Patents by Inventor Nagappan Ramaswamy

Nagappan Ramaswamy 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: 11799088
    Abstract: A cathode configured for use within a fuel cell system is provided. The cathode includes a cathode substrate. The cathode further includes a coating disposed upon the cathode substrate and including a fluorocarbon polymer additive configured for sintering at a temperature of less than 200° C. The fluorocarbon polymer additive may be mixed with a catalyst ink coating or may be applied separately as a topcoat layer.
    Type: Grant
    Filed: January 11, 2022
    Date of Patent: October 24, 2023
    Assignee: GM Global Technology Operations LLC
    Inventors: Nagappan Ramaswamy, Roland J. Koestner, Swaminatha P. Kumaraguru
  • Publication number: 20230223552
    Abstract: A cathode configured for use within a fuel cell system is provided. The cathode includes a cathode substrate. The cathode further includes a coating disposed upon the cathode substrate and including a fluorocarbon polymer additive configured for sintering at a temperature of less than 200° C. The fluorocarbon polymer additive may be mixed with a catalyst ink coating or may be applied separately as a topcoat layer.
    Type: Application
    Filed: January 11, 2022
    Publication date: July 13, 2023
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Nagappan Ramaswamy, Roland J. Koestner, Swaminatha P. Kumaraguru
  • Patent number: 11302926
    Abstract: Systems, methods, fuel cells, and mixtures to inhibit ionomer permeation into porous substrates using a crosslinked ionomer are described. A method includes preparing an ionomer premix, mixing a crosslinking additive with the ionomer premix to thereby form a crosslinked-ionomer solution, and adding catalyst particles to the crosslinked-ionomer solution to produce a catalyst ink. The ionomer premix includes an ionomer dispersed within a solvent. The catalyst ink includes the catalyst particles distributed homogenously therethrough. The catalyst ink may be cast onto a porous substrate and dried to thereby form a catalyst layer for use in a fuel cell.
    Type: Grant
    Filed: August 27, 2019
    Date of Patent: April 12, 2022
    Assignee: GM Global Technology Operations LLC
    Inventors: Nagappan Ramaswamy, Roland J. Koestner, Swaminatha P. Kumaraguru
  • Publication number: 20210066726
    Abstract: Systems, methods, fuel cells, and mixtures to inhibit ionomer permeation into porous substrates using a crosslinked ionomer are described. A method includes preparing an ionomer premix, mixing a crosslinking additive with the ionomer premix to thereby form a crosslinked-ionomer solution, and adding catalyst particles to the crosslinked-ionomer solution to produce a catalyst ink. The ionomer premix includes an ionomer dispersed within a solvent. The catalyst ink includes the catalyst particles distributed homogenously therethrough. The catalyst ink may be cast onto a porous substrate and dried to thereby form a catalyst layer for use in a fuel cell.
    Type: Application
    Filed: August 27, 2019
    Publication date: March 4, 2021
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Nagappan Ramaswamy, Roland J. Koestner, Swaminatha P. Kumaraguru
  • Patent number: 10784527
    Abstract: A controller-executed method for conditioning a membrane electrode assembly (MEA) in a fuel cell for use in a fuel cell stack includes humidifying a fuel inlet to the stack to a threshold relative humidity level, and maintaining a current density and cell voltage of the fuel cell at a calibrated current density level and hold voltage level, respectively, via the controller in at least one voltage recovery stage. The recovery stage has a predetermined voltage recovery duration. The method includes measuring the cell voltage after completing the predetermined voltage recovery duration, and executing a control action with respect to the fuel cell or fuel cell stack responsive to the measured cell voltage exceeding a target voltage, including recording a diagnostic code via the controller indicative of successful conditioning of the MEA. A fuel cell system includes the fuel cell stack and controller.
    Type: Grant
    Filed: December 19, 2017
    Date of Patent: September 22, 2020
    Assignee: GM Global Technology Operations LLC
    Inventors: Swaminatha P. Kumaraguru, Jingxin Zhang, Nagappan Ramaswamy, Pinkhas A. Rapaport
  • Publication number: 20190280307
    Abstract: A polymer electrolyte membrane fuel cell includes a proton-conductive polymer electrolyte membrane, an anode catalyst layer overlying a first face of the polymer electrolyte membrane, and a cathode catalyst layer overlying a second face of the polymer electrolyte membrane. At least one of the anode catalyst layer or the cathode catalyst layer includes a composite electrode layer that comprises a colloidal or soluble ionomer binder component, a catalyst dispersed along with the colloidal or soluble ionomer binder component, and insoluble ionomer nanofibers disseminated throughout a thickness of the composite electrode layer. The presence of the insoluble ionomer nanofibers within the composite electrode layer may enhance the voltage performance of the fuel cell, particularly at high current densities and/or low relative humidity operating conditions. A method of making a composite electrode layer for a polymer electrolyte membrane fuel cell is also disclosed.
    Type: Application
    Filed: March 8, 2018
    Publication date: September 12, 2019
    Inventors: Nagappan Ramaswamy, Timothy Fuller, Swaminatha Kumaraguru
  • Publication number: 20190190040
    Abstract: A controller-executed method for conditioning a membrane electrode assembly (MEA) in a fuel cell for use in a fuel cell stack includes humidifying a fuel inlet to the stack to a threshold relative humidity level, and maintaining a current density and cell voltage of the fuel cell at a calibrated current density level and hold voltage level, respectively, via the controller in at least one voltage recovery stage. The recovery stage has a predetermined voltage recovery duration. The method includes measuring the cell voltage after completing the predetermined voltage recovery duration, and executing a control action with respect to the fuel cell or fuel cell stack responsive to the measured cell voltage exceeding a target voltage, including recording a diagnostic code via the controller indicative of successful conditioning of the MEA. A fuel cell system includes the fuel cell stack and controller.
    Type: Application
    Filed: December 19, 2017
    Publication date: June 20, 2019
    Applicant: GM Global Technology Operations LLC
    Inventors: Swaminatha P. Kumaraguru, Jingxin Zhang, Nagappan Ramaswamy, Pinkhas A. Rapaport
  • Publication number: 20180366738
    Abstract: Systems and methods of the present disclosure include supplying a porous substrate, heating the porous substrate to produce a pre-heated substrate, applying an electrode ink to the pre-heated substrate to produce a coated substrate, and drying the electrode ink of the coated substrate to produce an electrode on the porous substrate. The pre-heated substrate has a temperature greater than 23° C. The applying occurs via a coating mechanism. The electrode ink includes a catalyst and an ionomer dispersed in a solvent. The drying occurs via a drying mechanism.
    Type: Application
    Filed: June 16, 2017
    Publication date: December 20, 2018
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Nagappan Ramaswamy, Ellazar V. Niangar, Balasubramanian Lakshmanan
  • Patent number: 10158128
    Abstract: Disclosed are fuel cell stack break-in procedures, conditioning systems for performing break-in procedures, and motor vehicles with a fuel cell stack conditioned in accordance with disclosed break-in procedures. A break-in method is disclosed for conditioning a membrane assembly of a fuel cell stack. The method includes transmitting humidified hydrogen to the anode of the membrane assembly, and transmitting deionized water to the cathode of the membrane assembly. An electric current and voltage cycle are applied across the fuel cell stack while the fuel cell stack is operated in a hydrogen pumping mode until the fuel cell stack is determined to operate at a predetermined threshold for a fuel cell stack voltage output capability. During hydrogen pumping, the membrane assembly oxidizes the humidified hydrogen, transports protons from the anode to the cathode across the proton conducting membrane, and regenerates the protons in the cathode through a hydrogen evolution reaction.
    Type: Grant
    Filed: March 7, 2017
    Date of Patent: December 18, 2018
    Assignee: GM Global Technology Operations LLC
    Inventors: Jingxin Zhang, Nagappan Ramaswamy, Balasubramanian Lakshmanan, Swaminatha P. Kumaraguru
  • Publication number: 20180261858
    Abstract: Disclosed are fuel cell stack break-in procedures, conditioning systems for performing break-in procedures, and motor vehicles with a fuel cell stack conditioned in accordance with disclosed break-in procedures. A break-in method is disclosed for conditioning a membrane assembly of a fuel cell stack. The method includes transmitting humidified hydrogen to the anode of the membrane assembly, and transmitting deionized water to the cathode of the membrane assembly. An electric current and voltage cycle are applied across the fuel cell stack while the fuel cell stack is operated in a hydrogen pumping mode until the fuel cell stack is determined to operate at a predetermined threshold for a fuel cell stack voltage output capability. During hydrogen pumping, the membrane assembly oxidizes the humidified hydrogen, transports protons from the anode to the cathode across the proton conducting membrane, and regenerates the protons in the cathode through a hydrogen evolution reaction.
    Type: Application
    Filed: March 7, 2017
    Publication date: September 13, 2018
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Jingxin Zhang, Nagappan Ramaswamy, Balasubramanian Lakshmanan, Swaminatha P. Kumaraguru
  • Patent number: 9866056
    Abstract: Provided are methods and apparatus for charging a lithium sulfur (Li—S) battery. The Li—S battery has at least one unit cell comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between. One method provides controlled application of voltage pulses at the beginning of the charging process. An application period is initiated after a discharge cycle of the Li—S battery is complete. During the application period, voltage pulses are provided to the Li—S battery. The voltage pulses are less than a constant current charging voltage. Constant current charging is initiated after the application period has elapsed.
    Type: Grant
    Filed: March 31, 2016
    Date of Patent: January 9, 2018
    Assignee: Nissan North America, Inc.
    Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory Dileo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara
  • Patent number: 9627684
    Abstract: An anode active material for a lithium-ion battery cell comprises low density silicon. The anode active material is provided in an anode for a lithium-ion battery. Also disclosed are methods of making the anode active material.
    Type: Grant
    Filed: February 14, 2014
    Date of Patent: April 18, 2017
    Assignee: Nissan North America, Inc.
    Inventors: Nagappan Ramaswamy, Peter Aurora, Taehee Han
  • Patent number: 9590252
    Abstract: A cathode for a lithium-sulfur battery cell includes positive active material comprising sulfur and carbon coated onto an electrode substrate and gold nanoparticles affixed to the positive active material and configured to direct growth and deposition of lithium sulfide. A lithium ion battery cell, battery stack and method of making the cathodes are also provided.
    Type: Grant
    Filed: February 14, 2014
    Date of Patent: March 7, 2017
    Assignee: Nissan North America, Inc.
    Inventors: Nagappan Ramaswamy, Peter Aurora, Taehee Han
  • Publication number: 20160218522
    Abstract: Provided are methods and apparatus for charging a lithium sulfur (Li—S) battery. The Li—S battery has at least one unit cell comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between. One method provides controlled application of voltage pulses at the beginning of the charging process. An application period is initiated after a discharge cycle of the Li—S battery is complete. During the application period, voltage pulses are provided to the Li—S battery. The voltage pulses are less than a constant current charging voltage. Constant current charging is initiated after the application period has elapsed.
    Type: Application
    Filed: March 31, 2016
    Publication date: July 28, 2016
    Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory DiLeo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara
  • Patent number: 9379417
    Abstract: Methods and apparatus are provided for discharging a Li—S battery having at least one battery unit comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between. One method comprises electrochemically surface treating the sulfur-containing cathode during discharge of the battery. A method of electrochemically surface treating a cathode of a lithium-sulfide battery comprises applying at least one oxidative voltage pulse during a pulse application period while the lithium-sulfur battery discharges and controlling pulse characteristics during the pulse application period, the pulse characteristics configured to affect a morphology of lithium sulfide forming on the sulfur-containing cathode during discharge.
    Type: Grant
    Filed: February 4, 2014
    Date of Patent: June 28, 2016
    Assignee: NISSAN NORTH AMERICA, INC.
    Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory DiLeo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara
  • Patent number: 9331364
    Abstract: Provided are methods and apparatus for charging a lithium sulfur (Li—S) battery. The Li—S battery has at least one unit cell comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between. One method provides controlled application of voltage pulses at the beginning of the charging process. An application period is initiated after a discharge cycle of the Li—S battery is complete. During the application period, voltage pulses are provided to the Li—S battery. The voltage pulses are less than a constant current charging voltage. Constant current charging is initiated after the application period has elapsed.
    Type: Grant
    Filed: February 4, 2014
    Date of Patent: May 3, 2016
    Assignee: NISSAN NORTH AMERICA, INC.
    Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory DiLeo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara
  • Patent number: 9186653
    Abstract: A catalyst for use in at the anode of direct methanol fuel cells is made from nanoparticles having a core-shell structure. The core is an alloy of platinum and gold. The core is surrounded by a first shell of ruthenium and a second shell containing a ternary alloy of platinum, gold, and ruthenium. The catalyst can be made by a reverse-micelle method or by a single-phase scalable method. The catalyst is highly stable under conditions of use and resists dissolution of ruthenium or platinum.
    Type: Grant
    Filed: June 17, 2011
    Date of Patent: November 17, 2015
    Assignee: Northeastern University
    Inventors: Sanjeev Mukerjee, Qinggang He, Nagappan Ramaswamy
  • Publication number: 20150236350
    Abstract: A cathode for a lithium-sulfur battery cell includes positive active material comprising sulfur and carbon coated onto an electrode substrate and gold nanoparticles affixed to the positive active material and configured to direct growth and deposition of lithium sulfide. A lithium ion battery cell, battery stack and method of making the cathodes are also provided.
    Type: Application
    Filed: February 14, 2014
    Publication date: August 20, 2015
    Applicant: Nissan North American, Inc.
    Inventors: Nagappan Ramaswamy, Peter Aurora, Taehee Han
  • Publication number: 20150236344
    Abstract: An anode active material for a lithium-ion battery cell comprises low density silicon. The anode active material is provided in an anode for a lithium-ion battery. Also disclosed are methods of making the anode active material.
    Type: Application
    Filed: February 14, 2014
    Publication date: August 20, 2015
    Applicant: Nissan North America, Inc.
    Inventors: Nagappan Ramaswamy, Peter Aurora, Taehee Han
  • Publication number: 20150221990
    Abstract: Provided are methods and apparatus for charging a lithium sulfur (Li—S) battery. The Li—S battery has at least one unit cell comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between. One method provides controlled application of voltage pulses at the beginning of the charging process. An application period is initiated after a discharge cycle of the Li—S battery is complete. During the application period, voltage pulses are provided to the Li—S battery. The voltage pulses are less than a constant current charging voltage. Constant current charging is initiated after the application period has elapsed.
    Type: Application
    Filed: February 4, 2014
    Publication date: August 6, 2015
    Applicant: Nissan North America, Inc.
    Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory DiLeo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara