For a full cell, sometimes people use two RC element two represent two charge transfer process of Anode and Cathode. Sometimes a single RC element is used to fit the curve ( as the time constant is close to each other). How can I decide the RC elements for a LFP battery? I use one Series resistance, one RC to represent both charge transfer processes of cathode and anode, one RC to represent to SEI and another CPE to represent the diffusion.
Mostly I have overlapped Charge transfer and SEI processes, the fitting is very random if I use two RC to represent one complete Semicircle(Nyquist plot).
It would be very helpful if someone help me understand the above uncertainities.
Thanks in advance.