Solid Electrolytes for Lithium Rechargeable Batteries (245)

Advanced consumer electronics, electric vehicles, and high performance aircraft requires high energy density and solid-state power sources. Lithium rechargeable batteries are potentially important power sources to satisfy this requirement. One of the primary components of solid-state lithium batteries is the solid electrolyte. The electrolyte resides between the anode and cathode and serves many purposes. First, the electrolyte must allow rapid transport of the lithium ion as the current is discharged into or drawn from the external circuit. To a large extent, the power and energy densities of a battery are determined by the conductivity of the electrolyte. The conductivity is also temperature dependent, and its large variation within the operational temperature range (-20 to 70°C) is undesirable. The electrolyte must also be thermally stable for a long period of time in the operational temperature range. Transport of charged species other than lithium through the electrolyte is detrimental to the performance of a lithium battery. The transport of other ionic species leads to polarization, which affects cell performance. Electrodes (anode and cathode) will short circuit if the electrolyte has significant electronic conductivity. These considerations require that the lithium ion transport number be as high as possible. Within a high voltage electrode couple, the electrolyte is constantly subjected to an electrical potential gradient, and the electrolyte should be able to withstand such a gradient during the entire life of the cell. Furthermore, anode-electrode and cathode-electrolyte interfaces are active sites for electrode reactions. Ideally, these electrode reactions should be reversible; irreversibility will lead to reduced cycle life and capacity fade. An electrolyte must meet these requirements to be commercially viable and useful. The University of Dayton has developed a method to identify and formulate new compositions of solid electrolytes that satisfy the aforementioned attributes.

The developed electrolyte consists of a polymer matrix (PEO:LiBF4) in which a ceramic phase (MgO, TiO2, BaTiO3) of a suitable particle size and specified volume fraction is dispersed. The composite, solid materials is processed without a solvent and the processing parameters are optimized to yield conductivity values in the range of 10-3 to 10-4 S cm-1 at ambient temperature. The electrolyte is truly solid, free-standing, electrochemically stable, and mechanically rigid. The specimens and relevant electrochemical data will be provided upon request.

U.S. Patent Application 09/605,179 filed June 28, 2000.

For more information, please contact the Office for Technology Partnerships at 937-229-3515.

Return to Technologies Available for Licensing.