Development of a Flexible, Cost-Effective, and Scalable High-Performance Lithium-Sulfur Battery

Flexible smart devices are increasingly used in applications, such as wearable electronics, flexible displays, medical devices, and human-machine interactions. 1 These applications demand advanced solutions for mechanically flexible, foldable and stretchable batteries. 2 Next-generation Li-S batteries address these demands by offering high specific energy (∼2,600 Wh/kg), and high theoretical specific capacity (1675 mAh/g). The added sustainable benefits of sulfur cathode are abundance in nature and non-toxicity to environment which are critical for the development of eco-friendly flexible battery technologies. 3 For flexible sulfur cathodes, carbon-based nanomaterials have gained popularity due to their mechanical strength, high surface area, and structure-enabled high conductivity. Various R&D efforts have been reported on carbon nanostructure-based cathodes for flexible Li-S batteries, such as carbonized textile, 4 carbon nanotube‐based cables, 5 mesoporous carbon nanofibers, 6 and carbon yolk-shell nanosheets. 7 However, these efforts involve complex synthesis processes which lead to high cost and low scalability for commercializing flexible Li-S batteries. In this study, we developed a novel approach to prepare freestanding, 3D carbon composite sulfur cathodes using commercially available carbon nanostructure (CNS) materials. One of the challenges of this sulfur cathode architecture (CNS-S) is rapid battery capacity fading over cycling. To overcome this challenge, we introduced a novel electrolyte system aiming to extend the cycle life of the Li-S batteries. This combination strategy yielded a highly flexible sulfur cathode ( Fig. 1a ), a high specific discharge capacity of ~1,300 mAh/g ( Fig. 1b ), and a robust long-term cycle stability at a high current rate of 1C with ~80% capacity retention over 300 cycles ( Fig. 1c ). We will discuss analytical and electrochemical characterizations, such as in-situ Raman spectroscopy and electrochemical impedance spectroscopy, to elucidate the performance mechanism of our flexible high-performance Li-S batteries. Acknowledgment This work was supported by the Linda and Larry Pearson Endowed Chair at the Leslie A. Rose Department of Mechanical Engineering, South Dakota School of Mines & Technology, SDBOR Competitive Research Grant Program, and NASA EPSCoR under Grant No. 80NSSC21M0326 and 80NSSC23M0072. References (1) Zhang, Q.; Gao, X. W.; Liu, X.; Mu, J. J.; Gu, Q. F.; Liu, Z. M.; Luo, W. B. Flexible wearable energy storage devices: Materials, structures, and applications. Battery Energy 2024 , 3 (2). DOI: 10.1002/bte2.20230061. (2) Park, J. W.; Jo, S. C.; Kim, M. J.; Choi, I. H.; Kim, B. G.; Lee, Y. J.; Choi, H. Y.; Kang, S.; Kim, T.; Baeg, K. J. Flexible high-energy-density lithium-sulfur batteries using nanocarbon-embedded fibrous sulfur cathodes and membrane separators. Npg Asia Mater 2021 , 13 (1). DOI: ARTN 30 10.1038/s41427-021-00295-y. (3) Chang, J.; Shang, J.; Sun, Y.; Ono, L. K.; Wang, D.; Ma, Z.; Huang, Q.; Chen, D.; Liu, G.; Cui, Y.; et al. Flexible and stable high-energy lithium-sulfur full batteries with only 100% oversized lithium. Nat Commun 2018 , 9 (1), 4480. DOI: 10.1038/s41467-018-06879-7 From NLM PubMed-not-MEDLINE. (4) Gao, P.; Xu, S.; Chen, Z.; Huang, X.; Bao, Z.; Lao, C.; Wu, G.; Mei, Y. Flexible and Hierarchically Structured Sulfur Composite Cathode Based on the Carbonized Textile for High-Performance Li-S Batteries. ACS Appl Mater Interfaces 2018 , 10 (4), 3938-3947. DOI: 10.1021/acsami.7b16174 From NLM PubMed-not-MEDLINE. (5) Chong Woon Gie; Huang Jian Qiu; Xu Zhenglong; Xianying., Q.; Wang Xiangyu; Kyo, K. J. Lithium–Sulfur Battery Cable Made from Ultralight, Flexible Graphene/Carbon Nanotube/Sulfur Composite Fibers. Advanced Functional Materials 27 (4). DOI: https://doi.org/10.1002/adfm.201604815. (6) He, G.; Mandlmeier, B.; Schuster, J.; Nazar, L. F.; Bein, T. Bimodal Mesoporous Carbon Nanofibers with High Porosity: Freestanding and Embedded in Membranes for Lithium-Sulfur Batteries. Chemistry of Materials 2014 , 26 (13), 3879-3886. DOI: 10.1021/cm403740r. (7) Pei Fei; Lin Lele; Ou Daohui; Zheng Zongmin; Mo Shiguang; Fang Xiaoliang; Nanfeng, Z. Self-supporting sulfur cathodes enabled by two dimensional carbon yolk-shell nanosheets for high energy-density lithium-sulfur battery. Nature Communications 2017 , 8 , 482. DOI: DOI: 10.1038/s41467-017-00575-8. Figure 1