A method of fabricating an energy storage device (1) comprising forming a stack comprising at least a first electrode layer (6), a first current collecting layer (12) and an electrolyte layer 8 disposed between the first electrode layer (6) and the first current collecting layer (12). Forming a first groove (24) in the stack through the first electrode layer (6) and the electrolyte layer (8), thereby forming exposed edges of the first electrode layer 6 and the electrolyte layer (8). Filling at least part of the first groove (24) with an electrically insulating material thereby covering the exposed edges of the first electrode layer (6) and the electrolyte layer (8) with the insulating material. Cutting through the insulating material and the first current collecting layer (12) along at least part of the first groove (24) in order to form an exposed edge of the first current collecting layer (12).