Formation method of lithium iron phosphate power battery

Abstract

The invention discloses a method for forming a lithium iron phosphate power battery, comprising the following steps: S1, injecting electrolyte solution into the power battery and standing it for a preset time; S2, charging the battery cell of the power battery with a first preset current constant current to the preset state of charge, and then constant current discharge to the first preset voltage; S3, charge the cell of the power battery to the second preset current constant current to the second preset voltage, and then constant current discharge to the first preset voltage. Set the voltage, the second preset current is greater than the first preset current and the second preset voltage is greater than the first preset voltage; S4, charge the cell of the power battery with a third preset current to a third preset voltage at a constant current , and then constant current discharge to the first preset voltage, the third preset current is greater than the first preset current and the third preset voltage is greater than the first preset voltage; and S5, repeat step S4 for a preset number of times. According to the chemical formation method provided by the invention, the SEI film is stable, the thermal stability is better, and the safety performance is good.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, and in particular relates to a method for forming a lithium iron phosphate power battery. Background technique [0002] After the lithium-ion battery is manufactured, the process of activating its internal positive and negative electrode materials through a certain charge and discharge method to improve the battery's charge and discharge performance, self-discharge, storage and other comprehensive performance is called formation. The formation of lithium battery is the initialization of the battery, which can activate the active material of the battery. This process is a very complicated process, and it is also a very important process that affects the performance of the battery. When the lithium battery is charged for the first time, lithium ions will inevitably undergo an irreversible chemical reaction with the organic solvent in the electrolyte, and at the same time form a thin passi...

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Problems solved by technology

[0003] At present, the formation method used in lithium iron phosphate batteries is the traditional low-current pre-charging method. Although this method is conducive to the formation of a stable SEI film, long-term low-current charging will lead to an increase in the resistance of the formed SEI film, thereby affecting the formation of the SEI film. The rate performance of the battery and the unreasonable setting of the charging upper limit voltage will cause damage to the material structure and incomplete side reactions, which will affect the self-discharge and cycle performance of the battery, resulting in poor consistency of the battery and hidden dangers to the safety of the battery

For lithium iron phosphate power batteries for electric vehicles, the consistency and cycle performance of the battery are closely related to the performance of the vehicle. The existing formation methods are not suitable for the field of power batteries. To develop a stable and reliable The formation method of iron-lithium power battery has become a top priority in the power battery manufacturing industry

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