| abstract |
In accordance with an embodiment of the disclosure, an asymmetric supercapacitor includes a first active material with a high hydrogen over-potential and a second active material with a high oxygen over-potential. The first active material is based on a nitride, an oxynitride, a carbide, an oxycarbide, a boride, or an oxyboride of a metal selected from Groups III, IV, V, VI, and VII of the Periodic Table. |