Method and device for rapidly evaluating available capacity of decommissioned lithium battery

Abstract

The invention relates to a method and a device for rapidly evaluating available capacity of a decommissioned lithium battery. The method comprises the following steps: S1) obtaining an SOC-OCV relationship curve and a charge-discharge curve of a new lithium battery having the same physical and chemical characteristics as the decommissioned lithium battery; S2) measuring an initial open circuit voltage UP of the decommissioned lithium battery and obtaining an initial SOC value of the decommissioned lithium battery according to the SOC-OCV relationship curve of the new lithium battery; S3) obtaining a charge-discharge curve of the decommissioned lithium battery; S4) calculating the available capacity C1 of the decommissioned lithium battery by utilizing an ampere-hour integral method and according to the initial SOC value and the charge-discharge curve of the decommissioned lithium battery, and calculating the available capacity C2 of the decommissioned lithium battery based on the charge-discharge curves of the new lithium battery and the decommissioned lithium battery and by utilizing a charge-discharge curve matching method; and S5) determining weights of the C1 and the C2 respectively based on the SOC-OCV curve, and fusing estimated values obtained through the two available capacity estimation methods to obtain a final capacity estimation result. Compared with the prior art,the method and device have the advantages of being accurate and fast and the like.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a rapid evaluation method and evaluation device for available capacity of decommissioned lithium batteries. Background technique [0002] As the world's energy consumption increases and environmental pollution is serious, green travel tools represented by electric vehicles have attracted much attention due to their high efficiency and low pollution. Lithium-ion batteries are an important source of power for electric vehicles. When the performance drops to 80% of the original performance, the battery is a retired battery and is no longer suitable for use in electric vehicles, but the retired battery can still show good performance at a lower rate. If these decommissioned batteries are recycled, it will cause great waste, so the decommissioned batteries can be considered for cascade recycling. Due to the different factors such as self-discharge degree and ambient tempera...

AI Technical Summary

Problems solved by technology

Making full use of the open circuit voltage of the battery, combined with the high-rate charge or discharge strategy can reduce the battery test time, and some batteries have a large error in the SOC information obtained according to the initial open circuit voltage due to the voltage platform.

On the other hand, based on the constant current charge and discharge voltage curve of the battery under specified conditions, combined with a reasonable algorithm, the constant current charge and discharge voltage curve under the current state of the battery can be translated and stretched to match the standard curve to obtain the battery capacity. Part of the test cost can be saved, but the results obtained depend on the accuracy of curve change matching, and the reliability still needs further investigation

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