Apparatus for estimating state of secondary battery including blended positive electrode material and method thereof

An apparatus for estimating a state of a secondary battery comprising a blended positive electrode material, wherein the secondary battery comprises a positive electrode including a first positive electrode material and a second positive electrode material having different operating voltage ranges from each other, a negative electrode including a negative electrode material and a separator interposed therebetween, the apparatus comprising:

• a sensor unit configured to measure, at time intervals, voltage and current of the secondary battery;
• and
• a control unit electrically connected with the sensor unit, and configured to estimate the state of the secondary battery, wherein the state of the secondary battery comprises a state of charge of at least one of the first positive electrode material, the second positive electrode material, and the negative electrode material, by implementing an Extended Kalman Filter algorithm using a state equation and an output equation, wherein the state equation comprises, as a state parameter, the state of charge of at least one of the first positive electrode material, the second positive electrode material, and the negative electrode material, and the output equation comprises, as an output parameter, the voltage of the secondary battery,
• wherein the state equation and the output equation are derived from a circuit model comprising a first positive electrode material circuit unit and a second positive electrode material circuit unit respectively corresponding to the first and the second positive electrode materials, and connected in parallel with each other, and optionally, a negative electrode material circuit unit corresponding to the negative electrode material and connected in series with the first and the second positive electrode material circuit units, and
• each of the first positive electrode material circuit unit, the second positive electrode material circuit unit, and the negative electrode material circuit unit comprises, as an optional element, an open-circuit voltage element varying voltage according to the state of charge of a corresponding electrode material, and/or an impedance element.

A method for estimating a state of a secondary battery comprising a blended positive electrode material, wherein the secondary battery comprises a positive electrode including a first positive electrode material and a second positive electrode material having different operating voltage ranges from each other, a negative electrode including a negative electrode material and a separator interposed therebetween, the method comprising:

• measuring, at time intervals, voltage and current of the secondary battery;
• and
• estimating the state of the secondary battery, wherein the state of the secondary battery comprises a state of charge of at least one of the first positive electrode material and the second positive electrode material, by implementing an Extended Kalman Filter algorithm using a state equation and an output equation, wherein the state equation comprises, as a state parameter, the state of charge of at least one of the first positive electrode material and the second positive electrode material, and the output equation comprises, as an output parameter, the voltage of the secondary battery,
• wherein the state equation and the output equation are derived from a circuit model, wherein the circuit model comprises a first positive electrode material circuit unit comprising an open-circuit voltage element corresponding to the first positive electrode material, and optionally, an impedance element, a second positive electrode material circuit unit comprising an open-circuit voltage element corresponding to the second positive electrode material and optionally, an impedance element, and being connected in parallel with the first positive electrode material circuit unit, and optionally, a negative electrode material circuit unit comprising an open-circuit voltage element corresponding to the negative electrode material and optionally, an impedance element, and being connected in series with the first and the second positive electrode material circuit units.

A method for estimating a state of a secondary battery comprising a blended positive electrode material, wherein the secondary battery comprises a positive electrode including a first positive electrode material and a second positive electrode material having different operating voltage ranges from each other, a negative electrode including a negative electrode material and a separator interposed therebetween, the method comprising:

• measuring, at time intervals, voltage and current of the secondary battery;
• and
• estimating the state of the secondary battery, wherein the state of the secondary battery comprises a state of charge of at least one of the first positive electrode material, the second positive electrode material, and the negative electrode material, by implementing an Extended Kalman Filter algorithm using a state equation and an output equation, wherein the state equation comprises, as a state parameter, the state of charge of at least one of the first positive electrode material, the second positive electrode material, and the negative electrode material, and the output equation comprises, as an output parameter, the voltage of the secondary battery,
• wherein the state equation and the output equation are derived from a circuit model, wherein the circuit model comprises a first positive electrode material circuit unit comprising an open-circuit voltage element corresponding to the first positive electrode material, and optionally, an impedance element, a second positive electrode material circuit unit comprising an open-circuit voltage element corresponding to the second positive electrode material and optionally, an impedance element, and being connected in parallel with the first positive electrode material circuit unit, and optionally, a negative electrode material circuit unit comprising an open-circuit voltage element corresponding to the negative electrode material and optionally, an impedance element, and being connected in series with the first and the second positive electrode material circuit units.