It was clarified that the polarization of the memory-effect was caused by the reduction of the active population by relaxation during a previous rest. Through this mechanism, we suggested a new polarization behavior, so-called relaxation-induced-polarization (RIP), which affects the polarization in the (dis)charging profile after the rest. The RIP can be triggered by only the last rest, whereas the appearance of the memory-effect needs specific processes with at least three steps. We also investigated path-dependence behavior, which is a well-known but unusual polarization behavior of LiFePO4 electrodes, and suggested a mechanism for this behavior. Unlike the former two polarizations, the path-dependence was considered to be caused by kinetically inhomogeneous reactions for each particle. Using mathematical simulations incorporating a many-particle model, we further predicted that narrowing the particle size distribution was effective to reduce this polarization, but it cannot be fully erased. The comprehensive understanding of the three polarization behaviors by our model can give us more accurate estimation of the state-of-charge of Li-ion batteries with the LiFePO4 electrode.
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