Summary variables with degradation mechanisms

[Akila1993]

Hello @DrSOKane and All,

I am running the following code for the cycling experiment for the coupled degradation model. But when I enable
"particle mechanics":("swelling and cracking", "swelling only"), "SEI on cracks": "true", option the summary variable plot I am getting is as below.

Cracking enabled

But I am getting an acceptable figure capacity variation for other options SEI and Plating. Does anyone have an idea about this behavior or is it acceptable form?

SEI enabled

model = pybamm.lithium_ion.DFN(
    {   
        "thermal": "lumped", #lumped thermal submodel 
        "surface form": "differential", #Adding capacitance to the model 
        #"SEI":"solvent-diffusion limited", #"reaction limited",
        #"SEI porosity change": "true",
        #"lithium plating": "partially reversible",
        #"lithium plating porosity change": "true",  # alias for "SEI porosity change"
        "particle mechanics":("swelling and cracking", "swelling only"),
        "SEI on cracks": "true",
        #"loss of active material": "stress-driven",
        
    }
)

var_pts = {
    "x_n": 5,  # negative electrode
    "x_s": 5,  # separator
    "x_p": 5,  # positive electrode
    "r_n": 30,  # negative particle
    "r_p": 30,  # positive particle
}

def get_chen2020_parameters():
    parameter_values = pybamm.ParameterValues("Chen2020")
    parameters = parameter_values
    return parameters

def get_okane2022_degradation_parameters():

 degradation_parameters = {
 'Dead lithium decay constant [s-1]': 1e-06,
 'Dead lithium decay rate [s-1]':pp["Dead lithium decay rate [s-1]"],
 'Initial plated lithium concentration [mol.m-3]': 0.0,
 'Lithium metal partial molar volume [m3.mol-1]': 1.3e-05,
 'Lithium plating kinetic rate constant [m.s-1]': 1e-09,
 'Lithium plating transfer coefficient': 0.65,
 'Negative electrode LAM constant exponential term': 2.0,
 'Negative electrode LAM constant proportional term [s-1]': 2.7778e-07,
 "Negative electrode Paris' law constant b": 1.12,
 "Negative electrode Paris' law constant m": 2.2,
 "Negative electrode Poisson's ratio": 0.3,
 "Negative electrode Young's modulus [Pa]": 15000000000.0,
 'Negative electrode cracking rate':pp["Negative electrode cracking rate"],
 'Negative electrode critical stress [Pa]': 60000000.0,
 'Negative electrode initial crack length [m]': 2e-08,
 'Negative electrode initial crack width [m]': 1.5e-08,
 'Negative electrode number of cracks per unit area [m-2]': 3180000000000000.0,
 'Negative electrode partial molar volume [m3.mol-1]': 3.1e-06,
 'Negative electrode reference concentration for free of deformation [mol.m-3]': 0.0,
 'Negative electrode volume change':pp["Negative electrode volume change"],
 'Positive electrode LAM constant exponential term': 2.0,
 'Positive electrode LAM constant proportional term [s-1]': 2.7778e-07,
 'Positive electrode OCP entropic change [V.K-1]': 0.0,
 "Positive electrode Paris' law constant b": 1.12,
 "Positive electrode Paris' law constant m": 2.2,
 "Positive electrode Poisson's ratio": 0.2,
 "Positive electrode Young's modulus [Pa]": 375000000000.0,
 'Positive electrode active material volume fraction': 0.665,
 'Positive electrode cracking rate':pp["Positive electrode cracking rate"],
 'Positive electrode critical stress [Pa]': 375000000.0,
 'Positive electrode initial crack length [m]': 2e-08,
 'Positive electrode initial crack width [m]': 1.5e-08,
 'Positive electrode number of cracks per unit area [m-2]': 3180000000000000.0,
 'Positive electrode partial molar volume [m3.mol-1]': 1.25e-05,
 'Positive electrode reference concentration for free of deformation [mol.m-3]': 0.0,
 'Positive electrode volume change':pp["Positive electrode volume change"],
 'Typical plated lithium concentration [mol.m-3]': 1000.0,
 'Exchange-current density for stripping [A.m-2]':pp["Exchange-current density for stripping [A.m-2]"],
 'Exchange-current density for plating [A.m-2]':pp["Exchange-current density for plating [A.m-2]"],
      
    }
 return degradation_parameters

def update_parameters():
    # Load Chen2020 parameters
    chen2020_params = get_chen2020_parameters()

    # Load OKane2022 degradation parameters
    okane2022_degradation_params = get_okane2022_degradation_parameters()

    # Update Chen2020 parameters with OKane2022 degradation parameters
    chen2020_params.update(okane2022_degradation_params, check_already_exists=False)

    return chen2020_params

updated_parameters = update_parameters()

cycle_number = 50
exp = pybamm.Experiment(
    [
        (
            "Discharge at 1C until 2.5 V",  # ageing cycles
            "Charge at 0.3C until 4.2 V (5 minute period)",
            "Hold at 4.2 V until C/100 (5 minute period)",
        )
    ]
    * cycle_number
)

sim = pybamm.Simulation(model, parameter_values=updated_parameters,experiment=exp,solver=pybamm.CasadiSolver(mode='safe without grid'),var_pts=var_pts)
#sim = pybamm.Simulation(model, parameter_values=updated_parameters,solver=pybamm.CasadiSolver(mode='safe without grid'),var_pts=var_pts)

solution = sim.solve()

pybamm.plot_summary_variables(solution)

[Akila1993]

@DrSOKane Can you please comment on this observation kindly?

[DrSOKane]

You have enabled SEI on cracks without enabling any of the SEI growth mechanisms, so no, there will be no degradation.