Impact of Micropores and Dopants to Mitigate Lithium Polysulfides Shuttle over High Surface Area of ZIF-8 Derived Nanoporous Carbons

The shuttling of polysulfides (PS) is a major technical issue for lithium-sulfur batteries (LSB). Coating the LSB separator is an effective and simple way to mitigate the PS shuttle. However, these coating materials need to be carefully designed to produce an architecture with a high porosity, high surface area, and functional chemical binding sites. The judicious design of these materials will improve the sulfur utilization and hinder the PS shuttle. Here, conductive and chemically interactive zinc (Zn)- and nitrogen (N)-doped ZIF-8 derived carbon (ZnN-cZIF-8) with micropores <= 2 nm) is prepared through pyrolysis of pure ZIF-8. The ZnN-cZIF-8 is further activated in KOH to produce an ultrahigh surface area carbon (UHS-cZIF-8) with both micropores and mesopores. The aim of this study is to understand the relative importance of these material architectures on mitigating the PS shuttle in LSBs. Our research concludes that the ZnN-cZIF-8 with the chemically interactive sites (Zn and N contents) and a microporous structure enhances physisorption and chemisorption of PS, leading to a good long-term stability at a high sulfur loading.