How Is Ultrasonic Atomization Spraying Used For Battery Tab Insulation Coating?

When ultrasonic atomization spraying is used for battery tab insulation coating, it first matches and pre-treats suitable insulating materials, then forms a film through a precise atomization and deposition process. Parameter control can also ensure coating quality, making it suitable for large-scale production. The specific process and details are as follows:

**Preliminary Material Preparation and Adaptation:** Battery tabs are mostly made of aluminum or copper, requiring the selection of insulating materials resistant to electrolyte corrosion. Commonly used are polymer slurries such as PVDF (polyvinylidene fluoride) and PTFE (polytetrafluoroethylene). Composite slurries containing binders and inorganic insulating materials can also be used to prevent electrolyte corrosion of the tabs.
**Subsequent Slurry Pretreatment:** The viscosity of the material is adjusted to the range suitable for ultrasonic atomization. Ultrasonic dispersion eliminates particle agglomeration in the slurry, ensuring uniform and stable slurry, preventing subsequent clogging of the atomization head, and guaranteeing coating density.

Before coating, the electrode surface must be cleaned to remove oil, burrs, and other impurities to prevent them from affecting the adhesion between the coating and the electrode and reducing the risk of insulation failure. Simultaneously, the ultrasonic coating equipment must be debugged. Based on the electrode dimensions (such as width and thickness) and coating requirements, a corrosion-resistant atomizing head is selected, and an automated three-axis motion system or robotic arm controls the spraying path. The ultrasonic frequency, spraying rate, and substrate temperature are preset via a computer PLC system to ensure spraying accuracy.

 

Atomization and Precise Film Deposition: The pretreated insulating slurry is first fed to the ultrasonic atomizing nozzle via a feeding system. The piezoelectric ceramic transducer inside the nozzle generates high-frequency mechanical vibrations of 10-180kHz under high-frequency electrical signal excitation. This vibrational energy is transferred to the slurry surface, causing the slurry to overcome surface tension and break into uniform micro-droplets of 1-50μm, forming an atomizing cone. Then, driven by an inert carrier gas such as nitrogen, these micro-droplets are directionally transported to the designated area of ​​the battery electrode. This non-contact spraying process avoids physical damage to the tabs.

After the droplets are deposited on the tab surface, the solvent in the slurry is removed through low-temperature drying, forming a pinhole-free, highly dense insulating coating. During spraying, parameters such as atomization power and feed rate can be adjusted to control the coating thickness error within ±5%, meeting the ultra-thin coating requirements for tab insulation. Simultaneously, ultrasonic spraying achieves a material utilization rate of 85%-95%, reducing insulation material waste and lowering production costs.

 

For large-scale mass production, a multi-nozzle array design can be used to achieve wide-width spraying, accommodating batch processing of tabs of different specifications. The equipment also supports 24-hour continuous spraying, and with an automated control system, manual intervention is reduced. This ensures the consistency of the tab coating in each batch during mass production while improving production efficiency, meeting the needs of large-scale manufacturing in the battery industry.

 

Ultrasonic atomization spraying offers core advantages in battery tab coating applications, addressing the core demands of battery manufacturing (safety, consistency, cost control, and scalability). Compared to traditional spraying (air spraying, high-pressure airless spraying), dip coating, and other processes, its advantages are more prominent and readily applicable. The following explanation, based on specific industrial scenarios and data, illustrates these advantages:

I. Precise and Controllable Coating Uniformity and Thickness – Solving the Core Pain Point of "Insulation Failure"
Battery tabs (aluminum/copper material, typically 3-20mm wide and 0.1-0.3mm thick) require insulating coatings that are free of pinholes, have no missed areas, and are uniformly thick (typically 5-50μm). Failure to achieve this can lead to corrosion between the tab and the electrolyte, or short circuits between the positive and negative electrodes, posing safety hazards.

Advantages of Ultrasonic Spraying: Uniform atomized particle size (precisely controllable from 1-50μm), no "droplet aggregation" when droplets deposit on the tab surface, and coating thickness error ≤ ±5% (compared to ±15%-20% for traditional air spraying). Supports "precise localized spraying," allowing coating only on critical areas such as the edges of the tabs and welding areas, avoiding the coating covering the conductive contact surfaces of the tabs (such as the welding points between the tabs and electrode sheets), eliminating the need for subsequent laser etching processes.

Case Study: A power battery manufacturer used PVDF insulating slurry spraying to produce aluminum tabs, requiring a coating thickness of 15±2μm. Traditional air spraying resulted in uneven droplet size, leading to 30% of the tabs exhibiting "localized areas of excessive thinness (<10μm)" or "localized areas of excessive thickness (>20μm)." The thinner areas corroded within 3 months of electrolyte immersion. After switching to ultrasonic atomization spraying, the coating thickness uniformity improved to 15±0.7μm, the corrosion failure rate dropped to below 0.5%, and the battery cycle life increased from 1200 cycles to 1500 cycles.

 

II. Non-contact Spraying + Low-Damage Film Formation – Protecting the Integrity of the Tab Structure

Battery tabs are relatively thin (especially in pouch batteries, where the thickness can be as low as 0.08mm). Traditional contact coating methods (such as roller coating) or high-pressure spraying (airflow impact pressure > 0.3MPa) easily lead to tab deformation and wrinkling, affecting subsequent encapsulation sealing. Furthermore, scratches or indentations on the tab surface become stress concentration points, potentially causing cracking during the battery's expansion and contraction during charging and discharging.

Advantages of Ultrasonic Spraying: The atomization process relies on ultrasonic vibration (without high-pressure airflow impact), and droplet delivery uses low-pressure carrier gas (pressure < 0.05MPa). The impact force on the tabs is only 1/10 of that of traditional air spraying, completely avoiding tab deformation.

The spraying distance can be flexibly adjusted (50-200mm), eliminating the need for close contact with the tab surface and reducing the risk of friction and scratches between the nozzle and the tab.

Case Study: A consumer lithium battery manufacturer producing soft-pack copper tabs (0.1mm thick) experienced an 8% tab deformation rate and a 3% leakage rate after encapsulation when using traditional roller coating. After switching to ultrasonic atomization spraying, the tab deformation rate dropped to below 0.3%, the leakage rate was controlled to within 0.1%, and the tab surface roughness Ra < 0.2μm (meeting the requirements for encapsulation adhesive bonding).

 

III. High Material Utilization – Reducing the Cost of Precious Metals/High-Value Pastes Battery tab insulating coatings commonly use polymer pastes such as PVDF and PTFE, or composite pastes containing ceramic powders (such as alumina). Some high-end applications use conductive insulating composite pastes containing precious metals such as silver and nickel, resulting in higher material costs (e.g., PVDF paste costs approximately 500 RMB/kg).

Advantages of ultrasonic spraying: Strongly directional atomized droplets eliminate "flying mist," achieving a material utilization rate of 85%-95% (compared to only 30%-50% for traditional air spraying, with significant material wastage due to airflow).

The feeding speed (0.1-10 mL/min) can be precisely controlled via a PLC system, adapting to coating requirements for different tab widths and avoiding "over-coating."

Case Study: A power battery company produces 10 GWh of lithium batteries annually, requiring the coating of approximately 200 million aluminum tabs. Each tab requires 0.01 g of insulating slurry (theoretical usage). Traditional air spraying consumes 0.02-0.03g of slurry per unit, totaling 4-6 tons annually, with a cost of 2-3 million RMB. After switching to ultrasonic atomization spraying, the actual slurry consumption is only 0.011-0.013g per unit, totaling 2.2-2.6 tons annually, reducing costs to 1.1-1.3 million RMB, resulting in annual cost savings of approximately 1 million RMB.

 

IV. Low-Temperature Film Formation + Strong Compatibility – Suitable for Thermosensitive/Special Insulating Materials
Some high-end battery tabs require thermosensitive insulating materials (such as PVDF composite slurries containing elastomers, with a temperature resistance ≤80℃) or corrosive slurries (such as fluoropolymer dispersions). Traditional thermal spraying (requiring heating to above 100℃) can cause material decomposition, and high-pressure spraying is prone to equipment failure due to slurry corrosion of the nozzles.

Advantages of ultrasonic spraying: Ultrasonic atomization generates heat only through vibration, with the atomization zone temperature ≤50℃. This preserves the elasticity and insulation properties of heat-sensitive materials, preventing polymer chain breakage.

 

Nozzles can be made of corrosion-resistant materials such as PTFE, ceramics, and Hastelloy, and are compatible with corrosive slurries containing fluorine or weak acids and alkalis, eliminating the risk of equipment corrosion.

Case Study: A solid-state battery company used an elastic insulating slurry containing polyetheretherketone (PEEK) (temperature resistance ≤70℃). Traditional thermal spraying caused the slurry to decompose when heated to 120℃, reducing the coating insulation resistance from 10¹²Ω to 10⁸Ω. Switching to ultrasonic atomization spraying (room temperature film formation) maintained the coating insulation resistance at 10¹²Ω, and the elastic modulus met the requirements for tab bending (no cracking after 1000 bends).