Electrochemical impedance spectroscopy (EIS) is an indispensable technique for the investigation of polarization processes in Lithium-ion Batteries. These cause performance limitation or degradation. A physically meaningful impedance model is key when drawing conclusions on further cell improvement. This study introduces an in-depth impedance analysis of a commercial high-power graphite anode. The impedance spectra measured between 0 degrees C and 30 degrees C and 0%-100% SOC were analyzed by the distribution of relaxation times (DRT-method), enabling a separation of loss processes by their individual time constants. Using this method, we separated charge transfer resistance and solid electrolyte interface resistance at medium frequencies (10 Hz-200 Hz) and the contact resistance anode/current collector in the at high frequency range (5 kHz-100 kHz). Two fundamentally different model structures were set up, either (i) two modifications of a serial model connecting RQ-elements and a Warburg element for solid state diffusion, or (ii) three modifications of a transmission line model with one-path or two-path design. The suitability of all serial and TLM model structures was tested, and the fitting procedure was supported using microstructure parameters gained from x-ray tomography. The favored one-path transmission line model reveals that the lithium-ion transport in the electrolyte contributes more to polarization than expected. Impediment of lithium-ion transport is caused by the pore structure and the tortuosity of the high-power graphite anode, and has to be considered for meaningful interpretation of impedance spectra. (C) 2015 Elsevier B.V. All rights reserved.