Self-supporting 3D hierarchically porous CuNi–S cathodes with a dual-phase structure for rechargeable Al battery

Metal-based materials are considered as advanced cathodes to develop high-energy-density aluminum batteries. Powdery metal active materials are usually synthesized and loaded on a current collector. Weak stability and low loading mass are the limiting issues. A new self-supporting hierarchically porous CuNi–S/CC cathode with the dual-phase structure on carbon cloth (CC) for aluminum batteries is designed and constructed by the electrodeposition of porous Cu–Ni alloy on a gas–liquid–solid interface, chemical transformation to nanostructure (CuNi–O), and sulfur replacement (CuNi–S). It is found that CuNi–S/CC1.0 cathode delivers a high initial discharge capacity of 333.5 mA h g−1 at 200 mA g−1. After 200 cycles, the reversible discharge capacity could be maintained at 70.5 mA h g−1 with a coulombic efficiency of 99.4%, and the value is much higher than that of the conventional coating cathode. Particularly, the loading mass of CuNi–S is up to 4.2–4.8 mg cm−2, which is 2.6–8 times compared with those (0.6–1.6 mg cm−2) prepared by the slurry-coating method. This work provides a promising strategy to construct novel self-supporting metal-based cathodes for developing high-energy-density Al batteries.