Why do lithium batteries need to be pre-charged?
As we all know, lithium battery manufacturing is a highly technical, complex, and multi-process task, and each process has a vital impact on the battery. This article mainly explains to you the pre-charging in the lithium battery manufacturing process. Why is pre-charging required? What role does pre-charging play? Let’s explore together.
Manufactured lithium batteries usually need to be pre-charged before being officially charged. Pre-charging is the process of charging the battery with a lower current. Its main purpose is to extend battery life and improve battery performance. The following is a detailed explanation on the necessity of pre-charging lithium batteries.
Activating the battery: Newly produced batteries are in an extremely low voltage state. Pre-charging can slowly increase the voltage of the battery to a safe level by applying a smaller current to activate the battery and the chemicals in the battery, thereby increasing the battery capacity, improve its performance and reliability.
Form a protective layer: Lithium batteries need to be filled with electrolyte during the manufacturing process. The electrolyte is an organic liquid that contains chemical additives. It will react with the materials on the electrode surface to cause corrosion. In order to prevent the progression of corrosion, pre-charging plays an important role in it. During the pre-charging process, the following reactions will occur inside the lithium battery: the active material is activated, the positive electrode material releases lithium ions, enters the electrolyte, penetrates the separator, enters the electrolyte, and is finally embedded in the layered gaps of the negative electrode material. At this time, the electrons come out from the positive electrode along the outer loop and enter the negative electrode carbon material. A redox reaction occurs between electrons, solvents and lithium ions in the electrolyte. The solvent molecules receive electrons and combine with lithium ions to form a solid electrolyte interface film (SEI). As the thickness of the SEI increases, until electrons cannot penetrate, a passivation layer protection is formed. Inhibiting the continuation of the oxidation-reduction reaction, thereby avoiding further damage to the battery material and extending the service life of the battery.
Avoid potential safety risks: When a newly manufactured lithium battery is charged for the first time, if it is charged directly with normal current, it is likely to catalyze certain chemical reactions and mechanical reactions inside the battery, causing potential dangers. Low-current pre-charging can effectively alleviate this situation. The lower pre-charging current can slow down the degree of reaction, thereby keeping it within a safe range and avoiding potential safety risks.
Reduce the impact current: When charging is officially started, if the battery is in an extremely low voltage state, the charging current may increase sharply, causing impact to the battery. Pre-charging can slowly increase the voltage by applying a smaller current, thereby reducing the inrush current and helping to protect the battery.
Extended battery life: Pre-charging allows the battery to charge more slowly and evenly, which is especially important early in the battery’s life. Pre-charging helps extend the life of the battery by reducing the stress on the battery’s interior during initial charging.
In summary, lithium battery pre-charging can activate the battery, form a protective layer, avoid potential safety risks, reduce impact current, extend battery life, etc., so that the safety and performance of the battery can be guaranteed.
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