Researchers from the Skoltech Center for Energy Science and Technology (CEST) in Russia have developed a new cathode material based on titanium fluoride phosphate which enabled achieving superior energy performance and stable operation at high discharge currents in potassium-ion batteries.

The results of their study are published in an open-access paper in Nature Communications.

The rapid progress in mass-market applications of metal-ion batteries intensifies the development of economically feasible electrode materials based on earth-abundant elements. Here, we report on a record-breaking titanium-based positive electrode material, KTiPO₄F, exhibiting a superior electrode potential of 3.6 V in a potassium-ion cell, which is extraordinarily high for titanium redox transitions.

We hypothesize that such an unexpectedly major boost of the electrode potential benefits from the synergy of the cumulative inductive effect of two anions and charge/vacancy ordering. Carbon-coated electrode materials display no capacity fading when cycled at 5C rate for 100 cycles, which coupled with extremely low energy barriers for potassium-ion migration of 0.2 eV anticipates high-power applications.

Our contribution shows that the titanium redox activity traditionally considered as “reducing” can be upshifted to near-4V electrode potentials thus providing a playground to design sustainable and cost-effective titanium-containing positive electrode materials with promising electrochemical characteristics.

—Fedotov et al.

The rapid development of electric transport and renewable energy sources calls for commercially accessible, safe and inexpensive energy storage solutions based on metal-ion batteries. The high price of the existing lithium-ion technology is a weakness further exacerbated by speculations of supply limitations for lithium and cobalt essential to the production of the cathode.

Skoltech scientists succeeded in creating a commercially attractive advanced cathode material based on titanium fluoride phosphate, KTiPO₄F, exhibiting a high electrochemical potential and unprecedented stability at high charge/discharge rates.

This is an exceptional result that literally destroys the paradigm prevailing in the battery community and claiming 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.

—Professor Stanislav Fedotov

Resources

• Fedotov, S.S., Luchinin, N.D., Aksyonov, D.A. et al. (2020) “Titanium-based potassium-ion battery positive electrode with extraordinarily high redox potential.” Nat Commun 11, 1484 doi: 10.1038/s41467-020-15244-6