Effect of reference frame and ion-pair lifetime on the transport coefficients of polymer electrolytes
ORAL
Abstract
The transport coefficients of electrolyte solutions are important design parameters for electrochemical energy storage devices. The experimental measurements and simulations thereof help to understand the factors limiting the performance of electrolyte materials. We demonstrate the critical role of reference frame (RF) in reconciling the recent experimental observation of negative transference numbers in the polymer electrolyte PEO-LiTFSI, and establishing the link between experiment and simulation. We show that the quantitative comparison of transport coefficients is only possible upon proper RF transformation, and highlight the impact of anion mass fraction and anion-anion interaction on the reported transference numbers. By tuning the solvent polarity of the polymer electrolyte, we reveal two regimes characterized by different ion-pair lifetime with distinct ion-pair kinetics and ion-ion correlation.
*This work has been supported by the European Research Council (ERC), grant no. 771777 "FUN POLYSTORE" and the Swedish Research Council (VR), grant no. 2019-05012. The authors thanks funding from the Swedish National Strategic e-Science program eSSENCE, STandUP for Energy and BASE (Batteries Sweden). The simulations were performed on the resources provided by the Swedish National Infrastructure for Computing (SNIC) at PDC.
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Publication:H. Gudla, Y. Shao, S. Phunnarungsi, D. Brandell, and C. Zhang, "Importance of the ion-pair lifetime in polymer electrolytes", J. Phys. Chem. Lett. 12, 8460–8464 (2021); Y. Shao, H. Gudla, D. Brandell, and C. Zhang, "Transference number in polymer electrolytes: mind the reference-frame gap", J. Am. Chem. Soc. 144, 7583–7587 (2022).
