A method of determining state of health (SoH) of a battery is disclosed which includes receiving a predetermined open circuit voltage (VOC) vs. a state of charge (SoC) characteristics for a pristine battery, establishing a single battery model including physical diffusion characteristics and electrical characteristics based on lumped parameters thereby modeling diffusion resistance and capacitance of particles in the electrodes of the battery as well as electrical characteristics based on electrical resistance and capacitance from one electrode assembly to another, thereby generating equations describing voltage at the associated double-layers, solving the double-layer equations, thereby generating solutions for the double-layer electrical characteristics, and establishing a relationship between the solved double-layer characteristics and the SoC, thereby determining a SoH of the battery based on said relationship.