A Two-Channel Transmission Line Model for a Quantitative Analysis of Li-Ion Battery Electrode Performance

摘要

Lithium-Ion-Battery (LIB) is the key technology to store electrical energy for mobile and stationary applications, and reduction of linear and non-linear loss contributions have to be further reduced during charging and discharging of the cell. The nonlinear loss contributions in LIB electrodes, which are linked to microstructure, were analysed by electrochemical impedance spectroscopy [1] and quantitatively evaluated by a physically meaningful two-channel transmission line model (TLM). The introduced TLM approach allows us to reproduce all reaction and transport processes in a homogenized microstructure. Based on 3D reconstructions from FIB/SEM-tomography of LIB cathodes, comprehensive sets of structural parameters are obtained [3,4]. It will be shown, that the lithium-ion transport in the electrolyte-filled pore phase contributes considerably to the total electrode polarization, as the effective ionic conductivity of the electrolyte changes significantly with porosity and tortuosity of the pore phase. Furthermore, charge transfer resistance at the electrode/electrolyte interface and contact resistance at the electrode/current collector are quantified and discussed in the context of microstructure characteristics of high-energy and high-power lithium-ion batteries.