The present invention relates to a button-type secondary battery comprising: a can assembly configured to accommodate an electrode assembly and an electrolyte, wherein the can assembly comprises: a lower can configured to accommodate the electrode assembly and the electrolyte and serve as a first electrode terminal; an upper can coupled to surround the lower can and configured to serve as a second electrode terminal; and a gasket provided between the lower can and the upper can to seal a gap between the lower can and the upper can, wherein a first leakage detection member configured to detect whether the electrolyte leaks is provided on an outer surface of the lower can that is in close contact with the gasket, and the first leakage detection member is provided with a recessed lower coupling groove formed in the outer surface of the lower can.

A rechargeable battery according to an embodiment of the present invention includes: an electrode assembly in which a separator is disposed between a first electrode and a second electrode; a case having an opening on one side and accommodating the electrode assembly; and a cap assembly coupled to the opening so as to seal the case. The cap assembly includes: a cap plate coupled to the opening and provided with a terminal hole; a terminal plate disposed inside the terminal hole; and an insulating material, and also includes a sealing portion which covers a circumferential portion on the terminal hole side of the cap plate and a circumferential portion of the terminal plate so as to form a seal between the cap plate and the terminal plate.

Disclosed are an electrode sheet for a battery roll core, and a cylindrical or button battery. The electrode sheet includes a tab, a sheet-like current collector, and two electrode active materials attached to two surfaces of the sheet-like current collector respectively, wherein an edge of the electrode active material located on an inner side of a winding is indented at beginning and/or end of the winding relative to an edge of the other electrode active material so as to form a foil-free region, and one end of the tab is connected to the sheet-like current collector.

A button-type secondary battery includes an electrode assembly including a first separator, a negative electrode, a second separator, and a positive electrode that are sequentially stacked and wound, wherein ends of the first separator and the second separator are disposed closer to a center of the wound electrode assembly than ends of the positive electrode and the negative electrode; an electrolyte; and a can in which the electrode assembly and the electrolyte are accommodated. In the electrode assembly, an expansion member is attached to at least one central end of the first separator or the second separator, and the expansion member is expanded by absorbing the electrolyte.

To provide a positive electrode active material capable of further reducing positive electrode resistance and exhibiting better output characteristics.

A positive electrode active material includes a coating layer formed of a metal composite oxide of Li and one or more metal elements selected from Al, Ti, Zr, Nb, Mo, and W on at least a part of a surface of lithium transition metal-containing composite oxide particles, and has d50 of 3.0 to 7.0 μm, a BET specific surface area of 2.0 to 5.0 m.sup.2/g, a tap density of 1.0 to 2.0 g/cm.sup.3, and an oil absorption amount of 30 to 60 ml/100 g, in which the amount of metal elements other than Li contained in the coating layer is 0.1 to 1.5 atom % with respect to the total number of atoms of Ni, Mn, and Co contained in the composite oxide particles.

A secondary battery includes an outer package member, a battery device, an external terminal, and a coupling wiring line. The battery device is contained inside the outer package member, and includes a first electrode and a second electrode. The external terminal is attached to the outer package member and insulated from the outer package member. The coupling wiring line is coupled to each of the first electrode and the external terminal. A portion of the coupling wiring line is insulated from each of the outer package member and the second electrode, and is sandwiched by the outer package member and the battery device.

A secondary battery includes an outer package member, a battery device, and an insulating member. The battery device is contained inside the outer package member, and includes a positive electrode and a negative electrode that are opposed to each other and are wound. The insulating member is provided on the positive electrode. The positive electrode includes a positive electrode current collector, and a positive electrode active material layer provided on the positive electrode current collector. The negative electrode includes a negative electrode current collector, and a negative electrode active material layer provided on the negative electrode current collector on a side opposed to the positive electrode active material layer. The positive electrode includes an exposed part in which the positive electrode active material layer is not provided and the positive electrode current collector is exposed. The exposed part is opposed to the negative electrode active material layer. The insulating member covers at least the exposed part. The positive electrode has a first direction along which the positive electrode active material layer is provided intermittently via the exposed part on the positive electrode current collector, and a second direction intersecting the first direction. In the second direction, the negative electrode protrudes relative to the positive electrode toward opposite sides. Further, in the second direction, the insulating member protrudes relative to the positive electrode toward the opposite sides. A dimension of the positive electrode in the second direction, a dimension of the negative electrode in the second direction, a dimension of protrusion of the insulating member relative to the positive electrode on one of the opposite sides in the second direction, and a dimension of protrusion of the insulating member relative to the positive electrode on another of the opposite sides in the second direction satisfy a relationship represented by Expression (1) below.

[00001]$0.50\le \left(\text{W3}\text{+}\text{W4}\right)/\left(\text{W2}-\text{W1}\right)\le 3.00$

where: W1 is the dimension of the positive electrode in the second direction; W2 is the dimension of the negative electrode in the second direction; W3 is the dimension of protrusion of the insulating member relative to the positive electrode on the one of the opposite s

The present disclosure provides a secondary battery configured such that an electrode assembly including a positive electrode, a separator, and a negative electrode is housed in a battery case together with an electrolyte solution, wherein the battery case is made of metal, and a conductive layer made of one selected from the group consisting of a conductive carbon layer, a conductive polymer layer, and a conductive epoxy layer is formed on a part or the whole of the inner surface of the battery case coming into contact with the electrolyte solution.

A button-type secondary battery includes a lower can having a first sidewall in a vertical direction along a circumference of a first flat portion; an upper can having a second sidewall in a vertical direction along a circumference of a second flat portion, wherein the upper can is coupled to the lower can so that the second flat portion faces the first flat portion; an electrode assembly in an inner space between the lower can and the upper can; and a gasket between the second sidewall and the first sidewall to prevent the upper and lower cans from contacting. The second sidewall comprises a distant end that is bent to surround an edge configured to connect the first flat portion to the first sidewall and is below the first flat portion. The gasket extends between the distal end and the first flat portion.

A button-type secondary battery according to the present disclosure includes: an electrode assembly; a lower can configured to accommodate the electrode assembly; an upper can coupled to an opening of the lower can; a gasket configured to insulate a coupling portion between the lower can and the upper can; and a center part provided at a core portion of the electrode assembly, wherein the center part includes: a center pin inserted into the core portion of the electrode assembly; and an upper plate provided with an upper cover surface provided on an upper end of the center pin to protect an upper portion of the electrode assembly, wherein an edge of the upper cover surface is provided to be supported on an inner wall of the lower can.