Lith Corporation, founded in 1998 by a group of material science doctor from Tsinghua University, has now become the leading manufacturer of battery lab&production equipment. Lith Corporation have production factories in shenzhen and xiamen of China.This allows for the possibility of providing high quality and low-cost precision machines for lab&production equipment,including: roller press, film coater,mixer, high-temperature furnace, glove box,and complete set of equipment for research of rechargeable battery materials. Simple to operate, low cost and commitment to our customers is our priority.
Prismatic cell sealing refers to the critical manufacturing process in which the outer casing of a prismatic lithiumion battery cell is securely sealed after the internal components (electrodes, separator, and electrolyte) have been inserted. This step ensures that the cell remains hermetically sealed, preventing leakage of electrolyte, ingress of moisture or contaminants, and maintaining longterm electrochemical stability.
Prismatic cells are typically housed in aluminum or steel casings, and their rigid, rectangular shape allows for efficient stacking and integration into modules and packs. However, due to their design and intended use in highreliability applications such as electric vehicles (EVs) and energy storage systems (ESS), ensuring a highquality seal is essential for performance, safety, and longevity.
Why Is Sealing Important in Prismatic Cells?
The sealing process plays a vital role in the overall performance and safety of prismatic cells:
1. Prevents Electrolyte Leakage The electrolyte inside the cell is highly reactive and corrosive. A secure seal prevents leakage that could damage surrounding components or cause short circuits.
2. Protects Against Moisture Ingress Moisture can react with the electrolyte and electrodes, leading to gas generation, reduced capacity, and even thermal runaway. A proper seal ensures the internal environment remains dry and stable.
3. Maintains Internal Pressure Balance During charge/discharge cycles, internal pressure may fluctuate. The sealing system must allow for controlled venting (if applicable) while maintaining integrity under normal operating conditions.
4. Ensures LongTerm Reliability A robust seal contributes to the cell’s lifespan by protecting sensitive internal components from environmental degradation.
5. Meets Safety and Regulatory Standards Proper sealing is required to meet international standards such as: IEC 62660 (for automotive batteries) UL 1642 (lithium battery safety) UN38.3 (transport safety)
Types of Prismatic Cell Sealing Methods
There are several techniques used to seal prismatic cells, depending on the cell design, materials, and production requirements. The most common methods include:
1. Laser Welding Most widely used method in modern prismatic cell manufacturing. Offers: High precision Minimal heataffected zone Strong, hermetic seals Typically used to weld the cover plate or venting cap onto the cell casing. Equipped with vision systems to ensure alignment and quality control.
2. Resistance Welding Uses electrical current and pressure to join metal parts. Less common than laser welding but still used in some legacy or costsensitive applications. May not provide the same level of hermeticity or fine control.
3. Ultrasonic Metal Welding Used primarily for thin metal foils or small sealing areas. Provides fast, clean welds without melting the base materials. Occasionally used in specialized sealing steps or secondary sealing points.
4. Mechanical Sealing with Gaskets Some prismatic cells use rubber or polymer gaskets combined with mechanical clamping or bolting. Often used in conjunction with welding for added protection. Common in industrial or nonautomotive applications where disassembly may be required.
5. Pressure Sealing with Vent Valves Some cells include pressure relief valves that open at a specific threshold to prevent rupture during extreme conditions. These valves must be precisely sealed to function correctly and avoid premature leakage.
Key Components Involved in the Sealing Process
To achieve a reliable and consistent seal, prismatic cell sealing equipment integrates various advanced components:
Laser Welding Heads – For precise, highspeed welding of the cell casing. Fixtures and Clamps – To hold the cell and cover in perfect alignment during sealing. Vision Systems – For realtime inspection of weld seams and positional accuracy. Gas Purging Systems – To create an inert atmosphere during welding and prevent oxidation. Leak Detection Systems – Such as helium leak detectors or pressure decay testers, to verify seal integrity postwelding. Cooling Systems – To manage heat buildup during continuous operation.
Because sealing directly impacts the safety and reliability of the battery, rigorous quality checks are performed:
1. Weld Seam Inspection Visual and automated optical inspection of the weld line. Ensures uniformity, penetration depth, and absence of defects like cracks or porosity.
2. Helium Leak Testing A highly sensitive method to detect microleaks. Involves pressurizing the cell with helium and measuring escape through a mass spectrometer. Typical leak rate acceptance criteria: < 1 x 10⁻⁹ mbar·L/s
3. Pressure Decay Testing Measures changes in internal pressure over time. Detects larger leaks or improper sealing. Faster and less expensive than helium testing.
4. Xray Inspection (Optional) Used in some cases to inspect internal structural integrity and sealing layer thickness.
5. Environmental Aging Tests Simulated aging tests under high temperature and humidity to check longterm sealing durability.
Challenges in Prismatic Cell Sealing
Despite advancements in automation and welding technology, several challenges remain:
Material Compatibility: Aluminum and steel require different welding parameters and shielding gases. Thermal Distortion: Excessive heat can warp the casing or affect nearby components. Process Variability: Minor misalignments or contamination can lead to poor weld quality. Cost of Precision Equipment: Highend laser welders and leak detection systems are capitalintensive. Traceability Requirements: Each sealed cell must be tracked for quality assurance and recall prevention.
Applications That Rely on Reliable Prismatic Cell Sealing
Due to the critical nature of sealing, it's especially important in industries where battery failure can have serious consequences:
Electric Vehicles (EVs) – Cars, buses, trucks Energy Storage Systems (ESS) – Gridscale installations Industrial Equipment – Forklifts, AGVs, mining machines Aerospace and Defense – Missioncritical power systems Medical Devices – Portable and implantable equipment
Best Practices for Prismatic Cell Sealing
To ensure optimal results and compliance with industry standards, manufacturers should follow these best practices:
Use highprecision laser welding systems with vision alignment. Implement realtime quality monitoring during the sealing process. Perform postseal leak testing using helium or pressure decay methods. Maintain clean room conditions to avoid contamination during assembly. Document and store sealing data digitally for traceability and audits.
Leading Companies Offering Prismatic Cell Sealing Solutions
Several global companies specialize in supplying sealing equipment and systems for prismatic cell manufacturing:
Trumpf – Highperformance laser welding systems Coherent (formerly Rofin) – Industrial lasers for battery sealing IPG Photonics – Fiber lasers for precision welding Herrmann Ultraschall – Ultrasonic welding solutions KUKA Systems – Integrated robotic sealing lines B&R Automation (ABB) – Smart manufacturing platforms Gree EnergyTech – Turnkey battery production lines including sealing
Need Help with Prismatic Cell Sealing Processes or Equipment?
If you're involved in battery manufacturing, R&D, or equipment procurement, I can help you with:
Understanding the best sealing method for your cell type and application Selecting the right welding technology (laser, resistance, ultrasonic) Setting up quality control and leak testing protocols Troubleshooting sealing defects or process inefficiencies Cost estimation and supplier recommendations
Just share the following details:
Cell dimensions and casing material (aluminum/steel) Production volume per day Target application (EV, ESS, industrial, etc.) Current level of automation in your factory
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