Battery Cell Assembly Dust Collection

• For Lithium-Ion (Li-ion) pouch batteries, cell assembly includes electrode separation, stacking, tab welding, pouch preparation, electrode assembly insertion, electrolyte filling, and pouch sealing. Most dust is created during separation, stacking and packaging prior to filling and sealing. Weld fume is also created during tab welding. 
• For Li-on cylindrical and prismatic batteries, cell assembly will typically include winding, tab welding, casing preparation, electrode assembly insertion and casing sealing. Less dust is created during these processes, though there will be some weld fume from tab welding and potentially metal cutting dust from preparation of metal casings. 
• Other types of batteries (such as Nickel-Cadmium, Alkaline, and Lead-Acid) will have different cell assembly processes. 

Regardless of battery type, preventing contamination of battery cell components by fugitive dust from other manufacturing processes is essential. Fugitive dust in cell assembly processes can lead to product quality and safety issues down the line and will reduce overall production yield. Battery quality problems may include: 

• Short circuits within the cell, resulting in reduced battery performance, capacity loss, or even thermal runaway in severe cases.
• Impaired electrical contact between the electrodes and their respective current collectors, leading to increased internal resistance and reduced overall performance of the battery.
• Contamination of the separator, which can compromise the separator’s effectiveness, leading to potential short circuits or reduced ionic conductivity.
• Electrolyte contamination, potentially altering its properties and leading to reduced ion transport, increased internal resistance, or other adverse effects on battery performance.

• Worker health: Battery manufacturing, including cell assembly, can expose workers to hazardous dust and fumes, including toxic dusts from electrode production such as lithium compounds, cobalt, nickel, and lead. Carbon nanofibers, graphite and carbon black are also hazardous when inhaled. (Read more about the specific health concerns in Lithium-Ion, Lead-Acid, Alkaline, and Nickel-Cadmium battery production.) Inhalation risks may include respiratory and other health effects, such as lung inflammation, fibrosis, and cancer. Workers may also be exposed to weld fume if they are near tab welding processes. In addition to dry particulate, workers may be exposed to hazardous chemical fumes and vapors from electrolytes, solvents, or other materials used in the battery assembly process. Inhaling or coming into direct contact with these chemicals can result in skin, eye, or respiratory irritation and may pose long-term health risks.
• Combustion risk: Dust generated during electrode cutting or trimming can increase the risk of combustible dust explosions if not properly controlled. While these risks are not as great during cell assembly as during material handling and electrode manufacturing, it is still important to ensure that potentially combustible dusts (such as graphite, lithium or other metal dusts) are not allowed to accumulate in enclosed areas.

• Worker health and safety: Legally enforceable Permissible Exposure Limits (PELs) for respirable materials are set by the Occupational Health and Safety Administration (OSHA) in the U.S. Employers are required to keep exposure levels for regulated materials below the PEL for all workers at all times. Manufacturers can find the PEL specific to the materials they are working with in OSHA’s Annotated PEL Tables. Manufacturers should also be aware of Recommended Exposure Limits (RELs) from the National Institute of Occupational Safety and Health (NIOSH) and Threshold Value Limits (TLVs) from the American Conference of Governmental Industrial Hygienists (ACGIH), which as often lower than the OSHA-required PEL (though they do not carry the force of law).
• Environmental protection: The Environmental Protection Agency (EPA) sets rules governing how hazardous materials are handled and stored, how waste material is disposed of (including particulate collected in the dust collection system), and how much material may be emitted into the atmosphere. Battery manufacturers must follow regulations for emission control and material storage and disposal under the Clean Air Act, Clean Water Act, and Resource Conservation and Recovery Act (RCRA). These regulations govern the handling of electrode materials, solvents, electrolyte solutions and other chemicals used in cell assembly.
• Fire and explosion protection: Manufacturers are also responsible for complying with regulations and standards outlined in OSHA’s Combustible Dust National Emphasis Program (NEP), which outlines policies and procedures for inspecting workplaces that create or handle combustible dusts. The National Fire Protection Association (NFPA) also sets standards for handling combustible materials, including standards for dust control and dust collection system design, which manufacturers are legally required to follow in most jurisdictions. Relevant standards for collection of combustible battery manufacturing dust include NFPA 652, NFPA 654, NFPA 484, NFPA 68, and NFPA 69.

• Material sensitivity: Battery components, particularly the electrodes, separator, and electrolyte, are sensitive to contamination. Dust generated during the cell assembly process can negatively impact the performance and safety of the final product. Dust control measures must be effective in capturing and removing particulates without causing damage or contamination to the battery components.
• Multiple dust sources: Different stages of the battery cell assembly process can generate dust, such as electrode cutting and trimming. Implementing dust control measures at each stage can be challenging, particularly when dealing with different types and quantities of dust.
• Electrostatic issues: Dust particles, particularly those generated from the electrodes or separator materials, can become charged and cause electrostatic issues. These charged particles can be more difficult to capture and control, posing challenges to conventional dust collection systems.
• Combustible dust hazards: Some dust generated during battery cell assembly can be combustible, particularly when the dust is composed of metal or carbon particles. Dust control measures must be designed to safely handle combustible dust and minimize the risk of explosions or fires.
• Space constraints: Battery cell assembly lines can have limited space for installing large-scale dust control systems. Designing compact and efficient dust collection equipment that can be easily integrated into the assembly line is essential.