update effective conductivity

Author: Robert Timms

pybamm/input/parameters/lithium_ion/Chen2020.py

@@ -305,7 +305,7 @@ def get_parameter_values():
         "Negative electrode active material volume fraction": 0.75,
         "Negative particle radius [m]": 5.86e-06,
         "Negative electrode Bruggeman coefficient (electrolyte)": 1.5,
-        "Negative electrode Bruggeman coefficient (electrode)": 1.5,
+        "Negative electrode Bruggeman coefficient (electrode)": 0,
         "Negative electrode cation signed stoichiometry": -1.0,
         "Negative electrode electrons in reaction": 1.0,
         "Negative electrode charge transfer coefficient": 0.5,
@@ -325,7 +325,7 @@ def get_parameter_values():
         "Positive electrode active material volume fraction": 0.665,
         "Positive particle radius [m]": 5.22e-06,
         "Positive electrode Bruggeman coefficient (electrolyte)": 1.5,
-        "Positive electrode Bruggeman coefficient (electrode)": 1.5,
+        "Positive electrode Bruggeman coefficient (electrode)": 0,
         "Positive electrode cation signed stoichiometry": -1.0,
         "Positive electrode electrons in reaction": 1.0,
         "Positive electrode charge transfer coefficient": 0.5,

pybamm/input/parameters/lithium_ion/Chen2020_composite.py

@@ -406,7 +406,7 @@ def get_parameter_values():
         "Primary: Negative electrode active material volume fraction": 0.735,
         "Primary: Negative particle radius [m]": 5.86e-06,
         "Negative electrode Bruggeman coefficient (electrolyte)": 1.5,
-        "Negative electrode Bruggeman coefficient (electrode)": 1.5,
+        "Negative electrode Bruggeman coefficient (electrode)": 0,
         "Negative electrode cation signed stoichiometry": -1.0,
         "Primary: Negative electrode electrons in reaction": 1.0,
         "Negative electrode charge transfer coefficient": 0.5,
@@ -440,7 +440,7 @@ def get_parameter_values():
         "Positive electrode active material volume fraction": 0.665,
         "Positive particle radius [m]": 5.22e-06,
         "Positive electrode Bruggeman coefficient (electrolyte)": 1.5,
-        "Positive electrode Bruggeman coefficient (electrode)": 1.5,
+        "Positive electrode Bruggeman coefficient (electrode)": 0,
         "Positive electrode cation signed stoichiometry": -1.0,
         "Positive electrode electrons in reaction": 1.0,
         "Positive electrode charge transfer coefficient": 0.5,

pybamm/parameters/bpx.py

@@ -87,10 +87,14 @@ def _bpx_to_param_dict(bpx: BPX) -> dict:
         "Initial concentration in electrolyte [mol.m-3]"
     ]
 
-    # assume Bruggeman relation
+    # assume Bruggeman relation for effection electrolyte properties
     for domain in [negative_electrode, separator, positive_electrode]:
         pybamm_dict[domain.pre_name + "Bruggeman coefficient (electrolyte)"] = 1.5
-        pybamm_dict[domain.pre_name + "Bruggeman coefficient (electrode)"] = 1.5
+
+    # solid phase properties reported in BPX are already "effective",
+    # so no correction is applied
+    for domain in [negative_electrode, positive_electrode]:
+        pybamm_dict[domain.pre_name + "Bruggeman coefficient (electrode)"] = 0
 
     # BPX is for single cell in series, user can change this later
     pybamm_dict["Number of cells connected in series to make a battery"] = 1
@@ -194,6 +198,8 @@ def _positive_electrode_entropic_change(sto, c_s_max):
     E_a_n = pybamm_dict.get(
         negative_electrode.pre_name + "reaction rate activation energy [J.mol-1]", 0.0
     )
+    # Note that in BPX j = 2*F*k_norm*sqrt((ce/ce0)*(c/c_max)*(1-c/c_max))*sinh(...),
+    # and in PyBaMM j = 2*k*sqrt(ce*c*(c_max - c))*sinh(...)
     k_n = k_n_norm * F / (c_n_max * c_e**0.5)
 
     def _negative_electrode_exchange_current_density(c_e, c_s_surf, c_s_max, T):
@@ -222,6 +228,8 @@ def _negative_electrode_exchange_current_density(c_e, c_s_surf, c_s_max, T):
     E_a_p = pybamm_dict.get(
         positive_electrode.pre_name + "reaction rate activation energy [J.mol-1]", 0.0
     )
+    # Note that in BPX j = 2*F*k_norm*sqrt((ce/ce0)*(c/c_max)*(1-c/c_max))*sinh(...),
+    # and in PyBaMM j = 2*k*sqrt(ce*c*(c_max - c))*sinh(...)
     k_p = k_p_norm * F / (c_p_max * c_e**0.5)
 
     def _positive_electrode_exchange_current_density(c_e, c_s_surf, c_s_max, T):