The national joint project VentBatt is being funded by the Federal Ministry of Education and Research with 1.5 million euros. It is coordinated by the Research Center for Energy Storage Technologies at Clausthal University of Technology.
As energy storage devices, lithium-ion batteries (LIB) are currently unrivaled for many applications and can therefore be found in large numbers in almost all areas of life. However, they can release considerable amounts of energy if they are misused or if there are production errors. This leads to the development of high pressure and very high temperatures as well as the release of toxic, explosive and flammable gases, the so-called thermal runaway (TR). If very hot particles are carried out of the cell with the gas flow or if certain temperature and concentration limits are exceeded, the gases can (self-)ignite in air and/or even explode. The effects of a TR on the immediate surroundings, especially when spreading to other cells, known as thermal propagation, are considerable.
The aim of the VentBatt project is therefore to minimize or avoid risks associated with the operation of LIBs by reducing the temperature and concentration of the escaping gases below the safety-critical threshold values and to avoid thermal propagation by reducing the heat generation rate of the cell that suffers a TR. “The project objective thus corresponds to the implementation of the classic principles of fire prevention: keeping below the ignition temperature and avoiding a flammable gas and oxygen mixture,” says project manager Dr. Ralf Benger from the lead research center Energy Storage Technologies (EST) at Clausthal University of Technology. To this end, the project is developing and investigating measures to increase the safety of LIBs through controlled gas and thermal management.
Together with industrial project partners from all over Germany, three complementary concepts are being considered. FRÖTEK Kunststofftechnik from Osterode is researching and testing targeted pressure relief via valves in the cell housings, while Teubert Maschinenbau GmbH from Blumberg (southern Black Forest) is using particle foams to reduce the temperature and lower the concentration of flammable gases to a level below the fire and explosion limits. With BorgWarner Akasol GmbH from Darmstadt, the optimized design of a battery system, including housing and flow control for the outflowing gases, takes into account propagation barriers through insulation material, improved heat conduction and/or forced cooling. The conversion to a commercial cell format is being pursued with the company UniverCell Holding GmbH from Flintbek. The EST coordinates the overall project, undertakes the theoretical considerations and carries out the experimental safety tests at the battery test center. The project is being funded by the Federal Ministry of Education and Research with a total of 1.5 million euros.