Hollow tubular sea-urchin structure with high catalytic activity of NiCo₂Se₄@CS₂ cathodes for high-performance Al/S...

The shuttle effect of aluminum polysulfides (AlPSs) have been a source of concern for studying Al/S batteries. Due to the weak adsorption of CS composites, research on cathode materials for Al/S batteries has been delayed. As it is generally known that Al₂S₃ decomposition demands a large Gibbs free energy, this work has tried to reduce the Al₂S₃ decomposition potential energy. Herein, the Ni/Co bimetallic selenide reduces the energy barrier conversion and mitigates the polarization effects, while morphology control enables the storage and anchoring of S, alleviating the shuttle effect. Additionally, the intermediate products serve as single-atom catalysts, increasing the active sites, synergistically enhancing the ion diffusion kinetics. DFT calculations verify that NiCo₂Se₄ has a moderate Gibbs free energy change during the rate-limiting step of S reduction and the most robust adsorption energy to Al₂S₃. NiCo₂Se₄@CS₂/Al has a remaining capacity of 135 mAh/g after 450 cycles (at 200 mA g^-1), pioneering novel ideas for the development of Al/S batteries.