Bugs? SOC is not zero after discharging.

[L4XIA]

Slightly modified the code, I found that the SOC cannot go back to zero after discharging (see the figure below). Is this a bug?

below is the related code

import pybamm as pb
import matplotlib.pyplot as plt
pb.set_logging_level("NOTICE")
model = pb.lithium_ion.DFN(
{
"SEI": "ec reaction limited",
"SEI film resistance": "distributed",
"SEI porosity change": "true",
"lithium plating": "irreversible",
"lithium plating porosity change": "true",
}
)

param = pb.ParameterValues("Mohtat2020")
experiment = pb.Experiment(
[
(
"Charge at 1 C until 4.2 V",
"Hold at 4.2 V until C/10",
"Rest for 5 minutes",
"Discharge at 1 C until 2.8 V",
"Rest for 5 minutes",
)
]
* 2,
period = "5 seconds",

)

sim = pb.Simulation(model, experiment=experiment, parameter_values=param)
sim.solve(solver=pb.CasadiSolver(mode="safe"))
sol = sim.solution
t = sol["Time [min]"].entries
vv = sol["Terminal voltage [V]"].entries
SOC = sol["Negative electrode SOC"].entries*100

fig, axs = plt.subplots(figsize=(13,9))
axs.plot(SOC, vv, color="blue", linestyle="solid", label="Simulation")

axs.set_xlabel("SOC [%]")

axs.legend()
axs.set_ylabel("Voltage [V]")
axs.grid(True)

[valentinsulzer]

• "Negative electrode SOC" is not the same as cell SOC (we just renamed it to "Negative electrode stoichiometry" to make this clearer)
• It would probably go back to zero if you included a CV hold at 2.8V
• Cell SOC is not currently available but should be soon, see Cell-level State of Charge #2553 for a discussion

[L4XIA]

Thanks for clarifications!