Supercapacitor and a method for expanding the voltage range of an aqueous electrolyte suprcapacitor

A supercapacitor comprising an electrolyte, said electrolyte comprising a mixture of water, one or more non-aqueous solvent and a salt forming a mixture of an aqueous solution and a non-aqueous solution;

• wherein
• said non-aqueous solution has a larger electrochemical stability window than said aqueous solution;
• said salt has a solubility above 0.1M in water and/or in said one or more non-aqueous solvent between −25 and 100° C.;
• said mixture has a buffer capacity □ lower than 10−5;
• hydron (H+) and hydroxide ion (OH−) solubility is lower in said non-aqueous solution than in said aqueous solution;
• wherein the ratio vol/vol between said aqueous solution and said non-aqueous solution is in the range between 100:1 and 1:1;
• said supercapacitor further comprising two electrodes and wherein said electrolyte is located between said two electrodes, wherein said two electrodes have a higher affinity towards said non-aqueous solution than towards said aqueous solution.