While lithium based battery technologies are becoming increasingly widespread in our energy landscape, both in electric vehicles and grid scale storage, room for improvement remains in continuing to increase energy density, reducing their costs, and improving the sustainability of their manufacturing. Lithium metal batteries offer great promise for higher energy density, but are presently limited by significant side reactions, poor quality deposition, and the potential to form hazardous dendrites. Furthermore, fluorinated electrolytes show high performance in Li metal batteries but pose environmental concerns related to the longevity of PFAS compounds.
In this presentation, I will discuss electron paramagnetic resonance (EPR) spectroscopy used to identify radical reaction intermediates and clarify electrolyte reduction mechanisms. SEI formation mechanisms in fluorinated electrolytes will be discussed in the context of moving toward more environmentally friendly fluorine-free electrolytes. This understanding is applied to develop fluorine-free localized high concentration electrolytes (LHCE) with high Coulombic efficiency. With the understanding developed through this EPR approach, we provide new insight into electrolytes and the formation of interphase components that promote stable cycling of lithium metal cells.
