• Energy Research

Abstract In order to develop a deeper understanding of the behaviour of commercial automotive lithium-ion pouch cells under short-circuiting conditions, two scenarios were experimentally investigated and compared. Firstly, experiments were conducted by internally shorting 15 Ah cells by full nail penetration using three different nail materials; copper, steel and plastic. A second set of experiments involved externally shorting the cell tabs using an external circuit with a range of resistance values. In both scenarios the cell electrical and thermal response were determined by the shorting resistance. In the case of nail penetration there was a clear distinction between the outcome of the conducting and non-conducting nails, although the outcome using conducting nails suffered from poor reproducibility. The poor reproducibility was attributed to the variation in the contact resistance between the nail and the cell layers. Correlating the outcome of both tests can be used to estimate the shorting resistance and construct the current profile during nail penetration test.

Diagrams showing equilibrium potentials (relative to the standard chlorine electrode) plotted vs the negative logarithms of oxide-ion activity (pO 2 - ) have been constructed for titanium species including oxides, chlorides, and metal, in molten calcium chloride over the temperature range 800-1100°C. The utility of such diagrams is particularly evident in the field of the molten salt extractive metallurgy of titanium via recently developed electrochemical processing methods. These plots suggest ideal process routes that produce low-oxygen titanium under controlled melt composition and potential.

Abstract Ti–W alloys were produced via electrochemical reduction of TiO2–WO3 mixed oxide preforms in a pre-electrolysed, molten calcium chloride electrolyte at 1173 K. Electrolysis voltages of 1500–3200 mV were applied for times ranging from 6 to 24 h across a graphite anode and Grade 2 commercial purity (CP) titanium cathodic current collector, which supported the ceramic precursors. Low-oxygen, homogeneous material was subsequently water washed and characterized to determine the level of residual species remaining from the reduction process, such as Cl and Ca. The microstructure (porosity and microchemistry) of the reduced material and microstructural examination of the mixed oxide feedstock (particle morphology, size and chemistry) were characterized using a field emission gun scanning electron microscope (FEG-SEM) with backscattered electron imaging (BSE) and X-ray energy dispersive spectrometry (X-EDS).

Abstract not Available.