We introduce a bipolar assembly of ion-exchange membranes as the separator for aqueous supercapacitors, which enables positive and negative electrode to operate in acidic and alkaline electrolyte, separately, thus increasing device-operating voltage. The assembled supercapacitors have better safety than those made with non-aqueous electrolyte; they also have higher energy density than those made with conventional aqueous-electrolyte based devices.
Features & Benefits
Background of Invention
Supercapacitors are indispensable in power cranking for transportation, energy recovery in heavy-duty systems and potentially laser generation. Most commercial supercapacitors employ non-aqueous electrolyte rather than aqueous electrolyte despite the facts that aqueous electrolytes are typically more conductive, safer and cheaper. The overwhelming advantage of non-aqueous electrolyte is its much wider stable electrochemical potential window than its aqueous counterpart, where the latter is limited to 1.23 V. Although the electrode capacitance in aqueous supercapacitors is often higher than that in non-aqueous supercapacitors, the overall energy density of aqueous supercapacitors still falls far below that of the non-aqueous ones. In order to cultivate the advantages of aqueous supercapacitors, it is highly desirable to increase its operating voltage without decomposing its electrolyte.
Patent pending and available for exclusive licensing