A series of optimized graphite anodes and NMC cathodes with thicknesses from 70μm to 305μm were prepared to study the influence of the ratio of active material to inactive substrate foil on the cycle stability and energy density of lithium ion full cells. Cells with electrodes of up to 155μm thickness showed no capacity losses for C-rates up to C/2 and excellent cycling stability. For thicker electrodes the kinetic losses increased with C-rate and cycle stability deteriorated. However, for a given C-rate and in a realistic cell design, the energy density could be increased by up to 29% compared to the standard thickness.