NOVELTY - A winding portion (4) in a coil formation at a battery container e.g. steel-can wraps a cathode film in which lithium ions store and from which lithium ions extract and a anode film in which lithium ions store and from which lithium ions extract. The cathode film and the anode film are electrically separated from each other through a porous separator. A heat sink (8) located inside the battery container contacts the battery container and transmits heat inside the winding portion to the battery container.    USE - Lithium-ion secondary battery e.g. cylindrical or prismatic lithium-ion secondary battery for use in automotive application and electric power storage application.    ADVANTAGE - The cathode and anode terminals can not be corroded or there is no risk of electrical shorting caused by electrically conductive matter adhering onto the insulating areas since there is no need to directly cool the electrode terminals. Even in an operating environment in which the output fluctuates significantly or an operating environment where steep electrical charge/discharge is repeated, good heat absorption response (velocity) is assured and the battery temperature can be sustained at the optimal level. The heat generated inside the container can be efficiently transferred to the container without having to drastically alter the battery structure and the deterioration of the battery characteristics attributable to high temperature is prevented, to achieve an extended service life since a large heat dissipation area is created. The service life of the battery is further extended since the rise in battery temperature during electrical charge/discharge is minimized. A thermally conductive unit is located to range from the center pin at the winding portion to the heat dissipation portion of the container and the thermally conductive unit is formed so that its heat transfer area becomes larger as it ranges closer to the heat dissipating portion of the container, thus the heat generated inside the container be transferred to the container with great efficiency and the heat can then be released to the outside from the heat dissipating portion of the container. An external cooling assembly is added as an additional unit so as to achieve pinpoint cooling in the area at which the heat sink is mounted and prevent corrosion or electrical shorting attributable to electrically conductive matter adhering to the heat sink. The temperature of the winding portion is controlled so that it does not rise above the optimal range during electrical charge/discharge and thus, degradation of the battery characteristics caused by an excessive temperature increase can be prevented. Since heat generated through chemical reactions between the electrolyte and the active materials under abnormal conditions at the battery, such as an excessive electrical charge, can also be released through the heat dissipating portion of the container, the container is sustained in a sound condition.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic sectional view of lithium-ion secondary battery.    Lithium-ion secondary battery (1)    Steel-can (2)    Top cap (3)    Winding portion (4)    Heat sink (8)