From lab to market: the future of zinc-air batteries powered by MOF/MXene hybrids

Zinc-air batteries (ZABs) stand at the forefront of future energy storage technologies, lauded for their exceptional energy density, cost-efficiency, and eco-compatibility. This review meticulously explores the cutting-edge advancements in the engineering of Metal-Organic Framework (MOF) and MXene hybrid materials, specifically designed to elevate the performance of ZABs. This review begins by elucidating the fundamental architecture and operational mechanisms of ZABs, delving into the roles of critical components such as the current collector, catalytic layer, and gas diffusion film in enhancing the batteries electrochemical efficacy. A detailed discourse is provided on the intricacies of the electrochemical reactions underpinning ZAB functionality, with a focus on the Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER). The review offers an in-depth examination of ORR mechanisms, encompassing both the four-electron and two-electron pathways, alongside a rigorous analysis of OER mechanisms, which include the direct combination and metal-OOH intermediate routes. The kinetic challenges inherent to these reactions are scrutinized, underscoring the pivotal role of catalyst design in mitigating these barriers. MOF/MXene hybrids emerge as transformative materials in this context, attributed to their synergistic structural and electronic properties. We explore the synthesis methodologies for these hybrids, emphasizing both in situ and ex situ tactics, and evaluate their profound impact on ORR and OER activities. The discussion extends to the performance metrics of ZABs—such as energy efficiency, power density, and cycling durability—while highlighting the critical influence of the electrolyte in determining overall system performance. Design considerations for rechargeable ZABs are presented, with a particular emphasis on optimizing the air electrode and addressing challenges related to bifunctional catalyst stability and gas diffusion layer efficiency. The review meticulously examines the formidable challenges that ZAB technology faces, particularly the kinetic constraints of ORR and OER, material robustness, and the complexities of system integration. In conclusion, the review offers forward-looking perspectives on the future expansion of advanced MOF/MXene hybrid materials and innovative design strategies for ZABs. These insights aim to push the boundaries of performance, efficiency, and durability in ZAB technology, thereby paving the way for their widespread commercial adoption. The summary synthesizes the critical findings and accentuates the transformative potential of MOF/MXene hybrids in advancing ZAB technology, suggesting strategic directions to overcome existing limitations and accelerate the deployment of sustainable energy storage solutions.