PyBamm version compatibility issue when saving data to CSV (version 23.3 works, version 23.5 does not)

[MirAbbasAli2A]

Hello PyBamm Team -

I have been running aging experiments in pybamm with RPT experiments and CC-CV aging experiments. The aging experiments save every 10 cycles. I am having issues saving the data from the CCCV and RPT experiments. It should be noted that the exact same code is used in another version of pybamm i have on another computer (V23.3) with python 3.8 (current computer generating error is python v 3.11 and pybamm version 23.5). Here is my code:

Experiments:

N=50

cccv_experiment = pybamm.Experiment([
("Charge at 2C until 4.2V",
"Hold at 4.2V until C/20",
"Discharge at 2C until 2.5V",
"Hold at 2.5V until C/20",
)
]*N
)

rpt_experiment = pybamm.Experiment([(
"Rest for 30 minutes",
"Charge at 1C until 4.2V",
"Hold at 4.2V until C/20",
"Rest for 30 minutes",
"Discharge at 1C until 2.5V",
"Rest for 30 minutes",
)])

Run the sims:

M = 6
for i in range(M):
sim = pybamm.Simulation(model, experiment=rpt_experiment,parameter_values=param, var_pts=var_pts, solver=solver)
rpt_sol = sim.solve(starting_solution=cccv_sol)
sim = pybamm.Simulation(model, experiment=cccv_experiment,parameter_values=param, var_pts=var_pts, solver=solver)
cccv_sol = sim.solve(starting_solution=rpt_sol, save_at_cycles= 10)
cccv_sols.append(cccv_sol)
rpt_sols.append(rpt_sol)

Trying to save data:

cccv_sol.save_data("2C100pdodcccv450xbeta_45C_soldata.csv",[
'Time [s]',
'Current variable [A]',
'Total current density [A.m-2]',
'Current [A]',
'C-rate',
'Discharge capacity [A.h]',
'Throughput capacity [A.h]',
'Discharge energy [W.h]',
'Throughput energy [W.h]',
'X-averaged negative electrode porosity',
'X-averaged separator porosity',
'X-averaged positive electrode porosity',
'X-averaged negative electrode interface utilisation variable',
'X-averaged negative electrode interface utilisation',
'X-averaged positive electrode interface utilisation variable',
'X-averaged positive electrode interface utilisation',
'X-averaged negative particle crack length [m]',
'X-averaged negative particle cracking rate [m.s-1]',
'X-averaged positive particle crack length [m]',
'X-averaged positive particle cracking rate [m.s-1]',
'X-averaged negative electrode active material volume fraction',
'Negative electrode capacity [A.h]',
'X-averaged negative particle radius [m]',
'X-averaged negative electrode surface area to volume ratio [m-1]',
'X-averaged negative electrode active material volume fraction change [s-1]',
'Loss of lithium due to loss of active material in negative electrode [mol]',
'X-averaged positive electrode active material volume fraction',
'Positive electrode capacity [A.h]',
'X-averaged positive particle radius [m]',
'X-averaged positive electrode surface area to volume ratio [m-1]',
'X-averaged positive electrode active material volume fraction change [s-1]',
'Loss of lithium due to loss of active material in positive electrode [mol]',
'X-averaged separator pressure [Pa]',
'X-averaged negative electrode transverse volume-averaged velocity [m.s-1]',
'X-averaged separator transverse volume-averaged velocity [m.s-1]',
'X-averaged positive electrode transverse volume-averaged velocity [m.s-1]',
'X-averaged negative electrode transverse volume-averaged acceleration [m.s-2]',
'X-averaged separator transverse volume-averaged acceleration [m.s-2]',
'X-averaged positive electrode transverse volume-averaged acceleration [m.s-2]',
'X-averaged negative electrode volume-averaged acceleration [m.s-2]',
'X-averaged negative electrode pressure [Pa]',
'X-averaged positive electrode volume-averaged acceleration [m.s-2]',
'X-averaged positive electrode pressure [Pa]',
'Average negative particle concentration [mol.m-3]',
'X-averaged negative particle surface concentration',
'X-averaged negative particle surface concentration [mol.m-3]',
'X-averaged negative electrode extent of lithiation',
'Minimum negative particle concentration [mol.m-3]',
'Maximum negative particle concentration [mol.m-3]',
'Minimum negative particle surface concentration [mol.m-3]',
'Maximum negative particle surface concentration [mol.m-3]',
'Average positive particle concentration [mol.m-3]',
'X-averaged positive particle surface concentration [mol.m-3]',
'X-averaged positive electrode extent of lithiation',
'Minimum positive particle concentration [mol.m-3]',
'Maximum positive particle concentration [mol.m-3]',
'Minimum positive particle surface concentration [mol.m-3]',
'Maximum positive particle surface concentration [mol.m-3]',
'X-averaged negative electrode potential [V]',
'X-averaged negative electrode ohmic losses [V]',
'X-averaged positive electrode potential [V]',
'X-averaged positive electrode ohmic losses [V]',
'Total lithium in electrolyte [mol]',
'X-averaged electrolyte potential [V]',
'X-averaged electrolyte overpotential [V]',
'X-averaged negative electrolyte potential [V]',
'X-averaged separator electrolyte potential [V]',
'X-averaged positive electrolyte potential [V]',
'Ambient temperature [K]',
'X-averaged cell temperature [K]',
'Volume-averaged cell temperature [K]',
'X-averaged SEI thickness [m]',
'X-averaged total SEI thickness [m]',
'X-averaged negative electrode resistance [Ohm.m2]',
'X-averaged SEI interfacial current density [A.m-2]',
'X-averaged SEI on cracks thickness [m]',
'X-averaged total SEI on cracks thickness [m]',
'X-averaged SEI on cracks interfacial current density [A.m-2]',
'X-averaged lithium plating concentration [mol.m-3]',
'X-averaged dead lithium concentration [mol.m-3]',
'X-averaged lithium plating thickness [m]',
'X-averaged dead lithium thickness [m]',
'Loss of lithium to lithium plating [mol]',
'Loss of capacity to lithium plating [A.h]',
'X-averaged negative electrode lithium plating reaction overpotential [V]',
'X-averaged lithium plating interfacial current density [A.m-2]',
'X-averaged negative electrode roughness ratio',
'X-averaged positive electrode roughness ratio',
'X-averaged negative electrolyte transport efficiency',
'X-averaged separator electrolyte transport efficiency',
'X-averaged positive electrolyte transport efficiency',
'X-averaged negative electrode transport efficiency',
'X-averaged separator electrode transport efficiency',
'X-averaged positive electrode transport efficiency',
'X-averaged separator volume-averaged acceleration [m.s-2]',
'X-averaged volume-averaged acceleration [m.s-1]',
'X-averaged negative electrode open-circuit potential [V]',
'X-averaged negative electrode entropic change [V.K-1]',
'X-averaged positive electrode open-circuit potential [V]',
'X-averaged positive electrode entropic change [V.K-1]',
'Positive current collector potential [V]',
'Voltage [V]',
'X-averaged negative electrolyte concentration [mol.m-3]',
'X-averaged separator electrolyte concentration [mol.m-3]',
'X-averaged positive electrolyte concentration [mol.m-3]',
'X-averaged negative electrolyte concentration [Molar]',
'X-averaged separator electrolyte concentration [Molar]',
'X-averaged positive electrolyte concentration [Molar]',
'X-averaged electrolyte concentration [mol.m-3]',
'X-averaged electrolyte concentration [Molar]',
'X-averaged concentration overpotential [V]',
'X-averaged electrolyte ohmic losses [V]',
'X-averaged negative electrode surface potential difference [V]',
'X-averaged positive electrode surface potential difference [V]',
'X-averaged Ohmic heating [W.m-3]',
'Volume-averaged Ohmic heating [W.m-3]',
'X-averaged irreversible electrochemical heating [W.m-3]',
'Volume-averaged irreversible electrochemical heating [W.m-3]',
'X-averaged reversible heating [W.m-3]',
'Volume-averaged reversible heating [W.m-3]',
'X-averaged total heating [W.m-3]',
'Volume-averaged total heating [W.m-3]',
'Current collector current density [A.m-2]',
'X-averaged inner SEI concentration [mol.m-3]',
'X-averaged outer SEI concentration [mol.m-3]',
'X-averaged SEI concentration [mol.m-3]',
'Loss of lithium to SEI [mol]',
'Loss of capacity to SEI [A.h]',
'X-averaged negative electrode SEI interfacial current density [A.m-2]',
'X-averaged positive electrode SEI volumetric interfacial current density [A.m-2]',
'X-averaged negative electrode SEI volumetric interfacial current density [A.m-3]',
'X-averaged inner SEI on cracks concentration [mol.m-3]',
'X-averaged outer SEI on cracks concentration [mol.m-3]',
'X-averaged SEI on cracks concentration [mol.m-3]',
'Loss of lithium to SEI on cracks [mol]',
'Loss of capacity to SEI on cracks [A.h]',
'X-averaged negative electrode SEI on cracks interfacial current density [A.m-2]',
'X-averaged positive electrode SEI on cracks volumetric interfacial current density [A.m-2]',
'X-averaged negative electrode SEI on cracks volumetric interfacial current density [A.m-3]',
'X-averaged negative electrode lithium plating interfacial current density [A.m-2]',
'X-averaged lithium plating volumetric interfacial current density [A.m-3]',
'X-averaged positive electrode lithium plating interfacial current density [A.m-2]',
'X-averaged positive electrode lithium plating volumetric interfacial current density [A.m-3]',
'X-averaged negative electrode lithium plating volumetric interfacial current density [A.m-3]',
'X-averaged negative electrode interfacial current density [A.m-2]',
'X-averaged negative electrode total interfacial current density [A.m-2]',
'X-averaged negative electrode total volumetric interfacial current density [A.m-3]',
'X-averaged negative electrode exchange current density [A.m-2]',
'X-averaged negative electrode reaction overpotential [V]',
'X-averaged negative electrode volumetric interfacial current density [A.m-3]',
'X-averaged SEI film overpotential [V]',
'X-averaged positive electrode interfacial current density [A.m-2]',
'X-averaged positive electrode total interfacial current density [A.m-2]',
'X-averaged positive electrode total volumetric interfacial current density [A.m-3]',
'X-averaged positive electrode exchange current density [A.m-2]',
'X-averaged positive electrode reaction overpotential [V]',
'X-averaged positive electrode volumetric interfacial current density [A.m-3]',
'Negative electrode stoichiometry',
'Negative electrode volume-averaged concentration [mol.m-3]',
'Total lithium in primary phase in negative electrode [mol]',
'Positive electrode volume-averaged concentration [mol.m-3]',
'Total lithium in primary phase in positive electrode [mol]',
'X-averaged reaction overpotential [V]',
'X-averaged solid phase ohmic losses [V]',
'Battery open-circuit voltage [V]',
'X-averaged battery reaction overpotential [V]',
'X-averaged battery solid phase ohmic losses [V]',
'X-averaged battery electrolyte ohmic losses [V]',
'X-averaged battery concentration overpotential [V]',
'Battery voltage [V]',
'Change in open-circuit voltage [V]',
'Terminal power [W]',
'Power [W]',
'Resistance [Ohm]',
'Total lithium in negative electrode [mol]',
'LAM_ne [%]',
'Loss of active material in negative electrode [%]',
'Total lithium in positive electrode [mol]',
'LAM_pe [%]',
'Loss of active material in positive electrode [%]',
'LLI [%]',
'Loss of lithium inventory [%]',
'Loss of lithium inventory, including electrolyte [%]',
'Total lithium [mol]',
'Total lithium in particles [mol]',
'Total lithium capacity [A.h]',
'Total lithium capacity in particles [A.h]',
'Total lithium lost [mol]',
'Total lithium lost from particles [mol]',
'Total lithium lost from electrolyte [mol]',
'Total lithium lost to side reactions [mol]',
'Total capacity lost to side reactions [A.h]'

],
to_format="csv")

Error Message:

Cell In[5], line 1
cccv_sol.save_data("2C100pdodcccv450xbeta_45C_soldata.csv",[

File ~\anaconda3\Lib\site-packages\pybamm\solvers\solution.py:634 in save_data
data = self.get_data_dict(variables=variables, short_names=short_names)

File ~\anaconda3\Lib\site-packages\pybamm\solvers\solution.py:594 in get_data_dict
[data_short_names["Cycle"], i * np.ones_like(cycle.t)]

AttributeError: 'NoneType' object has no attribute 't'

Why is this happening and how can I fix it to save all these variables to a csv?

Thank you for your help.