Molten-Salt Battery Response to Open-Circuit and Puncture Testing

Abstract

Molten-salt thermal batteries may pose hazards in industrial settings if they are damaged or inadvertently ignited. Tests have been performed to determine how a thermal battery would behave without a suitable electrical load, open-circuit, and whether it could be ignited by puncturing the case. Some intact and damaged batteries were ignited by normal means to observe the open-circuit response. None of these batteries ruptured, but some showed evidence of internal short circuits developing. The consequences of puncturing side-fired Ca/CaCrO4 and Li-Si/FeS2 thermal batteries were investigated. Fourteen batteries were punctured on the side of the cylindrical case with a steel rod propelled by a gas gun. The gas gun pressure was modulated to interrogate the probability of battery activation as a function of kinetic energy using the Neyer method. The batteries were observed to activate with kinetic energies in the range of 100–156 J [74–115 ftlb] and velocities between 3.2–4.0 m/s [10–13 ft/s], producing voltages at or below the design value and a normal thermal response. No thermal runaways occurred. The relationships between the kinetic energy and the probability of ignition are presented for both battery chemistries.