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New Lithium Salts for Safe Operation of High-Energy, High-Rate Lithium Ion Batteries--Electrophorics, Inc., 75 Forrest Lane, Placitas, NM  87043; 505-720-1115

Dr. Larry J. Kepley, Principal Investigator

Dr. Larry J. Kepley, Business Official

DOE Grant No. DE-FG03-00ER82994

Amount:  $99,996

 

Although small-scale lithium ion batteries have specific energy exceeding 100 Wh/kg, electric vehicles (EVs) require discharge rates that push the envelope of safe operation of liquid-filled lithium ion batteries.  Current densities tolerable in small cells create unacceptable safety concerns in large capacity EV batteries, particularly at high power levels, because solvent-lithium reactivity, heat, and solvent volatility can generate explosive or pyrotechnic mixtures.  The electrolyte conductivity and stability limit safe power levels and remain dominant limitations to battery performance.  LiPF₆, the salt used in commercial lithium batteries, is not as stable or conductive as one would like and is less stable than imide-based anions.  Whereas solid-polymer-based electrolytes reduce the danger of catastrophic battery failure on the one hand, they enable lower power densities on the other, due to lower conductivity compared to liquid electrolytes.  The proposed work will develop a new class of lithium salts containing covalently attached ligands to solvate anions and enable Li⁺ dissociation and conductivity, using little or no molecular solvent.  The effort will use new precursors that enable addition of aza-type substituents for solvation and stabilization of anions.  The project will utilize known synthetic chemistry and economical starting materials to create hybrid anions containing greater charge delocalization and ligands for anion solvation.  Electrolyte gels and glasses will be tested in small lithium cells to determine minimum solvent level needed for phase transition to provide adequate conductivity for safe, high rate (10C) operation of lithium ion cells.

 

Commercial Applications and Other Benefits as described by the awardee:  Large, safe, high rate, rechargeable lithium ion batteries are needed for a variety of applications, including electric vehicle propulsion, aircraft and space vehicles, and communications equipment.  Improved consumer electronic products, such as portable telephones, computers, cameras, and power tools, could also be a market for the proposed technology.  The electric vehicle market alone could reach several billion dollars.