Upgrading Electrolyte Antioxidant Chemistry by Constructing Potential Scaling Relationship

• Published in: Angewandte Chemie 2024-07, Vol.136 (31), p.n/a
• Main Authors: Li, Ruhong, Wu, Zunchun, Zhang, Shuoqing, Liu, Jia, Fan, Liwu, Deng, Tao, Chen, Lixin, Fan, Xiulin
• Format: Article
• Language: English
• Subjects: antioxidant chemistry; Antioxidants; Cyclohexane; Electrochemistry; Electrode potentials; Electrolytes; fluoroalkanes; Li metal electrolyte; Oxidation; Oxidation resistance; potential scaling relationship; Solvation; solvation structure
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202406122

Rational design of advanced electrolytes to improve the high‐voltage capability has been attracting wide attention as one critical solution to enable next‐generation high‐energy‐density batteries. However, the limited understanding of electrolyte antioxidant chemistry as well as the lack of valid quantization approaches have resulted in knowledge gap, which hinders the formulation of new electrolytes. Herein, we construct a standard curve based on representative solvation structures to quantify the oxidation stability of ether‐based electrolytes, which reveals the linear correlation between the oxidation potential and the atomic charge of the least oxidation‐resistant solvent. Dictated by the regularity between solvation composition and oxidation potential, a (Trifluoromethyl)cyclohexane‐based localized high‐concentration electrolyte dominated by anion‐less solvation structures was designed to optimize the cycling performance of 4.5 V 30 μm‐Li||3.8 mAh cm−2‐LiCoO2 batteries, which maintained 80 % capacity retention even after 440 cycles. The consistency of experimental and computational results validates the proposed principles, offering a fundamental guideline to evaluate and design aggressive electrochemical systems. An external method to quantitatively analyze the oxidation stability of electrolyte systems is proposed. It was shown that “anion‐less” solvated structures are more resistant to oxidation than “anion‐rich” ones owing to the weakening of the anion polarization effect. These findings provide a molecular perspective for electrolyte design in rechargeable high‐energy Li‐metal Batteries.