These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
2 files

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

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.


John Fell Fund

Sir Henry Royce Institute - Oxford Equipment

Engineering and Physical Sciences Research Council

Find out more...

Italian Ministry of University and Research (MIUR)


Email Address of Submitting Author


University of Oxford


United Kingdom

ORCID For Submitting Author


Declaration of Conflict of Interest



Logo branding