[Bug]: Dead lithium not recorded in irreversible lithium plating model

[tomjholland]

PyBaMM Version

23.5

Python Version

3.10.13

Describe the bug

"Dead lithium" is recorded as a variable when the "partially reversible" lithium plating model is used, but not when the "irreversible" plating model is used. In the "irreversible" model, all plated lithium would be expected to become "dead lithium".

Steps to Reproduce

Following code plots dead lithium concentration for both model types as it is formed:

params = pybamm.ParameterValues("OKane2022")
sol = []
plt.figure()
for plating_model in plating_models:
    model = pybamm.lithium_ion.DFN(options={"lithium plating": plating_model})
    sim = pybamm.Simulation(model, parameter_values = pybamm.ParameterValues("OKane2022"))
    sol=sim.solve([0, 3600])
    Qt = sol["Throughput capacity [A.h]"].entries
    Dead = sol["Dead lithium concentration [mol.m-3]"].entries[-1,:] # index at interface
    plt.plot(Qt,Dead,label=plating_model)
    plt.xlabel("Throughput capacity [A.h]")
    plt.ylabel("Dead lithium concentration [mol.m-3]")
    plt.legend()
plt.show()

### Relevant log output

_No response_

[rtimms]

cc @DrSOKane

[DrSOKane]

Hi Tom, this is nothing to worry about. In the irreversible plating model, all plated lithium is dead, so there is no need for a separate dead lithium variable. Lithium is still conserved. That said, it will be an easy change to make once PR #3198 is complete.

[brosaplanella]

I think it would be good to add the dead lithium variable for all models (even if it matches the plated lithium) just for clarity. Happy to wait until #3198 is merged