Background
Li-ion batteries has become a dominant mean to store energy from e.g., PVs (Photo Voltic’s) and by this level grid electricity prices. Moreover, li-ion is the current battery technology that fuels vehicles for both land and sea transport, for example in cars, bicycles, and ferry’s etc.
To an increased degree there’s also a demand to harvest excess energy from various electrical equipment and store it in li-ion batteries. A recent example is the surplus energy from refrigerated display cases in supermarkets. At this point of time there is very limited standardization as to the testing and classifying the protection of li-ion batteries in both operation as end-of-life transport and storing in a fire context.
Project Description
Li-ion batteries are difficult to extinguish as even a minimal charged li-ion battery, contains oxidation agents and fuel, as the energy is stored as chemical energy in a redox reaction. A fire can reignite after initially appeared extinguished and continue to burn for an extended period. Thus, it is very difficult to extinguish li-ion batteries, and these can only be cooled with extensive amounts of water, or preferably moved to avoid propagation to adjacent structures.
As li-ion generates their own oxygen during fire, it is not possible to use gaseous extinguishing agents which excludes the oxygen but only suppresses the fire in the electrolyte.
Explosions in li-ion fires are very frequent as are jet flames. In addition to the active materials, the battery contains an electrolyte, which consists of a salt dissolved in an organic solvent. When a closed battery cell is heated, a pressure is created inside the battery cell. The pressure inside the battery increases because it is low-boiling organic liquids. When the temperature becomes high enough, the cell bursts due to the pressure and flammable organic liquid sprays out and ignites.
In connection with a fire in the electrolyte, highly toxic Hydrogen Fluoride gas is generated. This gas presents a substantial challenge and danger to first responders and human close to a li-ion battery fire.
The purpose of the project is to assess the fire development in a bicycle battery from approx. 0,5 kWh up to a domestic, PV connected battery at approx. 10-15 kWh. Thus:
- assessment of a realistic fire curve,
- assessment and mitigation of the explosion risk in the test environment,
- containment or safe diversion of Hydrogen Fluoride gas associated to fire.
Eventually the aim is to develop a solution based on a passive fire protection approach, to offer to the market, covering the reasonably limited battery setups and risks as given above.
ROCKWOOL is highly focused on megatrends in the built environment and wants to contribute with novel, well-thought-out and proven solutions, and services to the market. To create and provide such, we want to stay in the frontline of knowledge to develop science-based applications that meets both market and legal demands in a global perspective. We aim for solutions which contributes to human safety, health and protection of the environment.
Suggestions for sub-tasks could be:
- Literature study of fire behaviour for lithium-ion batteries
- Desk top study of prior art within protection linked to lithium-ion battery fires
- Interviews with Specifiers, Building and Fire authorities, and First Responders
- Ideation on protective measures
- Small and mid-scale fire testing
- Dissemination
ROCKWOOL Supervisors/ competencies
- Søren Rud Pedersen (Senior R&D Specialist, Resistance to Fire testing, Product Development, First Responder knowledge, srp@rockwool.com)
- Kurt Munk (Chief Specialist Fire Protection, Resistance to Fire testing etc, kurt.munk@rockwool.com)
- Kurt Ejlersen, (Chief Technician, Reaction to Fire testing, kurt.ejlersen@rockwool.com)
- Karen Guldhammer Skov, (R&D Engineer, Modelling and Simulation Analysis, karen.guldhammer@rockwool.com)
Facilities
- Access to ROCKWOOL R&D Fire Labs (Resistance and Reaction to fire, small to medium scale)
- Access to ROCKWOOL R&D Stone Wool characterisation and test labs (inorganic and organic chemistry, mechanical and physical testing)
- Possibilities for external testing can be included if relevant
Confidentiality
Students are required to sign a non-disclosure agreement (NDA) with Rockwool. Exam and report will be kept confidential.
References
RISE Fire Research, PhD Andreas Sæter Bøe