ENERGY STORAGE DEVICE

Methods for manufacturing an energy storage device. Such methods comprise providing a first stack on a first side of a substrate and a second stack on a second side of the substrate, opposite to the first side of the substrate. In examples, a first and third groove are formed in the first stack, with different depths than each other, and a second and fourth groove are formed in the second stack, with different depths than each other. In other examples, a first groove is formed in the first stack and a second groove is formed in the second stack, in substantial alignment with the first groove but with a different depth than the first groove.