Regulating Zn2+/H+ Selectivity through Functional Group Design of Separators for Long-lifespan Aqueous Zinc Batteries

Authors: Jiaxian Zheng,† Ali Sufyan† Chong Li, Zheng Han, Xin Liu, Yuguo Zheng, J. Andreas Larsson,* Gang Huang, Binbin Wei, Zhengbing Qi, Zhoucheng Wang, Qiugen Zhang,* Hanfeng Liang,*

Abstract: 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 Zn2+, H+ and H2O, and further suggest that separators should ideally exhibit strong binding strength with H+ and H2O but weak with Zn2+. 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 Zn2+, H+ and H2O, 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-2 and 1 mAh cm-2. Furthermore, the full battery can deliver an impressive lifespan of over 6400 cycles at 3 A g-1. This work not only introduces a new separator for high-performance AZBs but also provides guiding principles for functional separator design.

DOI:https://doi.org/10.1039/D5MH00358J