The invention discloses a method for manufacturing an electrode. The method comprises the following steps of: 1, dry-mixing active carbon which serves as an active substance, conductive carbon black or conductive graphite or a mixture of the conductive carbon black and the conductive graphite, which serves as a conductive agent, and polytetrafluoroethylene (PTFE) dispersion resin which serves as an adhesive, in a mixer; 2, internally mixing the mixed material in an internal mixer; 3, repeatedly putting the internally mixed material into an open mill; 4, putting the material subjected to open milling into a roller press, and rolling the material to form a self-supporting diaphragm; and 5, coating a conductive adhesive on an aluminum foil current collector, adhering the aluminum foil current collector to the self-supporting diaphragm before the conductive adhesive is not dried, and drying to obtain the electrode. The invention also discloses an electric energy storage device, in particular a method for manufacturing the electric energy storage device. An electrode slice has the characteristics of high compaction density, high capacity, low internal resistance and longer service life. The prepared energy storage device has similar characteristics. In a manufacturing process of the electrode slice, water or solvent is not added, so environmental pollution is reduced, and energy is saved.