This proposed Phase I effort focuses on the development of a high power and high efficiency energy system for eVTOL platforms using the combination of the highest specific energy batteries and the highest specific power solar cells that are currently available. This will enable longer flight endurance for the eVTOL than currently possible. MicroLink Devices (solar cells) and Amprius (Li-ion batteries with Si nanowire anode) have been integrated and flown on the Zephyr S high altitude long endurance (HALE) UAV platform manufactured by Airbus, which achieved world record performance for flight endurance in the stratosphere (26 days). The University of Illinois at Urbana-Champaign (Dept of Aerospace Engineering) has extensive experience in the integration of power systems for small satellites. Phase I will be focused on the demonstration of a prototype integrated advance power system that can be scaled up for a full-size eVTOL platform in Phase II. Clearly, an increase in the energy density of the batteries will enable the eVTOL to increase its endurance and payload. Current Li-ion battery technology can provide a specific energy density of 300 Whr/kg. The proposed Li-ion battery with Si anode nanowire has increased the specific energy density to 450 Whr/kg which is a 50% increase. Lightweight, flexible solar arrays will provide additional energy to the eVTOL, and the energy contribution will be dependent upon the wing surface area and the amount of solar radiation. The proposed team has a very strong background in power systems which has been demonstrated in HALE and small satellites, and the knowledge is directly applicable to the power systems for eVTOL. MicroLink Devices and Amprius are now producing solar cells and batteries in mass production, and the capacity of both facilities can be expanded to meet the demands of the emerging eVTOL market. The market potential of eVTOL provides an excellent opportunity for MicroLink Devices and Amprius to work closely together in developing an advance solution for the energy requirements of eVTOL platforms.
