Resistance calculation device, resistance calculation method, and program

A resistance calculation method that is executed by a computer of a resistance calculation device, the method comprising:

• acquiring an opening end potential curve for each single electrode before deterioration of a deteriorated secondary battery by a differential analysis of a voltage and a capacity and charging and discharging curve fitting;
• calculating a shrinkage rate for each single electrode based on a capacity shift amount of a positive electrode of the deteriorated secondary battery, a capacity shift amount of a negative electrode of the deteriorated secondary battery, a deterioration amount of the positive electrode, and a deterioration amount of the negative electrode, and calculating a curve representing characteristics of a state of charge and an open circuit voltage of an equivalent circuit of the deteriorated secondary battery by deforming the opening end potential curve for each single electrode before deterioration of the deteriorated secondary battery by the shrinkage rate for each single electrode based on a fixed point;
• calculating an amount of change in the open circuit voltage of the equivalent circuit to which a pulse current is applied based on a difference between the opening end potential curve for each single electrode before the deterioration and the curve representing the characteristics of the state of charge and the open circuit voltage of the equivalent circuit;
• calculating a DC resistance of the equivalent circuit by dividing a result of addition of an amount of change in a DC voltage of the equivalent circuit to which the pulse current is applied and the amount of change in the open circuit voltage of the equivalent circuit by a current value when the pulse current is applied to the equivalent circuit;
• and
• outputting, via a display device operatively connected to the resistance calculation device, information indicative of an analysis result, determined by the resistance calculation device, to an occupant of a vehicle.

A computer-readable non-transitory recording medium that includes a program causing a computer to execute:

• acquiring an opening end potential curve for each single electrode before deterioration of a deteriorated secondary battery by a differential analysis of a voltage and a capacity and charging and discharging curve fitting;
• calculating a shrinkage rate for each single electrode based on a capacity shift amount of a positive electrode of the deteriorated secondary battery, a capacity shift amount of a negative electrode of the deteriorated secondary battery, a deterioration amount of the positive electrode, and a deterioration amount of the negative electrode;
• calculating a curve representing characteristics of a state of charge and an open circuit voltage of an equivalent circuit of the deteriorated secondary battery by deforming the opening end potential curve for each single electrode before deterioration of the deteriorated secondary battery by the shrinkage rate for each single electrode based on a fixed point;
• calculating an amount of change in the open circuit voltage of the equivalent circuit to which a pulse current is applied based on a difference between the opening end potential curve for each single electrode before the deterioration and the curve representing the characteristics of the state of charge and the open circuit voltage of the equivalent circuit,
• calculating a DC resistance of the equivalent circuit by dividing a result of addition of an amount of change in a DC voltage of the equivalent circuit to which the pulse current is applied and the amount of change in the open circuit voltage of the equivalent circuit by a current value when the pulse current is applied to the equivalent circuit;
• and
• outputting, via a display device, information indicative of an analysis result, determined by the program, to an occupant of a vehicle.