The increasing demand for sustainable mobility requires high-performance lithium-ion batteries (LIBs) with long range and fast-charging capability, leading to the growing use of silicon (Si) as an anode material over graphite (Gr) due to its higher capacity and advantageous potential for fast charging; however, conventional electrochemical models are unable to physically capture the voltage hysteresis of silicon-based active materials and their implications, such as energy balance and open circuit potential (OCP), relying instead on empirical approaches and quasi-open circuit potentials (qOCPs), which this work addresses by presenting a new electrochemical multiphase model for silicon in combination with experiments that more precisely map the processes in the material and model the cell behavior.