Abstract: Disclosed herein is a unit cell for a lithium ion secondary battery, which includes an electrode laminate formed in such a manner that a plurality of unit structures are stacked, each of which includes and least one electrode and at least one separation layer; and at least one conductive sheet layer located between certain layers in the electrode laminate and electrically connected to an electrode lead. The conductive sheet layer of the unit cell for the lithium ion secondary battery rapidly conducts current to the outside or generates heat in quantity smaller than the quantity of heat generated in positive and negative electrodes when short-circuit occurs due to a physical or electrical impact applied to the battery. Accordingly, it is possible to reduce the risk of firing or explosion due to the physical or electrical impact to improve the safety of the lithium ion secondary battery.

Abstract: The present invention relates to a electrode stacking method, wherein electrodes are stacked in such a manner that the electrodes are disposed to face each other on both sides of a separation layer to which predetermined tension force is applied along the longitudinal direction of said separation layer, and the electrode assembly is turned so that another separation layer is formed outside the electrodes. According to the rechargeable lithium ion batteries in accordance with the present invention, the electrode stack in which the arrangement of anode electrodes and cathode electrodes is not disordered because uniform stress is applied to the entire battery and the separation layer maintains a constant tension force can be fabricated. Accordingly, the lifespan of a rechargeable lithium ion battery can be increased, and the input and output characteristic of the battery can be improved.

Abstract: The present invention discloses a crude cell for a large secondary battery comprising unit cells alternately stacked in the fold/fold type or a crude cell for a large secondary battery comprising unit cells wound and stacked in the jelly roll type, each unit cell having an anode, a cathode and a separator, in which a polymer film is inserted in the crude cell to support the crude cell. According to the present invention, it is possible to prevent structural distortion caused by external impact and self reaction of the crude cell by firmly supporting the crude cell. Consequently, it is possible to prevent short of the anode and the cathode in the crude cell by electrical connection and to improve interfacial properties of the anode, the cathode and the separator.