The reuse and repurposing of lithium-ion batteries for transportation in stationary energy systems improve the economic value of batteries. A precise suitability test at the beginning of the second life is therefore necessary. Common methods such as electrochemical impedance spectroscopy (EIS) and current interrupt (CI) analysis, as well as capacity analysis, can be used for testing. In this paper, these methods are studied from the aspects of test duration, sensitivity and acquisition costs of the measuring instruments. For this purpose, tests are carried out on battery modules, which were used for transportation. It is shown that subtle differences are better detected with EIS and less accurately with the CI method. The test duration is fastest with the CI method, followed by EIS and the capacity test. Strongly aged modules are reliably detected with all methods.

Battery safety tests are defined by several international standards in different ways and with heterogenous termination and failure criteria. In this work, lithium-ion cells were examined regarding their behavior in the event of overcharging and also in the event of an external short circuit with varied parameters specified by standards. The voltage, current, and temperature curves were evaluated. In addition, the changes in the cells were analyzed using electrochemical impedance spectroscopy (EIS). It is shown that the cells exhibit reproducible behavior in a clamped state. Further, it could be determined that the position of the cell opening during an overcharge has an influence on the further behavior of the cell. EIS data showed that the cells have a significantly higher internal resistance after an overcharge. The short-circuit tests at different ambient temperatures indicated that the internal resistance of the cell decreases with increasing temperature. However, no reproducible effects in impedance spectra were present after the short-circuit test. This work illustrates that the choice of test parameters and termination criteria undoubtedly influence the test results and thus may change the classification of cells as either safe or unsafe. Thus, cells may be classified as safe regarding a certain standard but unsafe regarding another.