Investigation of the increased stack pressure on anode-less lithium batteries

Sammanfattning

Lithium-ion batteries (LIBs) are the most commonly used type of battery today, thanks to its mature chemistry and superior performance. However, as the demand for innovative green solutions continues to increase, so are the requirements for the batteries in terms of their performance, energy density and safety. In this context, whereas the lithium metal battery (LMB) is seen as the next generation LIB, the anode-less lithium metal battery (AL-LAB) could be as an even more advanced solution. Nevertheless, the nascent chemistry of AL-LMB continues to be restrained by various challenges, including inhomogeneous plating of Li and irreversibility of the charge and discharge reaction. With a view to addressing these challenges, this thesis examines the effect of an increased stack pressure for the anode-less configuration. Both the Cu-Li half-cell and LiFePO4 (LFP)-Cu full-cellare studied using galvanostatic cycling. In addition, the LFP-Cu system is studied with acoustic emission (AE) sensing. The thesis concludes that the increase in stack pressure appears to decrease both the overall overpotential for the system and, unexpectedly, the capacity retention over prolonged cycling. The AE sensing results indicates that an increased stack pressure provides less mechanical response compared to cells experiencing no extra pressure. While the direct reason behind these observations has not been identified, it would be reasonable to consider that several factors contribute to such peculiar behavior, including the solid electrolyte interphase (SEI) layer and irreversible loss of Li via parasitic reactions. Additionally, other factors could also be the reasonbehind the performance, such as the choice of separator. However, in order to better understandthe effect of the increased stack pressure for the AL-LMB system, further research is required using additional characteristic techniques to examine above mentioned factors