Question about Cell Design Parameters in PyBaMM_Parameterset_Mohtat2020

[YeChao9595]

Hello,

I have a question regarding the cell design parameters in PyBaMM, specifically within the Mohtat2020 parameter set. The default values for the electrode height, width, and the number of electrodes connected in parallel to make a cell are as follows:

"Electrode height [m]": 1.0,
"Electrode width [m]": 0.205,
"Number of electrodes connected in parallel to make a cell": 1.0

However, when I refer to the paper titled "Journal of The Electrochemical Society, 2021, 168, 100520", it seems that the number of electrodes connected in parallel to make a cell is not 1.

If I want to change the number of electrodes connected in parallel according to this citation to calculate the cell expansion, are there any other parameters that need to be adjusted? Additionally, could anyone please explain the reasoning behind setting the number of electrodes connected in parallel to 1 by default?

FYI: I've already made updates as such:

def nmc_volume_change_mohtat(sto,c_s_max):
t_change = -1.10/100*(1-sto)
return t_change

def graphite_volume_change_mohtat(sto,c_s_max):
stoichpoints = np.array([0,0.12,0.18,0.24,0.50,1])
thicknesspoints = np.array([0,2.406/100,3.3568/100,4.3668/100,5.583/100,13.0635/100])
x = [sto]
t_change = pybamm.Interpolant(stoichpoints, thicknesspoints, x, name=None, interpolator='linear', extrapolate=True, entries_string=None)
return t_change

def get_parameter_values():
parameter_values = pybamm.ParameterValues(chemistry=pybamm.parameter_sets.Mohtat2020)
parameter_values.update(
{
# mechanical properties
"Positive electrode Poisson's ratio": 0.3,
"Positive electrode Young's modulus [Pa]": 375e9,
"Positive electrode reference concentration for free of deformation [mol.m-3]": 0,
"Positive electrode partial molar volume [m3.mol-1]": 7.28e-7,
"Positive electrode volume change": nmc_volume_change_mohtat,
# Loss of active materials (LAM) model
"Positive electrode LAM constant exponential term": 2,
"Positive electrode critical stress [Pa]": 375e6,
# mechanical properties
"Negative electrode Poisson's ratio": 0.2,
"Negative electrode Young's modulus [Pa]": 15e9,
"Negative electrode reference concentration for free of deformation [mol.m-3]": 0,
"Negative electrode partial molar volume [m3.mol-1]": 3.1e-6,
"Negative electrode volume change": graphite_volume_change_mohtat,
# Loss of active materials (LAM) model
"Negative electrode LAM constant exponential term": 2,
"Negative electrode critical stress [Pa]": 60e6,
# Other
"Cell thermal expansion coefficient [m.K-1]": 1.48E-6,
"Lower voltage cut-off [V]": 3.0,
# Initializing Particle Concentration
# "Initial concentration in negative electrode [mol.m-3]": x100parameter_values["Maximum concentration in negative electrode [mol.m-3]"],
# "Initial concentration in positive electrode [mol.m-3]": y100parameter_values["Maximum concentration in positive electrode [mol.m-3]"]
},
check_already_exists=False,
)
return parameter_values

PyBaMM Simulation Code:
experiment = pybamm.Experiment([
(
"charge at 0.25A until 4.2V",
)
])

model = pybamm.lithium_ion.DFN(name='DFN_w_thermal',
options = {
"particle": "Fickian diffusion",
"cell geometry": "arbitrary",
"thermal": "lumped",
"particle mechanics": "swelling only"
})

sim = pybamm.Simulation(model,experiment=experiment,parameter_values = param)
sim.solve(initial_soc=0)
sim.plot(["Terminal voltage [V]", "Current [A]", "Cell thickness change [m]"])

PyBaMM Simulation Output

I think the Cell thickness change output is 28 times smaller. Correct me if I'm wrong:P

Thank you for your help!