Authors: Yong Jiang, Yalan Liao, Jiaqi Yu, Xue Li, Tianyu Jin, Yi Xu, Wenrong Li, Shoushuang Huang, Shuixin Xia, Bing Zhao, Xueliang Sun, Jiujun Zhang
Published: 2025-03-12
Source: Full article
AbstractLithium‐sulfur (Li‐S) batteries are considered the most promising alternative for energy storage, however, their practical applications are still limited by lithium dendrites growth, slow lithium polysulfides (LiPSs) conversion kinetics, shuttle effect, and deposition of “dead sulfur” at Li anode surface. Herein, a novel ionic liquid tetrabutylammonium triiodide (TBAI3) is adopted as a multi‐effect electrolyte additive to solve low coulombic efficiency and short life issues of Li‐S batteries. A series of in situ characterization technologies, theoretical calculations, potentiostatic Li2S deposition experiments, and different kinds of symmetric and asymmetric cells are conducted to reveal the multifunctional electrochemical work mechanism. It is found that the TBA+ cations can coordinate with solvent molecules, reduce desolvation barrier, and accelerate Li+ transport kinetics; they can also form a dynamic electrostatic shielding layer at the lithium protrusions and induce uniform lithium deposition. The I3−/I− redox pairs continuously eliminate “dead sulfur” by transforming Li2S deposits into soluble LiPSs and release active substances during cycling, while the reduzate I− can be electrochemically rejuvenated into I3− when charged to 2.89 V. Therefore, Li‐S batteries with TBAI3 additives exhibit a ultra‐long cycle performance of 503 mAh g−1 at 2 C after 1000 cycles with an average coulombic efficiency of 99.99%.