A lithium-ion battery is being discharged with a current density of i mA cm-2. The positive electrode has a porous structure, and the electronic conductivity is much greater than the ionic conductivity, . Assume an open-circuit potential where U+ is essentially flat, but increases for high SOC and drops for low SOC. (a)Sketch the ionic current density, i2, across the separator and porous electrode at the start of the discharge. (b) Sketch the divergence of the current density; physically explain the shape of this curve. (c) Repeat (a) and (b) when the cell has nearly reached the end of its capacity. Again explain the shape. (d) How would the internal resistance change with the depth of discharge for this cell?