomposition of the chemically inert discharge product Li${}_2$CO${}_3$. Meanwhile, the abundant pores and excellent electron transfer ability of graphene aerogel are conducive to the gas diffusion and ion transport, thus reducing the mass and charge transfer resistance. As a result, the assembled Li-CO${}_2$ battery presents an excellent discharge capacity of 27 880 mAh g${}^{-1}$ with a stable discharge plateau of 2.77 V and low overpotential of 1.5 V based on the TiVC-graphene aerogel electrocatalytic cathode. The density functional theory calculations are further performed to deeply reveal the unique electronic structure information between Ti and V in the solid-solution TiVC. This study provides inspiration for exploring more bimetallic MXene solid solutions and developing advanced cathode catalysts for flexible Li-CO${}_2$ batteries. (© 2022 Wiley‐VCH GmbH)