„in operando“ studies of materials fatigue in commercial battery-types by neutron tomography and diffraction
Prof. Dr. Helmut Ehrenberg, Materialwissenschaft Darmstadt,
Umicore AG & Co. KG Hanau
Lithium-ion batteries are at present the rechargable energy storage systems for mobile applications with the highest specific energy and power densities. They are already used in hybrid electrical vehicles (HEVs) and will soon become the standard energy source for full ectrical vehicles (EVs). The break through of this emission free and, therefore, environmently friendly power train technology requires materials with even higher energy densities. This requirement will further increase safety aspects, triggering the need to understand the underlying degradation mechanisms and to optimize the applied materials. This approach has already been established for test cells and is now transferred to complete devices and commercial batteries. Reliable information about the processes within a working battery can only be obtained under real operation conditions. Therefore, a dedicated „in operando“ method will be developed, combining neutron diffraction and tomography. Both methods provide information on complementary length scales and will contribute to reveal fatigue at high cycle numbers and to minimize safety risks. Only „in operando“ studies allow to follow ongoing deterioration from the very beginning until failure. Concepts for improved materials will be proposed based on this understanding of fatigue in real commercial devices.