The simulation of lithium-ion batteries based on a fundamental multi-physicochemical model requires extensive computational resources and remains sluggish for real-time or battery pack analysis applications. In these applications, simplification of the model is required to reduce computational costs while maintaining the model accuracy in estimation of one or more performance parameters. In this study, the effects of neglecting the lithium-ion diffusive charge transfer and the salt concentration gradient in electrolyte on the model accuracy are investigated. The results indicate the feasibility of simplifying the model for a range of cell designs and discharge rates without sacrificing the preciseness of the cell energy and power density predictions.