Contact person
Anders Lönnermark
Enhetschef
Contact AndersBattery thermal runaway and fire simulations
Multi-physics simulations together with full-scale testing is a cost-effective method for designing safer batteries. RISE is expert in this area.
Thermal runaway in lithium-ion batteries — and its potential to propagate from cell to cell, and from module to module — is one of the central safety challenges of today's electrified world, relevant across electric vehicles, battery energy storage systems, manufacturing, maintenance, retrofitting, and recycling. It is a complex, multi-physics process: electrochemical reactions inside the cell, self-heating, decomposition of battery materials, evaporation of the electrolyte, venting of flammable and toxic gases, ejection of solid particles and droplets, and the burning of that gas and debris, all interacting across scales from a single cell to an entire system.
Testing individual cells helps manufacturers design out much of this risk at the cell level. But as battery energy storage systems grow larger and more complex, full-scale experimental safety testing becomes costly, time-consuming, and hard to repeat. Numerical simulation offers a practical, cost-efficient, and more environmentally sound way to study how thermal runaway propagates through a battery system — but simulation is only trustworthy when it is validated against real experimental data. That validation is at the core of how we work at RISE, checked against full-scale
fire tests run at our own battery safety testing facility.
Our research is needs-driven, grounded in real safety questions raised by industry and society, and carried out with rigorous scientific method. We publish our results in peer-reviewed journals, and we go a step further by sharing our work openly with the research and industrial community: the OpenFOAM-based models behind our simulations are
made publicly available, for example via [Zenodo](https://doi.org/10.5281/zenodo.20392473) and [GitHub](https://github.com/cenghuang-debug/battery-flame-2D), so that others can inspect, reuse, and build on them.
Publications:
Cell level — effect of battery chemistry and state of charge on fire behaviour
At the cell level, we study how battery chemistry and state of charge (SOC) shape a battery's fire behaviour once thermal runaway begins. Using CFD simulations built in the open-source OpenFOAM framework, we modelled the venting and jet-fire combustion of cylindrical cells across four common cathode chemistries — LCO, NMC, LFP, and NCA — and across a range of states of charge. We also examined how CO₂-enriched atmospheres, relevant to fire suppression in confined spaces such as ship cargo holds, affect flame temperature and fire growth. In a study currently undergoing peer review, our results indicate that suppression effectiveness depends strongly on chemistry: NCA, LCO, and NMC cells appear to respond well to CO₂ suppression, while LFP cells look far more resistant, due to slower gas venting, lower total gas release, and higher heat capacity of the ejected gases.
Module level — thermal propagation across cylindrical and prismatic cell formats
At the module level, we have simulated thermal runaway propagation for two of the most common cell formats. For an automotive battery module built from 12 prismatic cells, we developed a 3D finite-element thermal propagation model, validated it against full-scale experiments, and used it to identify which parameters — critical temperature and the specific heat capacity of the cell jelly roll among them — most strongly influence propagation speed. For a much larger 507-cell cylindrical-cell module (100 Ah, NMC chemistry), we coupled a 3D finite-element thermal propagation model with an open-source CFD fire model to capture both how thermal runaway spreads from cell to cell and how the resulting fire develops — again validated against full-scale fire testing, this time on a complete battery energy storage module.
In close collaboration with RISE battery abuse tests, multi-physics simulations can be used:
• to study thermal propagation in battery cells, modules, packs and system level.
• to perform parametric studies of improved safety design of battery module and system.
• to give recommendations on the most relevant scenarios for abuse tests.
• to study battery thermal runaway mitigation strategies, e.g., integrated fire extinguishment channels in the battery module and pack, and immersion of battery in coolant liquid.
