Chemistry in rechargeable zinc-air battery: A mechanistic overview

The progress in civilization can be related to the development of newer technological development and associated energy demand to run those systems. The personalized healthcare systems, the depletion of conventional fossil fuel reserve led us to think about alternative energy storage devices. Thus, it is important to develop energy storage materials with the property of good mechanical strength and stability for longer hours. Zn-air batteries (ZAB) show the promises to be an alternative of Li-air batteries for this purpose. ZABs can fulfill our need of stringent requirements such as high energy density, cost-effectiveness and it is safer as compared to Li-ion batteries. The stability of zinc in aqueous and air environments makes ZAB technology more reliable and effective for small to large-scale flexible electronics. To further enhance its efficiency, different scientific materials and methods have been developed over decades, of which this review provides detailed insight into the parameters and mechanisms related to the key components of the ZAB for enhancing the performance of ZAB. We summarized the working mechanism of overall reversible-ZABs and then independently we explained the mechanism and problems associated with cathode, anode, and electrolyte, followed by the current breakthrough related to each. Aspects such as role of optimal e_g occupancy in bifunctional activity, inhibition of zinc dendrite, and gel polymer electrolytes with enhanced conductivity and strength are specifically highlighted. To facilitate a broad discussion among different research communities, important scientific hurdles and their potential solution related to R-ZABs are also summarized.