AUTHOR=Wang Qing , Shaffer Christian Edward , Sinha Puneet K. TITLE=Controlling Factors of Cell Design on Large-Format Li-Ion Battery Safety during Nail Penetration JOURNAL=Frontiers in Energy Research VOLUME=3 YEAR=2015 URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2015.00035 DOI=10.3389/fenrg.2015.00035 ISSN=2296-598X ABSTRACT=

In this paper, we investigate the controlling design parameters of large-format Li-ion batteries on safety while undergoing nail penetration. We have identified three critical design parameters that control the safety during the nail penetration process: nail diameter (Dnail), single sheet foil area (Afoil), and cell capacity (Qcell).Using commercial AutoLion™ software, we have investigated two typical design problems related to the selection of cell thickness and aspect ratio, namely, (1) the safety ramifications of increasing cell capacity via greater cell thickness for a fixed footprint and (2) the effect of aspect ratio, or single sheet foil size, on safety at a given capacity. For a fixed footprint, our results indicate that the safety of the cell can be predicted by QcellDnail−0.5. For a given cell capacity, our results indicate that typically a larger single sheet foil area leads to a greater likelihood for thermal runaway due to its effect of making the heating more local in nature; however, for small cells (~5 Ah) and large nails (~20 mm), the greater aspect ratio can lead to a safer cell, as the greater surface area strongly cools the global heating of the cell.