Aqueous zinc-ion batteries (AZIBs) are emerging as promising alternatives to lithium-ion batteries due to their increased safety, abundance, and cost-effectiveness.[1] However, various challenges associated with zinc metal anodes have restricted commercialisation, including zinc dendrite formation, corrosion, and passivation. Consequently, designing zinc metal-free, “rocking-chair” AZIBs has emerged as a compelling strategy to accelerate commercialisation.[1]
Copper monosulfide (CuS) remains a promising anode material for AZIBs due to its high theoretical specific capacity (560 mAh g-1),[2] high elemental abundance, low cost, and environmental compatibility.[1, 3, 4] Despite this, currently reported CuS-based anodes for AZIBs typically underperform relative to theoretical expectations, while the zinc-ion charge storage mechanism of CuS based materials is insufficiently understood. Furthermore, although the structure-performance relationships for different structural morphologies of CuS have been explored extensively for lithium-ion batteries,[5] considerably less research has been conducted for CuS in AZIBs.[1] Moreover, while binder-free electrodes have shown promise in other reported battery chemistries, a binder-free CuS electrode has yet to be reported in AZIBs.
We hereby investigate the zinc storage behaviour of nanostructured CuS films prepared on conductive substrates via scalable, solution-based synthesis approaches that enable controlled variation of the CuS morphology. By investigating the electrochemical characteristics of different CuS morphologies in half cells against zinc metal, this work provides new insights into the role of electrode architecture on the electrochemical performance of AZIBs. Additionally, the intrinsic flexibility of the nanostructured CuS films enables the fabrication of flexible full cell AZIBs with potential application to wearable electronics. Strategies for enhancing the areal capacity of CuS film anodes are also explored, offering a broader perspective on the design strategies available for the scalable and facile development of high-performance rocking-chair AZIBs to drive future commercialisation.
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