To provide a new Li precipitation evaluation method that enables non-destructive evaluation of a metal Li deposition that occurs on the surface of a negative electrode plate of a lithium ion secondary battery.SOLUTION: A Li precipitation evaluation method includes a first voltage measuring step S1 of measuring a first battery voltage V1 of a battery 10 in a state where the battery 10 is pressed with a pressure Pb1 having a magnitude such that the metal Li deposited on the surface 17a of a negative electrode plate 17 is not absorbed by the negative electrode plate 17, or in a state where the battery 10 is not pressed, second voltage measuring steps S2, S3 of measuring a second battery voltage V2 of the battery 10 in a state where the battery 10 is pressed with the pressure Pb2 having a magnitude such that the deposited metal Li is absorbed by the negative electrode plate 17 after the first voltage measuring step S1, and an evaluation step S4 of evaluating the deposition of the metal Li in the battery 10 on the basis of the value of the battery voltage ratio V2/V1.SELECTED DRAWING: Figure 5
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