Battery cells are a key component of modern technologies and are more in demand than ever. Studies assume a global annual battery demand of up to 5,500 gigawatt hours in 2040. In 2021, this figure was still 250 GWh. However, the production of battery cells is complex. Plant operators face a number of challenges, particularly when it comes to scaling up their production processes. How can these be mastered to ensure maximum safety, hygiene and precision as well as efficient production processes?
Challenges in the production of batteries
Battery cells are the centrepiece of numerous applications and are of great importance for e-mobility, but also for the storage of renewable energies such as solar or wind power. The quality of the batteries is already determined when weighing and dosing the materials for the electrode paste. The materials used, some of which are toxic such as lithium, nickel or manganese, also require the highest safety and cleanliness standards.
- Ensuring dosing accuracy
- Avoiding contamination
- Protecting from moisture
- Minimising contamination risks
- Balancing production volume and product quality
Dosing accuracy is a decisive factor for quality and safety in the production of battery cells. Precise dosing of the required substances, such as electrolytes and active materials, ensures that the chemical processes in the battery run optimally and that the performance and service life of the batteries are maximised. Inaccurate dosing can lead to significant quality problems, such as uneven charge distribution or reduced capacity, which ultimately affects the efficiency and safety of the battery. When considering dosing accuracy, dead load must also be taken into account, which is primarily related to the empty weight of a container. Dead load refers to the amount of unused material that remains in the dosing systems. This can have an impact on the accuracy of the measurement and, conversely, on the dosing and therefore the battery cell quality. In addition, pressure fluctuations within the dosing system can strongly influence the dosing accuracy. These fluctuations often occur during the refilling process. They can cause the amount of material being dosed to vary. These variations are very problematic, as even the smallest deviations can negatively affect the properties and performance of the battery. The right dosing technology is therefore crucial to avoid such fluctuations in the process and to ensure consistent product quality.
Avoiding contamination is another decisive factor in the production of cells. Contamination, such as metal abrasion, can cause considerable damage, which can lead to loss of quality or even cell failure. Metal abrasion can cause short circuits within the battery cell, which significantly jeopardizes the safety of the battery. Another important aspect is the avoidance of cross-contamination, which occurs when different components or raw materials are weighed in a container and material deposits form in dead spaces, for example. To keep out dust and dirt particles, it would theoretically be possible to work with overpressure in the machine. However, this approach increases the risk of hazardous substances escaping into the environment in the event of a leak. There is also a risk that overpressure could lead to undesirable pressure fluctuations and thus have a corresponding effect on dosing accuracy.
Many of the materials used are hygroscopic, making it difficult to clean the production facilities if contamination occurs. Moisture can negatively affect the quality of the raw material mixture. If the materials react with water, they can decompose or form undesirable aggressive by-products. The formation of toxic gases is also possible. Even contact with humid air can lead to a deterioration of the properties and thus limit battery performance. Strict measures are therefore required to prevent contact with moisture.
Last but not least, there are contamination risks in the vicinity of the systems, as toxic bulk materials are sometimes processed during battery production. An uncontrolled release of these substances must be prevented. Refilling the weighing containers in batch processes poses a particular challenge, as the air displaced during refilling must not be allowed to escape unfiltered. A negative pressure in the machine can help to keep hazardous substances inside the system and thus provide comprehensive protection for employees.
The sudden and strong increase in demand for battery cells and the associated construction of gigantic battery factories harbors a multitude of challenges. The aim is to produce large quantities of battery cells while ensuring consistently high product quality. However, the scale-up of battery factories in particular can result in scrap rates of up to 50% in the first few months of ramp-up, which can lead to significant material losses running into millions. The high capital investment and the initial difficulties in achieving stable production processes pose both organisational and financial challenges. Factory planning and realisation is also characterised by high cost and volume pressure with limited availability of skilled workers, high energy requirements and complex cause-and-effect relationships in the process.
Battery cell production: Precision, hygiene and safety are crucial
Producing battery cells demands strict adherence to quality standards, focusing on precise recipe adherence and contamination prevention. This comes with various challenges that need to be solved by equipment suppliers.
Design and control measures
The selection of suitable scales and the right dosing technology enables optimum dosing of the components, increases process reliability and ultimately helps to optimally fulfill the constantly increasing requirements.
Avoidance of metal abrasion
When planning the weighing and dosing system, care should always be taken to ensure that there is no metal-to-metal contact between the moving parts. A coating may be required to completely prevent metal abrasion. Static parts such as the trough and the outlet can be coated with PTFE (polytetrafluoroethylene) at the points where the product comes into contact. A ceramic coating is recommended for rotating parts such as the agitator and screw. In addition, smooth surfaces and a controlled speed of the moving parts ensure that abrasion is avoided as far as possible.
Targeted handling of moisture and minimization of contamination
There is a risk of damage due to humidity if ambient air enters the system when the fill level in a weighing hopper drops. The space released should therefore be filled in a targeted and continuous manner by blowing in dried air or nitrogen. To ensure that no impurities escape into the environment, the air may only escape from the system if it is filtered. The choice of filter depends on the containment concept, whereby the specified emissions (OEB values) must not be exceeded. This effectively minimises the risk of contamination.
Intelligent control system
With special controllers such as CONiQ Control, refilling processes can be better coordinated and pressure fluctuations avoided. This is because pressure compensation is particularly important when filling the weighing hoppers. The systems monitor the refilling process and ensure stable and even dosing of the materials. This reduces waste and increases the efficiency of the entire production process.
Precise dosing of battery materials
Special feeders such as the new CS+ loss-in-weight feeder system from Qlar are perfect for optimising weighing or dosing processes in battery production. Customers benefit from a sustainable feeding solution based on reliable containment concepts to control the spread of harmful substances or materials. In this way, we support the scaling of battery cell production. We have based our design on proven products, following the ‘design to cost’ approach, and offer a system that is easy to clean and maintain. The CS+ loss-in-weight feeder system is specially tailored to the requirements of electrode production and is suitable for both continuous and batch processes for the production of battery mass. Thanks to its modular design, the system can be flexibly adapted to the customer's requirements. Material trickling is prevented, as is the formation of metal abrasion. Intelligent control systems round off the innovative concept.
Conclusion
From lithium carbonate to lithium hydroxide monohydrate, from graphite powder to nickel powder - the strict requirements in battery cell production can be optimally met with suitable scales and dosing devices. The right dosing technology and intelligent control of the filling and refilling processes are of central importance. Implementing containment systems and special filters can also prevent particles from being emitted and contaminating the environment.
