Glyoxal-based electrolytes for potassium-ion batteries

In this study we reported for the first time the use of an electrolyte containing 1.5 M KFSI (potassium(bis)-fluorosulfonylimide) dissolved in a mixture of propylene carbonate (PC), tetraethoxy-glyoxal (TEG) and vinyl-ethylene carbonate (VEC) in potassium-ion batteries (KIB). We showed that this electrolyte displays good transport properties, high thermal stability and broad electrochemical stability. Graphite and Prussian White (PW) electrodes used in combination with 1.5 M KFSI in PC/TEG display high capacity, even at high C-rates, and remarkable cycling stability. These electrodes can be successfully combined in a KIB displaying high efficiencies and high stability for more than 500 cycles. Considering these results, glyoxal-based electrolytes can be therefore considered as an attractive new class of electrolyte for KIBs.