Synthesis of a Macroporous Conjugated Polymer Framework: Iron Doping for Highly Stable, Highly Efficient Lithium–Sulfur Batteries

作者：Pan Jia, Tianding Hu, Qingbin He, Xiao Cao, Junpeng Ma, Jingbiao Fan, Quan Chen, Yi‐hong Ding, Jeffrey Pyun, Jianxin Geng · 发表于：ACS Applied Materials & Interfaces · 年份：2018 · DOI：10.1021/acsami.8b19593 · 被引用次数：57 · 研究领域：Advanced Battery Materials and Technologies、Covalent Organic Framework Applications、Advancements in Battery Materials

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 cm 3 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 fr...