The injection process of lithium-ion batteries refers to the process of injecting precisely measured electrolyte into the sealed (but not completely sealed) battery cells in a dry environment. This process is the core link in battery production, directly affecting the performance, lifespan, and safety of the battery.

The workflow mainly consists of the following steps:

Cell preparation and drying: Transfer the bare cells after winding or stacking to a low dew point (usually ≤ -40 ℃) drying room or drying oven, and perform vacuum baking to thoroughly remove residual moisture inside the cells, creating an absolutely dry environment for liquid injection.

Accurate metering and injection of electrolyte: Using a high-precision metering pump, a specific formula and weight of electrolyte is accurately and uniformly injected into the interior of the battery cell through the injection port on the battery cell in a vacuum or low-pressure environment. A vacuum environment helps to expel some of the air inside the battery cell, facilitating faster and more thorough infiltration of the electrolyte into the electrodes.

Initial infiltration and sealing: After the injection is completed, the battery cell needs to be briefly allowed to settle, and capillary action is used to initiate the initial diffusion of the electrolyte. Subsequently, immediately perform preliminary sealing on the injection port (such as steel ball sealing or laser pre welding), isolate the battery cell from the external environment, and prevent moisture absorption.

The core control points of this process are: environmental humidity (waterproofing), precision of injection volume (quantitative), injection speed (avoiding uneven infiltration), and vacuum degree (aiding infiltration and exhaust). Accurate injection is a fundamental prerequisite for ensuring consistent internal resistance, long cycle life, and safety and reliability of batteries.