Phase separating electrode materials - chemical inductors?

Abstract

We unreveal mechanistic background of the presence of chemical inductive effects in phase separating ion intercalation energy storage materials, in particular lithium iron phosphate (LFP) and lithium titanate oxide (LTO), by applying a detailed phase field model. These materials feature fast (de)intercalation and slow diffusion relaxation phenomena, which are prerequisites for observing such inductive effects. The results are based on the mechanistic model and analytical considerations, which show that all equilibrium states that lie within the miscibility gap of the phase-separating material exhibit a strong inductive response in the low frequency part of the spectrum. We also explain why such inductive effects are not observed outside the miscibility gap. In this letter, we present the first mechanistic justification for the previously reported experimental observation of electrode level inductance in impedance measurements at low currents.