LITHIUM SECONDARY BATTERY AND CONTROL SYSTEM THEREOF, AND METHOD FOR DETECTION OF STATE OF LITHIUM SECONDARY BATTERY

摘要

Provided is a control system for a lithium secondary battery, which can detect a deterioration state inherent in a lithium secondary battery that utilizes a silicon oxide as a negative electrode active material, i.e., a heterogeneous reaction state of a negative electrode in the lithium secondary battery, in a quantitative manner. The control system for a lithium secondary battery comprises a positive electrode, a negative electrode utilizing a silicon oxide as a negative electrode active material, and a lithium reference electrode having a reference voltage for the negative electrode. The control system additionally comprises a measurement means for measuring a voltage (V) of the negative electrode for the lithium reference electrode and a discharge capacity (Q) of the lithium secondary battery upon the discharge of an electrical current from the lithium secondary battery, a production means for producing a V-dQ/dV curve which represents the relationship between a dQ/dV value that is a ratio of the amount of change (dQ) in the discharge capacity (Q) to the amount of change (dV) in the voltage (V) and the voltage (V), a calculation means for calculating the intensity ratio between two peaks that appear on the V-dQ/dV curve and correspond to two voltage values in the voltage (V), and a detection means for detecting the state of the negative electrode utilizing the intensity ratio.