Dual-Continuum Models of Lithium-Ion Batteries are Fast and Accurate Alternatives to the Doyle-Fuller-Newman Approach: II. Model Extensions

In Part I of this work, we derived and validated a dual-continuum model of a lithium-ion battery using the volume-averaging technique. Such models employ a fully macroscale description of the battery, thus avoiding the strong assumption made in the Doyle-Fuller-Newman (DFN) model that active material particles are isolated spheres. In all cases studied, our dual-continuum model predicted cell voltage more accurately than the DFN model, and required 70–80% less computation time. The physical insight offered by volume averaging gives rise to several interesting extensions of our derivation. Here in Part II, four of these are considered. Firstly, while Part I relied on a quasi-steady-state assumption for the closure problem, we now consider its transient behaviour to improve accuracy under changing battery loads. Secondly, we simulate electrodes with carbon additives and polymer binder, which can be explicitly modelled in the closure problem. Thirdly, we extend the dual-continuum theory to a multi-continuum model, which is particularly interesting for electrodes with a large particle size distribution. Finally, we reduce the dual-continuum theory to two single-continuum formulations, which are comparable with the well-known single-particle model—these maintain much of the accuracy of the dual-continuum approach whilst further reducing computation time.