|
|||||
|
|
The Origin of Solvent Deprotonation in LiI-added Aprotic Electrolytes for Li-O2 Batteries |
|
| Authors: | Aiping Wang Xiaohong Wu Zheyi Zou Yu Qiao Da Wang Lidan Xing Yuhui Chen Yuxiao Lin Maxim Avdeev Siqi Shi |
| Institution: | 1. State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai, 200444 China
Contribution: Investigation (equal), Writing - original draft (equal);2. State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 China Contribution: Investigation (supporting);3. School of Materials Science and Engineering, Xiangtan University, Xiangtan, 411105 China Contribution: Investigation (supporting);4. State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 China Contribution: Methodology (supporting);5. State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai, 200444 China Contribution: Investigation (supporting);6. China National and Local Joint Engineering Research Center of MPTES in High Energy and Safety LIBs, Engineering Research Center of MTEES (Ministry of Education), Research Center of BMET (Guangdong Province), School of Chemistry, South China Normal University, Guangzhou, 510006 China Contribution: Methodology (supporting), Writing - review & editing (supporting);7. State Key Laboratory of Materials-oriented Chemical Engineering, School of Energy, Nanjing Tech University, Nanjing, 211816 China Contribution: Methodology (supporting);8. School of physics and electronic engineering, Jiangsu Normal University, Xuzhou, 221116 China;9. Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee, DC NSW 2232 Australia School of Chemistry, The University of Sydney, Sydney, 2006 Australia Contribution: Writing - review & editing (supporting);10. State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai, 200444 China |
| Abstract: | LiI and LiBr have been employed as soluble redox mediators (RMs) in electrolytes to address the sluggish oxygen evolution reaction kinetics during charging in aprotic Li-O2 batteries. Compared to LiBr, LiI exhibits a redox potential closer to the theoretical one of discharge products, indicating a higher energy efficiency. However, the reason for the occurrence of solvent deprotonation in LiI-added electrolytes remains unclear. Here, by combining ab initio calculations and experimental validation, we find that it is the nucleophile  that triggers the solvent deprotonation and LiOH formation via nucleophilic attack, rather than the increased solvent acidity or the elongated C−H bond as previously suggested. As a comparison, the formation of  in LiBr-added electrolytes is found to be thermodynamically unfavorable, explaining the absence of LiOH formation. These findings provide important insight into the solvent deprotonation and pave the way for the practical application of LiI RM in aprotic Li-O2 batteries. |
| Keywords: | Ab Initio Calculation Acidity Aprotic Li-O2 Battery Redox Mediator (LiI or LiBr) Solvent Deprotonation |