Jin Weihua, Guo Yunpeng, Gan Taorong, Shen Zhengyuan, Zhu Xuebing, Zhang Peng, Zhao Yong
Department of Chemistry, College of Science Northeastern University, Shenyang, 110819, Liaoning, PR China.
Key Lab for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, School of Materials Science and Engineering, Collaborative Innovation Center of Nano Functional Materials and Applications, Henan University, Kaifeng, 475004, PR China.
Angew Chem Int Ed Engl. 2025 Feb 17;64(8):e202420544. doi: 10.1002/anie.202420544. Epub 2025 Jan 9.
Sluggish reaction kinetics of sulfur species fundamentally trigger the incomplete conversion of S↔LiS and restricted lifespan of lithium-sulfur batteries, especially under high sulfur loading and/or low electrolyte/sulfur (E/S) ratios. Developing redox mediators (RMs) is an effective strategy to boost the battery reaction kinetics, yet their multifunctionality and shuttle inhibition are still not available. Here, a unique ethyl viologen (EtV) RM with two highly reversible redox couples (EtV/EtV, EtV/EtV) is demonstrated to well match the redox chemistry of sulfur species, in terms of accelerating the electron transfer in S reduction, LiS nucleation and the LiS oxidation. When coupling with a functionalized separator with electronegative -SOLi groups, a synergetic chemistry is established to ensure the substantial inhibition of the shuttle effect and the acceleration of charge transfer. As a result, the activation energies during sulfur species conversion (S→LiS→LiS/LiS→LiS→S) are decreased, especially for LiS nucleation step. The correspond lithium-sulfur batteries achieve a high specific capacity of 1006.9 mAh g- (0.1 C; sulfur loading of 5 mg cm; E/S ratios of 6 μL mg ), and an outstanding cycling stability. This study provides a paradigm of solving complex problems via multifunctional molecule engineering and strategic cooperation towards Li-S batteries and other battery communities.
硫物种迟缓的反应动力学从根本上导致了S↔LiS的不完全转化以及锂硫电池寿命受限，尤其是在高硫负载和/或低电解液/硫（E/S）比的情况下。开发氧化还原介质（RMs）是加速电池反应动力学的有效策略，但其多功能性和穿梭抑制作用仍未实现。在此，一种具有两个高度可逆氧化还原对（EtV²⁺/EtV⁺、EtV⁺/EtV）的独特乙基紫精（EtV）氧化还原介质被证明在加速S还原、Li₂S成核和Li₂S氧化过程中的电子转移方面，与硫物种的氧化还原化学很好地匹配。当与带有电负性-SOLi基团的功能化隔膜耦合时，建立了一种协同化学作用，以确保有效抑制穿梭效应并加速电荷转移。结果，硫物种转化过程（S→Li₂S→Li₂S/Li₂S₂→Li₂S→S）中的活化能降低，尤其是Li₂S成核步骤。相应的锂硫电池实现了1006.9 mAh g⁻¹的高比容量（0.1 C；硫负载为5 mg cm⁻²；E/S比为6 μL mg⁻¹）以及出色的循环稳定性。本研究为通过多功能分子工程以及针对锂硫电池和其他电池体系的战略合作来解决复杂问题提供了一个范例。
