The present invention relates to a battery cell for evaluating an internal short circuit, and a method for evaluating using the battery cell, wherein an internal short circuit state of a battery cell can be easily induced and, at the same time, an effective internal short circuit evaluation is possible, and the battery cell comprising: first and second electrodes which comprise a coated region on which an electrode mixture layer is coated on a metal current collector and a non-coated region on which an electrode mixture layer is not coated, and which comprise first and second electrode tabs which protrude in one direction from the coated region and do not have an electrode mixture layer coated thereon.

Disclosed is a secondary battery in which a negative electrode has a covered portion covered with a negative electrode active material covering portion and a negative electrode active material non-covered portion on a strip-shaped negative electrode foil, the negative electrode active material non-covered portion is joined to a negative electrode current collector plate at the other end portion of the electrode winding body, the electrode winding body has a flat surface formed by bending any one or both of a positive electrode active material non-covered portion and the negative electrode active material non-covered portion toward a central axis of the wound structure and overlapping the positive electrode active material non-covered portion and the negative electrode active material non-covered portion, and a first groove formed in the flat surface, at least one C-shaped second groove is included in a can bottom of a battery can.

An electrolyte-solution composition and a secondary battery using the same. The electrolyte-solution composition is configured in contact with an aluminous surface of a cathode. The electrolyte-solution composition includes an electrolyte solution and a hydroxyquinoline compound. With the hydroxyquinoline compound included in the electrolyte-solution composition, oxidation and corrosion occurred on the aluminous surface, which are caused by the electrolyte-solution composition, is reduced. Accordingly, the capacity of the secondary battery is improved, and the occurrence of self-discharge phenomenon is avoided.

The present disclosure provides a current collector of a secondary battery in which the current inside the battery is easily blocked at the time of inside short circuit, and in which the capacity retention rate and the decreasing rate of the electric resistance are outstanding. The current collector herein disclosed includes a laminate structure in which a resin layer and a metal layers formed on the both surfaces of the resin layer are laminated. The surface of the metal layer includes a rough surface part provided with a plurality of protruding parts and a plurality of recessed parts. On the rough surface part, a resin coat layer is formed, and at least one part of the protruding part among the plurality of protruding parts includes an exposed part that is exposed from the resin coat layer.

A separator for a rechargeable battery includes a porous substrate and a heat resistance layer on at least one surface of the porous substrate. The heat resistance layer includes an acryl-based copolymer, an alkali metal, and a filler. The acryl-based copolymer includes a unit derived from (meth)acrylate or (meth)acrylic acid, a cyano group-containing unit, and a sulfonate group-containing unit.

An embodiment of the present invention provides a copper foil which comprises a copper layer and an anticorrosive film placed on the copper layer, and has a Young's modulus of 3800 to 4600 kgf/mm.sup.2 and a modulus bias factor (MBF) less than 0.12, wherein the modulus bias factor (MBF) is obtained by formula 1 below.
MBF=(maximum Young's modulus−minimum Young's modulus)/(average Young's modulus)  [Formula 1]

Provided is a bipolar all-solid-state sodium ion secondary battery that can increase the voltage without impairing safety. A bipolar all-solid-state sodium ion secondary battery includes: a plurality of all-solid-state sodium ion secondary batteries 1 in each of which a positive electrode layer 3 capable of absorbing and releasing sodium, a solid electrolyte layer 4 made of a sodium ion-conductive oxide, and a negative electrode layer 5 capable of absorbing and releasing sodium are laid one upon another in this order; and a current collector layer 2 provided between the positive electrode layer 3 of each of the plurality of all-solid-state sodium ion secondary batteries 1 and the negative electrode layer 5 of the adjacent all-solid-state sodium ion secondary battery 1 and shared by the positive electrode layer 3 and the negative electrode layer 5.

An electrolytic copper foil includes a raw foil layer having a first surface and a second surface opposite to the first surface. In the X-ray diffraction spectrum of the first surface, a ratio of the diffraction peak intensity I(200) of the (200) crystal face of the first surface relative to the diffraction peak intensity I(111) of the (111) crystal face of the first surface is between 0.5 and 2.0. In the X-ray diffraction spectrum of the second surface, a ratio of the diffraction peak intensity I(200) of the (200) crystal face of the second surface relative to the diffraction peak intensity I(111) of the (111) crystal face of the second surface is also between 0.5 and 2.0. A method for producing the electrolytic copper foil, and a lithium ion secondary battery is also provided.

Systems and methods for a battery electrode having a solvent level to facilitate peeling are disclosed. In examples, a battery may include one or more electrodes and an electrolyte. The electrodes include an electrode slurry layer with a solvent. The electrode slurry is coated on a substrate, where the electrode slurry and substrate produce an active material with a residual amount of solvent in response to a heat-treatment, and where the active material comprises 10% to 25% residual solvent by weight following the heat-treatment. The amount of residual solvent facilitates peeling of the active material from the substrate, which, once pyrolyzed, may be used to create a multi-layer film with the current collector film and the active material.

A lithium metal electrode has no more than five ppm of non-metallic elements by mass, and is bonded to a conductive substrate. Optionally, the lithium metal electrode may be bonded on one side to a conductive substrate and on another side to a lithium ion selective membrane. The lithium metal electrode may be integrated into lithium metal batteries. The inventive lithium metal electrode may be manufactured by a process involving electrolysis of lithium ions from an aqueous lithium salt solution through an ion selective membrane, carried out under a blanketing atmosphere having no more than 10 ppm of non-metallic elements, the electrolysis being performed at a constant current between about 10 mA/cm.sup.2 and about 50 mA/cm.sup.2, and wherein the constant current is applied for a time between about 1 minute and about 60 minutes.