Patents by Inventor Ratnakumar V. Bugga
Ratnakumar V. Bugga 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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Publication number: 20120007560Abstract: Provided herein are electrolytes for lithium-ion electrochemical cells, electrochemical cells employing the electrolytes, methods of making the electrochemical cells and methods of using the electrochemical cells over a wide temperature range. Included are electrolyte compositions comprising a lithium salt, a cyclic carbonate, a non-cyclic carbonate, and a linear ester and optionally comprising one or more additives.Type: ApplicationFiled: June 15, 2011Publication date: January 12, 2012Inventors: Marshall C. Smart, Ratnakumar V. Bugga
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Publication number: 20100047695Abstract: The invention discloses various embodiments of Li-ion electrolytes containing flame retardant additives that have delivered good performance over a wide temperature range, good cycle life characteristics, and improved safety characteristics, namely, reduced flammability. In one embodiment of the invention there is provided an electrolyte for use in a lithium-ion electrochemical cell, the electrolyte comprising a mixture of an ethylene carbonate (EC), an ethyl methyl carbonate (EMC), a fluorinated co-solvent, a flame retardant additive, and a lithium salt. In another embodiment of the invention there is provided an electrolyte for use in a lithium-ion electrochemical cell, the electrolyte comprising a mixture of an ethylene carbonate (EC), an ethyl methyl carbonate (EMC), a flame retardant additive, a solid electrolyte interface (SEI) film forming agent, and a lithium salt.Type: ApplicationFiled: August 18, 2009Publication date: February 25, 2010Applicants: California Institute of Technology, University of Southern CaliforniaInventors: Marshall C. Smart, Kiah A. Smith, Ratnakumar V. Bugga, Surya G. Prakash, Frederick Charles Krause
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Publication number: 20090253046Abstract: There is provided in one embodiment of the invention an electrolyte for use in a lithium ion electrochemical cell. The electrolyte comprises a mixture of an ethylene carbonate (EC), an ethyl methyl carbonate (EMC), an ester cosolvent, and a lithium salt. The ester cosolvent comprises methyl propionate (MP), ethyl propionate (EP), methyl butyrate (MB), ethyl butyrate (EB), propyl butyrate (PB), or butyl butyrate (BB). The electrochemical cell operates in a temperature range of from about ?60 degrees Celsius to about 60 degrees Celsius. In another embodiment there is provided a lithium ion electrochemical cell using the electrolyte of the invention.Type: ApplicationFiled: April 7, 2009Publication date: October 8, 2009Applicant: CALIFORNIA INSTITUTE OF TECHNOLOGYInventors: Marshall C. Smart, Ratnakumar V. Bugga
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Publication number: 20080305401Abstract: An embodiment lithium-ion battery comprising a lithium-ion electrolyte of ethylene carbonate; ethyl methyl carbonate; and at least one solvent selected from the group consisting of trifluoroethyl butyrate, ethyl trifluoroacetate, trifluoroethyl acetate, methyl pentafluoropropionate, and 2,2,2-trifluoroethyl propionate. Other embodiments are described and claimed.Type: ApplicationFiled: January 25, 2008Publication date: December 11, 2008Inventors: Marshall C. Smart, Ratnakumar V. Bugga, G.K. Surya Prakash, Kiah Smith, Pooja Bhalla
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Patent number: 6764525Abstract: A process for making thin-film batteries including the steps of cleaning a glass or silicon substrate having an amorphous oxide layer several microns thick; defining with a mask the layer shape when depositing cobalt as an adhesion layer and platinum as a current collector; using the same mask as the preceding step to sputter a layer of LiCoO2 on the structure while rocking it back and forth; heating the substrate to 300° C. for 30 minutes; sputtering with a new mask that defines the necessary electrolyte area; evaporating lithium metal anodes using an appropriate shadow mask; and, packaging the cell in a dry-room environment by applying a continuous bead of epoxy around the active cell areas and resting a glass slide over the top thereof.Type: GrantFiled: March 11, 2003Date of Patent: July 20, 2004Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Jay F. Whitacre, Ratnakumar V. Bugga, William C. West
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Patent number: 6558836Abstract: A process for making thin-film batteries including the steps of cleaning a glass or silicon substrate having an amorphous oxide layer several microns thick; defining with a mask the layer shape when depositing cobalt as an adhesion layer and platinum as a current collector; using the same mask as the preceding step to sputter a layer of LiCoO2 on the structure while rocking it back and forth; heating the substrate to 300° C. for 30 minutes; sputtering with a new mask that defines the necessary electrolyte area; evaporating lithium metal anodes using an appropriate shadow mask; and, packaging the cell in a dry-room environment by applying a continuous bead of epoxy around the active cell areas and resting a glass slide over the top thereof. The batteries produced by the above process are disclosed.Type: GrantFiled: February 8, 2001Date of Patent: May 6, 2003Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Jay F. Whitacre, Ratnakumar V. Bugga, William C. West
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Patent number: 6492064Abstract: Multi-component organic solvent systems, electrolytes and electrochemical cells characterized by good low temperature performance are provided. In one embodiment, an improved organic solvent system contains a ternary mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate. In other embodiments, quaternary systems include a fourth component, i.e, an aliphatic ester, an asymmetric alkyl carbonate or a compound of the formula LiOX, where X is R, COOR, or COR, where R is alkyl or fluoroalkyl. Electrolytes based on such organic solvent systems are also provided and contain therein a lithium salt of high ionic mobility, such as LiPF6. Reversible electrochemical cells, particularly lithium ion cells, are constructed with the improved electrolytes, and preferably include a carbonaceous anode, an insertion type cathode, and an electrolyte interspersed therebetween.Type: GrantFiled: May 3, 1999Date of Patent: December 10, 2002Assignee: California Institute of TechnologyInventors: Marshall C. Smart, Ratnakumar V. Bugga, Subbarao Surampudi, Chen-Kuo Huang
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Patent number: 6074453Abstract: A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery.Type: GrantFiled: October 28, 1997Date of Patent: June 13, 2000Assignees: Iowa State University Research Foundation, Inc., California Institute of TechnologyInventors: Iver E. Anderson, Timothy W. Ellis, Vitalij K. Pecharsky, Jason Ting, Robert Terpstra, Robert C. Bowman, Charles K. Witham, Brent T. Fultz, Ratnakumar V. Bugga
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Patent number: 5888665Abstract: An at least ternary metal alloy of the formula AB.sub.(Z-Y) X.sub.(Y) is disclosed. In this formula, A is selected from the rare earth elements, B is selected from the elements of Groups 8, 9, and 10 of the Periodic Table of the Elements, and X includes at least one of the following: antimony, arsenic, germanium, tin or bismuth. Z is greater than or equal to 4.8 and less than or equal to 6.0. Y is greater than 0 and less than 1. Ternary or higher-order substitutions to the base AB.sub.5 alloys that form strong kinetic interactions with the predominant metals in the base metal hydride are used to form metal alloys with high structural integrity after multiple cycles of hydrogen sorption.Type: GrantFiled: December 13, 1996Date of Patent: March 30, 1999Assignee: California Institute of TechnologyInventors: Ratnakumar V. Bugga, Brent Fultz, Robert Bowman, Subra Rao Surampudi, Charles K. Witham, Adrian Hightower
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Patent number: 5656388Abstract: An at least ternary metal alloy of the formula, AB.sub.(5-Y)X(.sub.y), is claimed. In this formula, A is selected from the rare earth elements, B is selected from the elements of groups 8, 9, and 10 of the periodic table of the elements, and X includes at least one of the following: antimony, arsenic, and bismuth. Ternary or higher-order substitutions, to the base AB.sub.5 alloys, that form strong kinetic interactions with the predominant metals in the base metal hydride are used to form metal alloys with high structural integrity after multiple cycles of hydrogen sorption.Type: GrantFiled: June 7, 1995Date of Patent: August 12, 1997Assignee: California Institute of TechnologyInventors: Ratnakumar V. Bugga, Gerald Halpert, Brent Fultz, Charles K. Witham, Robert C. Bowman, Adrian Hightower
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Patent number: 5573873Abstract: The premature capacity failure of Ni/NiCl.sub.2 secondary cells due to agglomeration of nickel particles on the surface of the NiCl.sub.2 cathode is prevented by addition of a minor amount, such as 10 percent by weight of a transition metal such as Co, Fe or Mn to the cathode. The chlorides of the transition metals have lower potentials than nickel chloride and chlorinate during charge. A uniform dispersion of the transition metals in the cathodes prevents agglomeration of nickel, maintains morphology of the electrode, maintains the electrochemical area of the electrode and thus maintains capacity of the electrode. The additives do not effect sintering. The addition of sulfur to the liquid catholyte is expected to further reduce agglomeration of nickel in the cathode.Type: GrantFiled: August 16, 1994Date of Patent: November 12, 1996Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Ratnakumar V. Bugga, Subbarao Surampudi, Gerald Halpert
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Patent number: 5554457Abstract: Power density of a sodium/transition metal halide cell, particularly a Na/NiCl.sub.2 cell is enhanced by forming a high area foil nickel chloride electrode such as a film of sintered nickel chloride deposited on an expanded metal screen and folded or coiled into a compact form and immersed in the aluminate salt catholyte disposed within a beta alumina solid electrolyte tube.Type: GrantFiled: March 1, 1995Date of Patent: September 10, 1996Inventors: Ratnakumar V. Bugga, Alan I. Attia, Gerald Halpert
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Patent number: 5019470Abstract: In a method of fabricating a rechargeable battery which includes a positive electrode which contains a chloride of a selected metal when the electrode is in its active state, the improvement comprising fabricating the positive electrode by: providing a porous matrix composed of a metal; providing a solution of the chloride of the selected metal; and impregnating the matrix with the chloride from the solution.Type: GrantFiled: March 30, 1990Date of Patent: May 28, 1991Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Ratnakumar V. Bugga, Salvador DiStefano, C. Perry Bankston
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Patent number: 4966823Abstract: A liquid catholyte for a battery based on liquid metal such as sodium anode and a solid, ceramic separator such as beta alumina (BASE) comprises a mixture of a Group I-III metal salt such as sodium tetrachloroaluminate and a minor amount of an organic carbonitrile depolarizer having at least one adjacent ethylenic bond such as 1 to 40 percent by weight of tetracyanoethylene. The tetracyanoethylene forms an adduct with the molten metal salt.Type: GrantFiled: September 7, 1989Date of Patent: October 30, 1990Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Ratnakumar V. Bugga, Salvador DiStefano, Roger M. Williams, Clyde P. Bankston
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Patent number: 4945012Abstract: Higher energy and power densities are achieved in a secondary battery based on molten sodium and a solid, ceramic separator such as a beta alumina and a molten catholyte such as sodium tetrachloroaluminate and a copper chloride cathode. The higher cell voltage of copper chloride provides higher energy densities and the higher power densities result from increased conductivity resulting from formation of copper as discharge proceeds.Type: GrantFiled: September 11, 1989Date of Patent: July 31, 1990Assignee: The United States of America as represented by the Administrator, National Aeronautics and Space AdministrationInventors: Ratnakumar V. Bugga, Salvador Distefano, Ganesan Nagasubramanian, Clyde P. Bankston