Batteries for Lilium’s seven-seat eVTOL aircraft will be supplied by CustomCells under an agreement announced by the two German companies on July 28. CustomCells is an established supplier of lithium-ion batteries to the aviation, automotive, and defense sectors, and recently reached an agreement with carmaker Porsche to jointly produce high-performance silicon-anode batteries, like those required for the LiliumJet.
Based on technology licensed by Lilium, CustomCells will start preparing for series production of the pouch battery cells needed for the new eVTOL aircraft, which is due to enter service in 2024. Production will be from its factory in Tubingen.
According to Lilium's chief technology officer, Alastair McIntosh, the company has improved the design of its batteries to combine higher power (i.e., total energy in the cells) with the low state-of-charge needed to boost range. Before 2014, the batteries used for early Lilium eVTOL prototypes had a minimum state-of-charge of around 30 to 40 percent, but this has now been improved to around 10 to 15 percent.
In recent years, the performance of battery cells has improved and they are now delivering energy density of around 300 Wh/kg and power density of up to 3 kW/kg. Lilium believes that the batteries it has developed will mean that the LiliumJet can access 85 to 90 percent of the stored energy to support a range of up to around 155 miles. It expects the batteries—which should have an energy density of 330 Wh/kg—to fast charge to 80 percent capacity in 15 minutes, and to 100 percent in 30 minutes.
CustomsCells joins a roster of Lilium suppliers and partners that already includes Honeywell (avionics and fly-by-wire flight controls), Toray Industries (composites), Aciturri (manufacturing), Lufthansa Aviation Training, Tavistock Development Company (real estate), Ferrovial (vertiports), and Palantir (operating systems). Lilium says it evaluated almost 50 battery technology partners before reaching an agreement with CustomCells.