An ethyl bromofluoroacetate redox mediator enables a robust LiF-rich solid electrolyte interphase for advanced lithium-oxygen batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2023-08, Vol.11 (32), p.17257-17262
• Main Authors: Rong, Yuan-Jia, Zhang, Xiao-Ping, Li, Chu-Yue, Wang, Qian-Yan, Wu, Min-Sheng, Chen, Wei-Rong
• Format: Article
• Language: English
• Subjects: Aqueous electrolytes; Argon; Batteries; Charging; Electrochemistry; Electrolytes; Interphase; Lithium; Lithium fluoride; Lithium ions; Nonaqueous electrolytes; Robustness; Solid electrolytes; Stability
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta03451h

The high charging overpotential and poor stability of the lithium anode severely restrict the development of non-aqueous Li-O 2 batteries. Herein, to overcome both intractable challenges, ethyl bromofluoroacetate (EBFA) is introduced into Li-O 2 batteries as an innovative bifunctional redox mediator (RM). Through a particular electrochemical pretreatment method in an argon-filled atmosphere, EBFA reacts on the surface of the lithium anode, leading to the dissociation of Br − and F − from EBFA molecules. The generated Br − acts as the effective component of the RM, considerably reducing the charging overpotential of the Li-O 2 battery. At the same time, a robust LiF-rich solid electrolyte interphase (SEI) is in situ formed on the surface of the lithium anode. The formed SEI film, with high lithium-ion conductivity and outstanding stability, significantly protects the lithium anode from the growth of lithium dendrites. Hence, the addition of EBFA in a TEGDME-based non-aqueous electrolyte solution enables a stable Li-O 2 coin battery operation up to 265 cycles. An ethyl bromofluoroacetate redox mediator has been introduced into lithium-oxygen batteries to achieve high performance in long-term cycling by reducing the charging overpotential and simultaneously forming a LiF-rich SEI film.