A bifunctional thiobenzamide additive for improvement of cathode kinetics and anode stability in lithium-sulfur batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-10, Vol.498, p.155807, Article 155807
• Main Authors: Rao, Junpeng, Yu, Tong, Zhou, Youshuang, Xiao, Ru, Wang, Yaozu, Qu, Zhuoyan, Shi, Dean, Sun, Zhenhua, Li, Feng
• Format: Article
• Language: English
• Subjects: Anode stability; Electrolyte additive; Lithium-sulfur batteries; Sulfur kinetics; Thiobenzamide additive
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.155807

[Display omitted] •A bifunctional electrolyte additive is proposed to enhance the performance of Li-S cells.•This additive boosts the sulfur cathode kinetics by converting polysulfides to highly reactive T-Sn-T.•This additive strengthens the lithium anode by forming LiF/Li3 N-rich solid electrolyte interphase. Lithium-sulfur batteries (LSBs) are considered as the key candidates for the next generation of energy storage devices. However, the practical applications of LSBs are hindered by the slow conversion of sulfur species and the inhomogeneous Li+ precipitation /stripping of lithium anode. Here, we report a bifunctional thiobenzamide electrolyte additive, 4-(trifluoromethyl) thiobenzamide (TFBCA), which synergistically improves cathode redox kinetics and anode stability. Polysulfides (LiPSn) are in-situ transferred to more reactive polysulfide intermediates (T-Sn-T), which significantly improve the liquid–solid reduction process by promoting the deposition dimension of Li2S. A LiF/Li3N-rich solid electrolyte interphase is formed with TFBCA, the uniform lithium deposition is achieved and the growth of lithium dendrites is suppressed. Correspondingly, LSBs with TFBCA show a high capacity (888 mAh·g−1 at 5C) and cycling stability (0.055 % per cycle after 600 cycles at 2C). Even under high sulfur loading (7.1 mg·cm−2) and low E/S ratio of 7, the LSBs also exhibit an areal capacity of 7 mAh·cm−2 after 50 cycles, and an energy density of 314 Wh·kg−1 is achieved for the pouch cell. This work demonstrates an efficient additive strategy through molecular structure design to construct high-performance LSBs.