A possible contamination with impurities or material weak points generated in cell production of lithium-ion batteries increases the risk of spontaneous internal short circuits (ISC). An ISC can lead to a sudden thermal runaway (TR) of the cell, thereby making these faults especially dangerous. Evaluation regarding the criticality of an ISC, the development of detection methods for timely fault warning and possible protection concepts require a realistic failure replication for general validation. Various trigger methods are currently discussed to reproduce these ISC failure cases, but without considering a valid basis for the practice-relevant particle properties. In order to provide such a basis for the evaluation and further development of trigger methods, in this paper, the possibilities of detecting impurity particles in production were reviewed and real particles from pouch cells of an established cell manufacturer were analysed. The results indicate that several metallic particles with a significant size up to 1 mm × 1.7 mm could be found between the cell layers. This evidence shows that contamination with impurity particles cannot be completely prevented in cell production, as a result of which particle-induced ISC must be expected and the need for an application-oriented triggering method currently exists. The cause of TR events in the field often cannot be identified. However, it is noticeable that such faults often occur during the charging process. A new interesting hypothesis for this so-far unexplained phenomenon is presented here. Based on all findings, the current trigger methods for replicating an external particle-induced ISC were evaluated in significant detail and specific improvements are identified. Here, it is shown that all current trigger methods for ISC replication exhibit weaknesses regarding reproducibility, which results mainly from the scattering random ISC contact resistance.

The internal short circuit (ISC) in lithium-ion batteries is a serious problem since it is probably the most common cause of a thermal runaway (TR) that still presents many open questions, even though it has been intensively investigated. Therefore, this article focusses on the generation and characterisation of the local single-layer ISC, which is typically caused by cell-internal impurity particles that cannot be completely eliminated in the cell production. A new, very promising method of precise and slow (1 $\mathsf{\mu }$m s${}^{-1}$) needle penetration made it possible to generate the most safety-critical reliable short-circuit type—the contact between the Al-Collector and the graphite active material of the anode—as demonstrated on a 10 Ah Graphite/NMC pouch cell. The special efforts in achieving high reproducibility as well as the detailed analysis of the initiated internal short-circuit conditions led to more reliable and meaningful results. A comprehensive approach to characterisation has been made by detailed measurement of the dynamic short-circuit evolution and a subsequent post-characterisation, which included the application of different electrochemical measurement techniques as well as a post-abuse analysis. It was shown that the cells demonstrated a very individual and difficult-to-predict behaviour, which is a major challenge for early failure detection and risk assessment of cells with an existing or former ISC. On the one hand, it is found that despite high local temperatures of over 1260 ${}^{\circ }$C and significant damage to the cell-internal structure, the cell did not develop a TR even with further cycling. On the other hand, it was observed that the TR occurs spontaneously without any previous abnormalities. Based on the overall test results, it was shown that at the high state of charge (SOC = 100%), even small, dynamically developing voltage drops (<10 mV) must be classified as safety-critical for the cell. For reliable and early failure detection, the first voltage drops of the ISC must already be detected.

The increasing adoption of lithium-ion battery cells in contemporary energy storage applications has raised concerns regarding their potential hazards. Ensuring the safety of compact and modern energy storage systems over their operational lifespans necessitates precise and dependable monitoring techniques. This research introduces a novel method for the cell-specific surveillance of prismatic lithium-ion cells, with a focus on detecting pressure increases through the surface application of a fiber Bragg grating (FBG) sensor on a rupture disc. Commercially available prismatic cells, commonly used in the automotive sector, are employed as test specimens and equipped with proven pressure and innovative FBG sensors. Encompassing the analysis capacity, internal resistance, and pressure (under elevated ambient temperatures of up to 120 °C), this investigation explores the thermal degradation effects. The applied FBG sensor on the rupture disc exhibits reversible and irreversible state changes in the cells, offering a highly sensitive and reliable monitoring solution for the early detection of abuse and post-abuse cell condition analysis. This innovative approach represents a practical implementation of fiber optic sensor technology that is designed for strain-based monitoring of prismatic lithium-ion cells, thereby enabling customized solutions through which to address safety challenges in prismatic cell applications. In alignment with the ongoing exploration of lithium-ion batteries, this research offers a customizable addition to battery monitoring and fault detection.

In 2011, the concept of Industry 4.0 was introduced and later adopted by the German government, paving the way for a new industrial revolution in Germany. The high significance of this topic is reflected by the large number of corresponding publications. Additionally, the regional focus of research is widespread on a global level and often differs even at a national level. This paper generates transparency regarding the adoption of the concept of Industry 4.0 by analyzing the locations of main contributors within the research field on an international, European, and German-national level. Further, it examines the regionally different foci concerning the concept of Industry 4.0. Having identified four main aspects linked to Industry 4.0 within a pre-study, a quantitative literature research was conducted based on over 800 published papers. The results were further visualized with QGIS. Looking at the results, it can be concluded that the German research community is virtually the only user of the term Industry 4.0, while other institutions seem to link their research to other related concepts. On a German level, the majority of the analyzed studies originate from Southern and Western Germany. North Rhine-Westphalia and the Aachen/Jülich region, in particular, represent main contributors.