Electrolyte Filling

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Control the amount of liquid electrolyte and injection time, so that the liquid electrolyte is injected into the battery from the liquid injection port. The main purpose is to form ion channels, so as to ensure that the battery has enough lithium ions to migrate between the positive and negative electrodes during the charging and discharging process to achieve a reversible cycle.

The liquid injection process is mainly affected by two factors: the liquid injection system and the system pressure. The system pressure will affect the process of battery liquid injection preparation, liquid injection, pre-sealing infiltration and post-sealing infiltration, etc. It can be seen that the system pressure is the most important factor affecting the process of battery system liquid injection and infiltration.

Common liquid injection methods are mainly divided into two types, one is to directly inject liquid through the liquid injection hole (the most mainstream method), and the other is to put the battery into the electrolyte to let the electrolyte penetrate into the battery. The way of injecting liquid through the injection hole can be divided into single injection and multiple injection (affected by battery structure and batch) according to the amount of injection, several injection methods have different measures to promote infiltration, among them, the single injection method promotes the infiltration of the electrolyte in the cell through repeated pumping, however, the multiple liquid injection method is to promote the infiltration of the electrolyte in the battery cell by means of pressurization, while the immersion liquid injection method does not have measures to promote infiltration.

The working principle of the lithium-ion battery automatic liquid injection machine is to put the battery box upside down in the positioning module of the liquid injection plate, air pressure drives the upper box to move, the upper pressing plate moves synchronously so that the battery box and the liquid injection plate are tightly pressed and sealed. The interior of the battery box forms the same sealed space with the liquid injection box through the liquid injection hole, and the liquid injection box is evacuated, after the negative pressure is formed inside the battery, open the liquid injection valve, the battery liquid will automatically flow into the liquid injection tank from the transfer box due to the air pressure difference, and close the liquid injection valve.

One-time liquid injection is the first liquid injection. After the liquid injection, the electrolyte is soaked into the pole piece through the high-temperature aging room to participate in the chemical reaction and realize the conversion of chemical energy and electrical energy. It should be noted that additives such as overcharge protection agents are added to some electrolytes, and it is necessary to maintain the amount of electrolyte to ensure battery safety. The second liquid injection is a supplementary process for the electrolyte after formation. During the second liquid injection, sealing is also taken into account. The commonly used sealing methods include rubber plugs, aluminum sheet laser sealing, steel balls, and glue dispensing. In order to prevent dust pollution and enhance the infiltration effect, the battery can be manually sealed with a rubber plug after liquid injection, unplugged before formation, sealed again after formation, and pulled out before the second injection, only in this way can stacked discs be used safely for high temperature aging.