Modelling and analysis of polarisation characteristics in lithium insertion electrodes considering charge transfer and contact resistances

Abstract

The polarisation behaviour of Li[Li_0.1Al_0.1Mn_1.8]O₄ (LAMO) electrodes is influenced by charge transfer resistance (R_ct) and contact resistance (R_cont). In this study, using symmetric LAMO/LAMO cells, we find that polarisation curves shift from exponential (Tafel-like) to linear (Ohm's law-like) as R_ct decreases relative to R_cont, particularly at lower temperatures and higher frequencies. A new polarisation equation, based on an equivalent circuit model, explains the transition from exponential to linear polarisation curves observed in experiments. Our results indicate that reducing R_cont is more crucial than R_ct for improving electrode power capability.