METHOD FOR EVALUATING DETERIORATION OF LITHIUM ION SECONDARY BATTERY, AND BATTERY PACK
First Claim
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1. A method for evaluating deterioration of a lithium ion secondary battery, the method comprising the steps of:
- measuring an impedance spectrum of a lithium ion secondary battery, using alternating current of a predetermined frequency range,determining coordinates of a peak of an arc-like portion, when the impedance spectrum is represented by a diagram including the arc-like portion on a complex plane defined by a resistive component axis and a capacitive component axis, andevaluating a deterioration state of the lithium ion secondary battery, on the basis of the coordinates.
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Abstract
Disclosed is a method for evaluating deterioration of a lithium ion secondary battery, in which an impedance spectrum of a lithium ion secondary battery is measured using alternating current of a predetermined frequency range. In a diagram including an arc-like portion obtained when the impedance spectrum is represented on a complex plane defined by a resistive component axis and a capacitive component axis, the coordinates of a peak of the arc-like portion are determined. The deterioration state of the lithium ion secondary battery is evaluated on the basis of the determined coordinates of the peak.
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Citations
11 Claims
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1. A method for evaluating deterioration of a lithium ion secondary battery, the method comprising the steps of:
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measuring an impedance spectrum of a lithium ion secondary battery, using alternating current of a predetermined frequency range, determining coordinates of a peak of an arc-like portion, when the impedance spectrum is represented by a diagram including the arc-like portion on a complex plane defined by a resistive component axis and a capacitive component axis, and evaluating a deterioration state of the lithium ion secondary battery, on the basis of the coordinates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A battery pack comprising
at least one lithium ion secondary battery, a charging circuit for charging the lithium ion secondary battery with externally supplied power, a discharging circuit for externally discharging power stored in the lithium ion secondary battery, a controller for controlling the charging circuit and the discharging circuit, a measurement unit for measuring an impedance spectrum of the lithium ion secondary battery by an alternating current impedance method, and an evaluation unit for evaluating a deterioration state of the lithium ion secondary battery, on the basis of the measurement result of the measurement unit, wherein the evaluation unit determines coordinates of a peak of an arc-like portion, when the impedance spectrum is represented by a diagram including the arc-like portion on a complex plane defined by a resistive component axis and a capacitive component axis, and evaluates the deterioration state of the lithium ion secondary battery on the basis of the coordinates.
Specification