Clearing the Smoke: Revisiting the Liquid Phase Potential in Newman’s Battery Model

Abstract

Lithium ion battery cell-level and sub-cell modelling have become almost synonymous with Newman’s Model. This paper sheds light on a specific part of the model — the liquid phase potential — clarifying its difference from the liquid phase potential found in the Butler-Volmer expression. Critically, we show that these two potentials should not be used interchangeably. In fact, we show that the concentration potential gradient differs by a factor of six in standard LiPF6 electrolytes. This could affect the Butler-Volmer current density strongly, if the definitions of electrostatic liquid phase potential are inadvertently interchanged.