High temperature supercapacitator

A supercapacitor device having a housing and at least one supercapacitor cell disposed in the housing, where the supercapacitor cell may include: two working electrode layers separated by an electrode separator wherein each working electrode layer is electrically connected to a current collector supported upon an inert substrate layer; an electrolyte-impervious layer disposed between each working electrode layer and each conducting layer to protect the conducting layer; and an ionic liquid electrolyte disposed within the area occupied by the working electrode layers and the electrode separator, wherein the ionic liquid electrolyte has at least one cationic component comprising a central cation with an asymmetric arrangement of substituents bonded thereto. The ionic liquid electrolyte may be gelled by a silica gellant to inhibit electrolyte flow. The operating range of the supercapacitor device is at least 20-220.degree. C.