Regulating Zn/H selectivity through functional group design of separators for long-lifespan aqueous zinc batteries.

Zn anodes in aqueous rechargeable zinc batteries (AZBs) are plagued by irreversibility issues stemming from dendrite growth, hydrogen evolution, and corrosion. The design of separator offers a promising approach to enhance the reversibility of Zn anodes, but a universal strategy for rational separator design remains elusive. In this study, we propose a comprehensive design principle that takes into account the selective binding with Zn, H and HO, and further suggest that separators should ideally exhibit strong binding strength with H and HO but weak with Zn. We explore four typical scenarios based on varying binding strengths and identify polyethersulfone (PES) as a highly promising separator through screening of various commercial separators. Both experiment and theoretical calculations reveal that PES effectively regulates the transfer of Zn, H and HO, thereby concurrently suppressing dendrite growth, hydrogen evolution, and corrosion. As a result, the Zn‖Zn symmetric battery can operate for over 4000 h at 1 mA cm and 1 mA h cm. Furthermore, the full battery can deliver an impressive lifespan of over 6400 cycles at 3 A g. This work not only introduces a new separator for high-performance AZBs but also provides guiding principles for functional separator design.