An Overview of Challenges and Strategies for Stabilizing Zinc Anodes in Aqueous Rechargeable Zn-Ion Batteries

Abstract

Aqueous rechargeable zinc ion batteries (ZIBs) have been revived and are considered a promising candidate for scalable electrochemical energy storage systems due to their intrinsic safety, low cost, large abundance, mature recyclability, competitive electrochemical performance, and sustainability. However, the deployment of aqueous rechargeable ZIBs is still hampered by the poor electrochemical stability and reversibility of Zn anodes, which is a common, inherent issue for most metal-based anodes. This review presents a comprehensive and timely overview of the challenges and strategies of Zn anodes toward durable ZIBs. First, several challenges that significantly reduce the Coulombic efficiency and cycling stability of Zn anodes are briefly discussed including dendrite formation, hydrogen evolution, and corrosion. Then, the mitigation strategies are summarized in terms of modifying the electrode/electrolyte interfaces, designing electrode structures, and optimizing electrolytes and separators. Further, we comprehensively discuss the mechanisms behind these issues and improvement strategies with respect to the anodes, electrolytes, and separators. Lastly, we provide perspectives and critical analyses of remaining challenges, outlook, and future direction for accelerating the practical application of aqueous rechargeable ZIBs.

Functional Oriented Design of Composite Artificial Interface Layers Towards Stable Zinc Anodes In Aqueous Zinc‐ion Batteries

“…Uneven Zn deposition is well established as a chief reason for Zn dendrites during the Zn plating/ stripping processes, leading to an uneven surface. [68] The inhomogeneous electrode surface may result in an inhomogeneous electric field and swelling anode, aggravating dendrite growth and capacity decay. [69] On the other hand, asyntactic dead Zn on the electrode formed by the separation of the dendrite root from the Zn anode is no longer as an active component, which ultimately leads to the low CE and reduced battery cycling lifespan.…”

“…As a notorious problem, the formation of Zn dendrites limits the practical application of Zn metal anodes in neutral or slightly acidic AZIBs. Uneven Zn deposition is well established as a chief reason for Zn dendrites during the Zn plating/stripping processes, leading to an uneven surface [68] . The inhomogeneous electrode surface may result in an inhomogeneous electric field and swelling anode, aggravating dendrite growth and capacity decay [69] .…”

Synergistically Stabilizing Zinc Anodes by Molybdenum Dioxide Coating and Tween 80 Electrolyte Additive for High-Performance Aqueous Zinc-Ion Batteries

“…Aqueous metal-ion batteries have many advantages, including higher ionic conductivity, cost-effectiveness, easier processing, and higher safety with aqueous electrolytes, which makes them a promising candidate for energy storage systems . In this regard, aqueous zinc-ion batteries (ZIBs) have attracted intense interest due to the merits of Zn anodes with a high theoretical capacity (820 mAh g –1 ), low redox potential (−0.76 V vs. standard hydrogen electrode), low cost, inherent safety, low toxicity, and mature recyclability. , However, Zn metal anodes undergo dendritic issues due to inhomogeneous Zn 2+ ion deposition and dissolution on the electrode surfaces . Moreover, the Zn anode surface and electrolyte interaction can cause electrode corrosion.…”

“…Corrosion of Zn anodes creates an irregular surface, causing uneven nucleation sites for Zn 2+ ions and facilitating the hydrogen evolution reaction (HER) on such corroded Zn surfaces . Then, some passivated byproducts, such as zinc sulfate hydroxide hydrate (Zn 4 SO 4 (OH) 6 · x H 2 O), can be formed during the electrochemical process . Thus, Zn anodes suffer from poor electrochemical stability, low Coulombic efficiency (CE), short circuits, and limited cycle life, restricting the practical development of ZIBs .…”

“…4 Then, some passivated by- products, such as zinc sulfate hydroxide hydrate (Zn 4 SO 4 (OH) 6 •xH 2 O), can be formed during the electrochemical process. 3 Thus, Zn anodes suffer from poor electrochemical stability, low Coulombic efficiency (CE), short circuits, and limited cycle life, restricting the practical development of ZIBs. 5 Various strategies have been proposed to address these issues of Zn anodes, including modifying the anode surface, 6,7 optimizing the electrolyte composition, 8,9 constructing 3D-structured or alloyed anodes, 10,11 and fabricating functional separators.…”