ELECTROLYTE SOLUTION FOR POTASSIUM ION BATTERIES, POTASSIUM ION BATTERY, ELECTROLYTE SOLUTION FOR POTASSIUM ION CAPACITORS, AND POTASSIUM ION CAPACITOR

摘要

Provided are: an electrolyte solution for potassium ion batteries or capacitors, which enables the achievement of a potassium ion battery or capacitor having excellent passive state formability; and a potassium ion battery or capacitor, which is provided with this electrolyte solution. An electrolyte solution for potassium ion batteries or capacitors, which contains at least one potassium salt compound selected from the group consisting of potassium bis(trifluoromethanesulfonyl)amide and potassium bis(fluorosulfonyl)amide and at least one solvent selected from the group consisting of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, ethylene carbonate and propylene carbonate, and wherein the concentration of the potassium salt compound is from 1.5 mol/kg to 12.0 mol/kg (inclusive).