Welded structure in battery, forming method of the same, secondary battery cell and secondary battery module
A plating layer 4 is formed on a surface of a battery cover 3 , and a peripheral edge part 37 b of a cover case 37 is arranged on an upper surface of the plating layer 4 . A welding part 40 is formed at a tip part of the peripheral edge part 37 b . The welding part 40 includes a melted part 41 in which the tip of the peripheral edge part 37 b is melted, and an elution part 42 flowing from the tip onto the plating layer 4 , and the melted part 41 and the elution part 42 are welded to the plating layer 4 in the upper surface of the plating layer 4.
1. A method of forming a welded structure in a battery, comprising:
arranging a second conductive member, made of a second material different from that of a first material of a first conductive metal member, on a surface of a metal plating layer which is formed on a surface of the first conductive metal member, the second conductive metal member extending a first length along the surface of a metal plating layer from an outer periphery of the first conductive metal member to a tip portion of the second conductive metal member having a shape defined by (i) a top surface extending a portion of the first length and (ii) an edge extending a tip height from the metal plating layer to the top surface;
controlling an output of laser light irradiated to the second conductive metal member to:
irradiate the second conductive metal member at a position inside the tip portion and form a melted part of the tip portion of the second conductive member and an elution part of the tip portion of the second conductive member which flows from the tip portion onto the surface of the metal plating layer: and
after forming the melted part and the elution part by the irradiation, simultaneously weld the melted part and the elution part to the metal plating layer and anneal the metal plating layer such that the melted part and the elution part are welded to the metal plating layer at a depth below the surface of the metal plating layer which does not reach the surface of the first conductive metal member.
2. The method of forming the welded structure according to claim 1 , wherein the metal plating layer is made of a third material different than the first material and the second material, and
the melted part and the elution part are welded to the metal plating layer at a depth below the surface of the metal plating layer which does not reach the surface of the first conductive metal member via a first joining force of the metal plating layer to the first conductive metal member being higher than a second joining force of the metal plating layer to the second conductive metal member.
3. The method of forming the welded structure according to claim 1 , wherein (i) the laser light irradiated to the second conductive member and (ii) a line intersecting the top surface of the tip portion of second conductive member and parallel to the edge of the second conductive member define an irradiation angle of 20 degrees or less.
4. The method of forming the welded structure according to claim 3 , wherein the irradiation angle is about 10 degrees.
5. The method of forming the welded structure according to claim 1 , wherein the irradiating further comprises irradiating the second conductive metal member such that the melted part decreases in height as the melted part extends to the elution part and the elution part extends past the location of the edge of the tip portion relative to the outer periphery of the first conductive metal member.