In addition to the development of high-energy density electrode materials for lithium-ion (Li-ion) batteries, other engineering approaches, such as electrode optimization, should be considered in order to meet the energy requirements of plug-in hybrid electric vehicles (PHEV). This work investigates the impact of the electrode thickness on the energy density of (Li-ion) batteries. The impedance results from the hybrid pulse power characterization (HPPC) test indicate that the electrode resistance is inversely proportional to the electrode thickness. This feature makes it possible to use thicker electrodes in (Li-ion) batteries to meet PHEV power requirements. The practical electrode thickness is determined to be around 100μm, if considering the electrode mechanical integrity when using conventional PVDF binders. Furthermore, cycle performance shows that cells with a higher loading density have a similar capacity retention to cells with a lower loading density.