A secondary battery includes outer package members each having flexibility and a battery device. The outer package members each include a thermal-fusion-bonding layer. The battery device is contained in an inside of the outer package members, and includes a positive electrode, a negative electrode, and an electrolytic solution. The outer package members are sealed at a thermal-fusion-bonding part. The thermal-fusion-bonding part is formed by the thermal-fusion-bonding layers being thermal-fusion-bonded to each other. The thermal-fusion-bonding layer includes polypropylene. The electrolytic solution includes a solvent and an electrolyte salt. The solvent includes a chain carboxylic acid ester. The thermal-fusion-bonding layer has a thickness of greater than or equal to 25 μm and less than or equal to 60 μm. The thermal-fusion-bonding part has a length of greater than or equal to 160 mm and less than or equal to 650 mm. The thermal-fusion-bonding part has a width of greater than or equal to 3 mm and less than or equal to 6 mm. A dimensional ratio defined by the thickness of the thermal-fusion-bonding layer, the length of the thermal-fusion-bonding part, and the width of the thermal-fusion-bonding part satisfies a condition represented by Expression (1). A drawn amount of the outer package members is less than or equal to 7.8 mm. A content of the chain carboxylic acid ester in the solvent is greater than or equal to 30 vol % and less than or equal to 60 vol %.

0.16≤(T×L)/W≤0.32   (1)

Where:
(T×L)/W is the dimensional ratio;
T is the thickness (cm) of the thermal-fusion-bonding layer;
L is the length (cm) of the thermal-fusion-bonding part; and
W is the width (cm) of the thermal-fusion-bonding part.

A secondary battery includes outer package members each having flexibility and a battery device. The outer package members each include a thermal-fusion-bonding layer. The battery device is contained in an inside of the outer package members, and includes a positive electrode, a negative electrode, and an electrolytic solution. The outer package members are sealed at a thermal-fusion-bonding part. The thermal-fusion-bonding part is formed by the thermal-fusion-bonding layers being thermal-fusion-bonded to each other. The thermal-fusion-bonding layer includes polypropylene. The electrolytic solution includes a solvent and an electrolyte salt. The solvent includes a chain carboxylic acid ester. The thermal-fusion-bonding layer has a thickness of greater than or equal to 25 μm and less than or equal to 60 μm. The thermal-fusion-bonding part has a length of greater than or equal to 160 mm and less than or equal to 650 mm. The thermal-fusion-bonding part has a width of greater than or equal to 3 mm and less than or equal to 6 mm. A dimensional ratio defined by the thickness of the thermal-fusion-bonding layer, the length of the thermal-fusion-bonding part, and the width of the thermal-fusion-bonding part satisfies a condition represented by Expression (1). A drawn amount of the outer package members is less than or equal to 7.8 mm. A content of the chain carboxylic acid ester in the solvent is greater than or equal to 30 vol % and less than or equal to 60 vol %.

0.16≤(T×L)/W≤0.32   (1)

Where:
(T×L)/W is the dimensional ratio;
T is the thickness (cm) of the thermal-fusion-bonding layer;
L is the length (cm) of the thermal-fusion-bonding part; and
W is the width (cm) of the thermal-fusion-bonding part.

Provided is a packaging material for batteries, which has excellent insulating properties. A packaging material for batteries, which is formed of a laminate that is obtained by sequentially laminating at least a base layer, a bonding layer, a metal layer and a sealant layer, and wherein the base layer comprises a resin layer A that is formed of a thermoplastic resin having a volume resistivity of 1×10.sup.15 Ω.Math.cm or more.

A packaging material for a power storage device and a power storage device using the same, a method of producing a packaging material for a power storage device, and a method of selecting a sealant film used as a sealant layer in the packaging material for a power storage device are provided.

A packaging material for a power storage device and a power storage device using the same, a method of producing a packaging material for a power storage device, and a method of selecting a sealant film used as a sealant layer in the packaging material for a power storage device are provided.

A terminal-coating resin film according to one aspect of the present disclosure is so disposed in a power storage device including a power storage device body and a terminal electrically connected to the power storage device body as to cover an outer peripheral surface of part of the terminal. The terminal-coating resin film has a single-layer structure or a multilayer structure and includes a resin layer having at least one secondary dispersion peak γ within a range of −130° C. to −50° C. in a profile of a loss tangent tan δ obtained by dynamic viscoelastic measurement under a condition of 1.0 Hz. The terminal-coating film is comprised of a resin composition including a first resin including polyolefin and a second resin including at least one resin selected from polyester, polyamide, polycarbonate, and polyphenylene ether.

A lithium ion secondary battery includes a pair of exterior films having outer edges bonded together in a stacked state to form an internal space, a battery body housed in the internal surface, a positive electrode tab terminal connected to the battery body in between the pair of exterior films and extending to an outside, and a negative electrode tab terminal connected to the battery body in between the pair of exterior films and extending to the outside. The pair of exterior films each include a first resin layer constituting an inner surface, the inner surfaces opposing each other. The inner surface of at least one of the pair of exterior films has a plurality of projections arranged thereon apart from each other.

A lithium ion secondary battery includes a pair of exterior films having outer edges bonded together in a stacked state to form an internal space, a battery body housed in the internal surface, a positive electrode tab terminal connected to the battery body in between the pair of exterior films and extending to an outside, and a negative electrode tab terminal connected to the battery body in between the pair of exterior films and extending to the outside. The pair of exterior films each include a first resin layer constituting an inner surface, the inner surfaces opposing each other. The inner surface of at least one of the pair of exterior films has a plurality of projections arranged thereon apart from each other.

The present invention is directed to a laminated film for packaging of pouch-type battery cells, the laminated film comprising a plurality of layers including: a first polymer layer, a second polymer layer, a metal barrier layer disposed between the first polymer layer and the second polymer layer, characterized in that the layers further include a heat spreading layer made of a thermally conductive material, wherein the heat spreading layer is integrated within the laminated film such as to be disposed between the first polymer layer and the second polymer layer.

The present invention is directed to a laminated film for packaging of pouch-type battery cells, the laminated film comprising a plurality of layers including: a first polymer layer, a second polymer layer, a metal barrier layer disposed between the first polymer layer and the second polymer layer, characterized in that the layers further include a heat spreading layer made of a thermally conductive material, wherein the heat spreading layer is integrated within the laminated film such as to be disposed between the first polymer layer and the second polymer layer.