Veröffentlichung im Journal of the Electrochemical Society

In dieser Veröffentlichung werden zum einen eine neu entwickelte kalorimetrische Messmethode und zum anderen neu konstruierte Zellhalter vorgestellt, die eine verbesserte dynamische Messung an Knopfzellen ermöglichen. Zudem ist es gelungen, den Wärmestromanteil der Zelle von der Dynamik des Messgerätes mittels einem Deconvolution-Algorithmus zu separieren. Dies ermöglicht die genauere Untersuchung von Phänomenen an Aktivmaterialien der nächsten Generation, wie Silicium für die Anode und Lithium- und Mangan-reiche NCMs für die Kathode.

Isothermal microcalorimetry is used to study the heat flow of lithium-ion cells to provide insight into active material characteristics and to provide data required for a thermal optimization on the cell and system level. Recent research has shown the application of this technique to cells during high cycling rates, for example fast charging. However, the limitation of isothermal microcalorimetry is the low-pass characteristic of the measured heat flow, introduced by the thermal inertia of the setup and the calorimeter itself. To solve this problem, we introduce an optimized cell holder design and a novel data processing method for a time-resolved measurement of highly dynamic heat flow profiles. These are described in detail and validated using a synthetic power profile applied to a dummy cell. Experiments on a graphite-lithium half-cell illustrate the improvement of the method and the optimized cell holder when compared to the state-of-the-art setup, demonstrating the 3.6 times faster time response, which was further improved using a post-processing deconvolution technique. The thus improved time resolution provides the acquisition of more detailed features than currently shown in the literature and allows an accurate correlation of the thermal signals to electrochemical features like, e.g., the differential voltage of the cell.

link: https://doi.org/10.1149/1945-7111/ac8625

BMBF project affilation: HysKaDi  (03XP0321B)