Zhang Zhengmin, Mo Jiangyang, Yu Peng, Feng Lanxiang, Wang Yu, Lu Yuyuan, Yang Wei
College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan, 610065, China.
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China.
Adv Sci (Weinh). 2022 Sep;9(26):e2201881. doi: 10.1002/advs.202201881. Epub 2022 Jul 19.
The electrochemical performance of lithium-sulfur batteries is fundamentally determined by the structural and mechanical stability of their composite sulfur cathodes. However, the development of cost-effective strategies for realizing robust hierarchical composite electrode structures remains highly challenging due to uncontrollable interactions among the components. The present work addresses this issue by proposing a type of self-assembling electrode slurry based on a well-designed two-component (polyacrylonitrile and polyvinylpyrrolidone) polar binder system with carbon nanotubes that forms hierarchical porous structures via optimized water-vapor-induced phase separation. The electrode skeleton is a highly robust and flexible electron-conductive network, and the porous structure provides hierarchical ion-transport channels with strong polysulfide trapping capability. Composite sulfur cathodes prepared with a sulfur loading of 4.53 mg cm realize a very stable specific capacity of 485 mAh g at a current density of 3.74 mA cm after 1000 cycles. Meanwhile, a composite sulfur cathode with a high sulfur loading of 14.5 mg cm in a lithium-sulfur pouch cell provides good flexibility and delivers a high capacity of 600 mAh g at a current density of 0.72 mA cm for 78 cycles.
锂硫电池的电化学性能从根本上取决于其复合硫阴极的结构和机械稳定性。然而，由于各组分之间不可控的相互作用，开发具有成本效益的策略以实现坚固的分级复合电极结构仍然极具挑战性。本工作通过提出一种基于精心设计的两组分（聚丙烯腈和聚乙烯吡咯烷酮）极性粘合剂体系与碳纳米管的自组装电极浆料来解决这一问题，该体系通过优化的水蒸气诱导相分离形成分级多孔结构。电极骨架是一个高度坚固且灵活的电子导电网络，多孔结构提供了具有强大多硫化物捕获能力的分级离子传输通道。硫负载量为4.53 mg cm²的复合硫阴极在1000次循环后，在电流密度为3.74 mA cm²时实现了非常稳定的比容量485 mAh g。同时，锂硫软包电池中硫负载量为14.5 mg cm²的复合硫阴极具有良好的柔韧性，在电流密度为0.72 mA cm²时可实现78次循环的600 mAh g高容量。
