| abstract |
The present invention relates to an electrical energy storage device, such as an electrochemical capacitor or a secondary battery, that utilizes an oxidation and reduction cycle of a sterically hindered imidazolidinone nitroxide radical as an active element. Further aspects of the present invention are methods for providing such energy storage devices, the use of each compound as an active element in the energy storage device, and selected novel imidazolidinone nitroxide compounds. |