# US 12,002,932 B2 · Surface reforming of negative electrode layers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,002,932 B2 - Document ID: US12002932B2 - Status: Granted - Kind: B2 - Application number: 17/353,027 - Filed: 2021-06-21 - Published: 2022-12-22 - Granted: 2024-06-04 - Earliest claimed: 2021-06-21 - Assignees: GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC - Inventors: Jing Gao; Xingcheng Xiao; Brian J. Koch - Web page: https://patentgrep.com/patent/US12002932B2 ## CPC - H01M 10/44: Methods for charging or discharging (circuits for charging H02J7/00) - H01M 10/052: Li-accumulators - H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries - H01M 10/4242: {Regeneration of electrolyte or reactants} - 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 50/569: Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals (battery terminal connectors with integrated measuring arrangements G01R31/364) - 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 method of reforming a negative electrode layer of a secondary lithium battery may include execution of a reforming cycle that reforms a major facing surface of the negative electrode layer by eliminating at least a portion of a lithium dendrite or other lithium-containing surface irregularity that has formed on the major facing surface of the negative electrode layer. ## Claims ### Claim 1 A method of reforming a negative electrode layer of a secondary lithium battery, the method comprising: measuring an electrical parameter associated with a porous sensory layer disposed between a major facing surface of a negative electrode layer and an opposing surface of a positive electrode layer, the porous sensory layer including an electrically conductive material and being electrically isolated from the negative electrode layer and the positive electrode layer; evaluating the electrical parameter to determine whether a lithium dendrite is present on the major facing surface of the negative electrode layer that extends continuously from the major facing surface of the negative electrode layer to the porous sensory layer; and responsive to a positive determination that the lithium dendrite is present on the major facing surface of the negative electrode layer, executing a reforming cycle that reforms the major facing surface of the negative electrode layer and eliminates at least a portion of the lithium dendrite such that the lithium dendrite does not extend continuously from the major facing surface of the negative electrode layer to the porous sensory layer, wherein the reforming cycle is executed by at least one of: (i) passing a pulsed electric current between the negative electrode layer and the porous sensory layer and through the lithium dendrite, or (ii) applying a voltage pulse across the negative electrode and the porous sensory layer such that electric current flows through the lithium dendrite. ### Claim 2 (depends on 1) The method of claim 1 wherein the electrical parameter is an electrical potential difference between the porous sensory layer and the negative electrode layer, and wherein the method further comprises: executing the reforming cycle when a measurement of the electrical potential difference between the porous sensory layer and the negative electrode layer is about zero. ### Claim 3 (depends on 1) The method of claim 1 wherein the reforming cycle is executed by passing a pulsed electric current between the negative electrode layer and the porous sensory layer and through the lithium dendrite. ### Claim 4 (depends on 1) The method of claim 1 wherein execution of the reforming cycle generates heat within the lithium dendrite. ### Claim 5 (depends on 1) The method of claim 1 wherein the reforming cycle is executed by applying a discharge current to the negative electrode layer that at least partially discharges the electrochemical cell. ### Claim 6 (depends on 5) The method of claim 5 wherein the discharge current applied to the negative electrode layer exhibits a pulsed current profile that includes at least two current pulses separate in time. ### Claim 7 (depends on 1) The method of claim 1 further comprising: recording a number of charge and discharge cycles experienced by the electrochemical cell, and executing the reforming cycle when the number of charge and discharge cycles experienced by the electrochemical cell is greater than a predetermined number of charge and discharge cycles. ### Claim 8 (depends on 1) The method of claim 1 wherein the negative electrode layer: consists essentially of lithium and comprises, by weight, greater than 97% lithium. ### Claim 9 (depends on 1) The method of claim 1 further comprising: cycling the electrochemical cell by repeatedly charging and discharging the electrochemical cell by respectively applying a charging current to the positive electrode layer and a first discharge current to the negative electrode layer; measuring at least one of: (i) a number of charging and discharge cycles of the electrochemical cell, (ii) a measured electrical resistance of the electrochemical cell, or (iii) a measured electric potential difference between the negative electrode layer and the positive electrode layer; and executing the reforming cycle when: (i) the number of charging and discharge cycles is greater than a predetermined number, (ii) the measured electrical resistance is greater than a predetermined electrical resistance value, or (iii) the measured electrical potential difference is less than a predetermined electrical potential difference value, wherein cycling the electrochemical cell forms lithium dendrites or lithium-containing surface irregularities on the major facing surface of the negative electrode layer, and wherein execution of the reforming cycle eliminates at least a portion of the lithium dendrites or the lithium-containing surface irregularities on the major facing surface of the negative electrode. ### Claim 10 (depends on 9) The method of claim 9 wherein execution of the reforming cycle includes applying a second discharge current to the negative electrode layer to at least partially discharge the electrochemical cell, and wherein the second discharge current is greater than the first discharge current. ### Claim 11 (depends on 10) The method of claim 10 wherein the second discharge current exhibits a pulsed current profile that includes at least two current pulses separate in time. ### Claim 12 (depends on 1) The method of claim 1 wherein the electrical parameter is an electric current flowing through the porous sensory layer, and wherein the method further comprises: executing the reforming cycle when a measurement of the electric current flowing through the porous sensory layer is greater than zero. ### Claim 13 (depends on 1) The method of claim 1 wherein the reforming cycle is executed by applying a voltage pulse across the negative electrode layer and the porous sensory layer such that electric current flows through the lithium dendrite. ### Claim 14 (depends on 1) The method of claim 1 wherein the negative electrode layer comprises an electrochemically active host material of graphite or silicon.