DETECTION DEVICE, MANAGEMENT DEVICE, AND DETECTION METHOD

A detection device for detecting a status of a lithium-ion secondary battery includes a control module that acquires real part of AC impedance at a frequency at which the real part of the AC impedance is increased 10 times or more than the real part of the AC impedance at 1 kHz due to a skin effect, and detects deposition of lithium and/or the presence of foreign metal inside the lithium-ion secondary battery by using the acquired real part of the AC impedance.