Abstract: An energy storage device has an anode, a cathode and an electrolyte membrane, installed in between the anode and the cathode, wherein at least one of the anode, the cathode and the electrolyte membrane is incorporated with a copolymer and the copolymer is grafted to a functional group with ionic conductive function. Therefore, the energy storage device, which utilizes copolymers and electrolyte membranes, has better efficiency of charge/discharge performance; thus the efficiency thereof increases; the lifetime thereof is prolonged effectively.

Abstract: An energy storage device has an anode, a cathode and an electrolyte membrane, installed in between the anode and the cathode, wherein at least one of the anode, the cathode and the electrolyte membrane is incorporated with a copolymer and the copolymer is grafted to a functional group with ionic conductive function. Therefore, the energy storage device, which utilizes copolymers and electrolyte membranes, has better efficiency of charge/discharge performance; thus the efficiency thereof increases; the lifetime thereof is prolonged effectively.

Abstract: A method for forming an U-shaped metal frame includes a preparing means: bend forming a straight tube in a continuous curve shape to be a billet including a spaced section and a first and a second side segments twisted toward opposite directions individually; a forming means: placing the billet into a cavity of a forming mold, closing two ends of the billet, and feeding a high-pressure fluid into the billet; a cutting means: cutting the billet into the first and the second pipes, the first pipe including a first connecting portion formed in a first cut position thereof, the second pipe including a second connecting portion formed in a second cut position thereof; a connecting means: twisting the first side segment and the second side segment toward the same direction, and connecting the first connecting portion and the second connecting portion together to obtain the U-shaped metal frame.