Lithium-ion secondary battery and manufacturing method for same
View Patent ↗An object of this present invention is to provide: a lithium-ion secondary battery 1 constructed to easily interpose an electrical insulating protection film 41 between a battery container 2 and an electricity-generating element 3 , to facilitate automatic mounting of the insulating protection film 41 , and thus to be highly producible; and a method of manufacturing the battery. The lithium-ion secondary battery 1 of the invention is characterized in that the battery is electrically insulated between the battery container 2 and the electricity-generating element 3 , and in that the insulating protection film 41 of a sheet-like form is wrapped around the electricity-generating element 3.
1. A lithium-ion secondary battery, comprising:
an electricity-generating element including a wound electrode structure that is formed by winding electrodes into a flat form, wherein the electrodes are connected to a pair of electrode terminals;
a battery container that includes:
a battery casing having an opening,
a battery cover configured to cover the opening in the battery casing, and
one pair of electrode terminals provided on the battery cover via an electrical insulating member; and
an electrical insulating protection film of a sheet-like form that is wrapped around the wound electrode structure and the pair of electrodes in a direction that is orthogonal to an axial direction of the winding of the wound electrode structure, wherein the electrical insulating protection film includes:
a protruding end portion on a lateral end of the insulating protection film that extends beyond the wound electrode structure towards a bottom of the battery casing and away from the battery cover, wherein the protruding end portion have opposed portions that are joined together into mutual surface contact,
a fold over integral to the protruding end portion that is formed by folding lowermost edges of the opposed portions, and
a sealed portion formed by sealing off the lowermost edges of the opposed portions.
2. The lithium-ion secondary battery according to claim 1 , wherein:
the insulating protection film is sealed off at the protruding end portion by thermal deposition.
3. The lithium-ion secondary battery according to claim 1 , wherein:
the insulating protection film is formed from a sticky film coated with a pressure-sensitive adhesive material on at least one surface of the film.
4. A method for manufacturing a lithium-ion secondary battery
the method for manufacturing comprising:
mounting a pair of electrode terminals on a battery cover of battery container via an insulating member and thereby fabricating a cover assembly;
connecting an electricity-generating element to the pair of electrode terminals on the cover assembly and thereby fabricating an electricity-generating element assembly;
winding, in an axial direction, electrodes of the electricity-generating element into a flat form to form a wound electrode structure;
wrapping an electrical insulating protection film around the electricity-generating element in a direction orthogonal to the axial direction of winding of the wound electrode structure;
forming a protruding end portion on a lateral end of the insulating protection film that extends beyond the wound electrode structure away from cover assembly;
bringing opposed portions of the insulating protection into mutual surface contact;
folding lowermost edges of the opposed portions of the insulation protection film over; and
sealing off the protruding end portion.
5. The lithium-ion secondary battery manufacturing method according to claim 4 , wherein the wrapping comprises:
while one end of the insulating protection film is in close contact with the electricity-generating element, another end of the insulating protection film is wrapped around the electricity-generating element.
6. The lithium-ion secondary battery manufacturing method according to claim 4 , wherein the wrapping further comprises:
while the insulating protection film is being kept in close contact at an intermediate section thereof with the electricity-generating element, one end of the insulating protection film and another end thereof are wrapped around the electricity-generating element.