Highlights Fully coupled (electro-chemo mechanics) phase field approach to characterize the fracture behavior. Highly heterogeneous electrochemical and mechanical response of randomly oriented polycrystalline NMC active particle is predicted. Mechanical degradation of polycrystalline NMC particle caused by significant particle cracking in the first charge cycle. Quantifying the electrochemically active surface area due to intergranular and intragranular particle fracture. Electrochemical performance analysis of polycrystalline NMC particle during the first charge cycle considering particle cracking plus electrolyte penetration.