Researchers from the Skoltech Centre for Energy Science and Technology (CEST) in Russia created a new battery cathode material based on titanium fluoride phosphate
The development addresses the high price of lithium ion materials and the supply chain risks of cobalt. Potassium, instead of lithium. As for cobalt, it can be replaced by the more common and environmentally friendly iron, manganese and even titanium. The tenth most common element in the Earth's crust, titanium is mined all over the world and the main titanium-containing reagents are easily available, stable and non-toxic. However the low electrochemical potential limits the battery's specific energy and restricts its use as a battery cathode material.
The researchers used titanium fluoride phosphate, KTiPO4F, which exhibits a high electrochemical potential and high levels of stability at high charge/discharge rates, for the battery cathode.
The potassium-ion cell has an electrode potential of 3.6 V which is high for titanium redox transitions. The researchers believe this comes from cumulative inductive effect of two anions and charge/vacancy ordering. A carbon-coated battery cathode in a cell showed no reduction in capacity cycled at 5C rate for 100 charging cycles. When this is coupled with extremely low energy barriers for potassium-ion migration of 0.2 eV, the electrodes can potentially be used for high power applications such as stationary storage.
"This is an exceptional result that literally destroys the dominant paradigm long-present in the "battery community" stating that titanium-based materials can perform as anodes only, due to titanium's low potential. We believe that the discovery of the "high-voltage" KTiPO4F can give fresh impetus to the search and development of new titanium-containing cathode materials with unique electrochemical properties," said Professor Stanislav Fedotov at Skoltech.