Natural okra gum as functional binder enables highly stable Lithium-Selenium batteries

Lithium-selenium (Li-Se) batteries are garnered significant attention due to their high theoretical specific capacity, high volumetric energy density and moderate output voltage. Nevertheless, Li-Se batteries are still restricted by severe volume expansion and "shuttle effect" of polyselenides, resulting in deteriorated electrochemical performance. Binders are a crucial component of Li-Se batteries, playing a key role in addressing the mentioned issues. Herein, a non-toxic, bio-friendly, hydro-soluble binder of okra gum (OG) extracted from okra pods is proposed to ameliorate the electrochemical performance of Li-Se batteries. The as-prepared OG binders are rich in branched-chain polysaccharides (glucoside) and polar functional groups (-C-O-C-, -COOH), which not only have a good interpenetrating binding network to ensure the mechanical stability of Se cathode, but also have excellent interfacial chemical binding force for immobilizing polyselenides. Consequently, the OG binder endows Li-Se batteries with high initial discharge capacity (607 mA h g-1 at 0.2C), good cycling stability (218 mA h g-1 after 100 cycles at 0.2C), and remarkable rate performance (364 mA h g-1 at 1C), all of which are superior to Li-Se batteries with PVDF binder. Our study demonstrates the feasibility of natural mucilage as functional binder for Li-Se batteries and paves a research path in developing natural plant-based binders to stabilize electrode materials for reliable high-energy batteries.