Note

This notebook is already available in your BattMo installation. In Matlab, run

open runImpedanceScript

Battery impedance computation

We compute the impedance of a lithium-ion battery cell at different states of charge (SOC) using the Battmo framework. The impedance is computed using the ImpedanceSolver class, which takes into account the electrochemical properties of the battery cell as defined in a JSON file. The results are plotted in a Nyquist plot, showing the real and imaginary parts of the impedance.

Battery input parameters

We load a JSON file containing the parameters of a lithium-ion battery cell, and set up the model using the setupModelFromJson function. We also disable thermal effects and current collectors for this impedance computation.

filename = fullfile(fullfile('ParameterData'        , ...
                             'BatteryCellParameters', ...
                             'LithiumIonBatteryCell', ...
                             'lithium_ion_battery_lco_graphite.json'));
jsonstruct = parseBattmoJson(filename);

jsonstruct.use_thermal                = false;
jsonstruct.include_current_collectors = false;

[model, inputparams, jsonstruct, gen] = setupModelFromJson(jsonstruct);

Impedance computation

%
% Plot settings
set(0, 'defaultlinelinewidth', 1);
set(0, 'defaultaxesfontsize', 15);

figure
hold on

%
% We compute the impedance for different SOC values, and plot the results in a Nyquist plot. The impedance is normalized
% by the face area of the model and converted to Ωcm^2 for better visualization.

socs = linspace(0.1, 1, 5);

options = [];
options.stateInitialization.initializationSetup = 'soc';

for isoc = 1 : numel(socs)

    soc = socs(isoc);

    options.stateInitialization.soc = soc;
    impsolv = ImpedanceSolver(inputparams, options);

    omegas = linspace(-3, 6, 500);
    omegas = 10.^omegas;
    Z = impsolv.computeImpedance(omegas);

    Z = (Z*gen.faceArea)/((centi*meter)^2);

    legtxt = sprintf('SOC=%g', soc);
    plot(real(Z), -imag(Z), 'displayname', legtxt);
    xlabel('real(Z) / Ωcm^2')
    ylabel('-imag(Z) / Ωcm^2')

end

legend show
title('Impedance')
axis equal

%{
Copyright 2021-2026 SINTEF Industry, Sustainable Energy Technology
and SINTEF Digital, Mathematics & Cybernetics.

This file is part of The Battery Modeling Toolbox BattMo

BattMo is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

BattMo is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with BattMo.  If not, see <http://www.gnu.org/licenses/>.
%}