# US 10,374,219 B2 · Lithium ion secondary battery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,219 B2 - Document ID: US10374219B2 - Status: Granted - Kind: B2 - Application number: 14/119,201 - Filed: 2012-04-13 - Published: 2014-05-08 - Granted: 2019-08-06 - Earliest claimed: 2011-06-10 - Assignees: NEC Corporation - Applicants: Ryuichi Kasahara; Jiro Iriyama; Shin Serizawa; Hiroo Takahashi; Tatsuji Numata - Inventors: Ryuichi Kasahara; Jiro Iriyama; Shin Serizawa; Hiroo Takahashi; Tatsuji Numata - Web page: https://patentgrep.com/patent/US10374219B2 ## CPC - H01M 4/13: Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof - H01M 4/0404: {by coating on electrode collectors} - H01M 4/134: Electrodes based on metals, Si or alloys - H01M 4/1395: of electrodes based on metals, Si or alloys - H01M 4/622: {being polymers} - H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries - H01M 10/0568: characterised by the solutes - H01M 10/0585: of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators - Y02E 60/10: Energy storage using batteries - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - Y02T 10/70: Energy storage systems for electromobility, e.g. 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 - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract The object of an exemplary embodiment of the invention is to provide a lithium ion secondary battery having an excellent charge and discharge cycle property. An exemplary embodiment of the invention is a lithium ion secondary battery, comprising a battery assembly in which a positive electrode and a negative electrode are stacked through a separator and a package in which the battery assembly and an electrolyte are placed; wherein the negative electrode comprises a negative electrode collector which is composed of a metal and a negative electrode active material layer which is formed on the negative electrode collector and which comprises a negative electrode active material and a binder; wherein the negative electrode collector and the negative electrode active material layer have a crack which is formed so as to be communicated with each of them; and wherein the crack reaches an outer peripheral edge from an inside of the negative electrode. ## Claims ### Claim 1 A lithium ion secondary battery, comprising a battery assembly in which a positive electrode and a negative electrode are placed oppositely through a separator and a package which accommodates the battery assembly and an electrolyte; wherein the negative electrode comprises a negative electrode collector, which is composed of a metal, and a negative electrode active material layer which comprises a negative electrode active material and a binder and which is formed on the negative electrode collector; wherein the negative electrode collector has a first crack and the negative electrode active material layer has a second crack, and the first and second cracks form a slit; wherein the slit reaches an outer peripheral edge from an inside of the negative electrode; wherein the negative electrode active material comprises at least a particle comprising simple substance silicon, wherein the weight ratio of the simple substance silicon in the negative electrode active material layer is 5% or more and less than 50%; and wherein the slit is formed by cutting both the negative electrode collector and the negative electrode active material layer. ### Claim 2 (depends on 1) The lithium ion secondary battery according to claim 1, wherein the negative electrode collector is composed of a metal foil. ### Claim 3 (depends on 1) The lithium ion secondary battery according to claim 1, wherein the binder comprises a thermoset resin. ### Claim 4 (depends on 3) The lithium ion secondary battery according to claim 3, wherein the binder comprises a polyamide, a polyimide, or a polyamide-imide. ### Claim 5 (depends on 1) The lithium ion secondary battery according to claim 1, wherein the electrolyte is a non-aqueous electrolyte liquid in which a lithium salt is dissolved in a non-aqueous solvent. ### Claim 6 (depends on 1) The lithium ion secondary battery according to claim 1, wherein the package is a laminate film. ### Claim 7 (depends on 1) The lithium ion secondary battery according to claim 1, wherein the positive electrode and the negative electrode have a flat shape. ### Claim 8 (depends on 7) The lithium ion secondary battery according to claim 7, wherein the area of the negative electrode is larger than the area of the positive electrode; wherein the positive electrode is disposed in the inside of the outer peripheral edge of the negative electrode; and wherein the slit reaches at least a portion which is opposite to the inside of the outer peripheral edge of the positive electrode from the outer peripheral edge of the negative electrode. ### Claim 9 (depends on 1) The lithium ion secondary battery according to claim 1, wherein the weight ratio of the simple substance silicon in the negative electrode active material layer is 20% or more and less than 45%. ### Claim 10 (depends on 1) The lithium ion secondary battery according to claim 1, wherein the first crack reaches the back surface opposite to that front surface of the negative electrode collector contacting with the negative electrode material layer.