Patent ID: 8742727

Claim:
An apparatus for estimating a voltage of a secondary battery which includes a cathode comprising a first cathode material and a second cathode material with different operating voltage ranges, an anode comprising an anode material and a separator for separating the cathode from the anode, the apparatus comprising: a control unit configured to estimate a voltage of a secondary battery during charging or discharging of the secondary battery based on a circuit model comprising a first cathode material circuit having a circuit element whose voltage changes according to State Of Charge (SOC) of the first cathode material varying with a current flowing through the first cathode material circuit, a second cathode material circuit connected to the first cathode material circuit in parallel and having a circuit element whose voltage changes according to SOC of the second cathode material varying with a current flowing through the second cathode material circuit, and an anode material circuit connected to the first and second cathode material circuits in series and having a circuit element whose voltage changes according to SOC of the anode material varying with a current flowing through the anode material circuit.