Lithium-ion batteries are a promising choice for electric vehicles and grid storage, given the excellent cycle life and superior voltage response. A key thrust in current research efforts centers on improvement in energy and power density, which in turn is a strong function of the porous electrode microstructure. In particular, positive electrodes (cathode) can be limiting owing to poorer lithium storage capacity and inferior electronic conductivity. Consequently, positive electrode microstructures contain additional non-intercalating phases (such as, conductive additive and binder), which however have a bearing on the underlying transport mechanisms and ultimately on the electrochemical performance attributes. In this work, a hierarchical, mesoscale model has been developed to comprehend the implications of secondary phases on the cathode properties and cell performance. The cell response is quantified by rate capability, internal resistance, and electrochemical impedance response. The results reveal a highly non-linear dependence on the secondary phase characteristics and emphasize the significance of transport-electrochemical coupling.