Inhibiting the shuttle effect in lithium-sulfur batteries: A bio-based approach with an alginate-graphene oxide composite separator

Lithium-sulfur (Li-S) batteries are regarded as prospective energy storage devices based on their high theoretical specific capacity and energy density. Nevertheless, their practical application of Li-S batteries has been significantly hindered by the shuttle effect of polysulfides. Here, a bio-based separator coating was synthesized by grafting graphene oxide (GO) to sodium alginate (SA) and coated on commercial polypropylene (PP) separators to inhibit the shuttle effect. SA-GO coatings exhibit a porous structure and polar functional groups, which enable the effective inhibition of polysulfide shuttling and the acceleration of lithium-ion diffusion and redox reaction kinetics. Meanwhile, the formation of enhanced hydrogen bonding between the functional groups of GO and SA effectively improves the mechanical stability of the SA-GO coating. Thus, the initial capacity of Li-S batteries based on SA-GO/PP separators is 896 mAh g −1 at 0.5 C, and the discharge capacity is 702 mAh g −1 at 2 C. Furthermore, after 950 cycles at 1 C, the capacity of the battery remains at 400 mAh g −1 , exhibiting remarkable long-term cycling performance. This study provides a visible method for the application of bio-based materials in functionalized separators for Li-S batteries. SYNOPSIS: The SA-GO/PP separator can effectively inhibit the shuttle effect of polysulfides and accelerate the kinetics of the lithium polysulfide redox reaction.