Abstract
Enhancing the solar energy storage and power delivery afforded by emerging molten salt-based technologies requires a fundamental understanding of the complex interplay between structure and dynamics of the ions in the high-temperature media. Here we report results from a comprehensive study integrating synchrotron X-ray scattering experiments,ab initiomolecular dynamics simulations and rate theory concepts to investigate the behavior of dilute Cr3+metal ions in a molten KCl-MgCl2salt. Our analysis of experimental results assisted by a hybrid transition state-Marcus theory model reveals unexpected clustering of chromium species leading to the formation of persistent octahedral Cr-Cr dimers in the high-temperature low Cr3+concentration melt. Furthermore, our integrated approach shows that dynamical processes in the molten salt system are primarily governed by the charge density of the constituent ions, with Cr3+exhibiting the slowest short-time dynamics. These findings challenge several assumptions regarding specific ionic interactions and transport in molten salts, where aggregation of dilute species is not statistically expected, particularly at high temperature.
| Original language | English |
|---|---|
| Pages (from-to) | 8026-8035 |
| Number of pages | 10 |
| Journal | Chemical Science |
| Volume | 12 |
| Issue number | 23 |
| DOIs | |
| State | Published - Jun 21 2021 |
Funding
This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center, funded by the U.S. Department of Energy Office of Science. MSEE work at Iowa was supported via subcontract from Brookhaven National Laboratory (BNL). BNL and ORNL operate under DOE contracts DE-SC0012704 and DE-AC05-00OR22725, respectively. The project used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC05-00OR22725. The 28-ID-1 beamline of the National Synchrotron Light Source II was used, which is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. S. S., W. V. K., F. W. and C. J. M. acknowledge the computational resources at the University of Iowa high performance computing facility. The authors thank Dr James F. Wishart (BNL) for critically reading the manuscript and offering helpful suggestions. This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center, funded by the U.S. Department of Energy Office of Science. MSEE work at Iowa was supportedviasubcontract from Brookhaven National Laboratory (BNL). BNL and ORNL operate under DOE contracts DE-SC0012704 and DE-AC05-00OR22725, respectively. The project used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC05-00OR22725. The 28-ID-1 beamline of the National Synchrotron Light Source II was used, which is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. S. S., W. V. K., F. W. and C. J. M. acknowledge the computational resources at the University of Iowa high performance computing facility. The authors thank Dr James F. Wishart (BNL) for critically reading the manuscript and offering helpful suggestions. This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan .
