Researchers develop improved NMC battery pack for electric buses
The electric bus market includes vehicles equipped with a variety of battery cell chemistries. Some use nickel-based chemistries, while others rely on lithium iron phosphate (LFP). Battery systems for heavy-duty applications must meet stringent requirements, particularly regarding energy density, safety, lifespan, fast-charging capability, and weight.
The SIERRA project, led by France’s CEA (Commissariat à l’énergie atomique et aux énergies alternatives), aims to advance NMC chemistry as a technology for the electric bus sector. “Nickel-rich NMC cells offer great potential for increasing specific energy,” states the AIT Austrian Institute of Technology, a project partner. In total, SIERRA brings together eleven partners from seven European countries, and is designed to cover ‘key competencies along the battery value chain – from material development and system integration to validation.’ The project is funded by the European Union under the Horizon Europe research and innovation programme with nearly €8 million.
As energy densities in NMC cells increase, so do the demands on thermal management, structural integrity, and continuous state monitoring. “Conventional battery pack architectures are increasingly reaching their limits in terms of safety, durability, and system weight,” explains the AIT. For this reason, the SIERRA project aims to develop an exceptionally lightweight and high-performance battery pack that will be validated up to Technology Readiness Level 6 (TRL6) to pave the way for future industrialisation. Key technological innovations include:
- Multiscale modelling for compact and safe battery pack design, as well as simulation of thermal and mechanical behaviour
- Resource-efficient one-shot manufacturing of lightweight multi-material housings
- Multi-level monitoring concepts (structural monitoring, thermal mapping, state-of-charge and state-of-health determination) while reducing the complexity of the battery management system
- Fully integrated cooling systems and printed busbars to support high charging powers across a wide operating window
The integration of the battery pack into the overall vehicle will also be simulated using a digital twin. Furthermore, all development work follows the ‘safe and sustainable by design’ approach, incorporating safety and sustainability considerations from the outset. The AIT contributes its expertise in model-based battery system development to the European consortium.
“In the SIERRA project, we use simulation-based methods at the battery pack and vehicle level to develop safe and energy-efficient lightweight battery concepts for heavy-duty transport,” explains Dr Mirza Popovac, Project Manager at AIT. “This allows us to validate design decisions at an early stage and specifically improve the performance of future electric commercial vehicles.”
In addition to CEA and AIT, the project involves Verkor, FEV France, Plastic Omnium Clean Energy Systems Research, Rina Consulting, Acondicionamiento Tarrasense Association, Asociacion de Investigacion Metalurgica del Noroeste, Gen 2 Carbon, Icomat, and associate partner FPT Motorenforschung.
1 Comment