NOVELTY - The method involves mixing Beta-nucleating agent and nano silicon dioxide particle with polypropylene resin powder into extruding machine. The melt is flowed from mold head on casting piece roller to manufacture thick piece. The thick piece is put into longitudinal tension machine. The singly extended film is put into horizontal tension machine. The side and thickness are automatically controlled and adjusted by cutting. The production rolled film is cut in different lengths and width in accordance with request from user.    USE - Method for manufacturing high-power lithium ion battery.    ADVANTAGE - Since preheating, tensioning and molding temperature in longitudinal and horizontal tension machines are maintained at specific range, the quality of high-power lithium ion battery is enhanced while reducing production cost.    DETAILED DESCRIPTION - The temperature of extruding machine is controlled at 195-230 plus minus 1 degrees C. The temperature of fusing wire and mold head are controlled at 200-250 plus minus 2 degrees C and 210-220 plus minus 0.5 degrees C. The diameter of casting piece roller is 1800 mm diameter and casting temperature is at 120-128 plus minus 1 degrees C. Preheating, tensioning and molding in longitudinal tension machine are performed at temperature of 85-120 plus minus 1 degrees C, 90-115 plus minus 1 degrees C and 100-150 plus minus 1 degrees C. The preheating, tensioning and molding in horizontal tension machine are performed at temperature of 120-125 plus minus 2 degrees C, 128-135 plus minus 1 degrees C and 138-145 plus minus 2 degrees C. The side and thickness are automatically controlled and adjusted by cutting so that thickness deviation is not larger plus minus 2%, limited deviation is not larger than plus minus 5% for rolling and rolling tension is less than 5 kg.    DESCRIPTION OF DRAWING(S) - The drawing shows a flow diagram explaining the process for manufacturing high-power lithium ion battery. (Drawing includes non-English language text)