| Summary: | Room temperature sodium-sulfur (Na-S) batteries are promising devices for energy storage system, but for practical applications volume expansion and detrimental shuttle effect of the sulfur cathode should be solved. Herein, we introduced a novel sulfur cathode system of using polydopamine (PDA) as an interlayer in between sulfurized polyacrylonitrile (SPAN) active material and pullulan-graft-sodium polyacrylic acid (PuA) binder. Active NH and OH functional groups of PDA interlayer serve as facile hydrogen bonding (H bonding) and/or chemical reaction sites to various functional groups of SPAN and PuA, thus forming an intimately packed SPAN/PDA/PuA composite with sufficient mechanical and interfacial adhesive strengths to survive from the dimensional variation of sulfur cathode during charge/discharge cycling. Moreover, various functional groups of the SPAN/PDA/PuA are capable of absorbing polysulfides to limit the shuttle effect. Sulfur cathode derived from SPAN/PDA/PuA exhibited a high specific capacity of 1340 mAh g−1 after 100 cycles at 0.2 C. Without the PDA interlayer, sulfur cathode derived from SPAN/PuA exhibits a much lower capacity of 790 mAh g−1. The role of PDA in promoting the stability and electrochemical performance of sulfur cathode is thus verified in this study.
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