An architecting binder derived from Antarctic red algae to accelerate sulfur redox kinetics in Li-S batteries

Abstract

Volume changes during charge/discharge cycles can lead to substantial cracking, disrupting electron and ion transfer channels, and hindering the performance of lithium-sulfur (Li-S) batteries. Binders are crucial for mitigating these issues because they preserve the structural integrity of electrodes and ensure reliable operation. Herein, this study presents the first report of a hybrid carrageenan, Antarctic macroalgae Curdiea racovitzae-derived polysaccharide (CRP), consisting of a diverse-blocked copolymer including kappa, iota, mu, nu carrageenans, and porphyran as Li-S battery binders. CRP prevents binder agglomeration and enables the electrode to form a uniform 3D-network structure reminiscent of an ant tunnel, enhancing the electrolyte permeability and utilization of the sulfur species. Additionally, the abundant functional groups in CRP, such as sulfate and hydroxyl groups, facilitate efficient Li- ion transport. By leveraging these properties, the CRP-based sulfur electrode achieves a high initial capacity of similar to 1500 mAh g 1 at 0.1C, approximately 90 % of the theoretical capacity, and demonstrates superior cycle stability at 1C. Moreover, the Li2S nucleation rate was nearly 100 times higher compared to the PVDF-based sulfur electrode. The incorporation of a sustainable CRP binder in Li-S batteries marks a notable breakthrough, paving the way for future developments in the battery field.