Provided is a battery capable of preventing the entry of water even if a sealing width is reduced. A battery element comprising a cathode and an anode is accommodated in a film-shaped casing. The casing includes a metal layer, a resin layer disposed on a side of the metal layer closer to the battery element with an adhesive layer in between, and a resin layer disposed on a side of the metal layer opposite to the side where the resin layer is formed with an adhesive layer in between. The adhesive layer has a water vapor transmission rate of 800 g/m 2 ·day or less for a thickness of 25 μm at 40° C. and 90% RH and a thickness of 10 μm or less. Thereby, even if the sealing width is reduced, the entry of water into the battery can be prevented.
1. A battery, comprising:
a battery element including a cathode, an anode, and an electrolyte; and
a film-shaped case accommodating said battery element including
a) a sealing portion disposed in a edge portion of the case and having a width of 1 mm to 5 mm,
b) a metal layer,
c) a first resin layer disposed on the side of the metal layer closest to the battery element with a thermoplastic layer in between the metal layer and the first resin layer, and
d) a second resin layer disposed on the side of the metal layer farthest from the battery element with an adhesive layer in between the metal layer and the second resin layer;
wherein,
the thermoplastic layer has a thickness of 50 μm or less,
the resin piece is disposed between the casing and the cathode terminal of the battery element and between the casing and the anode terminal of the battery element to prevent the entry of air, and
the adhesive layer has a thickness of 20 μm or less and the adhesive of the adhesive layer includes at least two selected from a group of acrylic adhesives and polyurethane adhesives.
2. A battery according to claim 1 , wherein the thermoplastic layer includes a modified polyolefin resin.
3. A battery according to claim 2 , wherein the thermoplastic layer includes at least one kind selected from the group consisting of modified polypropylene having a carbonyl group and modified polyethylene having a carbonyl group.
4. A battery according to claim 1 , wherein the electrolyte includes a gel electrolyte or a solid electrolyte.
5. A battery according to claim 1 , wherein the anode includes an anode material capable of inserting and extracting lithium (Li).
6. A battery according to claim 5 , wherein the anode includes a carbon material.
7. A battery according to claim 1 , wherein the cathode includes a cathode material capable of inserting and extracting lithium (Li).
8. A battery according to claim 7 , wherein the cathode includes a complex oxide of lithium and a transition metal.
9. A battery according to claim 1 , wherein the scaling portion disposed in the edge portion of the case ha a width of 1 mm to less than 3 mm.