Bifunctional high-strength and anti-shuttling separator based on negatively-charged-cellulose-nanofibers for high-energy and stable flexible Zn-I2 batteries

Abstract

The flexible aqueous zinc-iodine batteries (FZIBs) show promise for wearable electronics, but the polyiodide shuttling effect limits iodine loading. Here, we develop a high-strength and negatively charged separator based on bio-sustainable and low-cost carboxylated cellulose nanofibers (c-CNFs) to obtain high-performed FZIBs. The negatively charged COO⁻ groups on the c-CNFs can repel the shuttling of iodine species and simultaneously enable a robust mechanical strength based on strong hydrogen bonding, allowing for shuttling-free high-loading FZIBs with improved energy and stability. Our research demonstrated the cellulose-based separator to enable FZIBs as a high-energy and stable flexible power supply.