Orbital electron coupling of Ga-Cd dual-atom sites catalyzes sulfur redox in potassium-sulfur battery

Dual-atom catalysts are a class of important catalytic systems for accelerating the kinetics of solid-phase conversion of K2S2 to K2S in potassium-sulfur battery cathodes, yet their uncontrolled metal-metal interactions greatly limit their catalytic capability, leading to low conversion efficiency of potassium-sulfur batteries. Herein, we report the precise synthesis of Ga-Cd dual-atom catalysts with strong orbital electron coupling of p-block Ga and d-block Cd, anchored on hollow mesoporous carbon spheres (Ga-Cd DAs-HMCS) for boosting the performance of potassium-sulfur batteries. Ga shows strong adsorption capacity for potassium polysulfides, but lacks sufficient valence electrons to promote their conversion. We demonstrate that the introduction of Cd with a more filled valence electron configuration enables the transfer of electrons into the empty orbitals of Ga via strong orbital electron coupling, which enhances the catalytic ability of the Ga site to activate the S-S bond in potassium-sulfur chemistry, and thus accelerates the conversion kinetics from K2S2 to K2S. This enables a S/Ga-Cd DAs-HMCS cathode material with an improved rate performance up to 589 mAh g−1 at 5 A g−1.