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Paving the Way Toward Highly Efficient High-Energy Potassium-Ion Batteries with Ionic-Liquid Electrolytes

preprint
submitted on 16.03.2020, 16:26 and posted on 17.03.2020, 10:43 by Michele Fiore, Kevin Hurlbutt, Samuel Wheeler, Isaac Capone, Jack Fawdon, Riccardo Ruffo, Mauro Pasta

Potassium-ion batteries (KIB) are a promising complementary technology to lithium-ion batteries because of the comparative abundance and affordability of potassium. Currently, the most promising KIB chemistry consists of a potassium manganese hexacyanoferrate (KMF) cathode, a Prussian blue analog, and a graphite anode (723Whl−1 and 359Whkg−1 at 3.6V). No electrolyte has yet been formulated that is concurrently stable at the high operating potential of KMF (4.02V vs K+/K) and compatible with K+ intercalation into graphite, currently the most critical hurdle to adoption. Here we combine a KMF cathode and a graphite anode with a KFSI in Pyr1,3FSI ionic liquid electrolyte for the first time and show unprecedented performance. We use high-throughput techniques to optimize the KMF morphology for operation in this electrolyte system, achieving 119 mA h g−1 at 4 V vs K+/K and a coulombic efficiency >99.3%. In the same ionic liquid electrolyte graphite shows excellent electrochemical performance and we demonstrate reversible cycling by operando XRD. These results are a significant and essential step forward towards viable potassium-ion batteries.

Funding

John Fell Fund

Sir Henry Royce Institute - Oxford Equipment

Engineering and Physical Sciences Research Council

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Italian Ministry of University and Research (MIUR)

History

Email Address of Submitting Author

mauro.pasta@materials.ox.ac.uk

Institution

University of Oxford

Country

United Kingdom

ORCID For Submitting Author

0000-0002-2613-4555

Declaration of Conflict of Interest

N/A

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