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A consistency screening method for power lithium batteries

A screening method and consistent technology, applied in the field of consistency screening of power-type lithium batteries, can solve the problem of inability to fully respond to small differences in battery polarization internal resistance, and achieve improved charging consistency, the method is simple and sensitive, and the consistency is high. Effect

Active Publication Date: 2021-09-24
郑州中科新兴产业技术研究院
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method only considers the polarization values ​​under the same current conditions, and cannot fully reflect the small differences in the polarization internal resistance of different batteries.

Method used

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  • A consistency screening method for power lithium batteries
  • A consistency screening method for power lithium batteries
  • A consistency screening method for power lithium batteries

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] S1: capacity screening:

[0032] Select the design capacity of 16Ah, the maximum output power P max A 900W power type lithium cobalt oxide battery is used as the research object. It is charged with a constant current of 16A to the upper voltage limit of 4.2V, and then charged at a constant voltage of 4.2V to a cut-off current of 0.32A; . Cycle for 3 weeks according to the above method, and the discharge capacity C of the single battery in the 3rd week 0 As the screened initial capacity value, the screened out capacity is 99%-100%C 0 The single cells within the range are objects connected in series.

[0033] Discharge each battery at a constant current of 16A to a voltage lower limit of 3V, then charge at a constant current of 16A to 3.75V, then charge at a constant voltage of 3.75V to a cut-off current of 0.32A, and measure the voltage of each single battery after standing for 3 hours. Twelve batteries with less than 2mV were used as research objects.

[0034] S2: ...

Embodiment 2

[0043] S1: capacity screening:

[0044] Select the design capacity of 16Ah, the maximum output power P maxA 900W power type lithium cobalt oxide battery is used as the research object. It is charged with a constant current of 16A to the upper voltage limit of 4.2V, and then charged at a constant voltage of 4.2V to a cut-off current of 0.32A; . Cycle for 3 weeks according to the above method, and the discharge capacity C of the single battery in the 3rd week 0 As the screened initial capacity value, the screened out capacity is 100-101%C 0 range of single cells.

[0045] Discharge each battery at a constant current of 16A to a voltage lower limit of 3V, then charge at a constant current of 16A to 3.75V, then charge at a constant voltage of 3.75V to a cut-off current of 0.32A, and measure the voltage of each single battery after standing for 6 hours. Twelve batteries with less than 2mV are connected in series.

[0046] S2: "Constant current charging - shelving - constant po...

Embodiment 3

[0055] S1: capacity screening:

[0056] Select the design capacity of 15Ah, the maximum output power P max A 720W power type lithium iron phosphate battery is used as the research object. Charge it with a constant current of 15A to a voltage upper limit of 3.7V, then charge it at a constant voltage of 3.7V to a cut-off current of 0.3A; after 20 minutes, switch to a constant current of 15A and discharge it to 2.5V, and leave it for 20 minutes stop. Cycle for 3 weeks according to the above method, and the discharge capacity C of the single battery in the 3rd week 0 As the screened initial capacity value, the screened out capacity is 99-101%C 0 range of single cells.

[0057] Discharge each battery at a constant current of 15A to a voltage lower limit of 2.5V, then charge at a constant current of 15A to 3.25V, then charge at a constant voltage of 3.25V to a cut-off current of 0.3A, and measure the voltage of each single battery after standing for 6 hours. The 12 batteries wit...

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Abstract

The invention discloses a consistency screening method for power type lithium batteries, which comprises the following steps: (1) performing capacity consistency screening on the same batch of batteries, and replenishing power to the same initial voltage; (2) connecting the batteries in step (1) in series (3) Calculate the voltage difference △U between the two working steps of "constant current charging" and "shelving" for all batteries; and after removing the abnormal battery , calculate the average value of △U again and exclude the battery whose voltage difference exceeds the range, (4) draw the △V‑I curve of each battery in the same coordinate system, select the battery with high coincidence degree of the curve as the reference battery, and eliminate the voltage change A battery with a rate greater than 5mV / s of the reference battery. By screening the batteries, the invention can screen out the lithium batteries with large polarization internal resistance dispersion during high power output, the method is simple and sensitive, and the battery has little damage.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a consistency screening method for power lithium batteries. Background technique [0002] In recent years, with the aggravation of environmental pollution, new energy sources have received extensive attention. As a new energy storage method, lithium batteries are widely used in electric vehicles, drones, energy storage power stations and other fields. Due to the difference in the battery preparation process and equipment automation, the performance of the single battery has slight differences, and this difference will gradually increase with the increase in the number of uses after the batteries are connected in series and parallel. Especially for power-type lithium batteries, due to the large output power of the battery, the internal polarization resistance of the battery will seriously affect the output power of the battery when the output current is high. Therefore,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B07C5/344
CPCB07C5/344
Inventor 刘艳侠张若涛张延强李蒙张涛于天恒高桂红
Owner 郑州中科新兴产业技术研究院