Rechargeable battery having heat-resistant insulating layer
A rechargeable battery includes an electrode assembly including a positive electrode and a negative electrode, a case for accommodating the electrode assembly, a cap plate combined to the case, a vent plate disposed under the cap plate and formed with a notch, a middle plate disposed under the vent plate, and a heat-resistant insulating layer disposed between the vent plate and the middle plate.
1. A rechargeable battery, comprising:
an electrode assembly including a positive electrode and a negative electrode;
a case for accommodating the electrode assembly;
a cap plate combined to the case;
a vent plate disposed under the cap plate and formed with a notch;
a middle plate disposed under the vent plate, the middle plate having a through-hole in the center thereof, the through-hole penetrating the middle plate;
a first insulating layer disposed between the vent plate and the middle plate; and
a lower insulating member is provided between the first insulating layer and the vent plate, wherein:
the first insulating layer is in contact with sidewalls of the through-hole in the middle plate.
2. The rechargeable battery as claimed in claim 1 , wherein the first insulating layer is formed of a polyimide-based resin.
3. The rechargeable battery as claimed in claim 2 , wherein the first insulating layer has a higher melting point than the lower insulating member.
4. The rechargeable battery as claimed in claim 1 , wherein the first insulating layer is coated on the middle plate to be formed thereon.
5. The rechargeable battery as claimed in claim 1 , wherein the first insulating layer is formed as a film and is adhered to the middle plate.
6. The rechargeable battery as claimed in claim 1 , wherein the vent plate includes:
a stepped portion that protrudes towards an interior of the rechargeable battery;
a connection protrusion that protrudes towards the interior from a center of the stepped portion; and
a notch that is formed around the connection protrusion.
7. The rechargeable battery as claimed in claim 6 , wherein the middle plate includes:
a through-hole through which the connection protrusion of the vent plate is inserted; and
ventilation holes formed at an outer side of the through-hole to deliver pressure to the vent plate.
8. The rechargeable battery as claimed in claim 7 , wherein the first insulating layer includes:
a first hole that is aligned with the through-hole of the middle plate; and
respective second holes that are aligned with respective ventilation holes of the middle plate.
9. The rechargeable battery as claimed in claim 8 , wherein the first insulating layer includes an inner insulating portion that protrudes into the through-hole of the middle plate and is attached to an inner circumferential surface of the through-hole of the middle plate.
10. The rechargeable battery as claimed in claim 8 , further comprising:
a lead tab, the lead tab being electrically coupled to the positive electrode and fixed to the middle plate; and
a sub-plate under the middle plate, the sub-plate being welded to the middle plate and the connection protrusion.
11. The rechargeable battery as claimed in claim 10 , wherein the lower insulating member is formed to have a ring shape, and includes:
a groove portion, the groove portion receiving an inwardly-protruding stepped portion of the vent plate;
an opening at a center of the groove portion; and
a flange connected to an upper end of the groove portion.