A look at the electrified aircraft propulsion targets.
NASA state in their November 2021 presentation that they have the following requirements for the battery pack:
- 400 Wh/kg required at the system level
- 1000’s of cycles
- Extremely high power requirements (C-rates) during takeoff and landing
- Cruise power for long range flights
- High reliability, limited maintenance
- Improved safety for thermal runaway events
The targets at pack level are rather tough:
The gravimetric energy density plotted versus total pack energy shows that the automotive packs are currently plateauing around 180Wh/kg.
The roadmap to 400Wh/kg is going to be difficult.
There is a need to improve the power and energy gravimetric density of the cell and pack to enable these electrified aircraft.
In addition NASA have a number of research programs looking at safety. eg SPARRCI = Sensor-based Prognostics to Avoid Runaway Reactions and Catastrophic Ignition. In this project they ask the question: “Can catastrophic battery failures be avoided to enable safe next generation ultra-high energy batteries for propulsive aircraft power?”
- NASA Battery Research & Development Overview, Cody O’Meara, Bri DeMattia, NASA Glenn Research Center in collaboration with NASA JPL and ARC