Lewis metal salt synthesis of V2C (MXene) composite nickel diselenide as a high-performance cathode material for secondary aluminum batteries

Rechargeable aluminum batteries are promising energy storage devices that have advantages over lithium-ion batteries in terms of safety, cost, and capacity. Herein, a V2C (MXene) composite nickel diselenide (V2C@NiSe2) cathode is synthesized by etching V2AlC MAX phase via Lewis acidic molten salts and then calcining it with selenium. The V2C@NiSe2 cathode material exhibited reversible redox reactions of Ni2+/Nix+, and Se-/Sex+ in the charge–discharge process. Due to the fact that selenium can also replace functional groups on V2C, it can effectively avoid strong interactions between AlCl4- and V2C layers, thereby increasing their energy density. By using V2C@NiSe2 as the cathode material for aluminum batteries, the first cycle discharge specific capacity reached 486.8 mAh/g and remained at 166 mAh/g after about 3800 cycles at 1 A/g. To compare the performance of the V2C@NiSe2 cathode material, additional cathode materials (V2C@MnSe, V2C@FeSe, V2C@CuSe2, and V2C@CoSe) are created using a similar synthesis process. This work demonstrates a novel synthesis method of intercalation-type composite low-dimensional cathode materials for stable secondary aluminum batteries.