K-ion batteries: role of K metal in half-cells and assembly of reliable full-cells

K-ion batteries could be a possible alternative to Li-ion systems for renewable/intermittent energies storage if abundant and low cost materials are considered. Their development remains, however, limited by the highly reactive K metal that partially governs half-cells electrochemical performance. It is thus of high interest to assemble full-cells instead but to achieve this from half-cells results remains challenging. This presentation will first illustrate the parameters governed by K metal in half-cells: polarization and delivered capacities as well as cross contamination of SEI from the K metal to the working electrode. Second, an overview will be presented about the reactivity of K metal in conventional KPF6 (or KFSI) EC:DEC electrolytes, as obtained by combined analysis of gaseous and solid products using gas chromatography/Fourier transform infrared spectroscopy/mass spectrometry and X-ray photoelectron spectroscopy, respectively. Third, in order to assemble highly reliable K-ion full-cells, the impact of different parameters such as the electrolyte amount, anode/cathode diameter and capacity ratios will be discussed in the case of KVPO4F0.5O0.5//graphite cells. Overall, the various aspects covered by this presentation should benefit to the assembly of more reliable KIBs half- and full-cells.

13th France-Japan Symposium on Lithium Batteries and Next Generations, 2022