This study investigates the consistency of the thermal propagation reaction resulting from nail penetration, overheating, and overcharging of a single cell within a pouch cell pack. The experimental setup allows for the measurement of temperature, voltage, and for various exhaust gas properties. A statistical analysis of these resulting quantities is used to identify the reproducibility of the different trigger methods. Finally, the influence of the particular test chamber and operator are studied, using the trigger method identified as most reproducible.

As we presented previously, the thermal runaway of the Li-ion depends on the max power generated on the internal short spots. This paper will address the cell design influence of the max power generation and the needed measurements of various internal short impedances of the Li-ion cells. The images of the real cell internal short will be presented and discussed.

For LIB, a holistic safety assessment is in the focus, because the thermal runaway can have multiple interacting causes and effects. A test in an Accelerating Rate Calorimeter (ARC) reveals the entire process of the thermal runaway with the different stages of exothermic reactions. As a result quantitative and system relevant data for temperature, heat and pressure development of materials and cells are provided. In addition it will be explained how calorimeters can be combined with gas chromatography and mass spectroscopy to analyse the gases, which are occurring during abuse tests.

The increased demand for li-ion cells and batteries for a multitude of applications from portable electronics to electric vehicles and battery stationary grid energy storage systems has led to its production with low quality and questionable safety. Counterfeit cells and batteries can be purchased with a quick turnaround time and at low cost with the same label as OEMs. UL ESRI's nominal and off-nominal testing along with destructive analysis has confirmed that these products neither meet the label specifications nor have the required self-protective devices that are required to operate under off-nominal conditions. 

The presentation deals with thermal propagation tests at module and system level. The various test results of these investigations will be presented in the presentation.

Lithium-Ion has had a colorful safety history but now is a commodity we mostly understand. But, what about the, “beyond lithium-ion”, chemistries that are coming. The many flavors of lithium metal, including ASSB, liquid electrolyte, and hybrids. What about Sodium, Magnesium & Aluminum waiting in the wings. This presentation will look at de-risking these technologies sooner rather than later and some of the tools that should be proactively applied.

Is your organization prepared to handle a serious lithium battery field event?  In this presentation, we will cover key considerations with a particular focus on the pros and cons of engaging a third-party failure analysis provider.  This will be further expanded into tips for working with such providers as well as what you should and should not expect.

Metallized plastic current collectors in Li-ion cells reduce mass and reduce the internal short circuit hazard compared to aluminum and copper foils. Shorts induced by nail and by our internal short circuit device were performed on control 18650 cells and on cells with the collectors replaced with metallized polyester and aramid films. Tests were performed inside our fractional thermal runaway calorimeter to quantify the heat transferred and its distributions and those runs done at a synchrotron yielded fascinating very high speed X-ray videography. These show tolerance to nail penetration and activation of defect internal shorts and when thermally forced into thermal runaway, the heat output is significantly reduced. Very high resolution CT scans, cross sections, and cell tear downs give insights into the thermal and mechanism for these plastic collectors.

In various applications, lithium-ion batteries can be exposed to external mechanical damages, which may remain undetected, resulting in their continued usage. As the interaction of cell-external deformation with cell-internal forces may pose a significant long-term hazard, the cyclic aging behavior, electrical behavior (capacity, DVA, EIS) for potential damage detection, and safety behavior of damaged cells were characterized. Additionally, CT, SEM, and Post Mortem analysis was conducted to improve the understanding of external mechanical deformation in the aging process.

Lithium-ion batteries continue to become more and more prolific around the world. With higher energy densities and capacities in today’s lithium-ion batteries, interpreting battery remains after thermal runaway for root cause analysis has become increasingly complex. To meet this challenge, Exponent is developing new methodologies and techniques to determine the cause and origin of catastrophic failures and the results of those efforts will be shared in this presentation.

While Li-ion batteries are an amazing technological achievement to meet future energy requirements there is a need to develop higher energy batteries. For the past 20 years Si has been seen as a capable alternative to graphite due to it high specific capacity and in recent years there has been a rise in prototype production of Li-ion batteries containing a combination of Si and graphite or pure Si anodes. With the addition of Si, it is important to understand its role in cell failure and additional material analysis that will help tell the whole story. This presentation will aim to describe additional techniques that should be utilized in a cell teardown and a safety review to better understand how Si is impacting cell failure.