Lithium ion battery state of charge estimation method and lithium ion battery state of charge estimation device

摘要

A method for estimating the state of charge from a voltage change rate for a lithium ion battery using a lithium phosphate compound having an olivine type crystal structure as a positive electrode and an active material having no potential fluctuation due to lithium insertion / release reaction as a negative electrode. From the first step of storing a map representing the correspondence between the voltage change rate and the charge state at a plurality of charge / discharge rates, and from the measured voltage change rate calculated based on the measured value during charge / discharge And a third step of obtaining the current state of charge by comparing the state of charge candidate obtained during charging with the state of charge candidate obtained during discharging. .