Screening method for self-discharging of square lithium ion batteries

A technology of a lithium ion battery and a screening method is applied in the field of self-discharge screening of square lithium ion batteries, which can solve the problems of loose battery pole core structure and large battery self-discharge, and achieve the effects of improving product quality and improving detection rate.

Active Publication Date: 2013-12-25
HEFEI GUOXUAN HIGH TECH POWER ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In a normal pressure environment, the internal and external pressures of the battery are equal, the structure of the internal pole core of the battery is loose, and the micro-short circuit

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0016] Example 1:

[0017] Take 1000 12Ah lithium iron phosphate aluminum shell prismatic batteries, charge the battery to 100% SOC, and record the battery voltage V1. Then, the battery was placed in a 0.3 MPa environment at normal temperature and allowed to stand for 15 days. After taking out the battery, test the open circuit voltage V2 of the battery in a normal temperature and normal pressure environment, and judge that the self-discharge of the battery with V2 lower than 3.338V is large. As shown in Table 1, there are a total of 4 batteries whose voltage is lower than 3.338V and are selected as large self-discharge batteries.

Example Embodiment

[0020] Example 2:

[0021] Take 1000 12Ah lithium iron phosphate aluminum shell prismatic batteries, charge the battery to a state of charge of 50% SOC, and record the battery voltage V1. Then, the battery was placed in a 0.7 MPa environment at room temperature and allowed to stand for 10 days. After taking out the battery, test the open circuit voltage V2 of the battery in a normal temperature and normal pressure environment, and judge that the self-discharge of the battery with the difference of V1-V2 greater than 20mV is large. As shown in Table 1, there are 5 batteries with a voltage difference greater than 20mV, which are selected as self-discharge large batteries.

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PUM

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Abstract

The invention provides a screening method for self-discharging of square lithium ion batteries. The method comprises the following steps: (1) charging each battery at normal temperature and normal pressure to a preset charged state and recording an open-circuit voltage V1 of the battery; (2) placing the battery in a preset high pressure environment for a preset time t; (3) taking the batter out, placing the battery in a normal pressure environment and recording an open-circuit voltage V2 of the battery; and (4) screening out a battery, with a V2 value less than a set value U1 or a difference value between V1 and V2 greater than a set value U2, as a battery with great self-discharging. Preferably, the preset charged state in the step (1) is 50 to 100% SOC, the preset high pressure environment in the step (2) is 0.15 to 1 MPa, and the preset laying time t is 5 to 20 d. According to the invention, a preset high pressure is applied on the square battery to allow the positive plate and the negative plate of each battery to fully contact with the diaphragm of the battery so as to effectively screening out batteries with great self-discharging, so the detection rate of batteries with great self-discharging can be substantially increased, and product quality is improved.

Description

technical field [0001] The invention relates to a self-discharge screening method of a square lithium ion battery. Background technique [0002] At present, with the depletion of fossil fuels and the deterioration of the environment, lithium-ion batteries have become a new power source and a core component of electric vehicles, and are developing rapidly. The battery pack for electric vehicles is mainly composed of a large number of single cells connected in series and parallel. The consistency of the single battery is an important factor affecting the performance of the battery pack. The inconsistent self-discharge rate of single cells is one of the important reasons for the poor performance of battery packs. Therefore, it is necessary to screen out batteries with large self-discharge before the single batteries leave the factory. [0003] Battery self-discharge refers to the loss of capacity due to internal spontaneous reactions when the battery is in an open circuit st...

Claims

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Application Information

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IPC IPC(8): H01M10/058B07C5/344
CPCY02E60/10Y02P70/50
Inventor 贺狄龙刘爱菊
Owner HEFEI GUOXUAN HIGH TECH POWER ENERGY
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