Mathematical modelling of ionic transport in the electrolyte of Li-ion batteries

• Published in: Electrochimica acta 2008-07, Vol.53 (17), p.5569-5578
• Main Authors: Danilov, D., Notten, P.H.L.
• Format: Article
• Language: English
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electro-neutrality; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Ionic transport; Li-ion battery; Nernst–Plank equations; Organic electrolytes
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2008.02.086

The ionic conductivity of the organic electrolyte in Li-ion batteries has been modelled. The classical one-dimensional Nernst–Planck approach results in a system of two non-linear parabolic second-order partial differential equations. It is shown that under electro-neutrality conditions this complex system of equations can be reduced to simple diffusion equations with modified diffusion coefficient, facilitating the efficient use of numerical methods. As a result, detailed information about transient and steady-state behaviour of the electrolyte is revealed, including potential gradients and the diffusion and migration fluxes for both Li + and P F 6 − ions. Furthermore, an extension of the basic model is presented, taking into account salt dissociation in the electrolyte. The most characteristics of ionic transportation are illustrated with realistic examples of constant-current (dis)charging Li-ion batteries. Some of the numerical simulations are compared with recently reported experimental results.