Advanced development issues related to plasma-sprayed pyrite electrodes for thermal batteries

The use of LiCI-KCl eutectic electrolyte as a co-spray additive for the plasma spraying of pyrite electrodes for thermal batteries has been demonstrated to provide greater mechanical strength and superior electrochemical performance relative to the use of elemental sulfur. However, higher electrolyte contents in the deposit relative to that of the feedstock are of concern, in that this results in lower energy densities and specific energies. A systematic study of the effect of the electrolyte concentration in the feedstock on the final physical and chemical properties of the final plasm-sprayed deposit was undertaken. The resulting deposits were then tested in single cells to characterize the resultant electrochemical properties. A study was also initiated to examine the effects of various lithiation agents at several concentrations on the initial voltage spike that occurs at the onset of discharge of such electrodes in Li(Si)/LiCl-KCl-(MgO)/FeS₂ single cells. The main technical issues that need to be resolved to make this a commercially viable processing technique are described