A method for monitoring a lithium-ion battery cell includes monitoring a battery cell voltage and a corresponding state of charge of the battery cell during an electric power event which may include either an electric power charge event or an electric power discharge event. A measured potential-derivative is determined by differentiating the battery cell voltage in relation to the corresponding state of charge of the battery during the electric power event. The measured potential-derivative is compared with a preferred anode potential-derivative of an anode charge curve (for electric power discharge events) or an anode discharge curve (for electric power charge events), and with a preferred cathode potential-derivative of a cathode charge curve (for electric power charge events) or a cathode discharge charge curve (for electric power discharge events). A first state of health parameter of the battery cell corresponding to the comparison of the measured potential-derivative with the preferred anode potential-derivative of the anode curve is determined. And, a second state of health parameter of the battery cell corresponding to the comparison of the measured potential-derivative with the preferred cathode potential-derivative of the cathode curve is determined.