Physics-based modeling of sodium-ion batteries part II. Model and validation

Sodium-ion batteries (SIBs) have recently been proclaimed as the frontrunner 'post lithium' energy stor-age technology. This is because SIBs share similar performance metrics with lithium-ion batteries, and sodium is 10 0 0 times more abundant than lithium. In order to understand the electrochemical characteristics of SIBs and improve present-day designs, physics-based models are necessary. Herein, a physics-based, pseudo-two-dimensional (P2D) model is introduced for SIBs for the first time. The P2D SIB model is based on Na3V2(PO4)(2)F-3 (NVPF) and hard carbon (HC) as positive and negative electrodes, respectively. Charge transfer in the NVPF and HC electrodes is described by concentration-dependent diffusion coefficients and kinetic rate constants. Parametrization of the model is based on experimental data and genetic algorithm optimization. It is shown that the model is highly accurate in predicting the discharge profiles of full cell HC//NVPF SIBs. In addition, internal battery states, such as the individual electrode potentials and concentrations, can be obtained from the model at applied currents. Several key challenges in both electrodes and the electrolyte are herein unraveled, and useful design considerations to improve the performance of SIBs are highlighted. (c) 2021 The Author(s). Published by Elsevier Ltd.

Automated summary

This article introduces a physics-based pseudo-two-dimensional (P2D) model for sodium-ion batteries (SIBs) for the first time, using Na3V2(PO4)(2)F-3 (NVPF) and hard carbon (HC) as positive and negative electrodes, respectively. The model accurately predicts the discharge profiles of full cell HC//NVPF SIBs and provides information on internal battery states. It also highlights key challenges and design considerations to improve the performance of SIBs.