Direct Evidence of Reversible Changes in Electrolyte and its Interplay with LiO2 Intermediate in Li‐O2 Batteries

Lithium‐oxygen batteries show promising energy storage potential with high theoretical energy density; however, further investigation of chemical reactions is required. In this study, experimental Raman and theoretical analyzes are performed for a Li‐O2 battery with LiClO4/dimethyl sulfoxide (DMSO)...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-08, Vol.20 (31), p.e2306895-n/a
Main Authors: Sousa, Bianca P., Lourenço, Tuanan C., Anchieta, Chayene G., Nepel, Thayane C. M., Filho, Rubens M., Da Silva, Juarez L. F., Doubek, Gustavo
Format: Article
Language:English
Subjects:
Band theory
Carbon
Cathodes
Cathodic polarization
Chemical reactions
Decomposition reactions
Density functional theory
Dimethyl sulfoxide
Discharge
Electrolytes
Energy storage
Lithium
lithium‐oxygen battery
Molecular dynamics
operando raman
Oxygen
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Summary:Lithium‐oxygen batteries show promising energy storage potential with high theoretical energy density; however, further investigation of chemical reactions is required. In this study, experimental Raman and theoretical analyzes are performed for a Li‐O2 battery with LiClO4/dimethyl sulfoxide (DMSO) electrolyte and carbon cathode to understand the role of intermediate species in the reactional mechanism of the cell using a high donor number solvent. Operando Raman results reveal reversible changes in the DMSO bands, in addition to the formation and decomposition of Li2O2. On discharge, a decrease in DMSO polarizability is observed and bands of DMSO‐Li+‐anion interactions are evidenced and supported by ab initio density functional theory (DFT) calculations. Molecular dynamics (MD) force field simulations and operando Raman show that DMSO interacts with LiO2(sol), highlighting the stability of the electrolyte compared to the interaction with reactive O2−${\rm O}_2^{-}$. On charging, the presence of Li+ indicates the formation of a lithium‐deficient phase, followed by the release of Li+ and oxygen. Therefore, this study contributes to understanding the discharge/charge chemistry of a Li‐O2 cell, employing a common carbon cathode and DMSO electrolyte. The combination of a simple characterization technique in operando mode and theoretical studies provides essential information on the mechanism of Li‐O2 system. Experiments and calculations allowed a detailed explanation of the discharge/charge mechanisms of a Li‐O2 cell using a carbon electrode and high‐DN solvent. It revealed a dynamic reversible change in the DMSO molecule resulting from interaction of LiO2–(solvent)n, thereby confirming the solution mechanism for ORR through an unprecedented analysis of the electrolyte molecule using operando Raman, supported by simulations.
ISSN:1613-6810
1613-6829
1613-6829
DOI:10.1002/smll.202306895