Description

The EM solver is capable of mimicking the complex electrochemistry happening in the layers of lithium ion batteries via the introduction of a 'distributed Randles circuit' model in order to simulate the current flows and local heating. The battery tabs can be connected to various types of isopotentials simulating the different conditions of use of a battery. The current example features a simple discharge of a solid battery.

Simple layers succession in a unit cell: 

Positive Current Collector - Positive Electrode - Separator - Negative Electrode - Negative Current Collector

A Randles circuit is an equivalent electrical circuit that consists of an active electrolyte resistance r0 in series with the parallel combination of the capacitance c10 and an impedance r10. A certain number of Randles circuits are created between corresponding nodes on the two current collectors of a battery unit cell. They model the electrochemistry happening in the electrodes and separator between the two current collectors. The Randles circuit parameters are defined by the keyword *EM_BATTERY_RANDLES when using solid elements.

The current collectors are treated as conductors with electrical conductivities given in the keyword *EM_MAT. They are connected to the tabs by the keywords *EM_ISOPOTENTIAL and if necessary (unmerged nodes) *EM_ISOPOTENTIAL_CONNECT.