BATTERY MODULE AND ASSEMBLED BATTERY

摘要

A battery module includes a lithium ion secondary battery and a control circuit. The control circuit includes a measurement unit which measures voltage, current, and the time of charge/discharge of the lithium ion secondary battery; an operation unit which calculates a capacity based on the voltage, the current, and the time and calculates a differential value dQ/dV by differentiating the capacity with a voltage; a threshold voltage setting unit which specifies a peak of a low capacity side of the differential value dQ/dV generated on the basis of a stage structure of graphite and sets a voltage at the peak to a threshold voltage; a cutoff voltage setting unit which sets a discharge cutoff voltage of the lithium ion secondary battery on the basis of the threshold voltage; and a charge/discharge control unit which controls charge/discharge of the lithium ion secondary battery on the basis of the discharge cutoff voltage.

主权项

1. A battery module, comprising:
a lithium ion secondary battery which has a negative electrode mixture layer including a silicon-based active material and graphite on a surface of a negative electrode; and a control circuit which controls charge/discharge of the lithium ion secondary battery, wherein the control circuit includes a measurement unit which measures a voltage, a current, and a time of the charge/discharge of the lithium ion secondary battery, an operation unit which calculates a capacity Q of the lithium ion secondary battery on the basis of the voltage, the current, and the time and calculates a differential value dQ/dV by differentiating the capacity Q with the voltage V, a threshold voltage setting unit which specifies a peak of a low capacity side of the differential value dQ/dV generated on the basis of a stage structure of the graphite and sets a voltage at the peak to a threshold voltage, a cutoff voltage setting unit which sets a discharge cutoff voltage of the lithium ion secondary battery on the basis of the threshold voltage, and a charge/discharge control unit which controls the charge/discharge of the lithium ion secondary battery on the basis of the discharge cutoff voltage.