# Multi-Scale Multi-Domain Model

NREL's multi-scale multi-domain (MSMD) model overcomes the modeling challenges posed by the highly nonlinear multi-scale response of battery systems. The expandable, modular, and flexible architecture connects the physics of battery charge/discharge processes, thermal control, safety, and reliability in a computationally efficient manner.

Macroscopic design factors and highly dynamic environmental conditions significantly influence the electrical, thermal, electrochemical, and mechanical responses of a battery system. Better knowledge of the interplay across interdisciplinary multi-physics at varied scales is imperative to the development and design of affordable, long-lasting, high-performing, and safe large battery systems.

The MSMD framework resolves interactions among multiple physics occurring in varied length and time scales, effectively simulating battery lifespan and behavior with consideration of internal defects and environmental factors. The model resolves battery geometry into three coupled computational domains:

- Particle-domain models (PDMs), to solve collective response of electrically and ionically connected particle-batteries.
- Electrode-domain models (EDMs), to solve collective behavior of particle-domain (PD)-batteries.
- Cell-domain models (CDMs), to solve single- or multi-cell battery response.

The GH-MSMD significantly speeds up computational time, with the ability to run a 1,200-second driving profile simulation in only 0.74 seconds. The GH-MSMD model can deliver speeds greater than the standard MSMD model by a factor of 1,000 to 10,000.

The MSMD's modular architecture is highly flexible and expandable. Model domain separation for the physicochemical process interplay is carried out where the characteristic time or length scale is segregated. Computational efficiency makes it possible to run the model on a standard desktop computer.

The MSMD model has been implemented in multiple programing platforms (i.e., Matlab, C++, fluent API library).

For example, NREL's integrated C++ multi-scale, multi-domain, electrode-domain model (MSMD-EDM)a fully adaptive, fast, high-fidelity, flexible battery model has been coupled with Argonne National Laboratory's MINIPACK open-source optimization software to perform advanced model-based battery system characterization.