The quinone-based conjugated microporous polymer as an effective electrode additive for activated graphene host material in lithium-sulfur batteries

Lithium-Sulfur (Li-S) battery is receiving increasing attention for next-generation energy storage system due to its promising features such as high theoretical energy density and cost-effectiveness. However, sluggish redox re-action and fatal polysulfide dissolution have been considered as significant challenges which limit the practical application of Li-S batteries. Recently, anthraquinone-based organic molecule was used in the Li-S battery and exhibited good electrochemical performance with enhanced redox chemistry and structural stability. Herein, we used anthraquinone-based conjugated microporous polymer (CMP), namely PAQTA, as an electrode additive for activated graphene (AG) host material in Li-S batteries. Conjugated network of PAQTA with high surface area and porosity provided efficient redox activity and stable electrochemical performance compared to non -conjugated quinone material. We prepared reduced AG/sulfur (rAG/S) electrodes by varying amounts of PAQTA addition and the optimized rAG1h/S + PAQTA 5% showed the best electrochemical performance, proving a synergistic effect between rAG and PAQTA additive. In detail, rAG act as effective host material by taking advantage of in-plane nanopores and high surface area, resulting in enhanced polysulfide adsorption. The PAQTA additive, which improves redox kinetic, could further make intimate contact with rAG via 7C-7C stacking interaction, thereby enhancing the cycling stability. Thus, it is important to note that the synergistic effect be-tween AG host and PAQTA additive enabled improved redox chemistry and structural stability for good elec-trochemical performance. This study suggests the usage of PAQTA as effective electrode additive for high-performance Li-S batteries with improved long-term cycling stability.