NOVELTY - The method involves forming a crystalline silicon layer including a group of whiskers over a current collector (101) i.e. island-shaped titanium film, by a low pressure chemical vapor deposition process using nitrogen and gas containing silicon, where flow rate of the gas containing silicon is greater than or equal to 100 standard cubic centimeters per minute (sccm) and less than or equal to 3000 sccm. A positive electrode is provided opposite to the crystalline silicon layer, where a separator is provided between the crystalline silicon layer and the positive electrode.    USE - Method for manufacturing a stack-type sealed thin energy storage device e.g. button shaped energy storage device, cylindrical shaped energy storage device and rectangular shaped energy storage device such as secondary battery e.g. lithium ion battery, and capacitor e.g. double-layer capacitor and lithium ion capacitor, that is utilized in an electronic device e.g. portable information terminal such as electronic dictionary, and in an electric propulsion vehicle i.e. electric wheelchair. Can also be used in a camera such as digital camera and video camera, a digital photo frame, a mobile phone i.e. cellular phone, a portable game machine and an audio player, and in an electric vehicle, hybrid electric vehicle, train vehicle, maintenance vehicle and a cart.    ADVANTAGE - The method enables reducing resistance of interface between the current collector and the active material layer when the material layer is provided, thus increasing discharge capacity or charge capacity of the energy storage device. The method enables increasing adhesion between the current collector and the active material layer, thus reducing degradation of the energy storage device. The method enables increasing surface area per unit mass of the active material layer when majority of the group of whiskers is needle-like protrusions. The method enables forming the set of whiskers is an tight manner, so that the set of whiskers is unlikely to be broken even when the set of whiskers is long and thin, thus increasing strength of the active material layer along thickness direction, and hence reducing degradation of the electrode due to repetitive charge and discharge and improving durability the energy storage device.    DETAILED DESCRIPTION - The gas containing silicon includes silicon hydride, silicon fluoride and silicon chloride. The crystalline silicon layer serves as an active material layer (103). The group of whiskers comprises a set of needle-like protrusions.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional illustration of a method for manufacturing an electrode of an energy storage device.    Current collector (101)    Active material layer (103)    Circular region (103d)    Material layer (107)    Metal oxide layer (109)