The invention provides a preparation method of a 
lithium ion capacitor. The preparation method comprises the following steps that: a positive-pole 
current collector is prepared; 2, a positive-pole 
electrode sheet is prepared; 3, a negative-pole 
current collector is prepared; 4, a negative-pole 
electrode sheet is prepared; 5, a diaphragm is prepared; 6, a material for preparing 
electrolyte is selected; 7, an aluminum-
plastic film is prepared; 8, materials for preparing 
electrode lugs are selected; and 9, the 
capacitor is prepared. According to the step 9, the positive-pole electrode sheet, thediaphragm and the negative-pole electrode sheet are laminated so as to form a battery core; the positive-pole electrode lug and the positive-pole 
current collector are welded by means of 
ultrasonic soldering; the negative-pole electrode lug and the negative-pole current collector are welded by means of 
ultrasonic soldering; the battery core is packaged with the aluminum-
plastic film at temperaturefrom 100 to 250 DEG C; the 
electrolyte is injected from a 
liquid injection opening, the 
liquid injection opening is sealed; standing, formation, liquid extraction and grading are performed, so that the 
lithium ion capacitor can be prepared. The 
energy density of the 
lithium ion capacitor prepared by using the preparation method of the invention can achieve 60 wh / kg; the 
voltage of the lithium ioncapacitor ranges from 4.2 to 2.8 V; and the 
energy density and 
voltage of the 
lithium ion capacitor prepared by using the preparation method are significantly improved compared with the 
energy density and 
voltage of a general super-capacitor; the 
internal resistance of the capacitor can be reduced; and the high-rate cycle life of the capacitor can be prolonged.