Internal short circuit of a cell is one of the most critical failure modes in lithium-ion batteries. The challenges in the area of testing are how to evaluate the risk of internal short circuit
and how to test the stability against this failure mode. To create a realistic internal short circuit situation within the short period of testing is difficult and almost impossible in
a highly reproducible way.
Methods as nail penetration, blunt rod impact, and flat plate crush of cells with implanted particles are established methods for the simulation of an internal short circuit. However,
nail penetration has a much stronger mechanical and electrical impact on the cell compared to the internal short circuit caused e.g. by dendrite growth and is therefore critically
discussed. Implantation of particles on the other hand requires special preparation of the cells and the doors are wide open for manipulation not reflecting the conditions in the
series product.
Alternative methods for internal short circuit tests need to be developed, analyzed, and established. In this work pulse laser shooting will be presented as a novel approach to simulate
cell internal shorts. A major advantage of this method is that a short-term laser impact instead of mimicking the short itself already simulates the result of the short: a localized,
short-term energy release within the cell. Therewith, it can be evaluated if the energy release is kept local or if the released energy causes a chain reaction effect and a propagation
of the failure mode leading to the thermal run away of the cell. The method of pulse laser shooting is not yet established in the field and requires further investigations but shall
be presented for an open discussion and for getting a response for the chance of acceptance.
