ENERGY STORAGE DEVICE COMPRISING A GROOVE WITH CAPACITOR MATERIAL THEREIN

The invention relates to an energy storage device (21) comprising a substrate with a groove (3) having a first and a second face (9a, 9b). A capacitor material (5) in the groove (3), the capacitor material having an upper surface (25). The first and the second face (9a, 9b) of the groove (3) each having a coat of electrically conductive material (7) wherein the coats of electrically conductive materials (7) on the first and second faces (9a, 9b) are electrically separated. And wherein, a non-insulating element (23) is configured to be electrically contactable with the upper surface (25) of the capacitor material and when in electrical contact is electrically separated from the coats of electrically conductive materials (7) on the first and second surfaces by the capacitor material (9a, 9b).