NOVELTY - A flexibly packaged coiled battery preparing method involves preparing a carbon nanotube solution. Diaphragm surface oxidation treatment is performed by utilizing electrochemical deposition method, carbon nanotubes deposited on the membrane surface to form a dense carbon nanotubes-composite membrane at mass ratio of the components (potassium dichromate: concentrated sulfuric acid: water) of (2-10): 100: (2-30), immersing the membrane surface in 5% ethanol solution, and drying, followed by depositing carbon nanotubes to the diaphragm surface, and performing cutting treatment.    USE - Method for preparing flexibly packaged coiled battery for electric automobile and military product batteries, and other high-end lithium ion batteries.    ADVANTAGE - The battery has high energy density (greater than 190Wh/kg), high power density (greater than 4500W/Kg) and excellent cycle performances.    DETAILED DESCRIPTION - A flexibly packaged coiled battery preparing method involves preparing a carbon nanotube solution by selecting acidified carbon nanotubes having a diameter of 50-300 nm, a length of 1-5 Mm, grafting acid group and hydroxyl branches at rate of 2-10%, to obtain carbon nanotube solution. Diaphragm surface oxidation treatment is performed by utilizing electrochemical deposition method, carbon nanotubes deposited on the membrane surface to form a dense carbon nanotubes-composite membrane at mass ratio of the components (potassium dichromate: concentrated sulfuric acid: water) of (2-10): 100: (2-30), oxidation temperature conditions for 60-80 degrees C for 1-7 minutes, immersing the membrane surface in 5% ethanol solution for 5 min, after the removal, and drying at low temperature, followed by depositing carbon nanotubes to the diaphragm surface by washing, filtering and drying to prepare a carbon nanotube - composite collector diaphragm, performing cutting treatment by slitting a negative electrode and a separator sheet, winding flexible structure of the lithium-ion battery.