Researchers in Russia have developed potassium-based batteries that demonstrate high energy density in fast charge/discharge cycles.
The scientists were looking for a way to avoid dendritic growth by replacing pure alkali metals with their alloys, which become liquid at the battery operating temperature.
Scientists at the Skolkovo Institute of Science and Technology (Skoltech) in Moscow, were joined by colleagues from the Institute for Problems of Chemical Physics of RAS and the Ural Federal University.
The results of the studies have been published in the Journal of Materials Chemistry A, Journal of Physical Chemistry Letters and Chemical Communications.
The scientists used a potassium-sodium alloy (NaK) applied on carbon paper as an anode and the redox-active polymers obtained during earlier studies— one containing hexaazatriphenylene fragments and a dihydrophenazine-based polymer— as cathodes.
The team found the batteries could be charged-discharged in less than 10 seconds.
The batteries based on these two polymers showed nearly 100,000W/kg (593 Wh/kg), reported the team.
“In our study, we used poly-N-phenyl-5,10-dihydrophenazine in the potassium battery cathode for the first time. By thoroughly optimising the electrolyte, we obtained a specific energy of 593Wh/kg, a record-high value for all the currently known K-ion battery cathodes,” said Skoltech PhD student, Philipp Obrezkov.
The scientists were looking at alternatives to lithium-ion, such as sodium and potassium, that have similar chemical properties to lithium because of the predicted issue of depleting lithium reserves in the coming decades.
Skoltech PhD student Roman Kapaev, first author of the paper, said: “Versatility is one of the key advantages of organic materials.
“Their redox mechanisms are much less specific to the nature of the counter-ion, which makes it easier to find an alternative to lithium-ion batteries. With lithium prices going up, it makes sense to replace it with cheaper sodium or potassium that will never run out. As for inorganic materials, things are a lot more complicated.”