A high-durability aqueous Cu-S battery assisted by pre-copper electrochemistry

Although research interest in aqueous metal-sulfur batteries (AMSs) has surged due to their intrinsic low cost and high capacity, the practical application of AMSs remains a considerable challenge because of the restrictive cycling stability. To circumvent this issue, we propose an innovative and simple pre-copper strategy to realize a high-durability aqueous Cu-S battery. The pre-copper strategy can effectively promote a stable metal dissolution/deposition, compensate for charge carriers, and facilitate reaction kinetics during the subsequent process. As a result, the aqueous Cu-S battery when coupled with S-decorated porous Ti₃C₂ (S-d-Ti₃C₂) exhibits excellent electrochemical performance, delivering a highly reversible capacity of 1805.4 mAh·g⁻¹ in the initial cycle at 0.8 A·g⁻¹, impressive cycling stability with 90.2% capacity retention over 800 cycles, and ultralow polarization ~ 0.08 V even at a high current density of 3.1 A·g⁻¹. The findings obtained in this work could pave the way for the design of high-performance sulfur-based aqueous batteries, which fill the vacancy of the necessary metal anode, delivering merits in both cost and cycle life.