An Experimentally Parameterized Equivalent Circuit Model of a Solid-State Lithium-Sulfur Battery

Abstract

This paper presents and parameterizes an equivalent circuit model of an all-solid-state lithium-sulfur battery cell, filling a gap in the literature associated with low computational intensity models suitable for embedded battery management applications. The paper addresses this gap by parameterizing a three-state equivalent circuit model using experimental pulse power characterization data from a laboratory-fabricated lithium-sulfur cell. The cell is mechanically loaded during electrical cycling to achieve maximum ionic conductivity and consistent capacity. A nested combination of linear and nonlinear least squares regression is used to estimate the model parameters. The model captures slow cycling and fast pulse charge/discharge dynamics within 34 mV RMS error. The series resistance changes significantly at high/low states of charge and low C-rates. A sensitivity analysis determines that accurately modeling the dependence of resistance on C-rate and state of charge is important for model fidelity.