Effect of Cobalt on Lifetime of Sb₄O₅Cl₂-Graphene Anode in Chloride-Ion Batteries

Anode materials based on metal oxychlorides hold promise in addressing electrode dissolution challenges in aqueous-based chloride ion batteries (CIBs). However, their structural instability following chloride ion deintercalation can lead to rapid degradation and capacity fading. This paper investigates a cobalt-doped Sb4O5Cl2-graphene (Co-Sb4O5Cl2@GO) composite anode for aqueous-based CIBs. It exhibits significantly enhanced discharge capacity of 82.3 mAh g(-1) after 200 cycles at 0.3 A g(-1); while, the undoped comparison is only 23.5 mAh g(-1) in the same condition. It also demonstrated with a long-term capacity retention of 72.8 % after 1000 cycles (65.5 mAh g(-1)) and a favorable rate performance of 25 mAh g(-1) at a high current density of 2 A g(-1). Undertaken comprehensive studies via in-situ experiments and DFT calculations, the cobalt (Co) dopant is demonstrated as the crucial role to enhance the lifetime of Sb4O5Cl2-based anodes. It is found that, the Co dopant improves electronic conductivity and the diffusion of chloride ions beside increases the structural stability of Sb4O5Cl2 crystal. Thus, this element doping strategy holds promise for advancing the field of Sb4O5Cl2-based anodes for aqueous-based CIBs, and insights gain from this study also offer valuable knowledge to develop high-performance electrode materials for electrochemical deionization.