Application of Vertical Vacuum Furnace in Lithium Battery Industry

Although vertical vacuum furnaces have not been directly applied on a large scale in the lithium battery industry, they have demonstrated unique advantages in the application of vacuum technology. Their technical principles can be extended to key processes such as vacuum drying, vacuum injection, and vacuum sintering in lithium battery manufacturing, helping to improve battery performance and production efficiency. The following analysis will be conducted from three dimensions: technical principles, application scenarios, and advantages:

1. The convergence point between technical principles and lithium battery manufacturing
The core technology of a vertical vacuum furnace is to eliminate gas inside the furnace through a vacuum system, create a low oxygen or oxygen free environment, and combine precise temperature control to achieve high-purity synthesis or heat treatment of materials. This principle is highly compatible with the needs of multiple stages in lithium battery manufacturing:

Vacuum drying: The moisture in lithium battery electrodes has a significant impact on battery performance. Excessive moisture can cause electrolyte decomposition, increase battery internal resistance, and even lead to safety issues. A vertical vacuum furnace can quickly remove moisture from electrode plates by combining high vacuum environment (such as vacuum degree ≤ 10 ⁻ ² Pa) with low-temperature heating, while avoiding residual moisture caused by surface hardening during atmospheric pressure drying.
Vacuum injection: In the battery injection process, the vacuum environment can effectively eliminate the air inside the battery, ensure that the electrolyte fully infiltrates the electrode material, reduce residual bubbles, and improve the electrochemical performance and safety of the battery. The vertical structure of the vertical vacuum furnace facilitates automated liquid injection and improves production efficiency.
Vacuum sintering: For certain special lithium battery materials (such as solid electrolytes and high nickel ternary cathode materials), a vertical vacuum furnace can provide high vacuum degree (such as ≤ 10 ⁻⁴ Pa) and precise temperature control (± 1 ℃), suppress the oxidation reaction of the material at high temperatures, improve material purity and crystallinity, and optimize battery performance.

2. Specific application scenarios and cases
Pole drying: In the production of lithium batteries, pole drying is one of the key processes. The vertical vacuum furnace can achieve efficient drying of electrode plates by combining high vacuum environment with low-temperature heating. For example, a certain lithium battery production enterprise uses a vertical vacuum furnace to dry the electrode pieces, which shortens the drying time by 50% compared to traditional atmospheric drying, and improves the uniformity of the moisture content of the electrode pieces to ± 0.05%, significantly improving the performance stability of the battery.
Preparation of Solid State Electrolytes: Solid state lithium batteries are an important direction for the next generation of battery technology, with the core being the preparation of solid state electrolytes. A vertical vacuum furnace can provide a high vacuum environment for sintering solid electrolytes, avoiding the introduction of impurities and improving the ion conductivity of the electrolyte. For example, a research institution used a vertical vacuum furnace to prepare sulfide solid electrolytes. Through precise temperature control and vacuum environment control, the ion conductivity of the electrolyte was successfully increased to over 10 ⁻ S/cm, reaching the international advanced level.
Sintering of high nickel ternary positive electrode materials: High nickel ternary positive electrode materials (such as NCM811) have the advantage of high energy density, but are prone to oxidation at high temperatures, leading to performance degradation. The vertical vacuum furnace can achieve high-purity sintering of high nickel ternary cathode materials by combining high vacuum degree with pure oxygen atmosphere.

3. Advantage analysis
Improving material purity: The vertical vacuum furnace effectively eliminates impurities such as oxygen and water vapor in the furnace through a high vacuum environment, avoiding oxidation reactions of materials at high temperatures and significantly improving material purity. This is crucial for the preparation of high-purity lithium battery materials, such as solid electrolytes and high nickel ternary cathode materials.
Optimizing material performance: The combination of precise temperature control and high vacuum degree can achieve precise control of crystal phase during material sintering process, avoiding abnormal grain growth or agglomeration, thereby optimizing the electrochemical performance of the material. For example, in the preparation of solid electrolytes, a vertical vacuum furnace can improve the ion conductivity of the electrolyte; In the preparation of high nickel ternary cathode materials, the first efficiency and cycle life of the material can be improved.
Improving production efficiency: The vertical structure of the vertical vacuum furnace facilitates automated production, reduces manual intervention, and enhances production efficiency. Meanwhile, a high vacuum environment can accelerate the evaporation of water or solvents, shorten drying or sintering time, and further reduce production costs.
Enhance production safety: In lithium battery manufacturing, the presence of moisture or oxygen may cause safety accidents (such as battery expansion and explosion). The vertical vacuum furnace effectively eliminates these hidden dangers and improves production safety through a high vacuum environment.