Multiple Phases (composite electrode) + PSD (particle size distribution) Model Option Compatibility

[mleot]

Description

This issue is simply asking for the ability to specify multiple phases in addition to a particle size distribution. Since there are error raising statements already in place here, I am considering this to be a feature addition and not a bug.

Motivation

Simply put, if there is no fundamental blocker preventing these model options from being used together, it would be nice to be able to specify both of these physics at once.

Possible Implementation

I think the first step is to just remove the error raising statement linked above in the description, and see what other errors, if any, arise. If it does require some more careful refactoring, then I think further discussion should be had around the next steps.

Additional context

No response