Large-scale Zincophilic/Buffered alloy Architecture for Tough Zn-based Aqueous Batteries with High Depth-of-Discharge

Abstract

The aqueous rechargeable zinc batteries (ARZBs) are promising for broad application prospects in energy storage due to their high safety and low cost. However, the longevity and efficiency of ARZBs are compromised by dendrite growth and parasitic side reactions of the Zn anodes. The construction of a zincophilic coating on a zinc substrate is an effective strategy to enhance zinc deposition behavior and inhibit dendrite formation. Nevertheless, they are persecuted by the substantial morphological changes during repeated deposition and stripping processes, particularly at high discharge depths. Herein, under the assistance of the facile electroless strategy, a Cu₆Sn₅ alloy layer is constructed on a large (1200 mm × 250 mm) commercial copper foil (Cu₆Sn₅@Cu). Thereinto, the robust interaction between Cu₆Sn₅ and Zn²⁺ facilitates the regulation of Zn²⁺ flow, to further enhance lateral growth, minimize nucleation overpotential, and a dendrite-free morphology of zinc metal. In addition, the Cu–Zn alloy and Sn metal are constructed by an alloying process between the Cu phase of the Cu₆Sn₅ alloy and Zn. It is found that the Sn phase serves as a buffer medium to mitigate internal stress and volume changes from alloy reactions, preventing delamination of the alloy layer. As a result, the symmetrical batteries with Cu₆Sn₅@Cu anode exhibit remarkable performance for a cycle life of 7000 h with a high depth of discharge of 50%. Furthermore, the Mn-based full battery retains high capacity after 2000 cycles.