SECONDARY BATTERY INCLUDING SEALING STRUCTURE FOR ELECTROLYTE INJECTION HOLE AND METHOD OF MANUFACTURING THE SECONDARY BATTERY
A secondary battery including an electrolyte injection hole having an improved sealing structure, and a method of manufacturing the secondary battery. In the secondary battery, a sealing unit for sealing an injection hole of a cap plate is installed such that the sealing unit is aligned with or disposed below a top surface of the cap plate and, thus, does not protrude above the cap plate. Accordingly, components adjacent to the cap plate (such as a protection circuit module) may be closely adhered to the cap plate, and a compact secondary battery may be manufactured with an increased volume utilization efficiency.
1 . A secondary battery comprising:
an electrode assembly;
a case accommodating the electrode assembly;
a cap plate to cover the case and including an injection hole therethrough for injecting an electrolyte solution into the case; and
a sealing unit to seal the injection hole,
wherein the sealing unit is aligned with or disposed below an outer surface of the cap plate and does not protrude beyond the outer surface of the cap plate and comprises a sealing member inserted into the injection hole and a coating member that is coated on the sealing member.
2 . The secondary battery of claim 1 , wherein:
the cap plate includes a step portion in which the sealing unit is accommodated, the step portion surrounding an opening portion of the injection hole between the opening portion of the injection hole and the outer surface of the cap plate; and
the sealing member comprising a body portion that is inserted into the injection hole and a head portion that is integrally formed with the body portion so as to adhere to the step portion when the body portion is inserted into the injection hole.
3 . The secondary battery of claim 2 , wherein the coating member is coated on the sealing member to fill a gap between the sealing member and the injection hole.
4 . The secondary battery of claim 1 , wherein the coating member comprises a curing resin.
5 . The secondary battery of claim 2 , wherein the step portion comprises an immersion groove that is concavely disposed around a circumference of the injection hole, such that the head portion of the sealing member fits into the immersion groove.
6 . The secondary battery of claim 1 , further comprising a protection circuit module disposed on the outer surface of the cap plate.
7 . A method of manufacturing a secondary battery, the method comprising:
providing a cap plate in which an injection hole for injecting an electrolyte solution is formed therethrough;
forming a step portion around an opening portion of the injection hole between the opening portion of the injection hole and an outer surface of the cap plate;
coupling the cap plate to a case in which an electrode assembly is accommodated;
injecting an electrolyte into the case through the injection hole; and
sealing the injection hole by installing, in the step portion, a sealing unit that does not protrude beyond the outer surface of the cap plate.
8 . The method of claim 7 , wherein the sealing unit comprises a sealing member comprising a body portion that is inserted into the injection hole and a head portion integrally formed with the body portion so as to adhere to the step portion such that the sealing member does not protrude beyond the outer surface of the cap plate.
9 . The method of claim 8 , wherein the sealing of the injection hole comprises coating the sealing member with a coating member that fills a gap between the sealing member and the injection hole.
10 . The method of claim 9 , further comprising grinding a portion of the formed coating member that protrudes beyond the outer surface of the cap plate, such that the coating member does not protrude beyond the outer surface of the cap plate.
11 . The method of claim 9 , wherein the coating of the sealing member comprises coating the sealing member with the coating member so as not to protrude beyond the outer surface of the cap plate.
12 . The method of claim 9 , wherein the coating member comprises a curing resin.
13 . The method of claim 8 , wherein the step portion comprises an immersion groove that is concavely disposed around a circumference of the injection hole, such that the head portion of the sealing member fits into the immersion groove and is coupled to the immersion groove when the sealing unit is installed in the step portion.
14 . The method of claim 7 , further comprising installing a protection circuit module on the outer surface of the cap plate.
15 . A method of manufacturing a cap plate to cover a case of a secondary battery, the method comprising:
forming a step portion around an opening portion of an injection hole formed through the cap plate, the step portion being formed to have a lower surface that is not flat and the step portion extending between the opening portion of the injection hole and the outer surface of the cap plate; and
sealing the opening portion using a sealing unit.
16 . The method of claim 15 , wherein the lower surface of the step portion has a concave shape.
17 . The method of claim 15 , wherein sealing unit comprises a coating member comprising a curing resin.
18 . A cap plate to cover a case accommodating an electrode assembly of a secondary battery, the cap plate comprising:
a portion having an injection hole formed therethrough for injecting an electrolyte solution into the case; and
a step portion around an opening portion of the injection hole between the opening portion of the injection hole and an outer surface of the cap plate,
wherein the step portion has a lower surface that is not flat.
19 . The cap plate of claim 18 , wherein the lower surface of the step portion has a concave shape.
20 . A sealing unit to seal an injection hole formed through a cap plate to cover a case of a secondary battery for injecting an electrolyte solution into the case, the sealing unit comprising:
a sealing member that is inserted into the injection hole and aligned with or disposed below an outer surface of the cap plate so that the sealing unit does not protrude beyond the outer surface of the cap plate; and
a coating member coated on the sealing member to seal a gap between the sealing member and the injection hole.
21 . The sealing unit of claim 20 , wherein the sealing member comprises a body portion that is inserted into the injection hole and a head portion that is integrally formed with the body portion so as to adhere to a step portion of the cap plate when the body portion is inserted into the injection hole, the step portion surrounding an opening portion of the injection hole and located between the opening portion and the outer surface of the cap plate.
22 . The sealing unit of claim 21 , wherein a contact surface of the head portion has a convex shape corresponding to a concave shape of the step portion.
23 . The sealing unit of claim 20 , wherein the coating member comprises a curing resin.