Diffusion in Porous Electrode Diffusion in Free Electrolyte Diffusion of Active Mass Porous Composite Porous Composite Negative Separator Positive Electrode Electrode (LiCoO2) (Graphite) External Connector M+ X- Ln Ls External Connector Lp Negative Electrode Electrolyte (a) Anode Positive Electrode (b) Separator Cathode Anode Separator Li+ (c) (d) -60 163 mHz 217.3 mHz -50 2.1 mHz Im Z (mX) -40 2.1 mHz -30 -20 289.8 mHz -10 21.7 Hz j = 25 °C 0 100% SOC 80% SOC 50% SOC 30% SOC 21.7 mHz 10 20 285.7 Hz 40 50 60 70 80 90 100 110 120 130 140 150 160 170 Re Z (mX) (e) fig 2 The Li-ion cell sandwich: (a) the basic structure (adapted from [3]), (b) the diffusion process in such a cell (adapted from [1]), (c) Li-ion electrodes based on identical multiple particles (adapted from [3]), (d) a single particle representation of an electrode pair (adapted from [3]), and (e) a Nyquist plot (adapted from [25]). shown in Figure 1(c), dynamic effects occur within a wide range of time (from microseconds to years) and are a combination of several cases: 1) electrical and magnetic 2) electric double layer 3) mass transport 4) cycling and SOC 5) reversible 6) aging. The temperature effects are not shown in the figure, and the dynamics of the battery temperature depend on the heat capacity of the pack, the dissipated heat, and the December 2014 z IEEE PowEr ElEctronIcs MagazInE 25