A Novel Approach for Understanding Heterogeneous Lithium-Ion Battery Aging Using Phase-Field Model

Abstract

Aging due to capacity fade is a major cause of concern in the fast growing lithium-ion battery (LIB) industry. In particular, the evolution of Solid Electrolyte Interface (SEI) have been on the focus of battery scientist as one of the primary aging mechanism affecting the cycle life of the battery. According to the recent experimental studies, the formation of SEI possesses a heterogeneous morphology and it is attributed to the (i) anisotropic ionic mobility in the crystal and (ii) surface reactions governing the flux of ions across the electrode/electrolyte interface, depending on the local free energy difference (1, 2). In contrast to most previous study which utilise rough simplification on modelling of SEI growth, we employed a novel aging formulation that captures the heterogeneous multi-layered SEI morphology by including Cahn-Hilliard interstitial diffusion modelling approach coupled with Nernst-Planck and Butler-Volmer equations for mass transport and surface chemistry, respectively. Since the Cahn-Hilliard is able to captures the anisotropic surface intercalation reactions with depending the local free energy difference of active material, our numerical theory shows promising results for better explaining the cause of the heterogeneous SEI growths on active material surfaces than the classical diffusion-limited model. W. Huang, P. M. Attia, H. Wang, S. E. Renfrew, N. Jin, S. Das, Z. Zhang, D. T. Boyle, Y. Li and M. Z. Bazant, Nano letters, 19, 5140 (2019). P. Guan, L. Liu and X. Lin, Journal of The Electrochemical Society, 162, A1798 (2015). Figure 1