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DOE OSTI · 2589767

Automation-Accelerated Electrolyte Design Mitigates Solubility Competition between Redox-Active Molecules and Supporting Salts

Noh, Juran [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)]·Job, Heather Marie [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)]·Doan, Hieu A. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000314609004)·Han, Kee Sung [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000235351818)·Robertson, Lily A. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000287840568)·Zhang, Lu [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000303670862)·Assary, Rajeev Surendran [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000295713307)·Mueller, Karl T. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000196099516)·Murugesan, Vijayakumar [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000161491702)·Liang, Yangang [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000167123695)
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Abstract

In nonaqueous redox-flow batteries (NRFBs), redox-active organic molecules (ROMs) and supporting salts compete for solvation sites, limiting achievable energy density. We combine automated high-throughput experimentation (HTE) with camera-based saturation monitoring and quantitative NMR to measure paired (ROM, salt) solubilities across single and mixed organic solvents. Using 2,1,3-benzothiadiazole (BTZ) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as a model system, we find that a binary m-xylene/acetonitrile mixture dissolves ≈3 M of both BTZ and LiTFSI─surpassing the previously reported 2 M ceiling for neat acetonitrile─by leveraging complementary solvation (MX is BTZ-philic and salt-phobic; ACN stabilizes LiTFSI). A random-forest model (RMSE ≈ 0.24) trained on solvent descriptors highlights log P and salt concentration as dominant predictors and predicts MX/ACN ≈0.3/0.7 (v/v) to be near-optimal. These formulations retain practical viscosity and ∼5 mS·cm –1 conductivity at high loading. In conclusion, the workflow provides a reproducible, data-centric route to NRFB electrolyte design and motivates an open, standardized dual-solute solubility resource for accelerated electrolyte discovery.

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ElectrolytesSaltsSolubilitySolventsViscosityautonomous experimentationdual-solute solubilityelectrolyte formulationhigh-throughput experimentationmachine learningredox flow battery

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Noh, Juran [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)], Job, Heather Marie [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)], Doan, Hieu A. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000314609004), Han, Kee Sung [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000235351818), Robertson, Lily A. [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000287840568), Zhang, Lu [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000303670862), Assary, Rajeev Surendran [Argonne National Laboratory (ANL), Argonne, IL (United States)] (ORCID:0000000295713307), Mueller, Karl T. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000196099516), Murugesan, Vijayakumar [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000161491702), Liang, Yangang [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)] (ORCID:0000000167123695). 2025-09-02. Automation-Accelerated Electrolyte Design Mitigates Solubility Competition between Redox-Active Molecules and Supporting Salts. https://doi.org/10.1021/acsaem.5c02546

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