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Big Reveal of the Entire Lithium Battery Manufacturing Process
- Negative electrode slurry mixing
Negative electrode slurry mixing is one of the key links in lithium battery manufacturing. In this process, negative electrode active materials, conductive agents, binders and other components are mixed together to form a uniform paste through kneading. The mixed slurry needs to be processed. For example, methods such as ultrasonic degassing and vacuum degassing are used to remove bubbles and impurities and improve the fullness, stability and processability of the slurry.
- Positive electrode slurry mixing
Positive electrode slurry mixing is also extremely important. It mixes positive electrode active materials, conductive agents, binders and other additives into a uniform slurry, laying the foundation for subsequent processes such as coating and pressing. The advantage of the positive electrode slurry mixing process is that it can ensure that the positive electrode material is fully mixed with each component and improve battery performance and stability. By precisely controlling the slurry ratio and process parameters, positive electrode materials with stable performance and reliable quality can be prepared.
- Coating
Coating technology is a process of coating adhesives and other fluids on the substrate and forming a special functional film layer after drying or curing in an oven. It is widely used in many industries such as industry, people's livelihood, electronics and optoelectronics. Its advantages include high efficiency, which can realize high-speed and continuous coating operations; uniformity, ensuring uniform coating thickness through a precise control system; flexibility, suitable for a variety of substrates and coating materials; environmental protection, using low-pollution and low-energy-consumption equipment and processes.
- Rolling
The roller press decomposes anode and cathode materials into smaller particles or firmly fixes multiple thin sheets together to form a tight positive and negative electrode structure. It is composed of a main shaft, grinding wheels, a feeding device, a transmission system and a control system. When working, the lithium battery material is sent into the feed port, the main shaft drives the grinding wheel to rotate, and the material is sandwiched between two grinding wheels and compressed into the required shape and size. Its technical characteristics are reflected in high efficiency, uniformity, flexibility and environmental protection.
- Slitting
Slitting plays an important role in battery manufacturing. It longitudinally slits the coated wide film into multiple pieces and winds them into upper and lower single rolls of a certain width specification to prepare for subsequent battery assembly.
- Pole piece baking
Pole piece baking aims to remove moisture and volatile organic compounds in the pole piece to improve the stability and reliability of the pole piece. The baking process includes the preparation stage, which involves checking and preheating the equipment and pretreating the pole piece; the baking stage, which is carried out according to the set time and temperature; and the cooling stage, which protects the pole piece from thermal damage and stabilizes its performance.
- Winding
Winding tightly winds the positive electrode, negative electrode, separator and other components together to form a battery cell. Precise winding control can ensure uniform distribution of materials inside the battery and improve efficiency and safety. Key parameters such as winding speed, tension and alignment have important influences on battery performance and quality.
- Casing insertion
The casing insertion process is a key link in battery production. Putting the battery cell into the battery case can protect the battery cell and ensure safety and performance stability. The process includes battery cell assembly, battery case assembly, sealant application, battery cell placement, battery case closure and welding fixation.
- Spot welding
The battery spot welding process welds the electrode material on the battery component to the conductive strip. Using the principle of resistance heating, instant high-temperature heating melts the welding material to form a solder joint connection. The process flow includes preparation work, setting welding parameters, installing battery components, performing welding, inspecting welding quality and performing rework or grinding. The spot welding process is continuously optimized and developed. For example, introducing robot welding technology to improve efficiency and optimizing parameters to improve quality and stability.
- Baking
The battery baking process removes moisture inside and outside the battery to improve stability and reliability. It also helps with welding circulation and simulates the battery aging process. The specific process includes temperature setting, heating and preheating, stable baking, cooling and shutdown, and inspection and verification.
- Liquid injection
In battery manufacturing, liquid injection controls the amount and injection time of liquid electrolyte and injects the electrolyte into the battery from the injection port. The purpose is to form an ion channel to ensure the reversible circulation of lithium ions between the positive and negative electrode sheets. The process flow includes pretreatment, liquid injection, placement and detection.
- Welding the cap
The welding cap process fixes the battery cap on the battery to protect the interior of the battery from damage and ensure the safe isolation of the positive and negative electrodes. With the development of technology, welding equipment and technology are continuously optimized to reduce costs and improve performance.
- Cleaning
Battery manufacturing cleaning removes dirt, impurities and residues on the battery surface to improve battery performance and lifespan. Cleaning methods include immersion method, spraying method and ultrasonic cleaning method.
- Dry storage
Dry storage ensures a dry and moisture-free internal environment of the battery. Moisture will affect battery performance and lifespan and even cause safety accidents. Environmental requirements include temperature control at 20 - 30°C, humidity control at 30 - 50%, and the particle concentration of air quality should not be higher than 100,000 particles/cubic meter and be filtered. Two methods of vacuum drying and oven drying are adopted.
- Detecting alignment
Battery alignment refers to the accuracy of the relative positions and angles of internal components, which is related to the physical structure, electrochemical performance and safety of the battery. The detection process includes preparation stage, positioning the battery to be tested, taking images, image processing, edge detection, calculating alignment, determining alignment and recording results. Different types of batteries and application scenarios have different alignment requirements. For example, the double-sided alignment of lithium batteries is usually within 0.02mm.
- Case coding
Case coding marks variable information such as product batch number, barcode and QR code on the battery case to ensure product traceability and identifiability. Coding requirements include accurate content, precise location, clear quality, suitable ink adhesion and drying time.
- Formation
Formation, also known as activation, is an important process in battery manufacturing. Through charging and discharging methods, the electrochemically active substances inside the battery are activated to form a stable solid electrolyte interface film (SEI film) to ensure high-performance and safe operation of the battery. It includes steps such as forming the SEI film during the first charge, charging with stepped current to improve efficiency, and discharging and recharging to test performance.
- OCV measurement
OCV is the potential difference between the positive and negative electrodes of the battery in an open circuit state, reflecting the internal electrochemical state of the battery and being closely related to the state of charge, capacity and health status. The measurement principle is to disconnect the external load and wait for the internal chemical reaction of the battery to reach equilibrium and then measure the open circuit voltage. Methods include static test method, rapid test method and charge-discharge cycle test method.
- Normal temperature storage
Normal temperature storage is a link to ensure the stability of battery performance and quality. For short-term storage, the temperature is controlled at -20°C to 35°C and the humidity is 65±20% RH; for long-term storage, the temperature is 10°C to 25°C, the humidity is the same, and 50% - 70% of electricity needs to be charged and regular charge and discharge is required. The storage environment should be dry, free of corrosive gases, well ventilated, and away from water sources, fire sources and high temperatures.
- Capacity grading
Battery capacity grading is to sort and screen batteries by capacity and performance. Through charging and discharging to record data, data such as the capacity and internal resistance of each battery are obtained to determine the quality grade. The purposes include quality screening, capacity matching, voltage balancing, ensuring safety and improving efficiency.
- Final process
Appearance inspection, coding, scanning second inspection, packaging, and warehousing of finished products. The manufacturing process of lithium batteries is complex and meticulous. Every process is related to the performance and quality of the battery. From the mixing of raw materials to the final product inspection, every link embodies the power of technology and the spirit of craftsmen.
Laser flexible die-cutting machine (special for blades and stacked batteries)
The laser flexible die-cutting machine is a device that uses laser technology for die-cutting processing. It generates high thermal energy through the focusing of the laser beam to cut materials. It has high quality, high precision, high efficiency, is easy to use, and has high safety. It can be changed with one key and has low cost.
Laser pole piece surface treatment equipment
Laser scribing technology can improve battery cycle retention rate and reduce battery internal resistance, increase energy per unit area of the battery, and improve energy density and rate.
Laser die-cutting winding and flattening integrated machine (large cylinder φ18650 - φ60140)
Yixinfeng independently develops a laser cutting system with absolute POS energy following algorithm. The stable production speed is 120m/min. The integrated machine can be adjusted by die-cutting and is compatible with AB battery cell winding. It has a wide compatibility range. This equipment can make all models of battery cells such as 18/21/32/46/50/60.
This waste cabinet is a storage and extrusion integrated machine developed by our company specifically for the collection and compression of waste generated during the slitting or die-cutting process of positive and negative electrode materials for lithium batteries. It has the characteristics of simple operation, convenient waste discharge, small floor area, stable operation, and low noise. During the production process of lithium batteries, a certain amount of ear scrap will be generated. If it cannot be effectively collected and processed, it may affect the cleanliness of the production environment and may even cause safety hazards. By using the ear scrap collection and compaction integrated machine, waste on the production line can be cleaned up in time to keep the production environment clean and tidy, which is conducive to improving the safety and stability of production. Moreover, a relatively efficient waste collection method can reduce labor costs and time costs. From the perspective of resource recycling, compacted ear scrap is more convenient for subsequent processing and reuse, which is conducive to the recycling of resources and conforms to the concept of sustainable development.
The filter element automatic cleaning machine is a device used to clean filter elements. It usually uses a variety of technologies and functions to achieve efficient and thorough cleaning effects. The filter element automatic cleaning machine has the characteristics of simple operation and efficient cleaning, which can reduce costs and increase the service life of filter elements. It plays an important role in maintaining the good performance of lithium battery production equipment, ensuring product quality, controlling costs, and promoting the sustainable development of the industry.
This equipment adopts an online dust cleaning method. Through pulsed high-speed and high-pressure injection airflow to generate pressure bulging and micro-vibration to achieve the purpose of dust removal, and it repeats and circulates continuously. The dust removal machine for thousand-grade chip manufacturing provides a clean, safe, and stable environment for the production of lithium batteries by controlling dust, and plays an important supporting role in improving the quality, performance, and production efficiency of lithium batteries.