Battery sorting method based on alternating-current impedance spectrum

Abstract

The invention relates to a lithium ion secondary battery, in particular to a sorting method based on an alternating-current impedance spectrum. The method comprises the steps of (1) acquiring the alternating-current impedance spectrum; (2) analyzing equivalent-circuit parameters; and (3) conducting statistic analysis on the equivalent-circuit parameters. In the method provided by the invention, an electrode structure inside a battery system can be detected without damaging a battery, the inner information such as health condition of the battery, the electrolyte concentration, diaphragms and SEI (Solid Electrolyte Interface) membranes are accurately reflected; and according to the information, the coefficient of concordance is calculated by utilizing the principle of statistics, so that the consistency of the inner structure of the sorted battery can be ensured sufficiently, the differences of the sorted batteries are reduced obviously, and the defects of a sorting method in prior arts can be overcome.

Description

technical field [0001] The invention relates to lithium-ion secondary batteries, in particular to a method for sorting batteries into groups, and in particular to a sorting method based on AC impedance spectroscopy. Background technique [0002] Under the current technical level of power batteries, the energy storage system must use battery packs to meet the requirements of high power and large capacity. Due to the differences in the parameter values ​​of the voltage, internal resistance, capacity, etc. between the same type, the same specification, and the same type of batteries, that is, there are differences in the consistency of the battery performance, so that the performance indicators of the power battery pack cannot be reached when used in the energy storage system. According to the expected level of the single battery, the service life of the battery pack is several times or even ten times shorter than that of the single battery, which seriously affects the applicat...

AI Technical Summary

Problems solved by technology

Sorting by voltage, this method uses voltage consistency to classify, and considers the voltage situation when it is loaded, but it cannot eliminate the influence of factors such as charging time, load change, and output capacity; sorting by capacity can only explain The capacity under the set charge and discharge conditions is relatively close, but only one parameter of battery discharge capacity cannot reflect the overall performance of the battery. Due to the inconsistency of other performance indicators of the single batteries in the combination, the life of the battery pack will be shortened and the capacity will be reduced. The performance is reduced accordingly, which is the main reason for the short-term damage of the combined battery

Sorting based on the internal resistance of the battery ensures the resistance consistency of the battery at the initial stage of use, but after long-term use, due to the deterioration of the internal ion channels and electronic channels of the battery, and the decrease in the activity of the chemical substances inside the battery, the internal resistance of the battery will The increase of different degrees of resistance increases the polarization difference of the battery, so that the battery capacity cannot be released in time. Since this method is measured at a frequency of 1KHz, it does not fully reflect the battery's various charging and discharging conditions. degree of matching

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