A one-dimensional computational framework is developed that can solve for the evolution of voltage and current in a lithium-ion battery electrode under different operating conditions. A reduced order model is specifically constructed to predict the growth of mechanical degradation within the active particles of the carbon anode as a function of particle size and C-rate. Using an effective diffusivity relation, the impact of microcracks on the diffusivity of the active particles has been captured. Reduction in capacity due to formation of microcracks within the negative electrode under different operating conditions (constant current discharge and constant current constant voltage charge) has been investigated. At the beginning of constant current discharge, mechanical damage to electrode particles predominantly occurs near the separator. As the reaction front shifts, mechanical damage spreads across the thickness of the negative electrode and becomes relatively uniform under multiple discharge/charge cycles. Mechanical degradation under different drive cycle conditions has been explored. It is observed that electrodes with larger particle sizes are prone to capacity fade due to microcrack formation. Under drive cycle conditions, small particles close to the separator and large particles close to the current collector can help in reducing the capacity fade due to mechanical degradation. Due to their high energy and power density, lithium-ion batteries (LIBs) are being used extensively in the electrification of the automotive industry through the development of electric and hybrid electric vehicles (EVs and HEVs).1-3 Several mechanisms exist that can cause a reduction in the capacity of LIBs and subsequent loss of life. [4][5][6][7] Growth of a solid electrolyte interface (SEI) layer on the carbon active particles of the anode is the major reason behind the loss of cyclable lithium ions. [8][9][10] Lithium plating at low temperatures also results in loss of lithium and subsequent capacity fade.11 Delamination of the current collector from the electrode due to gas evolution in the electrolyte can significantly increase the internal resistance of the lithium-ion cell. 12 Crack propagation, rupture, and isolation of portions of active particles can also cause loss of active sites where lithium atoms can intercalate, resulting in effective capacity fade. 13 In the past two to three decades, capacity fade due to the formation of SEI 8,10,[14][15][16][17] and lithium plating 18,19 have been investigated thoroughly. On the other hand, resistance growth and capacity fade due to delamination and site loss have not been explored extensively. In the recent past, some research initiatives have focused on characterizing the generation of diffusion-induced stress within the active particles. 20 A computational methodology was developed to capture the formation of cracks based on the material heterogeneity of the anode active particles. 21 In the present article, the authors have developed a comprehensive reduced order model (RO...