Given the well-documented problems in the supply chains of many of the materials essential for producing lithium-ion batteries, alternative chemistries are the focus of many research institutes working in energy storage. Potassium has the potential to replace lithium while titanium is among a range of materials being investigated to replace cobalt in cathodes.
Interest in titanium for such a use has been limited by its apparently low potential, limiting battery specific capacity. Scientists at Russia’s Skoltech Center for Energy Science and Technology (CEST) claim to have overcome the concern, however, by achieving a breakthrough in the design of cathode materials for metal-ion batteries based on the element.
Tested in a potassium-ion battery, the material developed by the group – titanium fluoride phosphate (KTiPO4F) – reportedly achieved an electrode potential of 3.6 V, meaning a battery incorporating it could operate at that voltage and displayed no capacity fade after 100 cycles at a charge rate of 5C (five times the current relative to the battery capacity).
“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,” said Skoltech’s Stanislav Fedotov, who led the research. “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.”
The material is described in the paper Titanium-based potassium-ion battery positive electrode with extraordinarily high redox potential, published in Nature Communications. The Skoltech Center said the unexpectedly high performance of the cathode material was probably down to synergies in the cumulative inductive effect of two anions and charge/vacancy ordering.
“From the perspective of inorganic chemistry and solid-state chemistry, this is an excellent example showing once again that rather than blindly following the generally accepted dogmas we should look at things with eyes wide open,” added CEST director Artem Abakumov. “If you choose the right chemical composition, crystal structure and synthesis method, the impossible becomes possible and you can find new materials with unexpected properties and new opportunities for practical applications. This has been brilliantly demonstrated by Professor Fedotov and his team.”
The group said its discovery provided a “playground” for further efforts at designing cost-effective, sustainable materials for future battery designs.