Patents by Inventor RAGHUNATHAN K

RAGHUNATHAN K has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 10884062
    Abstract: A battery control system for a vehicle includes a battery state estimator configured to obtain a battery cell open circuit voltage (OCV) of a battery in response to a charging system charging the battery to a maximum charging voltage. The system includes a negative voltage determination module configured to determine a negative OCV of the battery based on the obtained cell or battery OCV. The system includes a voltage shift determination module configured to identify a difference between the negative OCV of the battery and a previous negative OCV of the battery. The system also includes a charge voltage module configured to selectively reduce the maximum charging voltage to a reduced maximum charging voltage based on the difference and transmit the reduced maximum charging voltage to the charging system. The charging system is instructed to charge the battery such that the battery does not exceed the reduced maximum charging voltage.
    Type: Grant
    Filed: October 30, 2018
    Date of Patent: January 5, 2021
    Assignee: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Raghunathan K, Ramona Y. Ying
  • Publication number: 20200388825
    Abstract: In an embodiment, an electrode comprises a current collector and an active layer located on at least one side of the current collector and in electrical communication with the current collector. The active layer comprises a binder and an expanded silicon; wherein the active layer expands by less than or equal to 10 volume percent when in use. In another embodiment, a method of forming an electrode comprises forming the electrode from a pre-cycled, expanded silicon.
    Type: Application
    Filed: June 10, 2019
    Publication date: December 10, 2020
    Inventors: Mark W. Verbrugge, Xiaosong Huang, Raghunathan K
  • Patent number: 10854882
    Abstract: A method of forming an electrode includes attaching a tab to a collector to form a pre-tabbed current collector; disposing the pre-tabbed current collector onto a non-stick substrate to form a workpiece; and casting a slurry onto the workpiece to form a film. The slurry includes an active material component, one or more carbon additives, and at least one of a filamentary copper additive and a dendritic copper additive. The method includes drying the film at a first temperature to form a dried film; curing the dried film under pressure at a second higher temperature to form a cured film; removing the cured film from the non-stick substrate to form a precursor film; and carbonizing and annealing the precursor film at a third higher temperature. Carbonizing forms a three-dimensional electrically-conductive network and annealing forms a second contiguous network of copper connected to the active material component to form the electrode.
    Type: Grant
    Filed: October 19, 2018
    Date of Patent: December 1, 2020
    Assignee: GM Global Technology Operations LLC
    Inventors: Ion C. Halalay, Raghunathan K
  • Publication number: 20200350558
    Abstract: Methods for fabricating electrodes include coating a current collector with a slurry and pyrolyzing the coated current collector to produce the electrode with a layer of silicon-based host material. The slurry can include one or more solvents and a dry fraction having silicon particles, one or more polymeric binders, and carbon fibers. Pyrolyzing includes heating at a first temperature, and subsequently heating at a second temperature higher than the first temperature. The silicon particles include single-phase silicon and/or Li2Si, have an average particle diameter of less than 10 ?m, and can be 70% of the dry fraction. The polymeric binders can be only polyacrylonitrile, or optionally one or more fluorinated polymers. The carbon fibers have an average diameter of at least about 50 nm, an average length of at least about 1 ?m, and can be up to 15 wt. % of the dry fraction.
    Type: Application
    Filed: May 2, 2019
    Publication date: November 5, 2020
    Inventors: Niccolo Jimenez, Michael P. Balogh, Ion C. Halalay, Raghunathan K
  • Patent number: 10741812
    Abstract: Methods of scavenging acid in a lithium-ion electrochemical cell are provided. An electrolyte solution that contains an acid or is capable of forming the acid is contacted with a polymer comprising a nitrogen-containing acid-trapping moiety selected from the group consisting of: an amine group, a pyridine group, and combinations thereof. The nitrogen-containing acid-trapping moiety scavenges acidic species present in the electrolyte solution by participating in a Lewis acid-base neutralization reaction. The electrolyte solution comprises a lithium salt and one or more solvents and is contained in the electrochemical cell that further comprises a first electrode, a second electrode having an opposite polarity from the first electrode, and a porous separator. Lithium ions can be cycled through the separator and electrolyte solution from the first electrode to the second electrode, where acid generated during the cycling is scavenged by the polymer comprising a nitrogen-containing acid-trapping moiety.
    Type: Grant
    Filed: June 19, 2017
    Date of Patent: August 11, 2020
    Assignees: GM GLOBAL TECHNOLOGY OPERATIONS LLC, BAR-ILAN UNIVERSITY
    Inventors: Shalom Luski, Doron Aurbach, Timothy J. Fuller, Ion C. Halalay, Anjan Banerjee, Baruch Ziv, Raghunathan K
  • Publication number: 20200132777
    Abstract: A battery control system for a vehicle includes a battery state estimator configured to obtain a battery cell open circuit voltage (OCV) of a battery in response to a charging system charging the battery to a maximum charging voltage. The system includes a negative voltage determination module configured to determine a negative OCV of the battery based on the obtained cell or battery OCV. The system includes a voltage shift determination module configured to identify a difference between the negative OCV of the battery and a previous negative OCV of the battery. The system also includes a charge voltage module configured to selectively reduce the maximum charging voltage to a reduced maximum charging voltage based on the difference and transmit the reduced maximum charging voltage to the charging system. The charging system is instructed to charge the battery such that the battery does not exceed the reduced maximum charging voltage.
    Type: Application
    Filed: October 30, 2018
    Publication date: April 30, 2020
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Raghunathan K, Ramona Y. YING
  • Publication number: 20200127292
    Abstract: A method of forming an electrode includes attaching a tab to a collector to form a pre-tabbed current collector; disposing the pre-tabbed current collector onto a non-stick substrate to form a workpiece; and casting a slurry onto the workpiece to form a film. The slurry includes an active material component, one or more carbon additives, and at least one of a filamentary copper additive and a dendritic copper additive. The method includes drying the film at a first temperature to form a dried film; curing the dried film under pressure at a second higher temperature to form a cured film; removing the cured film from the non-stick substrate to form a precursor film; and carbonizing and annealing the precursor film at a third higher temperature. Carbonizing forms a three-dimensional electrically-conductive network and annealing forms a second contiguous network of copper connected to the active material component to form the electrode.
    Type: Application
    Filed: October 19, 2018
    Publication date: April 23, 2020
    Applicant: GM Global Technology Operations LLC
    Inventors: Ion C. Halalay, Raghunathan K
  • Publication number: 20190379090
    Abstract: During the charging of lithium-ion batteries, comprising graphite anode particles, the goal is to intercalate lithium into the anode materials as LiC6. But it is possible to conduct the charging process at a rate that lithium is undesirably plated, undetected, as lithium metal on the particles of graphite. During an open-circuit period of battery operation, immediately following such a charging period, the presence of lithium plating can be detected, using a computer-based monitoring system, by continually measuring the cell potential (Vcell) over a brief period of open-circuit time, fitting the open-circuit voltage data to a best cubic polynomial fit, and then determining dVcell/dt (mV/s) from the polynomial fit over a like period of time. It is found that the presence of a maximum or a minimum in the derivative curve (a local minimum) reliably correlates with plated lithium on the graphite particles of the anode.
    Type: Application
    Filed: June 12, 2018
    Publication date: December 12, 2019
    Inventors: Mark W. Verbrugge, Charles W. Wampler, Daniel R. Baker, Raghunathan K, Brian J. Koch, Alfred Zhang
  • Publication number: 20190308630
    Abstract: A discharge module is configured to determine a change in capacity of the battery between: (i) a measurement of a first open circuit voltage (OCV) of a battery of a vehicle; and (ii) a measurement of a second OCV of the battery. A lookup table is stored in memory and includes reference states of charge (SOCs) indexed by reference OCVs and reference capacities. A relationship module is configured to: from the lookup table, identify a first set of the reference SOCs associated with the first OCV and the reference capacities, respectively; from the lookup table, identify a second set of the reference SOCs associated with the second OCV and the reference capacities, respectively; determine changes in SOC associated with the reference capacities; determine changes in capacity; and determine an equation that relates changes in capacity to capacity based on the changes in capacity and the reference capacities, respectively.
    Type: Application
    Filed: April 10, 2018
    Publication date: October 10, 2019
    Inventors: Raghunathan K, Ramona Y. Ying, Brian J. Koch, Charles W. Wampler, II
  • Patent number: 10408883
    Abstract: Evaluation of a DC power source can include communication with a voltmeter that is arranged to monitor electrical potential across positive and negative electrodes. The method includes determining a full-cell open-circuit voltage (“OCV”), an associated positive half-cell OCV, and an associated negative half-cell OCV at a start-of-life point of the DC power source. A lithium balance model is executed to determine a plurality of beginning states associated with an electrode alignment of the DC power source. An in-use state for the full-cell OCV is determined. An optimization routine is executed employing the lithium balance model to determine in-use states associated with the electrode alignment of the DC power source based upon the in-use state for the full-cell OCV and the beginning states associated with electrode alignment. A negative-to-positive (“N/P”) ratio is determined based upon the in-use states, and battery life is evaluated based upon the N/P ratio.
    Type: Grant
    Filed: March 31, 2017
    Date of Patent: September 10, 2019
    Assignee: GM Global Technology Operations LLC
    Inventors: Raghunathan K, Brian J. Koch
  • Publication number: 20190252671
    Abstract: A lithium ion battery has a positive electrode or cathode having a silicon modified mixed metal oxide including a compound having empirical formula Li[LiyMna-xSixMIIIbMIIc]O2??(I) wherein y=0.01-0.33; x=0.001-0.15; a, b, and c are each greater than zero; MIII is a trivalent metal or a combination of metals with an average valence of +3; MII is a divalent metal or a combination of metals with an average valence of +2; and y+4a+3b+2c is equal to 3 or about 3. Such a silicon modified mixed metal oxide may be exemplified by formula: Li [Li0.2 Mn0.49 Si0.05 Ni0.13 Co0.13]O2.
    Type: Application
    Filed: February 12, 2018
    Publication date: August 15, 2019
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Yan WU, Leah NATION, Raghunathan K
  • Publication number: 20190190012
    Abstract: A hybrid negative electrode having high energy capacity and high power capacity used in an electrochemical cell for lithium-ion electrochemical batteries is provided. The electrode may include about 40% to about 60% by mass of a high energy capacity electroactive material having a specific capacity of greater than or equal to about 310 mAh/g and about 40% to about 60% by mass of a high power capacity electroactive material having a potential versus Li/Li+ of greater than or equal to about 1 V during lithium ion insertion. The hybrid negative electrode is capable of a charge rate of greater than or equal to about 4 C at 25° C. In other variations, an electrochemical cell is provided that includes a first negative electrode with a high energy capacity electroactive material and a second negative electrode with a high power capacity electroactive material.
    Type: Application
    Filed: December 15, 2017
    Publication date: June 20, 2019
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Yan Wu, Meng Jiang, Mark W. Verbrugge, Raghunathan K
  • Patent number: 10288692
    Abstract: System and methods for estimating a relationship between a SOC and an OCV of a battery system included in a vehicle are presented. In certain embodiments, an initial relationship between an open circuit voltage (“OCV”) and a state of charge (“SOC”) of a cell of the battery system may be determined at a beginning of life of the cell. Changes in one or more stoichiometric points of a half-cell of the cell may be determined as the cell ages. Based on the determined stoichiometric point changes of the half-cell, an initial relationship between the OCV and the SOC of the cell may be adjusted to generate an updated relationship between the OCV and the SOC of the cell.
    Type: Grant
    Filed: June 15, 2015
    Date of Patent: May 14, 2019
    Assignee: GM Global Technology Operations LLC
    Inventors: Patricia M. Laskowsky, Patrick Frost, Raghunathan K, Brian J. Koch, John E. Novak
  • Publication number: 20180366781
    Abstract: Methods of scavenging acid in a lithium-ion electrochemical cell are provided. An electrolyte solution that contains an acid or is capable of forming the acid is contacted with a polymer comprising a nitrogen-containing acid-trapping moiety selected from the group consisting of: an amine group, a pyridine group, and combinations thereof. The nitrogen-containing acid-trapping moiety scavenges acidic species present in the electrolyte solution by participating in a Lewis acid-base neutralization reaction. The electrolyte solution comprises a lithium salt and one or more solvents and is contained in the electrochemical cell that further comprises a first electrode, a second electrode having an opposite polarity from the first electrode, and a porous separator. Lithium ions can be cycled through the separator and electrolyte solution from the first electrode to the second electrode, where acid generated during the cycling is scavenged by the polymer comprising a nitrogen-containing acid-trapping moiety.
    Type: Application
    Filed: June 19, 2017
    Publication date: December 20, 2018
    Inventors: Shalom Luski, Doron Aurbach, Timothy J. Fuller, Ion C. Halalay, Anjan Banerjee, Baruch Ziv, Raghunathan K
  • Publication number: 20180284195
    Abstract: Evaluation of a DC power source can include communication with a voltmeter that is arranged to monitor electrical potential across positive and negative electrodes. The method includes determining a full-cell open-circuit voltage (“OCV”), an associated positive half-cell OCV, and an associated negative half-cell OCV at a start-of-life point of the DC power source. A lithium balance model is executed to determine a plurality of beginning states associated with an electrode alignment of the DC power source. An in-use state for the full-cell OCV is determined. An optimization routine is executed employing the lithium balance model to determine in-use states associated with the electrode alignment of the DC power source based upon the in-use state for the full-cell OCV and the beginning states associated with electrode alignment. A negative-to-positive (“N/P”) ratio is determined based upon the in-use states, and battery life is evaluated based upon the N/P ratio.
    Type: Application
    Filed: March 31, 2017
    Publication date: October 4, 2018
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Raghunathan K, Brian J. Koch
  • Patent number: 10071648
    Abstract: A method avoids lithium plating of a negative electrode in a battery cell. A voltage level of a positive electrode is determined in an initial battery charging process having a charging power level. A charging rate is modified in response to the determined voltage by increasing or decreasing the charging rate when the voltage is respectively less or greater than a voltage threshold. A charging profile is recorded for the power level. A subsequent charging process at the same power level is controlled using the recorded profile, which is possibly age-indexed to an age of an actual battery used in the subsequent charging process. A system includes the battery cell and a battery cell cycler device programmed to execute the method. An electric machine may be connected to the battery cell and a load, with a controller controlling the subsequent charging process using the profiles.
    Type: Grant
    Filed: April 24, 2017
    Date of Patent: September 11, 2018
    Assignee: GM Global Technology Operations LLC
    Inventor: Raghunathan K
  • Publication number: 20180205114
    Abstract: An electrode material for an electrochemical cell is provided. The electrode includes a porous hydrophilic substrate, an electroactive material, and a binder. The porous hydrophilic substrate includes a plurality of voids and may be formed from cellulose or cellulosic derivative material. The electroactive material is dispersed in at least a portion of the voids of the hydrophilic substrate. In other aspects, another electrode material for an electrochemical cell is provided. The electrode includes a porous hydrophilic substrate, an electroactive material, an electrically conductive particle, and a binder. The porous hydrophilic substrate includes a plurality of voids and may be formed from cellulose or cellulosic derivative material. The electroactive material and the electrically conductive particle are dispersed in at least a portion of the voids of the hydrophilic substrate. In still other aspects, the porous hydrophilic substrate comprises a coating that is electrically conductive.
    Type: Application
    Filed: January 13, 2017
    Publication date: July 19, 2018
    Applicants: GM Global Technology Operations LLC, McMaster University
    Inventors: Allen D. Pauric, Meng Jiang, Gillian R. Goward, Raghunathan K
  • Publication number: 20160363630
    Abstract: System and methods for estimating a relationship between a SOC and an OCV of a battery system included in a vehicle are presented. In certain embodiments, an initial relationship between an open circuit voltage (“OCV”) and a state of charge (“SOC”) of a cell of the battery system may be determined at a beginning of life of the cell. Changes in one or more stoichiometric points of a half-cell of the cell may be determined as the cell ages. Based on the determined stoichiometric point changes of the half-cell, an initial relationship between the OCV and the SOC of the cell may be adjusted to generate an updated relationship between the OCV and the SOC of the cell.
    Type: Application
    Filed: June 15, 2015
    Publication date: December 15, 2016
    Inventors: PATRICIA M. LASKOWSKY, PATRICK FROST, RAGHUNATHAN K, BRIAN J. KOCH, JOHN E. NOVAK