A gel polymer electrolyte with Al2O3 nanofibers skeleton for lithium-sulfur batteries

As a promising secondary battery system, lithium-sulfur (Li-S) batteries have attracted extensive attention due to their high energy density. However, the development of Li-S batteries is hindered by the detrimental shuttling of soluble lithium polysulfides (LiPs) in traditional liquid electrolytes. In this work, we fabricate a functional gel polymer electrolyte for Li-S batteries. This electrolyte consists of poly(vinylidene fluoride-co-hexaflfluoropropylene) (PVDF-HFP) polymer matrix and a continuous gamma-Al2O3 three-dimensional skeleton with structural and thermal stability. PVDF-HFP offers lithium-ion transport pathways and equips the electrolyte with flexibility, whereas the inorganic gamma-Al2O3 skeleton as Lewis acid can suppress the shuttling of LiPs through strong Lewis acid-base interactions between gamma-Al2O3 and LiPs. In addition, gamma-Al2O3 has an effect on the Lewis base of bis(trifluoromethanesulphony)imide anion, facilitating the dissociation of lithium salts and leading to a high lithium-ion transference number. Moreover, gamma-Al2O3 can improve the ionic conductivity by reacting with LiF to partly form the lithium-ion conductors of LiAlO2 and Li3AlF6. Benefiting from the synergistic effect of PVDF-HFP and gamma-Al2O3, Li-S cells with this gel polymer electrolyte present improved cycling stability in terms of cathode capacity retention and anode morphology. This work provides a promising strategy for fabricating multifunctional gel electrolytes for high-energy Li-S batteries.

Automated summary

In this study, researchers developed a functional gel polymer electrolyte for lithium-sulfur batteries. The electrolyte consists of a PVDF-HFP polymer matrix and a gamma-Al2O3 three-dimensional skeleton, providing structural and thermal stability. PVDF-HFP facilitates lithium-ion transport, while gamma-Al2O3 suppresses the shuttling of LiPs through strong interactions. Furthermore, gamma-Al2O3 improves ionic conductivity. This research offers a promising strategy for fabricating multifunctional gel electrolytes for high-energy lithium-sulfur batteries.