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LFP lithium ion cell capacity grading and screening method

A screening method and lithium-ion technology, applied in circuits, electrical components, secondary batteries, etc., can solve the problem of low cell consistency, improve cycle performance and safety performance, and ensure consistency and consistency.

Active Publication Date: 2019-03-19
HEFEI GUOXUAN HIGH TECH POWER ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] A kind of LFP lithium-ion cell capacity screening method proposed by the present invention can overcome the technical problem of low consistency of the cells screened in the existing process

Method used

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  • LFP lithium ion cell capacity grading and screening method

Examples

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Effect test

example 1

[0050] A sorting and screening method for 30Ah cells with a square aluminum shell, including the steps of sorting and binning:

[0051] The specific steps are as follows:

[0052] (1) Clean the battery cells on the production line, and conduct visual inspection and screening;

[0053] (2) Put the batteries that pass the appearance screening into the capacity separation tray, scan the tray code and the battery barcode, and put it into the capacity separation cabinet. The temperature of the capacity separation room is controlled at 30±3°C;

[0054] (3) Set aside for 5 minutes;

[0055] (4) Charge with constant current and constant voltage at a certain current, the current is 9000mA, the voltage limit is 3.65V, the current limit is 500 mA, and the time limit is 180min;

[0056] (5) Set aside for 5 minutes;

[0057] (6) Discharge with a certain current, the current is 18500mA, the cut-off voltage is 2.0V, and the time limit is 120min;

[0058] (7) Set aside for 5 minutes;

[...

example 2

[0078] A method for sorting and screening 27Ah batteries with square aluminum shells, including the steps of sorting and binning:

[0079] The specific steps are as follows:

[0080] (1) Clean the battery cells on the production line, and conduct visual inspection and screening;

[0081] (2) Put the batteries that pass the appearance screening into the capacity separation tray, scan the tray code and the battery barcode, and put it into the capacity separation cabinet. The temperature of the capacity separation room is controlled at 30±3°C;

[0082] (3) Set aside for 5 minutes;

[0083] (4) Charge with constant current and constant voltage at a certain current, the current is 6000mA, the voltage limit is 3.65V, the current limit is 500 mA, and the time limit is 180min;

[0084] (5) Set aside for 5 minutes;

[0085] (6) Discharge with a certain current, the current is 18500mA, the cut-off voltage is 2.0V, and the time limit is 70min;

[0086] (7) Set aside for 5 minutes;

...

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Abstract

The invention discloses an LFP lithium ion cell capacity grading and screening method, which solves the technical problem of low uniformity of an existing process in cell screening. The method includes steps: subjecting to-be-tested cells to appearance screening, and putting into a capacity grading cabinet at a temperature of 30+ / -3 DEG C; adopting constant current and constant voltage to charge and discharge the to-be-tested cells in sequence until activation of the to-be-tested cells stops; adopting limited voltage for discharging the to-be-tested cells in sequence interruptedly from high current to low current to make the to-be-tested cells in an unloaded state; adopting low current for charging the to-be-tested cells in sequence interruptedly to achieve SOC state uniformity of the to-be-tested cells in 3.0V; detaching the to-be-tested cells from the capacity grading cabinet, measuring OCV3 and OCR3 in 15-24h, and performing capacity screening; measuring OCV4 and OCR4, calculating ak value, testing cell thickness, screening the cells according to the k value and the cell thickness to obtain qualified cells, and outputting for use. By application of limited-voltage low current for charge and discharge, great uniformity of initial states of the cells is guaranteed, and cycle performance and safety of battery packs are improved.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery manufacturing, in particular to a method for screening LFP lithium-ion batteries by capacity. Background technique [0002] Lithium-ion batteries have become the mainstream choice for automotive power batteries due to their high energy density and long cycle life. As the battery manufacturing process becomes more and more mature, and the competition among various manufacturers becomes more and more fierce, the consistency of the battery combination is especially important for improving product quality and reducing production costs. [0003] Cell consistency, mainly including initial capacity, initial voltage, self-discharge rate, initial internal resistance, fully charged thickness, empty state thickness, cell weight, capacity decay rate, internal resistance growth rate, cell charge and discharge temperature rise, etc. . [0004] At present, in the lithium battery industry, the produ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/058H01M10/42H01M10/44
CPCH01M10/058H01M10/4285H01M10/446Y02E60/10Y02P70/50
Inventor 齐永成叶志林
Owner HEFEI GUOXUAN HIGH TECH POWER ENERGY
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