Emulating true, field-like internal short-circuits (ISCs) by experimental methods is a complex task with mostly unsatisfactory outcome. However, understanding the evolution and impact of ISCs is crucial to mitigate safety issues related to lithium-ion batteries. Local short-circuit (LSC) conditions are applied to single-layered, small-sized (i.e. <60 mAh), and single-side coated graphite/NMC-111 pouch-type cells in a quasi-isothermal test bench using the nail/needle penetration approach. The cell’s impedance, capacity, and the contact resistance at the penetration site mainly define the short-circuit current and, hence, the terminal voltage and heat generation rate associated with polarization effects and electrochemical rate limitations, which are correlated to the cell’s behavior during external short-circuits (ESCs) at various short-circuit resistances. Measuring the electrical potential between the needle and the cell’s negative tab allows to evaluate the polarization across the electrodes and to estimate the short-circuit intensity. LSC simulation studies are used to correlate current flux and resistance to ESC conditions. Double-layered cells are penetrated to create short-circuit conditions within either a single or both electrode stacks to study the difference between multiple LSCs (e.g. during a nail penetration test) and a single LSC (e.g. due to a particle/dendrite). Post-mortem analysis reveals copper dissolution/deposition across both electrodes.

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In view of the development of superconducting fault current limiters, the properties of switching and recovering of YBa 2 Cu 3 O 7−δ /Au (YBCO/Au) thin films are studied at 77 K and 50 Hz for overcurrents. The bilayers present an abrupt transition to a high dissipative state leading to a current limitation at a maximum value of about 2.5 times the critical current I c , and allow the development of electric fields of 3 kV m −1 without any damage. After the overcurrent regime, the recovery of the superconducting state under the rated current I n is studied as a function of overcurrent parameters. These results show clearly the strong potential of YBCO/Au thin films which can recover their superconducting state under nominal mode. This last point is crucial for transformer connection, as experimentally shown in this paper.

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