1、what is lithium battery drying oven
Lithium battery drying oven is a equipment specially designed for drying materials, electrodes, cells, etc., in the production process of lithium batteries. Its main purpose is to remove moisture from the material to ensure the production quality and performance of lithium batteries. Because the lithium battery is extremely sensitive to water, even the presence of very small amounts of water may cause a series of adverse reactions inside the battery, such as electrolyte decomposition, electrode corrosion, etc., which seriously affects the capacity, cycle life and safety of the battery. Therefore, the performance of lithium battery drying oven is directly related to the quality and stability of lithium battery products.
2、the working principle of lithium battery drying oven
Lithium battery drying oven usually use the principle of combining heat transfer methods such as heat conduction, convection and radiation to achieve material drying. In the box, the air is heated by the heating element, the hot air forms a circulating air flow under the action of the fan, and the material is fully in contact with the heat transfer to the material, so that the water in the material evaporates into water vapor. At the same time, the box is equipped with a special dehumidification system, which can dehumidification the air containing water vapor, reduce the humidity in the box, and ensure the continuous drying process. Common dehumidification methods include freezing dehumidification and adsorption dehumidification. Different battery drying oven select appropriate dehumidification technologies based on actual requirements. For example, refrigeration dehumidification is the use of refrigeration system to cool the air below the dew point temperature, so that water vapor condenses into water droplets and discharge, thereby reducing air humidity; Adsorption dehumidification is through the adsorption of adsorbent on water vapor to achieve dehumidification, the adsorbent usually uses silica gel, molecular sieve and other materials with high specific surface area and strong adsorption capacity.
3、lithium battery drying oven structure characteristics
(1) Box design
The box of the lithium battery drying oven is generally made of high-strength, corrosion-resistant materials, such as stainless steel. This material can effectively prevent the deformation and corrosion of the box in the harsh environment such as high temperature and high humidity to ensure the long-term stable operation of the equipment. At the same time, the box has good thermal insulation performance, usually using multi-layer insulation materials for heat preservation, reduce heat loss, improve energy efficiency. For example, some high-end vacuum drying oven use vacuum insulated panels (VIP) as insulation materials, which have extremely low thermal conductivity and can significantly reduce the heat loss of the box.
(2) Heating system
The heating system is one of the core components of the lithium battery drying oven. It is generally composed of heating elements, temperature controllers and heating controllers. The heating element usually uses resistance wires, infrared heating tubes, etc., which can quickly convert electrical energy into heat energy to provide the heat required for the drying process. The thermostat is used to monitor the temperature in the box in real time and feed the temperature signal back to the heating controller. The heating controller automatically adjusts the power of the heating element according to the preset temperature value, so that the temperature in the box is kept in a stable range.
(3) Ventilation and circulation system
The ventilation and circulation system plays a key role in ensuring temperature uniformity and drying efficiency in the box. The fan evenly blows the heated air to all corners of the box, so that the material can fully contact the hot air and achieve rapid drying. At the same time, the ventilation system can also discharge the moisture in the box in time to maintain a dry environment. In order to further improve the temperature uniformity, some vacuum drying oven use special structures in the air duct design, such as diverter plates, deflectors, etc., so that hot air can be more evenly distributed in the box.
4、the type of battery vacuum drying oven
(1) Vacuum drying oven
Vacuum drying oven is a drying equipment in a vacuum environment. It reduces the air pressure in the box by vacuuming, so that the water in the material can quickly evaporate at a lower temperature, so as to achieve rapid drying. Vacuum drying oven is suitable for the drying of temperature-sensitive lithium battery materials and semi-finished products, which can effectively avoid the impact of high temperature on material performance. For example, for some electrode materials containing organic components, the use of vacuum drying oven can remove water at a lower temperature to prevent the decomposition and oxidation of organic components.
(2) Hot air circulation drying oven
Hot air circulation vacuum drying oven is the most common kind of lithium battery drying oven. It uses the circulation of hot air to transfer heat and dry the material. The hot air circulation drying box has the advantages of simple structure, convenient operation and high drying efficiency, and is suitable for drying various lithium battery materials and semi-finished products. In actual production, according to the characteristics of the material and drying requirements, you can choose different hot air circulation methods, such as horizontal circulation, vertical circulation.
(3) Tunnel drying oven
The tunnel vacuum drying oven is mainly used for continuous production of lithium battery production lines. It has a long tunnel-type box, and the material is continuously moved in the box through the conveyor belt, and is dried by hot air during the movement. The tunnel vacuum drying oven can realize large-scale and high-efficiency drying operation, and is suitable for continuous drying of a large number of lithium battery electrodes and cells. At the same time, reasonable design of temperature zone and wind speed distribution in the tunnel can meet the process requirements of different materials in different drying stages.
5、the application of battery drying oven in lithium battery production
(1) The positive electrode material is dry
Cathode material is an important part of lithium battery, and its performance directly affects the energy density and cycle life of the battery. In the production process of positive electrode materials, raw materials need to be dried to remove moisture and impurities. For example, in the synthesis process of lithium iron phosphate anode materials, because the raw material may contain a certain amount of water, if not dried, water will lead to changes in the crystalline structure of the material during the high temperature sintering process, affecting the electrochemical performance of the material. The use of vacuum drying oven to dry the positive electrode material can ensure the purity and stability of the material, and improve the quality of the positive electrode material.
(2) Anode material drying
The negative material is also sensitive to moisture. The presence of water will cause the negative electrode material to have a side reaction when in contact with the electrolyte, consume the lithium salt in the electrolyte, and reduce the capacity and cycle life of the battery. Lithium battery drying oven can effectively remove the moisture in the negative electrode material to ensure the quality of the negative electrode material. For example, for graphite anode materials, it is easy to absorb water during the processing process such as crushing and granulation, and by drying in the vacuum drying oven, the moisture content can be reduced to a very low level to meet the requirements of lithium battery production.
6、how to choose the right lithium battery drying oven
(1) Drying demand
First of all, we must choose the appropriate lithium battery drying oven according to our own drying needs. For example, the type, quantity, size and drying process requirements of the materials that need to be dried. If it is a small batch, multi-variety material drying, multi-layer vacuum drying oven may be more appropriate; For large-scale, continuous production of lithium battery production lines, the tunnel vacuum drying oven is more suitable. At the same time, it is necessary to consider the sensitivity of the material to temperature and humidity, and select the battery drying oven that can meet the corresponding process conditions.
(2) Equipment performance
Equipment performance is one of the key factors in the selection of vacuum drying oven. It is necessary to pay attention to the temperature uniformity, humidity control accuracy, heating rate, ventilation cycle effect and other performance indicators of the vacuum drying oven. For example, for the drying of lithium battery materials with high temperature uniformity requirements, a vacuum drying oven with a good air duct design and a high-precision temperature control system should be selected to ensure that the material is heated evenly during the drying process and to avoid local overheating or over-drying. Humidity control accuracy is also an important indicator, for the production of lithium batteries, it is usually necessary to control the humidity at a very low level, so choose a drying oven with good dehumidification effect and high humidity control accuracy.
