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).
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Patent number: 11799088Abstract: 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: GrantFiled: January 11, 2022Date of Patent: October 24, 2023Assignee: GM Global Technology Operations LLCInventors: Nagappan Ramaswamy, Roland J. Koestner, Swaminatha P. Kumaraguru
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Publication number: 20230223552Abstract: 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: ApplicationFiled: January 11, 2022Publication date: July 13, 2023Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLCInventors: Nagappan Ramaswamy, Roland J. Koestner, Swaminatha P. Kumaraguru
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Patent number: 11302926Abstract: 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: GrantFiled: August 27, 2019Date of Patent: April 12, 2022Assignee: GM Global Technology Operations LLCInventors: Nagappan Ramaswamy, Roland J. Koestner, Swaminatha P. Kumaraguru
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Publication number: 20210066726Abstract: 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: ApplicationFiled: August 27, 2019Publication date: March 4, 2021Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLCInventors: Nagappan Ramaswamy, Roland J. Koestner, Swaminatha P. Kumaraguru
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Patent number: 10784527Abstract: 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: GrantFiled: December 19, 2017Date of Patent: September 22, 2020Assignee: GM Global Technology Operations LLCInventors: Swaminatha P. Kumaraguru, Jingxin Zhang, Nagappan Ramaswamy, Pinkhas A. Rapaport
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Publication number: 20190280307Abstract: 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: ApplicationFiled: March 8, 2018Publication date: September 12, 2019Inventors: Nagappan Ramaswamy, Timothy Fuller, Swaminatha Kumaraguru
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Publication number: 20190190040Abstract: 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: ApplicationFiled: December 19, 2017Publication date: June 20, 2019Applicant: GM Global Technology Operations LLCInventors: Swaminatha P. Kumaraguru, Jingxin Zhang, Nagappan Ramaswamy, Pinkhas A. Rapaport
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Publication number: 20180366738Abstract: 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: ApplicationFiled: June 16, 2017Publication date: December 20, 2018Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLCInventors: Nagappan Ramaswamy, Ellazar V. Niangar, Balasubramanian Lakshmanan
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Patent number: 10158128Abstract: 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: GrantFiled: March 7, 2017Date of Patent: December 18, 2018Assignee: GM Global Technology Operations LLCInventors: Jingxin Zhang, Nagappan Ramaswamy, Balasubramanian Lakshmanan, Swaminatha P. Kumaraguru
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Publication number: 20180261858Abstract: 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: ApplicationFiled: March 7, 2017Publication date: September 13, 2018Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLCInventors: Jingxin Zhang, Nagappan Ramaswamy, Balasubramanian Lakshmanan, Swaminatha P. Kumaraguru
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Patent number: 9866056Abstract: 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: GrantFiled: March 31, 2016Date of Patent: January 9, 2018Assignee: Nissan North America, Inc.Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory Dileo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara
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Patent number: 9627684Abstract: 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: GrantFiled: February 14, 2014Date of Patent: April 18, 2017Assignee: Nissan North America, Inc.Inventors: Nagappan Ramaswamy, Peter Aurora, Taehee Han
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Patent number: 9590252Abstract: 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: GrantFiled: February 14, 2014Date of Patent: March 7, 2017Assignee: Nissan North America, Inc.Inventors: Nagappan Ramaswamy, Peter Aurora, Taehee Han
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Publication number: 20160218522Abstract: 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: ApplicationFiled: March 31, 2016Publication date: July 28, 2016Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory DiLeo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara
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Patent number: 9379417Abstract: 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: GrantFiled: February 4, 2014Date of Patent: June 28, 2016Assignee: NISSAN NORTH AMERICA, INC.Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory DiLeo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara
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Patent number: 9331364Abstract: 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: GrantFiled: February 4, 2014Date of Patent: May 3, 2016Assignee: NISSAN NORTH AMERICA, INC.Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory DiLeo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara
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Patent number: 9186653Abstract: 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: GrantFiled: June 17, 2011Date of Patent: November 17, 2015Assignee: Northeastern UniversityInventors: Sanjeev Mukerjee, Qinggang He, Nagappan Ramaswamy
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Publication number: 20150236350Abstract: 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: ApplicationFiled: February 14, 2014Publication date: August 20, 2015Applicant: Nissan North American, Inc.Inventors: Nagappan Ramaswamy, Peter Aurora, Taehee Han
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Publication number: 20150236344Abstract: 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: ApplicationFiled: February 14, 2014Publication date: August 20, 2015Applicant: Nissan North America, Inc.Inventors: Nagappan Ramaswamy, Peter Aurora, Taehee Han
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Publication number: 20150221990Abstract: 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: ApplicationFiled: February 4, 2014Publication date: August 6, 2015Applicant: Nissan North America, Inc.Inventors: Nagappan Ramaswamy, Peter Aurora, Gregory DiLeo, Xiaoguang Hao, Taehee Han, Rameshwar Yadav, Ellazar Niangar, Kenzo Oshihara