Development of a New Procedure for Nail Penetration of Lithium-Ion Cells to Obtain Meaningful and Reproducible Results

Internal short circuit tests of Lithium-Ion Batteries (LIBs) are used to test battery safety behavior in a custom made battery cell stressing chamber. However, systematic investigations regarding the test setup and test procedure are rare. In our research commercially available pouch cells (5 Ah) are employed for the method development and validation of nail penetration tests including measurement of gaseous reaction products. The effects of the thermal insulation material, the nail material (conductive and non-conductive), the influence of the penetration depth and the nail velocity were examined. It was observed that low penetration velocities (1 mm s−1) in combination with a conductive nail and a nail motion control, which is based on monitoring the temporal evaluation of the cell voltage change, provide the most promising results in terms of reproducibility at low standard deviation. By applying this method, only the energy required for a Thermal Runaway (TR) is released, which makes it possible to determine a novel key value for the assessment of battery safety. Based on this, a proposal has been made for a nail penetration test method which would allow the results to be compared between different test facilities

Immune responses against SARS-CoV-2 variants after heterologous and homologous ChAdOx1 nCoV-19/BNT162b2 vaccination.

Currently approved viral vector-based and mRNA-based vaccine approaches against coronavirus disease 2019 (COVID-19) consider only homologous prime-boost vaccination. After reports of thromboembolic events, several European governments recommended using AstraZeneca's ChAdOx1-nCov-19 (ChAd) only in individuals older than 60 years, leaving millions of already ChAd-primed individuals with the decision to receive either a second shot of ChAd or a heterologous boost with mRNA-based vaccines. However, such combinations have not been tested so far. We used Hannover Medical School's COVID-19 Contact Study cohort of healthcare professionals to monitor ChAd-primed immune responses before and 3 weeks after booster with ChAd (n = 32) or BioNTech/Pfizer's BNT162b2 (n = 55). Although both vaccines boosted prime-induced immunity, BNT162b2 induced significantly higher frequencies of spike-specific CD4+ and CD8+ T cells and, in particular, high titers of neutralizing antibodies against the B.1.1.7, B.1.351 and P.1 variants of concern of severe acute respiratory syndrome coronavirus 2