Zhang Ting-Ting, Yang Cheng-Ye, Qu Jin, Chang Wei, Liu Yu-Hao, Zhai Xian-Zhi, Liu Hong-Jun, Jiang Zhi-Guo, Yu Zhong-Zhen
State Key Laboratory of Organic-Inorganic Composites, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.
Beijing Key Laboratory of Advanced Functional Polymer Composites, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.
Chemistry. 2022 Jun 1;28(31):e202200363. doi: 10.1002/chem.202200363. Epub 2022 Apr 21.
As competitive next-generation rechargeable batteries, lithium-sulfur batteries (LSBs) suffer from the shuttle effect and the sluggish kinetics of intermediate polysulfides during charge and discharge processes, adversely affecting their electrochemical performances and actual applications. Herein, we demonstrate a polymer encapsulation strategy to synthesize atomic Fe and N co-doped hollow carbon nanospheres (Fe-NHC) with Fe-N sites for modifying commercial PP separator of LSBs to suppress the shuttle effect and promote the kinetics of intermediate polysulfides. Benefiting from the excellent structural design, the doped-N with positive charges could effectively adsorb negatively charged soluble polysulfides, help attract the soluble polysulfides to the Fe atoms and boost the catalytic transformation of the soluble polysulfides. Additionally, such a thin carbon shell could provide a short mass diffusion pathway and hence promote the adsorption and the catalytic conversion. Therefore, the battery with the Fe-NHC/PP separator delivers outstanding cycling and rate performances. At the large current density of 1 C, the specific capacity is 1079 mA h g and maintains a low loss of 0.076 % per cycle within 500 cycles. Even at a harsh current density of 4 C, a high capacity of 824 mA h g is still achieved, indicating the advantage of the Fe-NHC/PP separator in LSBs.
作为具有竞争力的下一代可充电电池，锂硫电池（LSBs）在充放电过程中存在穿梭效应和中间多硫化物动力学迟缓的问题，这对其电化学性能和实际应用产生了不利影响。在此，我们展示了一种聚合物封装策略，用于合成具有铁氮位点的原子级铁和氮共掺杂空心碳纳米球（Fe-NHC），以修饰锂硫电池的商用聚丙烯隔膜，从而抑制穿梭效应并促进中间多硫化物的动力学。得益于出色的结构设计，带正电荷的掺杂氮能够有效吸附带负电荷的可溶性多硫化物，有助于将可溶性多硫化物吸引到铁原子上，并促进可溶性多硫化物的催化转化。此外，如此薄的碳壳可以提供短的质量扩散路径，从而促进吸附和催化转化。因此，采用Fe-NHC/PP隔膜的电池具有出色的循环和倍率性能。在1 C的大电流密度下，比容量为1079 mA h g，在500次循环内每循环的低损失率为0.076 %。即使在4 C的严苛电流密度下，仍能实现824 mA h g的高容量，这表明Fe-NHC/PP隔膜在锂硫电池中的优势。
