A combined first principles and experimental study of super-concentrated aqueous solutions of KOH Jiajia Huang 1 , Yilin Ma 2 , Qing Chen3, Ding Pan 1,2
1 Department of Physics, The Hong Kong University of Science and Technology, P.R. China, 2 Department of Chemistry, The Hong Kong University of Science and Technology, P.R. China, 3 Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, P.R. China. The KOH aqueous solution is an important electrolyte in rechargeable batteries, featuring promising electrochemical properties for large-scale energy storage. The concentration of KOH significantly affects ionic conductivity, redox potential, and working temperature, all of which are critical for optimal battery performance. Here, we present a combined first principles and experimental study of KOH aqueous solutions up to 15 mol/L. Using ab initio molecular dynamics (AIMD) simulations, we found that the solvation structures of OH - and H 2 O at 15 mol/L differ significantly from those at 1 and 6 mol/L, leading to notable changes in ion mobility in the solutions. Additionally, we computed the Raman spectra of KOH solutions using AIMD trajectories and the electronic polarizability calculated on the fly, and we compared them to experimental spectra. We observed that the OH stretching band undergoes significant changes with increasing KOH concentration, attributed to the variation of the solvation structures of OH - and H 2 O. Our study provides a molecular-level understanding of the structural and dynamic properties of super-concentrated alkali hydroxide electrolytes, with valuable implications for rechargeable aqueous battery applications.
P20
© The Author(s), 2023
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