Aloe‐Derived Sustainable, Aqueous and Flame Retardant Binder Toward High‐Performance Li‐S Batteries

An aloe-based sustainable, aqueous, and flame-retardant binder for high-performance Li-S batteries improves the electrochemical stability and safety of Li-S batteries by reducing the flammability of sulfur cathodes, accommodating electrode volume expansion, and preventing the polysulfide shuttle effect and lithium dendrite growth.

Abstract

Lithium-sulfur (Li-S) batteries offer ultra-high theoretical energy density (2600 Wh kg⁻¹) but face commercialization hurdles from polysulfide shuttling and sulfur flammability. A multifunctional biomass-derived binder by modifying aloevera gel (AG) with phytic acid (PA) is designed for addressing these two issues. The AG-PA binder provides strong mechanical integrity for the sulfur cathode and features N-, O-, and P-rich polar groups that chemically anchor lithium polysulfides (LiPSs) and accelerate Li⁺ deposition. This enhances LiPSs redox kinetics and suppresses shuttling. Consequently, AG-PA-based Li-S cells deliver a high initial capacity of 776.1 mAh g⁻¹ and retain 527.0 mAh g⁻¹ at 4 C (1 C = 1675 mA g⁻¹) after 1000 cycles (ultralow decay: 0.032% per cycle). Crucially, during combustion, heat decomposes AG-PA's phosphorus groups, generating phosphoric acid and water vapor that form a physical barrier isolating oxygen/heat. Simultaneously, PO· radicals scavenge H·/HO· radicals, quenching chain reactions. This dual-action significantly enhances safety. This work establishes a scalable biomass engineering approach to concurrently boost energy density, cyclability, and safety in Li-S batteries, bridging gaps towards practical deployment.