C:\Program Files\ANSYS Inc\v231\fluent\fluent23.1.0\addons\msmdbatt\lib\echem_database.scm

If you know the LFP data I guess you can copy one of the existing elements and change the data. It might pop up. Didn’t try it on my own though.

Edit: you can edit the document, copy one of the cathode materials, change the data and you're good to go.