A method for evaluating the state of health of an energy storage battery

Abstract

The invention provides a health state evaluation method of an energy storage battery. The method comprises the following steps that I) external characteristic parameter data of the energy storage battery is collected, and a fluctuation ratio of the external characteristic parameter data is calculated; II) external characteristic parameter data is collected again after that the energy storage battery runs cyclically for several times, and a fluctuation ratio of the external characteristic parameter data is calculated; and III) change of the fluctuation ratios is calculated, whether the battery is healthy is determined. The method is used to evaluate the health state of the battery quantitatively by testing the fluctuation amplitude of the external characteristic parameter repeatedly under the same condition of the battery, and the method is simple in test, does not need a complex algorithm, can realize real-time online evaluation, and provides basis for daily use and maintenance of lithium ion batteries.

Description

technical field [0001] The invention relates to a method in the technical field of secondary battery energy storage, in particular to a method for evaluating the health state of an energy storage battery. Background technique [0002] Battery energy storage is an important branch of today's energy storage technology development. Lithium-ion secondary battery technology is one of the most potential technologies in battery energy storage, with many advantages such as high energy density, long cycle life, and low self-discharge rate. . However, its safety has not been well resolved. In recent years, many safety accidents caused by power batteries for electric vehicles have aroused people's safety concerns about lithium-ion secondary battery energy storage. In addition, due to the "barrel effect", that is, the difference in consistency between batteries, the life of lithium-ion batteries in groups will be significantly lower than the life of battery cells, and the aging of batt...

AI Technical Summary

Problems solved by technology

[0005] In the prior art, there are several methods for estimating SOH: ①Direct discharge capacity measurement method, which is the most reliable method for SOH evaluation, but it can only be measured offline and cannot meet the requirements of online measurement; ②Electrochemical impedance This method is the most commonly used method in laboratory research. The measurement and analysis results are highly targeted, but the cost is high and the data processing is complicated; ③The voltage curve model method is used to study the relationship between the terminal voltage of the battery and the SOH when the battery is charging and discharging. A method of building a model. Although this method has a short modeling period and a simple process, one type of battery corresponds to one model. The model needs to be rebuilt for different types of batteries, and for battery types with stable operating voltages (such as Lithium iron phosphate battery), the internal relationship between the terminal voltage of the battery and the SOH of the battery is not obvious, and the accuracy of SOH estimation needs to be improved

However, at present, these methods are based on technical means to judge the attenuation of battery capacity to indicate the health of the battery, and the health of the battery does not have an absolute one-to-one relationship with the attenuation of battery capacity. The attenuation of battery capacity, performance The aging of the battery and so on are only part of the performance of the deterioration of the battery's health status. This patent believes that in addition to the capacity decline, which is an expression method to indicate the battery health status, the stability of the battery's external characteristics should also be regarded as a battery health status. Performance, that is, the change in the fluctuation rate of the battery's internal and external characteristics during the operating cycle can also reflect the health of the battery, because the stability of the external characteristics of the battery determines the operating quality of the battery during the energy storage period, which is important for the stability of the entire energy storage system. Has a significant impact, and the existing battery health assessment technology cannot judge the stability of the battery's external characteristics

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