Porous conjugated polymers offer enormous potential for energy storage because of the combined features of pores and extended π-conjugated structures. However, the drawbacks such as low pore volumes and insolubilities of micro- and mesoporous conjugated polymers restrict the loading of electroactive materials and thus energy storage performance. Herein, we report the synthesis of iron-doped macroporous conjugated polymers for hosting sulfur as the cathode of high-performance lithium–sulfur (Li–S) batteries. The macroporous conjugated polymers are synthesized via in situ growth of poly­(3-hexylthiophene) (P3HT) from reduced graphene oxide (RGO) sheets, followed by gelation of the composite (RGO-g-P3HT) in p-xylene and freeze-drying. The network structures of the macroporous materials can be readily tuned by controlling the chain length of P3HT grafted to RGO sheets. The large pore volumes of the macroporous RGO-g-P3HT materials (ca. 34 cm3 g–1) make them excellent frameworks for hosting sulfur as cathodes of Li–S batteries. Furthermore, incorporation of Fe into the macroporous RGO-g-P3HT cathode results in reduced polarization, enhanced specific capacity (1,288, 1,103, and 907 mA h g–1 at 0.05, 0.1, and 0.2 C, respectively), and improved cycling stability (765 mA h g–1 after 100 cycles at 0.2 C). Density functional theory calculations and in situ characterizations suggest that incorporation of Fe enhances the interactions between lithium polysulfides and the P3HT framework.

Lithium–sulfur (Li–S) batteries have received significant attention due to the high theoretical specific capacity of sulfur (1675 mA h g–1). However, the practical applications are often handicapped by sluggish electrochemical kinetics and the “shuttle effect” of electrochemical intermediate polysulfides. Herein, we propose an in-situ copolymerization strategy for covalently confining a sulfur-containing copolymer onto reduced graphene oxide (RGO) to overcome the aforementioned challenges. The copolymerization was performed by heating elemental sulfur and isopropenylphenyl-functionalized RGO to afford a sulfur-containing copolymer, that is, RGO-g-poly­(S-r-IDBI), which is featured by a high sulfur content and uniform distribution of the poly­(S-r-IDBI) on RGO sheets. The covalent confinement of poly­(S-r-IDBI) onto RGO sheets not only enhances the Li+ diffusion coefficients by nearly 1 order of magnitude, but also improves the mechanical properties of the cathodes and suppresses the shuttle effect of polysulfides. As a result, the RGO-g-poly­(S-r-IDBI) cathode exhibits an enhanced sulfur utilization rate (10% higher than that of an elemental sulfur cathode at 0.1C), an improved rate capacity (688 mA h g–1 for the RGO-g-poly­(S-r-IDBI) cathode vs 400 mA h g–1 for an elemental sulfur cathode at 1C), and a high cycling stability (a capacity decay of 0.021% per cycle, less than one-tenth of that measured for an elemental sulfur cathode).

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Sulfur has received considerable attention as a cathode material for lithium− −sulfur (Li− −S) batteries due to its high theoretical energy density (2567 W h kg −1), high earth abundance, and environmental benignity. However, the insulating nature of sulfur and the shuttle effect of soluble lithium polysulfides result in serious technical issues, such as low utilization rate of sulfur, reduced columbic efficiency, and poor cycling stability, which compromise the high theoretical performance of Li− −S batteries. In the past years, various attempts have been made to achieve high specific capacity and reliable cycling stability of Li− −S batteries. Incorporation of sulfur into functional host materials has been demonstrated to be effective to improve the electrochemical performance of sulfur-based cathodes via enhancing the electron and Li ion conductivities, immobilizing sulfur/lithium polysulfides in cathodes, and accommodating the volume changes in sulfur-based cathodes. Therefore, the rational design of sulfur-containing composites needs to be emphasized as key strategies to develop high-performance cathodes for Li− −S batteries. In this perspective, after reviewing the achievements obtained in the design of sulfur-containing composites as cathodes for Li− −S batteries, we propose the new issues that should be overcome to facilitate the practical application of Li− −S batteries.

Graphene has demonstrated broad applications due to its prominent properties. Its molecular structure makes graphene achiral. Here, we propose a direct way to prepare chiral graphene by transferring chiral structural conformation from chiral conjugated amino acids onto graphene basal plane through π–π interaction followed by thermal fusion. Using atomic resolution transmission electron microscopy, we estimated an areal coverage of the molecular imprints (chiral regions) up to 64 % on the basal plane of graphene (grown by chemical vapor deposition). The high concentration of molecular imprints in their single layer points to a close packing of the deposited amino acid molecules prior to “thermal fusion”. Such “molecular chirality‐encoded graphene” was tested as an electrode in electrochemical enantioselective recognition. The chirality‐encoded graphene might find use for other chirality‐related studies and the encoding procedure might be extended to other two‐dimensional materials.