Option for voltage/current variable names and frequency response of internal variables

[whileman133]

@rtimms @noelhallemans, in my research group at the University of Colorado Colorado Springs, we've defined lumped-parameter LIB/LMB models with slightly different variable names ("vcell [V]" instead of "Voltage [V]" and "iapp [A]" instead of "Current [A]"). Rather than reference "Voltage [V]" and "Current [A]" directly in the EISSimulation class, could these names be passed to the initializer for improved generality with model definitions?

Also: we'd find it useful to evaluate the frequency response of a cell's internal variables (in addition to the cell-level impedance) for comparison with our transfer function models. Do you have thoughts on what changes are needed to support this?

Thanks!

[rtimms]

For the variable names, the simplest thing would be to also add “Current [A]” and “Voltage [V]” as extra variables in your model.

For other states, you would need to change the solve method to return other states. Ideally, you would make it so you can access the full x(omega) as part of the solution (or as some additional object).