# US 2014/0193679 A1 · Secondary battery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0193679 A1 - Document ID: US20140193679A1 - Status: Published application - Kind: A1 - Application number: 13/839,650 - Filed: 2013-03-15 - Published: 2014-07-10 - Earliest claimed: 2013-01-04 - Assignees: Samsung SDI Co., Ltd. - Applicants: Samsung SDI Co., Ltd - Inventors: Dae-Kyu Kim; Takao Abe - Web page: https://patentgrep.com/patent/US20140193679A1 ## CPC - H01M 50/3425: {in the form of rupturable membranes or weakened parts, e.g. pierced with the aid of a sharp member} - H01M 50/56: Cup shaped terminals - Y02E 60/10: Energy storage using batteries - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A secondary battery includes an electrode assembly having a first electrode plate, a second electrode plate and a separator interposed between the first and second electrode plates; a lower case accommodating the electrode assembly therein; and a cap assembly sealing the lower case. In the secondary battery, the lower case has the electrode assembly and a vent portion, and includes a surface facing the cap assembly. The vent portion includes an intersecting portion formed inside the surface, first and second curved portions curved to extend from the intersecting portion, and an extending portion extended in a straight line from the intersecting portion. The thickness of the intersecting portion includes the minimum thickness of the surface. ## Claims ### Claim 1 A secondary battery, comprising: an electrode assembly having a first electrode plate, a second electrode plate and a separator interposed between the first and second electrode plates; a lower case accommodating the electrode assembly therein; and a cap assembly sealing the lower case, wherein the lower case surrounds the electrode assembly and includes a surface facing the cap assembly and having a vent portion, wherein the vent portion includes an intersecting portion formed on the surface, first and second curved portions that are formed to extend from the intersecting portion, and an extending portion extended in a line from the intersecting portion, and wherein the thickness of the intersecting portion has the minimum thickness of the surface. ### Claim 2 (depends on 1) The secondary battery of claim 1, wherein the first and second curved portions extend toward the outer perimeter of the surface from the intersecting portion, and wherein the first and second curved portions are curved so that ends of the first and second curved portions face each other while being spaced apart from each other. ### Claim 3 (depends on 2) The secondary battery of claim 2, wherein an end of the extending portion is extended toward the opposite direction to the ends of the first and second curved portions. ### Claim 4 (depends on 3) The secondary battery of claim 3, wherein the intersecting portion and the extending portion are formed to correspond to a center line of the surface. ### Claim 5 (depends on 3) The secondary battery of claim 3, wherein the first and second curved portions are formed to have a pair of shapes corresponding to each other with the center line interposed therebetween. ### Claim 6 (depends on 3) The secondary battery of claim 3, wherein the secondary battery is a cylindrical secondary battery, wherein the outline of the surface forms an outer circle, and the closed curve obtained by connecting the end of the extending portion and the ends of the first and second curved portions corresponds to an inner circle, and wherein the inner circle is concentrically formed inside the outer circle and spaced apart from the outer circle at a predetermined distance. ### Claim 7 (depends on 6) The secondary battery of claim 6, wherein the radius of the inner circle is about half of that of the outer circle. ### Claim 8 (depends on 1) The secondary battery of claim 1, wherein the thickness of the section of the first or second curved portion is formed to be inclined in the direction facing the end of the first or second curved portion from the intersecting portion. ### Claim 9 (depends on 8) The secondary battery of claim 8, wherein the extending portion is formed in a straight line. ### Claim 10 (depends on 9) The secondary battery of claim 9, wherein the extending portion is formed to overlap with the center line of the surface. ### Claim 11 (depends on 9) The secondary battery of claim 9, wherein the thickness of the section of the extending portion is formed to be inclined in the direction facing the end of the extending portion from the intersecting portion. ### Claim 12 (depends on 11) The secondary battery of claim 11, wherein the thickness of the end of the extending portion is formed to be substantially identical to that of the end of the first or second curved portion. ### Claim 13 (depends on 9) The secondary battery of claim 9, wherein the thickness of the section of the extending portion is formed to be substantially identical to that of the intersecting portion. ### Claim 14 (depends on 1) The secondary battery of claim 1, wherein the intersecting portion is formed at the substantial center of the surface. ### Claim 15 (depends on 1) The secondary battery of claim 1, wherein the vent portion recessed inward is formed to the outer surface of the surface, and the inner surface of the surface is formed as a flat surface. ### Claim 16 A secondary battery, comprising: a can; and a vent portion formed at the base of the can having a plurality of fracture lines meeting at a point and at least one of the fracture lines having a varying thickness. ### Claim 17 (depends on 16) The secondary battery of claim 16, wherein the fracture lines include at least one straight line and at least two curved lines. ### Claim 18 (depends on 16) The secondary battery of claim 16, wherein the vent portion is formed as a recess in the bottom surface of the can. ### Claim 19 (depends on 16) The secondary battery of claim 16, further comprising a cap assembly affixed to the top of the can. ### Claim 20 (depends on 19) The secondary battery of claim 19, further comprising positive and negative electrodes and an electrolyte.