Yes, use the electrolyte NRTL as the thermodynamic method. And as Khalid mentioned you must specify all the ions. The database in ASPEN has many common ionic components but if you need more then you need an add on ion components database. In ASPEN go to the Electrolyte Wizard. It will help you.

Aspen Plus is a widely used process simulation software primarily focused on chemical processes involving thermodynamics, unit operations, and steady-state simulations. While Aspen Plus does not have built-in capabilities specifically designed for modeling electrochemical reactions, you can still incorporate electrochemical reactions into your simulation by utilizing its customization features.

Here are a few approaches you can consider:

It's important to note that accurately modeling electrochemical reactions involves considering various factors, including electrode kinetics, mass transport, and electrochemical cell design. You may need to develop customized models or utilize specialized software that caters specifically to electrochemical systems to achieve accurate and reliable simulations.

Before proceeding, I recommend consulting literature and resources on electrochemical modeling, discussing with experts in the field, or exploring other process simulation software options that are specifically designed for electrochemical reactions, such as COMSOL Multiphysics or HYSYS Electrolyzer.