A method of joining a first and a second object, each object having a substantially flat surface. The method includes the steps of: placing the objects with their surfaces in a contacting relationship along an interface, with their surfaces substantially parallel, the interface having a peripheral edge, irradiating a laser beam with a focal point onto the peripheral edge in the direction of the interface while the plates are in a contacting relationship, and moving the focal point of the laser beam along the interface in a direction transversely to the edge, to a position at a distance from the edge.

A plurality of values measured are relatively compared to determine an optical axis deviation direction in which an optical axis of a measurement beam S deviates from a laser beam L. In performing laser welding in the optical axis deviation direction, an irradiation position of the measurement beam S is changed so that the irradiation position of the measurement beam S is moved to a rear side of the center of the optical axis of the laser beam L in the welding direction.

A case includes a first member and a second member configured in such a way that a closed space is formed between the first and second members in a state where the first and second members abut against each other. The first member includes a shaft portion extending toward the second member. The second member includes a shaft support portion including a circumferential wall portion that surrounds one end portion of the shaft portion. The shaft portion includes an enlarged-diameter portion that is the one end portion melted in such a way as to be enlarged in diameter.

A secondary battery that includes an electrode assembly and an exterior body housing the electrode assembly. The exterior body includes a cup-shaped exterior member and a lid-shaped exterior member connected to each other by a welded part. An end part of at least one of the cup-shaped exterior member and the lid-shaped exterior member includes a stepped part on an inner surface thereof. The stepped part includes a first extending surface and a second extending surface extending in substantially a same direction and having different heights from each other, and a stepped surface connecting the two extending surfaces. The welded part is in a part of the stepped part, and the stepped surface of the stepped part is separated from an opposed part of the exterior body.

A welding method according to an embodiment includes a preparation process and a welding process. A first welding material and a second welding material are prepared in the preparation process. The first welding material and the second welding material are welded in the welding process by irradiating a laser beam on at least one of the first welding material or the second welding material. At least one of the first welding material or the second welding material includes a first portion and a second portion. A laser absorptance of the second portion is higher than a laser absorptance of the first portion. The first welding material and the second welding material are welded in the welding process by irradiating the laser beam on the second portion.

A welding method according to an embodiment includes a preparation process and a welding process. A first welding material and a second welding material are prepared in the preparation process. The first welding material and the second welding material are welded in the welding process by irradiating a laser beam on at least one of the first welding material or the second welding material. At least one of the first welding material or the second welding material includes a first portion and a second portion. A laser absorptance of the second portion is higher than a laser absorptance of the first portion. The first welding material and the second welding material are welded in the welding process by irradiating the laser beam on the second portion.

A rechargeable battery is produced by welding a metal foil to a contact element to make electrical contact with an electrode of the rechargeable battery. An edge region of the metal foil is brought into contact with a first surface of the contact element and welded to the contact element by applying a laser beam to a second surface of the contact element. The second surface being averted from (opposite to) the first surface of the contact element. The metal foil and further planar constituents of the rechargeable battery are wound to provide the rechargeable battery with an at least essentially cylindrical design. The contact element-is oriented at right angles to the metal foil.

A rechargeable battery is produced by welding a metal foil to a contact element to make electrical contact with an electrode of the rechargeable battery. An edge region of the metal foil is brought into contact with a first surface of the contact element and welded to the contact element by applying a laser beam to a second surface of the contact element. The second surface being averted from (opposite to) the first surface of the contact element. The metal foil and further planar constituents of the rechargeable battery are wound to provide the rechargeable battery with an at least essentially cylindrical design. The contact element-is oriented at right angles to the metal foil.

A method for establishing a weld joint comprises the step of projecting an energy beam such as a laser beam (2) onto an interface area (103) between two parts (101, 102) to be joined. The beam (2) is projected onto the interface area (103) so as to produce a primary spot on the interface area (103), and the beam (2) is repetitively scanned in two dimensions in accordance with a scanning pattern so as to establish an effective spot (21) on the object, the effective spot (21) having a two-dimensional energy distribution. The effective spot (21) is displaced along a track (104) over the interface area (103) so as to progressively melt mating portions of the first part (101) and the second part (102) so as to form the weld joint (105). The effective spot (21) can feature an asymmetric energy distribution.

A method for establishing a weld joint comprises the step of projecting an energy beam such as a laser beam (2) onto an interface area (103) between two parts (101, 102) to be joined. The beam (2) is projected onto the interface area (103) so as to produce a primary spot on the interface area (103), and the beam (2) is repetitively scanned in two dimensions in accordance with a scanning pattern so as to establish an effective spot (21) on the object, the effective spot (21) having a two-dimensional energy distribution. The effective spot (21) is displaced along a track (104) over the interface area (103) so as to progressively melt mating portions of the first part (101) and the second part (102) so as to form the weld joint (105). The effective spot (21) can feature an asymmetric energy distribution.