Lithium iron phosphate power battery consistency matching screening method

Abstract

A disclosed lithium iron phosphate power battery consistency matching screening method comprises the steps: evaluating lithium iron phosphate power batteries according to the performance parameters of the batteries, preliminarily screening the lithium iron phosphate power batteries into a group; performing heavy-current test on the lithium iron phosphate power batteries to reject batteries with abnormal voltage in the battery group; and finally performing self discharging rate screening test on the lithium iron phosphate power batteries to reject batteries with reduced voltage and further to screen out batteries with relatively good consistency. The method helps to realize the consistency of parameters such as battery capacity, static-state internal resistance, open-circuit voltage and the like of the lithium iron phosphate power battery group, also helps to realize the consistency of electrochemical polarization of the lithium iron phosphate power battery group during heavy-current discharging, and also helps to realized the consistency of the self discharging rate of the lithium iron phosphate power battery group.

Description

technical field [0001] The invention belongs to the technical field of batteries, and in particular relates to a method for screening consistency matching groups of lithium iron phosphate power batteries. Background technique [0002] As a power source, lithium-ion power batteries often need to be connected in series and parallel to form battery modules. However, due to raw materials, manufacturing processes, production equipment and environmental reasons, there will be deviations in consistency. Therefore, it is necessary to combine batteries with similar performance. Carry out grouping, if the grouping is not done properly, it will cause the performance of the battery to decline, and even safety accidents such as fire and explosion will occur. The existing battery matching technology mainly uses single or multiple parameters such as battery capacity, open circuit voltage, and static internal resistance as reference standards for battery matching, such as "a lithium battery...

AI Technical Summary

Problems solved by technology

[0002] As a power source, lithium-ion power batteries often need to be connected in series and parallel to form battery modules. However, due to raw materials, manufacturing processes, production equipment and environmental reasons, there will be deviations in consistency. Therefore, it is necessary to combine batteries with similar performance. If the matching is not done properly, the performance of the battery will decrease, and even safety accidents such as fire and explosion will occur.

The existing battery matching technology mainly uses single or multiple parameters such as battery capacity, open circuit voltage, and static internal resistance as reference standards for battery matching, such as "a lithium battery pack for energy storage Manufacturing method and an energy storage lithium battery pack", but this method has the following disadvantages: the internal resistance referenced during screening is static internal resistance, a series of electrochemical reactions will occur in the actual charging and discharging process of the battery, and there is a polarization internal resistance The battery with the same capacity cannot be fully charged and discharged at the same time, so it will affect the capacity and cycle life of the battery pack

In view of the above shortcomings, another Chinese patent CN201010018161.5 discloses "a method for grouping lithium-ion secondary batteries for power" which simulates the actual use of batteries, and discharges multiple batteries in series. The voltage difference is compared to find a more matching battery for grouping. The batteries sorted by this method have better consistency, but there are also certain disadvantages: power batteries often need to be discharged with a large current, and the battery inside the battery when discharged with a large current The polarization is greater, and the batteries with different polarization cannot be eliminated only by the discharge end voltage. At the same time, the lithium iron phosphate battery platform is very stable, and the batteries with the same self-discharge rate cannot be accurately screened by the voltage difference when the SOC capacity is high.

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