Zou Zhijuan, Liu Pengfei, Dou Ruiyang, Liu Kaijun, Wang Yunlong, Song Lixian, Tong Liping, Yin Guolu, Kang Wenbin, Cai Wenlong, Zhang Yaping, Chen Hongbing, Song Yingze
State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang, 621010, China.
Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, 621900, China.
Nat Commun. 2025 Jul 22;16(1):6729. doi: 10.1038/s41467-025-61942-4.
Binders are essential for maintaining positive electrode integrity in Li||S batteries and significantly affect their performance. However, commercial linear binders often have disordered networks, poor binding efficiency, and insufficient mechanical strength. To address these challenges, three-dimensional covalent binders offer a promising solution. Traditional methods for producing cross-linked binders require additives and result in poorly controlled polymer networks due to the stochastic nature of liquid-phase polymerization. Moreover, the mechanisms by which reticulated binders stabilize the positive electrode remain unclear, requiring investigation under operando conditions. Herein, we present an approach to tailor cross-linked polyacrylamide networks using solid-state operando γ-ray irradiation chemistry, which eliminates additives and produces a pure, ordered network with remarkable binding capabilities. By integrating in situ high-resolution optical frequency domain reflectometry, multiscale synchrotron radiation characterization, and virtual simulations, this study reveals the role of binders in dynamically encaging and confining sulfur. Specifically, γ-ray-enabled polyacrylamide networks enhance battery performance through mechanical strengthening, optimized sulfur regeneration, and improved re-occupancy. Consequently, the well-designed composite positive electrode structure with only 5.0 wt% binder improves soft-packaged Li||S battery performance across various scenarios. Notably, a 1.2-Ah pouch cell achieves 410.1 Wh kg specific energy with a low electrolyte/sulfur ratio of 3.0 µL mg.
粘结剂对于维持锂硫电池正极的完整性至关重要，并显著影响其性能。然而，商业线性粘结剂往往具有无序的网络结构、较差的粘结效率和不足的机械强度。为应对这些挑战，三维共价粘结剂提供了一个有前景的解决方案。传统的生产交联粘结剂的方法需要添加剂，并且由于液相聚合的随机性，导致聚合物网络控制不佳。此外，网状粘结剂稳定正极的机制仍不清楚，需要在原位条件下进行研究。在此，我们提出一种利用固态原位γ射线辐照化学来定制交联聚丙烯酰胺网络的方法，该方法无需添加剂，并能产生具有卓越粘结能力的纯净、有序网络。通过结合原位高分辨率光频域反射测量、多尺度同步辐射表征和虚拟模拟，本研究揭示了粘结剂在动态包裹和限制硫方面的作用。具体而言，γ射线引发的聚丙烯酰胺网络通过机械强化、优化硫再生和改善再占据来提高电池性能。因此，仅含5.0 wt%粘结剂的精心设计的复合正极结构在各种情况下都能提升软包锂硫电池的性能。值得注意的是，一个1.2 Ah的软包电池在低电解液/硫比为3.0 μL mg的情况下实现了410.1 Wh kg的比能量。
