# US 12,009,484 B2 · Battery cell comprising separator having magnetic body formed therein and method for evaluating battery cell safety against internal short circuit by using same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,009,484 B2 - Document ID: US12009484B2 - Status: Granted - Kind: B2 - Application number: 17/631,367 - Filed: 2020-08-27 - Published: 2022-10-13 - Granted: 2024-06-11 - Earliest claimed: 2019-09-20 - Assignees: LG Energy Solution, Ltd. - Applicants: LG Energy Solution, Ltd. - Inventors: Seo Young Yoon; Tae Jong Kim - Web page: https://patentgrep.com/patent/US12009484B2 ## CPC - H01M 10/4235: {Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence)} - G01R 31/392: Determining battery ageing or deterioration, e.g. state of health - G01R 31/52: Testing for short-circuits, leakage current or ground faults - H01M 10/052: Li-accumulators - H01M 10/48: Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569) - H01M 50/409: Separators, membranes or diaphragms characterised by the material - H01M 50/431: Inorganic material - H01M 50/446: Composite material consisting of a mixture of organic and inorganic materials - H01M 50/451: comprising layers of only organic material and layers containing inorganic material - H01M 50/46: Separators, membranes or diaphragms characterised by their combination with electrodes - H01M 50/463: Separators, membranes or diaphragms characterised by their shape - H01M 50/586: inside the batteries, e.g. incorrect connections of electrodes - Y02E 60/10: Energy storage using batteries - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract The present invention relates to a battery cell comprising a separator in which a perforated line and magnetic bodies adjacent to the perforated line are formed, and a method for evaluating battery cell safety by using same, wherein the battery cell can induce an internal short circuit without physical deformation of the cell structure, and can be effectively applied to evaluation of battery cell safety against an internal short circuit. ## Claims ### Claim 1 A secondary battery having a structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode is housed in a battery case, wherein the separator includes: a perforated line which forms a two-dimensional closed shape on a surface of the separator; and a magnetic body formed in an area adjacent to, but spaced apart from, the perforated line, so as not to overlap the perforated line, wherein the magnetic body comprises a plurality of distinct magnetic body portions which are arranged continuously or discontinuously along the perforated line. ### Claim 2 (depends on 1) The battery cell of claim 1, wherein the perforated line has a structure in which a plurality of through-type slits or bead-type non-penetrating grooves are arranged discontinuously. ### Claim 3 (depends on 1) The battery cell of claim 1, wherein the magnetic body is in a form of a powder and is fully or partially impregnated in the separator. ### Claim 4 (depends on 1) The battery cell of claim 1, wherein the magnetic body is in a form of a bar, and is attached to one side or both sides of the separator. ### Claim 5 (depends on 1) The battery cell of claim 1, wherein the magnetic body has a structure including a core having magnetic properties and an insulating polymer shell surrounding the core. ### Claim 6 (depends on 5) The battery cell of claim 5, wherein the core is an alloy including one or more selected from the group consisting of iron (Fe), nickel (Ni), cobalt (Co), gadolinium (Gd), terbium (Tb), and dysprosium (Dy). ### Claim 7 (depends on 5) The battery cell of claim 5, wherein the insulating polymer shell comprises a polymer film. ### Claim 8 (depends on 1) The battery cell of claim 1, wherein the battery cell is a lithium secondary battery. ### Claim 9 A method of evaluating a safety of a battery cell according to an internal short circuit, comprising: inducing a short circuit inside the battery cell, wherein the battery cell has a structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode is housed in a battery case, wherein the separator includes: a perforated line which forms a two-dimensional closed shape on a surface of the separator; and a magnetic body which is formed in a region adjacent to, but spaced apart from, the perforated line, so as not to overlap the perforated line, wherein the magnetic body comprises a plurality of distinct magnetic body portions which are arranged continuously or discontinuously along the perforated line, and wherein, in the inducing the short circuit inside the battery cell, the magnet is rotated while the magnet is adjacent to or in contact with an outer peripheral surface of the battery cell, and the perforated line of the separator is partially or completely broken in response to the rotational motion of the magnet. ### Claim 10 (depends on 9) The method of claim 9, wherein the inducing the short circuit inside the battery cell is performed during a charge/discharge cycle for the battery cell.