| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a state determination method for a lithium ion secondary battery that suitably determine whether the lithium ion secondary battery having a non-opposition part of a negative electrode active material layer has metallic lithium deposited on a negative electrode plate surface without breaking (disassembling) the battery. <P>SOLUTION: The state determination method for the lithium ion secondary battery includes a first standing step of leaving the lithium ion secondary battery as it is in a temperature environment of 25°C or lower for 40 days or longer in a state in which a battery voltage value is held equal to or less than a battery voltage value of 60% SOC, a first capacity measurement step, a second standing step of leaving the lithium ion secondary battery as it is in a temperature environment of 40 to 60°C in a state in which the battery voltage value is held equal to the battery voltage value in the first standing step, a second capacity measurement step, and a determination step of determining that metallic lithium is deposited on the negative electrode plate surface of the lithium ion secondary battery when the battery capacity measured in the second capacity measurement step is larger than the battery capacity measured in the first capacity measurement step. <P>COPYRIGHT: (C)2012,JPO&INPIT |
