Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
Theoretical Chemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany.
ACS Nano. 2023 Apr 25;17(8):7889-7900. doi: 10.1021/acsnano.3c01523. Epub 2023 Apr 4.
For lithium-sulfur (Li-S) batteries to become competitive, they require high stability and energy density. Organosulfur polymer-based cathodes have recently shown promising performance due to their ability to overcome common limitations of Li-S batteries, such as the insulating nature of sulfur. In this study, we use a multiscale modeling approach to explore the influence of the regiochemistry of a conjugated poly(4-(thiophene-3-yl)benzenethiol) (PTBT) polymer on its aggregation behavior and charge transport. Classical molecular dynamics simulations of the self-assembly of polymer chains with different regioregularity show that a head-to-tail/head-to-tail regularity can form a well-ordered crystalline phase of planar chains allowing for fast charge transport. Our X-ray diffraction measurements, in conjunction with our predicted crystal structure, confirm the presence of crystalline phases in the electropolymerized PTBT polymer. We quantitatively describe the charge transport in the crystalline phase in a band-like regime. Our results give detailed insights into the interplay between microstructural and electrical properties of conjugated polymer cathode materials, highlighting the effect of polymer chain regioregularity on its charge transport properties.
为了使锂硫（Li-S）电池具有竞争力，它们需要具有高稳定性和能量密度。基于有机硫聚合物的正极由于能够克服 Li-S 电池的常见限制，例如硫的绝缘性质，最近显示出了有前景的性能。在这项研究中，我们使用多尺度建模方法来探索共轭聚（4-（噻吩-3-基）苯硫醇）（PTBT）聚合物的区域化学性质对其聚集行为和电荷输运的影响。不同区域规整性的聚合物链自组装的经典分子动力学模拟表明，头对头/头对头规则可以形成平面链的有序结晶相，从而允许快速电荷输运。我们的 X 射线衍射测量结果与我们预测的晶体结构相结合，证实了电聚合 PTBT 聚合物中存在结晶相。我们定量地描述了在带状区域中结晶相中的电荷输运。我们的结果深入了解了共轭聚合物正极材料的微观结构和电学性质之间的相互作用，突出了聚合物链区域规整性对其电荷输运性质的影响。
