The coupling of thick and dense cathodes with anode-free lithium metal configuration is a promising path to enable the next generation of high energy density solid-state batteries. In this work, we consider LiCoO2 (30µm)/LiPON/Ti as a model system to study the correlation between fundamental electrode properties and cell electrochemical performance, and we propose a physical model to understand the governing phenomena. We demonstrate that the first cycle loss is constant and independent of both cathode thickness and anode configuration, and only ascribed to the diffusion coefficients abrupt fall at high lithium contents. We show that subsequent cycles achieve close to 100% coulombic efficiency. We also examine the effect of cathode thickness and demonstrate a nearly linear correlation with areal specific capacity for sub-100µm LiCoO2 and 0.1mA.cm-2 current density. These findings bring new insights to better understand the energy density limiting factors and to suggest potential optimization approaches