Zeng Shuaibo, Li Ligui, Xie Lihong, Zhao Dengke, Wang Nan, Chen Shaowei
Guangzhou Key Laboratory for Surface Chemistry of Energy Materials, New Energy Research Institute, College of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Center, Guangzhou, 510006, P. R. China.
Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, College of Environment and Energy, South China University of Technology, Guangzhou, 510006, P. R. China.
ChemSusChem. 2017 Sep 11;10(17):3378-3386. doi: 10.1002/cssc.201700913. Epub 2017 Aug 21.
Low electrical conductivity and a lack of chemical confinement are two major factors that limit the rate performances and cycling stabilities of cathode materials in lithium-sulfur (Li-S) batteries. Herein, sulfur is copolymerized with poly(m-aminothiophenol) (PMAT) nanoplates through inverse vulcanization to form the highly crosslinked copolymer cp(S-PMAT) in which approximately 80 wt % of the feed sulfur is bonded chemically to the thiol groups of PMAT. A cp(S-PMAT)/C-based cathode exhibits a high discharge capacity of 1240 mAh g at 0.1 C and remarkable rate capacities of 880 mAh g at 1 C and 600 mAh g at 5 C. Moreover, it can retain a capacity of 495 mAh g after 1000 deep discharge-charge cycles at 2 C; this corresponds to a retention of 66.9 % and a decay rate of only 0.040 % per cycle. Such a remarkable rate performance is attributed to the highly conductive pathways of PMAT nanoplates, and the excellent cycling stability is ascribed mainly to the chemical confinement of sulfur through a large number of stable covalent bonds between sulfur and the thiol groups of PMAT. The results suggest that this strategy is a viable paradigm for the design and engineering of conducting polymers with reactive functional groups as effective electrode materials for high-performance Li-S batteries.
低电导率和缺乏化学限域是限制锂硫（Li-S）电池中正极材料倍率性能和循环稳定性的两个主要因素。在此，硫通过反向硫化与聚（间氨基硫酚）（PMAT）纳米片共聚，形成高度交联的共聚物cp(S-PMAT)，其中约80 wt%的原料硫通过化学键合到PMAT的硫醇基团上。基于cp(S-PMAT)/C的正极在0.1 C时表现出1240 mAh g的高放电容量，在1 C时具有880 mAh g的显著倍率容量，在5 C时具有600 mAh g的倍率容量。此外，在2 C下进行1000次深度充放电循环后，它可以保持495 mAh g的容量；这对应于66.9%的保持率，且每循环的衰减率仅为0.040%。如此卓越的倍率性能归因于PMAT纳米片的高导电通路，而优异的循环稳定性主要归因于通过硫与PMAT的硫醇基团之间大量稳定的共价键对硫的化学限域。结果表明，该策略是设计和制备具有反应性功能基团的导电聚合物作为高性能Li-S电池有效电极材料的可行范例。
