A high-power Lithium-air battery based on a non-planar cell configuration.
Publication Date: 2014-Jan-27
The IP.com Prior Art Database
High Surface-Area Electrode Concept for a Lithium-Air Battery
Practical lithium-air battery designs based on planar electrodes are severely constrained by the current density and the volume needed for oxygen mass-transport. Improvements in current density, electrode area and oxygen transport architecture are needed to satisfy both the energy and power requirements for automotive applications. For example, bipolar plate cell design with an air flow field width of 1000 mm, similar to a fuel cell, requires a current density of 40 mA/cm2 to meet automotive power requirements; this current density is almost two orders of magnitude higher than state-of-the-art lithium-air performance. As an alternative to the planar electrode design of a bipolar plate cell, a cylindrical cell with a diameter of <500 mm would dramatically increase the available surface area of the electrode and improve oxygen transport to the cathode, improving performance. By taking advantage of higher surface area and improved oxygen transport, the cylindrical cell design can satisfy the energy and power requirements at current densities < 5 mA/cm2.
Electrodes with cylindrical (wire) geometry are proposed to take advantage of the inherently higher surface-area-to-volume ratio of a thin cylindrical shell compared to a planar electrode design. For a given electrode thickness, a wire element offers a factor of p/2 multiple of surface area over the exposed surface of a planar element with equivalent width. In addition, the surface area to volume ratio is 2X greater for an array of cylinders that span the same rectangular dimensions as a corresponding thin plate.
In the cylindrical wire cell design shown in Figure 1, the anode current collector is covered with the anode material (e.g., lithium metal or lithium alloy), followed by a separator (e.g., polymer electrolyte layer), and then coated with a porous, conductive cathode layer. Finally, a porous cat...