Reversible potassium-ion intercalation into graphite electrodes in glyoxal-based electrolytes

In this work the use of the solvents 1,1,2,2-tetramethoxyethan (tetramethylglyoxal, TMG) and 1,1,2,2-tetraethoxyethan (tetraethylglyoxal, TEG) in potassium-based systems is reported for the first time. We show that utilizing electrolytes based on these solvents, potassium bis(fluorosulfonyl)imide (KFSI) and the additive vinyl ethylene carbonate (VEC), it is possible to reversibly intercalate and extract potassium-ions into and from graphite electrodes. Graphite electrodes in combination with the electrolyte 1.5 M KFSI in TEG/VEC display an intercalation capacity of 200 mAh g-1, stable for 40 cycles at C/10. This performance is comparable to that achieved with conventional organic electrolytes.

Automated summary

This study reports the first use of TMG and TEG solvents in potassium-based systems, demonstrating their effectiveness in intercalating and extracting potassium ions reversibly. The graphite electrodes with 1.5 M KFSI in TEG/VEC electrolyte exhibit stable intercalation capacity of 200 mAh g-1 for 40 cycles at C/10, comparable to conventional organic electrolytes.