Cathode boost for potassium-ion battery
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European researchers say they have made a breakthrough that could help deliver a new generation of potassium-ion batteries
The international team of researchers led by chemists from the University of Glasgow in Scotland and battery testing experts at Helmholtz Institute Ulm in Germany have used a material made from chromium and selenium in a potassium-ion battery.
This brings low cost, fast charging potassium-ion battery cells a step closer to becoming a viable alternative to lithium-ion cells for energy storage systems (ESS).
- First potassium battery in 18650 format
- Non-flammable electrolyte for potassium battery cells
- Titanium cathode for potassium battery
Some of the best-performing current designs for potassium-ion batteries use cathodes made from Prussian White, which is also used for sodium ion battery cells. However Prussian White needs to be mixed with carbon to boost its conductivity to deliver the best results. Group1 in the US showed a potassium-ion battery cell based on Prussian White in a 18650 cylindrical format earlier this year.
Instead the conductive chromium selenide cathode achieves high performance with a less than 10 % carbon. The prototype has a capacity of 125 milliamp-hours per gram, very close to its maximum theoretical capacity of 127 milliamp-hours per gram.
A layered structure allows the potassium ions to travel more easily between the layers during charge and discharge. This allows the battery to maintain 85% of its capacity in lab conditions even when charged and discharged at high speed.
“Lithium-ion batteries have become widely adopted in devices from smartphones to electric cars in recent years, and are capable of excellent performance, but lithium is a relatively rare, and therefore strategically important, element,” said researcher Dr Alexey Ganin, of the University of Glasgow’s School of Chemistry and the Head of the Glasgow ElectroChemistry on Solids (GECOS) group.
“Potassium is a much more abundant material, and potassium-ion batteries have a lot of potential as an alternative method of storing and delivering large amounts electricity. Adopting potassium-ion batteries for stationary storage purposes could help free up lithium resources for use in more energy-intensive mobile applications in the future,” he said.
“These are promising results, but we believe the performance of the battery could be boosted further with the right electrolyte. Designer lithium-ion battery electrolytes can be bought off the shelf, but further work is required to refine the performance of electrolytes for potassium-ion batteries. We’re keen to partner with robotics experts who can help us test the thousands of potential chemical combinations to find the best possible candidate for use in our battery,” said Ganin.
The next step for the team is further research to identify an electrolyte which will help deliver improved performance in future refinements of the potassium-ion battery design.
Researchers from Ulm University, the Karlsruhe Institute of Technology, the University of Kent, the Catalan Institute of Nanoscience and Nanotechnology, and ICREA also contributed to the paper.
Reversible K-Ion Intercalation in CrSe2 Cathodes for Potassium-Ion Batteries: Combined Operando PXRD and DFT studies is published in Journal of Materials Chemistry A.
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