This paper proposes and validates a semi-empirical cycle-life model for lithium-ion pouch cells containing blended spinel and layered-oxide positive electrodes. For the model development and validation experimental data obtained during an aging campaign is used. During the campaign the influence of charge sustaining/depleting operation, minimum state of charge (SOC), charging rate and temperature on the aging process is studied. The aging profiles, which are prescribed in power mode, are selected to be representative of realistic plug-in hybrid electric vehicle (PHEV) operation. The proposed model describes capacity fade and resistance increase as function of the influencing stress factors and battery charge throughput. Due to its simplicity but still good accuracy, the applications of the proposed aging model include the design of algorithms for battery state-of-health (SOH) monitoring and prognosis, PHEV optimal energy management including battery aging, and the study of aging propagation among battery cells in advanced energy storage systems.