Secondary battery and assembled battery
According to the present disclosure, the thermal deterioration of metal junction parts formed on a contact interface of constitution members of electrode terminals is suppressed. The electrode terminal of the secondary battery disclosed herein includes a first member having a plate-shaped connection part and a plate-shaped second member connected to the connection part of the first member in a surface-contact manner. Then, the technique disclosed herein includes a metal junction part and a heat-insulating part formed on a contact interface between a connection part of the first member and the second member, and the heat-insulating part is formed outward of the metal junction part in a radial direction centered on the metal junction part. Due to this constitution, the heat-insulating part can block great heat even when such a great heat is applied to a region outside the heat-insulating part, and therefore, the heat deterioration of the metal junction part can be suppressed.
1 . A secondary battery comprising:
an electrode body;
a battery case housing the electrode body; and
an electrode terminal connected to the electrode body in the battery case and partly exposed to an exterior of the battery case,
the electrode terminal including:
a first metal member having one end positioned in the battery case and another end positioned outside the battery case; and
a plate-shaped second metal member covering an entire outer surface of the first metal member and connected to the first metal member at an outside of the battery case,
the first metal member including:
a shaft part penetrating the battery case; and
a plate-shaped connection part that is formed on a top edge of the shaft part and in surface contact with the second metal member, wherein
a metal junction part and a heat-insulating part are formed on a contact interface between a connection part of the first metal member and the second metal member on the outer surface of the first metal member,
the metal junction part is a part formed when the first metal member and the second metal member are joined by metal-to-metal joining performed by one of ultrasonic joining, laser welding, or resistance welding,
the heat-insulating part is formed outward of the metal junction part in a radial direction centered on the metal junction part,
the heat-insulating part comprises a cavity formed by a part of a bottom surface of the second metal member separating from a top surface of the connection part, and
a heat-insulating material is filled in the cavity.
2 . The secondary battery according to claim 1 , wherein the heat-insulating part is a ring-shaped heat-insulating part formed so as to surround the metal junction part.
3 . The secondary battery according to claim 1 , wherein the first metal member and the second metal member are constituted of different metal materials.
4 . An assembled battery comprising a plurality of secondary batteries mutually electrically connected via a flat plate-shaped bus bar,
at least one of the plurality of secondary batteries is the secondary battery according to claim 1 ;
the bus bar being thermally welded on a top surface of the second metal member in a surface contact state, the bus bar and the second metal member being connected by a thermally welded part penetrating the bus bar to reach the second metal member; and
the thermally welded part being formed upward of the heat-insulating part, or outward of the heat-insulating part in a radial direction centered on the metal junction part.
5 . The assembled battery according to claim 4 , wherein, a distance from a center of the metal junction part to an outer periphery of the metal junction part is taken as L1, a distance from a center of the metal junction part to an inner edge of the heat-insulating part is taken as L2, and a distance from a center of the metal junction to a center of the thermally welded part is taken as L3, the following formula (1) is satisfied:
L 3− L 2> L 2− L 1 (1).