NOVELTY - An electrode has a current collector and an active material layer formed on the current collector. The active material layer contains an active material, graphene, and polyimide. The active material includes nanowires which extend from silicon particles.    USE - Electrode is used for power storage device (claimed) e.g. lithium-ion secondary battery. Uses include but are not limited to smartphones, tablets, hybrid cars, electric cars, lighting devices, word processors, microwave ovens, air conditioners, futon dryers, freezers used for preserving DNA, smoke detectors and dialyzers.    ADVANTAGE - The electrode has excellent reliability. The application of undercoat to current collector reduces interface resistance between current collector and active material layer, and/or increases adhesion between active material layer and current collector, thus deformation/breakage of silicon particles is easily caused. The lithium-ion secondary battery using the electrode has excellent charging/discharging characteristics and high capacity.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) power storage device, which has a positive electrode including positive electrode current collector and positive electrode active material layer and negative electrode (410) including negative electrode current collector (411) and negative electrode active material layer (412). The negative electrode active material layer includes negative electrode active material, graphene (I), and polyimide. The positive electrode active material layer includes positive electrode active material, graphene (II), and polyvinylidene fluoride; and    (2) manufacture of electrode, which involves mixing silicon particles and graphene oxide, mixing the mixture of silicon particles and graphene oxide with a solution of polyimide precursor and solvent, obtaining slurry, applying mixture of silicon particles, graphene oxide and polyimide precursor in solvent, heating the applied mixture, forming nanowire that grows with silicon particles used as nucleus and extends into fine needle, reducing graphene oxide to graphene, and imidizing polyimide precursor to polyimide.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of negative electrode.    Negative electrode (410)    Negative electrode current collector (411)    Negative electrode active material layer (412)    Undercoat (413)