The storage cell comprises a flat roll electrode that includes a strip of positive electrode having a positive electrode current collector foil and a positive electrode layer formed thereon, a strip of negative electrode having an electrode current collector foil and a negative electrode layer formed, and a strip of electrically insulated separator, the strip of positive electrode and the strip of negative electrode being wound into a flat roll configuration with the strip of electrically insulated separator sandwiched therebetween; a sealed casing that hermetically seals the flat roll electrode impregnated with an electrolyte; a positive terminal and a negative terminal each electrically insulated from the sealed casing, connected to the positive current collector foil and the negative current collector foil, respectively.