Microregion Welding Strategy Prevents the Formation of Inactive Sulfur Species for High‐Performance Li–S Battery

• Published in: Advanced energy materials 2021-10, Vol.11 (39), p.n/a
• Main Authors: Qi, Congyu, Li, Zheng, Wang, Gan, Yuan, Huihui, Chen, Chunhua, Jin, Jun, Wen, Zhaoyin
• Format: Article
• Language: English
• Subjects: Contact resistance; Discharge; Electrochemical analysis; Failure mechanisms; inactive sulfur species; Lithium sulfur batteries; Li–S batteries; microregion welding; Substrates; Sulfur; Welding
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202102024

An in‐depth understanding of Li–S battery failure mechanisms is of significance for providing design guidance of promoting this class of batteries’ electrochemical performance. During discharge, deposition of solid sulfur species on substrates is observed, leading to large contact resistance and sluggish redox kinetics. Then, the cumulative effect leads to the formation of isolated inactive sulfur species on low‐dimensional substrates (0D, 1D, and 2D), which has been confirmed to be a performance‐determining factor for Li–S batteries through in situ technologies and revolution of electrochemical performance. In this regard, a microregion welding strategy to resist the formation of inactive sulfur species is proposed, which greatly promotes the electrochemical performance Li–S batteries. The battery shows high discharge capacity of 7.8 mAh cm‐2 and good cycling stability. An Ah‐level pouch cell with lean electrolyte (E/S ≈ 2.5 µL mg–1) and 20% excess lithium (anode/cathode ≈ 1.2) also shows low overpotential and high discharge specific capacity. A novel microregion welding strategy is proposed to construct a 3D sulfur host, and the resulting sulfur battery shows high discharge capacity of 7.8 mAh cm–2 and good cycling stability. An Ah‐level pouch cell with lean electrolyte (E/S ≈ 2.5 µL mg–1) and 20% excess lithium (anode/cathode ≈1.2) also shows low overpotential and high discharge capacity.