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Self-discharge detection method for lithium iron phosphate batteries

A technology of lithium iron phosphate battery and detection method, which is applied in the direction of measuring electricity, measuring device, measuring electrical variables, etc., can solve the problems such as time can not guarantee battery shelving, limited accuracy of testing equipment, etc.

Inactive Publication Date: 2012-06-20
JIANGSU FRONT NEW ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Especially for lithium iron phosphate batteries, the normal self-discharge rate is 1% / month. Even if the self-discharge rate of abnormal batteries reaches 2% / month, the difference between 1% and 2% is often ignored due to the limited accuracy of test equipment. Lose
Moreover, the process of normal production of batteries often cannot guarantee that the battery will be shelved for more than one month in terms of time.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0011] 1. Select 100 ferric phosphate ion batteries with a design capacity of 10Ah. In an environment of 25°C, select a charging and discharging device with an accuracy of ±0.1% to discharge them once. During the recharging process, the discharging and charging current is 0.33C (3.3 A), the discharge and charge cut-off voltages are 2.5V and 3.65V respectively, the cut-off current in the constant voltage charge stage is 0.05C (0.5A), and the charge capacity of the recorded battery is C i .

[0012] 2. Place the battery in a magnetic field generator, the magnetic field strength is adjustable at 0.01T, the ambient temperature is set at a constant temperature of 45°C, and the storage time is 15 days. After the storage is completed, take the battery out of the magnetic field, and after degaussing, place it at an ambient temperature of 25°C for 24 hours.

[0013] 3. Put the battery in an environment of 25°C, select a charging and discharging device with an accuracy of ±0.1% to char...

Embodiment 2

[0017] 1. Select 1,000 ferric phosphate ion batteries with a design capacity of 10Ah. In an environment of 25°C, select a charging and discharging device with an accuracy of ±0.1% to discharge them once. During the recharging process, the discharging and charging current is 0.33C (3.3 A), the discharge and charge cut-off voltages are 2.5V and 3.65V respectively, the cut-off current in the constant voltage charge stage is 0.05C (0.5A), and the charge capacity of the recorded battery is C i .

[0018] 2. Place the battery in a magnetic field generator, the magnetic field strength is adjustable at 1.3T, the ambient temperature is set at a constant temperature of 55°C, and the storage time is 3 days. After the storage is completed, take the battery out of the magnetic field, and after degaussing, place it at an ambient temperature of 25°C for 24 hours.

[0019] 3. Put the battery in an environment of 25°C, select a charging and discharging device with an accuracy of ±0.1% to char...

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Abstract

The invention discloses a self-discharge detection method for lithium iron phosphate batteries, which relates to the technical field of screening of lithium batteries. The self-discharge detection method is characterized in that the batteries are fully charged, and placed in a uniform magnetic field with magnetic intensity ranging from 0.01T to 1.3T, self-discharge of the batteries is accelerated by the aid of an effect of the high-intensity magnetic field to the lithium iron phosphate batteries, the lithium iron phosphate batteries are taken out from the high-intensity magnetic field after standing in the high-intensity magnetic field for 1 day to 15 days, self-discharge rates of the shelved batteries are tested after the batteries are degaussed, and batteries with abnormal discharge properties can be selected according to actually measured data of self-discharge rates. The method is used for screening the self-discharge properties of the lithium batteries, disqualified batteries can be selected within a short period of time, and the method has an important popularization value.

Description

technical field [0001] The invention relates to the screening of lithium ion secondary batteries, in particular to a self-discharge detection method of lithium iron phosphate batteries. Background technique [0002] When the storage battery and the primary battery are not connected to the external circuit, the battery capacity loss caused by the internal spontaneous reaction is generally called self-discharge. It is expressed by the percentage of capacity lost per year or per month. For example, the self-discharge of various lithium-ion batteries is very small, about 1-2% per month, and the metal hydride nickel battery is relatively large, reaching more than 10% per month. Due to the uncertainty of the production process and the uncontrollability of various production processes, a small number of batteries with manufacturing defects always exist, and the value of their self-discharge properties is often several times higher than that of the same batch of batteries. When thes...

Claims

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Application Information

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IPC IPC(8): G01R31/36
Inventor 王青吴晓东华美
Owner JIANGSU FRONT NEW ENERGY
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