Single-sulfur atom discrimination of polysulfides with a protein nanopore for improved batteries

Research on batteries mostly focuses on electrodes and electrolytes while few activities regard separator membranes. However, they could be used as a toolbox for injecting chemical functionalities to capture unwanted species and enhance battery lifetime. Here, we report the use of biological membranes hosting a nanopore sensor for electrical single molecule detection and use aqueous sodium polysulfides encountered in sulfur-based batteries for proof of concept. By investigating the host-guest interaction between polysulfides of different chain-lengths and cyclodextrins, via combined chemical approaches and molecular docking simulations, and using a selective nanopore sensor inserted into a lipid membrane, we demonstrate that supramolecular polysulfide/cyclodextrin complexes only differing by one sulfur can be discriminated at the single molecule level. Our findings offer innovative perspectives to use nanopores as electrolyte sensors and chemically design membranes capable of selective speciation of parasitic molecules for battery applications and therefore pave the way towards smarter electrochemical storage systems.