Lithium ion batteries play an increasing role in everyday life, giving power to handheld devices or being used in stationary storage solutions. Especially for medium or large scale solutions, the latter application confines a huge amount of energy within a small volume; however, increasing the hazard potential far above the common level. Furthermore, as the safety hazards of lithium ion cells have been known for years, impressively shown by several burning cars or laptops, the need for a further enhancement of the safety of these systems is rising. This manuscript presents measurements of the gas emission from lithium ion batteries in case of a malfunction for different scenarios, showing a large variety of species with mostly toxic to highly toxic properties. The measurements were carried out using a combination of gas chromatography-mass spectrometry (GC-MS), quadrupole mass spectrometry (QMS), photoacoustic spectroscopy, and chemical analysis. It is shown that the inflammation of a cell can be overcome, also preventing a cascading effect to neighboring cells, but giving rise to worse toxic gas emission. Furthermore, a filtration concept is presented that decreases the concentration of the emitted components significantly and promises filtration below immediately dangerous to life or health (IDLH) equivalent levels.

In this scientific publication, a new sensor approach for status monitoring, such as state of charge and state of health, of lithium ion batteries by using special Bragg gratings inscribed into standard optical glass fibers is presented. In addition to well-known core gratings, embedded into the anode of 5 Ah lithium ion pouch cells as a strain monitoring unit, the manufacturing of a surface cladding waveguide Bragg grating sensor incorporated into the cell’s separator, that is sensitive to changes of the refractive index of the surrounding medium, is demonstrated. On the basis of the experiments carried out, characteristics of the cell behavior during standard cyclization and recognizable marks in subsequent post-mortem analyses of the cell components are shown. No negative influence on the cell performance due to the integrated sensors have been observed; however, the results show a clear correlation between fading cell capacity and changes of the interior optical signals. Additionally, with the novel photonic sensor, variations in the electrolyte characteristics are determinable as the refractive index of the solution changes at different molar compositions. Furthermore, with the manufactured battery cells, abuse tests by overcharging were conducted, and it was thereby demonstrated how internal battery sensors can derive additional information beyond conventional battery management systems to feasibly prevent catastrophic cell failures. The result of the research work is an early stage photonic sensor that combines chemical, mechanical and thermal information from inside the cell for an enhanced battery status analysis.

Over the last years, battery safety becomes more and more important due to the wide spread of high-capacity lithium ion batteries applied in e.g. consumer electronics and electrical power storages for vehicles or stationary energy storage systems. However, for these types of batteries, malfunctions could be highly dangerous and all aspects of safety issues are not sufficiently considered, yet. Therefore, the improvement of the battery safety behavior is one of the most important issues discussed in actual research projects. In this paper the application of fiber optical sensors for enhanced battery safety is presented. The temperature is one of the most critical parameters indicating a failure of the cell, but even state-to-the-art battery management systems (BMS) are not able to monitor and interpret the distributed temperature field of a total battery storage system sufficiently. Furthermore, the volume expansion of the battery cell, which could be monitored by the strain on the cells' surfaces, is one additional parameter not considered up to now. Both parameters could be simultaneous monitored by fiber optical sensor arrays, consisting of discrete fiber Bragg grating (FBG) elements. The FBG sensors are directly attached on the surface of the cell, recording the temperature as well as the strain distribution highly accurate and close-meshed. Failures and malfunction such as overcharging, gassing, and thermal runaway can be early predicted and avoided to extend the battery lifetime and enhance the operational battery safety. Moreover, battery aging effects lead to variations in the volume change behavior which can be detected additionally. Hence, a battery fully equipped with fiber optical sensor arrays in combination with an appropriate BMS enables a safe and continuous utilization of the energy storage system even under harsh conditions like rapid charging

Socio-economic development in the rural regions of Africa cannot succeed without suitable infrastructure. An essential key to this is electrification. Despite various national and international activities and expansion programmes, and a wide variety of actors, their implementation is progressing slowly. In order to supply remote areas with electricity, off-grid system technologies have become increasingly common in recent years. In this article, we present the use of a photovoltaic system in conjunction with a 85 kWh second life lithium-ion battery (LIB) as an off-grid hybrid system to electrify an island in Lake Victoria in Tanzania as a socio-economic case study. This off-grid hybrid system was able to supply an average of 42.31 kWh of energy per day, with the daily demand of the key infrastructure successfully connected in the project, such as the local hospital and school, amounting to 18.75 kWh. The scaled annual production of 15,443.16 kWh offers enough potential to include private households as well as the local fishing industry in the power supply. Assuming an expected lifetime of 15 years, the described system amortises itself from the 4th year. In addition, this project should also serve as a possible second life scenario for batteries with regard to the rapidly developing global electromobility and the perspective return of used LIBs. An economic and an ecological evaluation shows a solution approach of using a second life lithium-ion battery compared to a conventional diesel generator solution. The consideration of health aspects is included in the evaluation. Zusammenfassung Eine sozioökonomische Entwicklung in den ländlichen Regionen Afrikas kann ohne geeignete Infrastruktur nicht gelingen. Ein wesentlicher Eckpfeiler hierfür stellt die Elektrifizierung dar. Trotz diverser nationaler wie internationaler Maßnahmen und Ausbauprogramme, unterschiedlichster Akteure, schreitet die Umsetzung nur langsam voran. Um abgelegene Gegenden dennoch mit Elektrizität zu versorgen, haben sich in den vergangenen Jahren verstärkt netzunabhängige Systemtechnologien durchgesetzt. In diesem Artikel zeigen wir den Einsatz einer Photovoltaikanlage in Verbindung mit einer 85 kWh Second Life Lithium-Ionen-Batterie (LIB) als netzunabhängiges Hybridsystem, zur Elektrifizierung einer Insel im Viktoriasee in Tansania als sozioökonomisches Projekt. Mit diesem netzunabhängigen Hybridsystem konnte täglich durchschnittlich 42,31 kWh Energie geliefert werden, wobei der tägliche Bedarf der im Projekt erfolgreich angeschlossenen Schlüsselinfrastruktur, wie das lokale Krankenhaus und die Schule, 18,75 kWh beträgt. Die skalierte Jahresproduktion von 15.443,16 kWh bietet genug Kapazität, private Haushalte sowie die lokale Fischerei mit in die Stromversorgung einzubeziehen. In der Annahme einer erwarteten Lebensdauer von 15 Jahren kann sich das beschriebene System bereits ab dem 4. Jahr amortisieren. Darüber hinaus soll dieses Projekt auch in Hinblick auf die sich rasant entwickelnde globale Elektromobilität und dem perspektivischen Rückla...