About:SPM
Single Particle Model - Efficient physics-based modeling that captures core electrochemical behavior
Overview
About:SPM is a physics-based model that represents the battery according to a set of physical equations and a corresponding parameter set. It is an implementation of the Single Particle Model (SPM), a simplification of the Doyle-Fuller-Newman model.
About:SPM predicts:
- Current-voltage relation
- Battery heat dissipation rate (excluding macroscopic Joule heating and mixing)
- Individual electrode overpotentials
- Lithiation distribution within active material particles (electrode-averaged)
About:SPM accounts for:
- State-of-charge (SOC)
- Temperature
- Charge-discharge hysteresis (at low C-rate)
- Rate capability (at low C-rate, according to physics-based loss computation)
- Cycling history (at low C-rate)
Technical Description
About:SPM implements a single particle model, in which microscopic active material particle properties are described for a single representative spherical particle of a Li insertion material in each electrode. The particle response is then scaled to a cell response according to the relative proportions of active material in the two electrodes. All particles of a given material are assumed to have constant size and equivalent behaviour; particle size and shape distributions are not considered, and electrolyte resistance is ignored.
Li insertion rate and the corresponding faradaic current density is coupled according to a specified volumetric surface area to a microscopic 1D model, which solves the spherically symmetric Fick’s law diffusion equation to predict inserted Li concentration as a function of particle radius.
Internal heating is computed, including activation overpotential. Heat of mixing is ignored, to the first approximation. Temperature dependence of various physical quantities is accounted for by the specification of Arrhenius activation energies.
Key features
- Faster solution time than About:DFN or About:SPMe, but may be accurate only at low C-rate
- Compatible with any thermal model
- Compatible with distributed electronic networks and 3D cell/module/pack models
- Implements a subset of About:DFN, in which (as in About:SPMe), for each electrode, all active material particles are considered equivalent. Compared to About:SPMe, the model is further simplified by considering the electrolyte to be uniform throughout the cell, and by ignoring resistive losses in the electrolyte.
Key applications
- System prototyping for cell integration
- Representation of cell performance in 3D thermal models
- Degradation analysis*
* with provision of supplementary degradation data