Lithium iron phosphate battery auto-discharge screening method

Abstract

The invention discloses a lithium iron phosphate battery auto-discharge screening method. First, batteries are selected, and the voltage sudden change points of the batteries in the low-voltage stateare determined through low-current discharge. A produced battery is discharged at three currents decreasing gradually to a preset cutoff voltage, and is then charged and discharged at a low current within a narrow voltage range, in order to eliminate battery polarization to the greatest extent, make the final real voltage a sudden change voltage, and increase the accuracy of auto-discharge screening based on voltage drop. Through the method, whether a lithium iron phosphate battery meets the requirements can be determined in a short time, the production cycle of lithium batteries can be shortened, judgment is accurate, zero error can be basically guaranteed, the standing time of batteries can be shortened, and the supply rate can be improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a self-discharge screening method for lithium iron phosphate batteries. Background technique [0002] At present, most of the methods for screening self-discharge adopt the method of voltage drop, that is, stand at a certain temperature for a period of time, and use the voltage drop before and after to screen large self-discharge batteries. However, due to battery polarization and other reasons, the measured voltage cannot be true. It reflects the open circuit voltage of the battery at that time, especially the voltage before the battery is left standing, but it will be an extremely long process to wait for the battery polarization to disappear or be reduced to a minimum, which is not allowed in the normal production process. For lithium iron phosphate batteries, especially in the high-voltage state, or when the charge and discharge current is large, its polarizatio...

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Problems solved by technology

[0002] At present, most of the methods for screening self-discharge adopt the method of voltage drop, that is, stand at a certain temperature for a period of time, and use the voltage drop before and after to screen large self-discharge batteries. However, due to battery polarization and other reasons, the measured voltage cannot be true. It reflects the open circuit voltage of the battery at that time, especially the voltage before the battery is left standing, but it will be an extremely long process to wait for the battery polarization to disappear or be reduced to a minimum, which is not allowed in the normal production process. For lithium iron phosphate batteries, especially in the high-voltage state, or when the charge and discharge current is large, its polarization is difficult to eliminate in a short time to reach the true value of the voltage, and the accuracy of self-discharge is screened by the voltage drop over a period of time. rate is very low

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