Lithium-ion battery electrodeposition detection method

A lithium-ion battery electrodeposition detection method that detects a lithium electrodeposition which occurs at a negative-electrode active material layer of a lithium-ion battery in which a positive electrode having a positive-electrode collector body and a positive-electrode active material layer located on at least one surface of the positive-electrode collector body, a negative electrode facing the positive electrode and having a negative-electrode collector body and the negative-electrode active material layer located on at least one surface of the negative-electrode collector body, and an electrolyte layer located between the positive electrode and the negative electrode are layered, the lithium-ion battery electrodeposition detection method comprising:

• a positive-electrode state-of-charge (SOC) map generation step of irradiating the lithium-ion battery with an X-ray, performing an X-ray diffraction measurement of the positive-electrode active material layer, and based on X-ray diffraction data obtained by the X-ray diffraction measurement of the positive-electrode active material layer, generating a positive-electrode SOC map that indicates a distribution of a charging depth representing an SOC along a thickness direction of the positive-electrode active material layer;
• an SOC difference value detection step of detecting an SOC difference value which is a difference between a maximum value of the SOC and a minimum value of the SOC in the positive-electrode SOC map generated in the positive-electrode SOC map generation step;
• an electrodeposition determination step of comparing the SOC difference value detected in the SOC difference value detection step with a preset threshold value and, based on a first result of the comparing, determining a presence or absence of the lithium electrodeposition of the negative-electrode active material layer;
• and
• a controlling step of:
• based on a second result of the determining of the presence or the absence of the lithium electrodeposition of the negative-electrode active material layer, controlling a charging condition of the lithium-ion battery to mitigate the lithium electrodeposition and degradation of the lithium-ion battery.