METHOD OF DIAGNOSING LITHIUM-ION BATTERY AND DIAGNOSTIC APPARATUS FOR LITHIUM-ION BATTERY

摘要

A first information is acquired, which contains a charge capacity of a lithium-ion battery in association with an index value. The first information is used to obtain a function f(x). f(x) represents the index value as a function of the charge capacity. An extremum point of a second derivative (f″(x)) of f(x) is calculated, in which the extremum point is a minimum point of f″(x). The lithium-ion battery is diagnosed by using the charge capacity at the extremum point (x_e). The lithium-ion battery includes a negative electrode containing at least silicon oxide and graphite. The index value is measurable from outside the lithium-ion battery. The index value is reflective of a volume of the silicon oxide and a volume of the graphite.