Views: 222 Author: Zhang Xin Publish Time: 2026-06-22 Origin: Site
Content Menu
● Understanding PET Heat Shrink Tubing
>> Key Functions of PET Heat Shrink Tubing
● Why PET Is the Preferred Material for Battery Sleeves
>> Excellent Mechanical Strength
>> Superior Electrical Insulation
>> Cost-Effective Manufacturing
● Overview of Popular Cylindrical Battery Formats
>> 18650 Cells
>> 21700 Cells
>> 4680 Cells
● Critical Factors When Selecting PET Heat Shrink Tubing
>>> For 18650 Cells
>>> For 21700 Cells
>>> For 4680 Cells
>> Shrink Ratio
>>> Benefits of Proper Shrink Ratio
>>> Thick-Wall Tubing Benefits
● Electrical Performance Requirements
● Mechanical Performance Requirements
● Flame Retardancy Considerations
>> Why Flame Retardancy Matters
>> Common Flame Retardant Requirements
● Color Selection for Battery Sleeves
>> Functional Advantages of Color Coding
● Printing and Customization Options
>> Benefits of Printed Sleeves
● PET Heat Shrink Tubing for Electric Vehicle Batteries
>> Enhanced Safety Requirements
● Special Considerations for 4680 Battery Cells
>> Larger Diameter Requirements
>> Premium Quality Expectations
>> Incoming Material Inspection
● Common Mistakes When Selecting PET Heat Shrink Tubing
>> Ignoring Dimensional Tolerances
>> Overlooking Supplier Capabilities
● Future Trends in Battery Heat Shrink Tubing
>> Smart Identification Technologies
>> Support for Emerging Cell Formats
>> Q1: Why is PET heat shrink tubing used on lithium-ion batteries?
>> Q2: What is the difference between tubing for 18650 and 21700 cells?
>> Q3: Can PET heat shrink tubing be customized?
>> Q4: Is flame-retardant PET tubing necessary?
>> Q5: What thickness is commonly used for battery heat shrink tubing?
>> Q6: How do manufacturers verify tubing quality?
>> Q7: Why are 4680 cells more demanding for heat shrink tubing?
As the demand for lithium-ion batteries continues to grow across electric vehicles, energy storage systems, power tools, consumer electronics, and industrial applications, the importance of battery safety and reliability has never been greater. While battery chemistry and cell design often receive the most attention, an equally important component is PET heat shrink tubing.
PET heat shrink tubing serves as the primary external insulation layer for cylindrical lithium-ion cells. It protects the metal can from accidental short circuits, provides mechanical protection, improves product appearance, and enables identification through colors and printed markings. Whether a battery manufacturer is working with traditional 18650 cells, increasingly popular 21700 cells, or advanced 4680 cells, selecting the right PET heat shrink tubing can significantly influence production quality, safety, and long-term performance.
This comprehensive guide explores everything you need to know about selecting PET heat shrink tubing for cylindrical lithium-ion batteries, including material properties, dimensional considerations, performance requirements, customization options, and quality control standards.
PET heat shrink tubing is a thermoplastic sleeve manufactured from polyethylene terephthalate. During production, PET material is extruded into a tube, expanded under controlled conditions, and cooled to maintain its expanded form. When exposed to heat during battery assembly, the tubing shrinks tightly around the battery cell.
The result is a durable and uniform protective layer that conforms closely to the battery surface.
PET heat shrink tubing performs several important functions:
* Electrical insulation
* Mechanical protection
* Surface decoration
* Product identification
* Brand presentation
* Enhanced battery safety
* Environmental protection against minor contaminants
Without a reliable insulating sleeve, cylindrical lithium-ion cells would be more vulnerable to short circuits, abrasion damage, and handling risks.
Several materials can be used for heat shrink applications, but PET has become one of the most widely adopted choices for cylindrical battery insulation.
PET offers high tensile strength and excellent resistance to tearing. This helps protect battery cells during transportation, assembly, and operation.
PET possesses strong dielectric properties, making it highly effective at preventing electrical contact between conductive surfaces.
Lithium-ion batteries often experience elevated temperatures during charging and discharging cycles. PET maintains dimensional stability and performance across a broad temperature range.
PET can be produced efficiently at large volumes, making it suitable for mass battery production while maintaining competitive costs.
PET is recyclable and widely recognized as a more environmentally responsible material compared to certain alternative plastics.
Before selecting PET heat shrink tubing, it is important to understand the dimensional characteristics of the battery cells involved.
The 18650 format has been an industry standard for many years.
Typical dimensions include:
* Diameter: 18 mm
* Length: 65 mm
Common applications:
* Laptop battery packs
* Portable electronics
* Medical equipment
* Flashlights
* Power tools
* Mature manufacturing ecosystem
* Proven reliability
* Broad market availability
* Competitive pricing
The 21700 format was developed to provide greater capacity and energy density.
Typical dimensions include:
* Diameter: 21 mm
* Length: 70 mm
Common applications:
* Electric vehicles
* Energy storage systems
* High-performance tools
* Increased energy capacity
* Improved thermal management
* Reduced battery pack complexity
* Higher energy density
The 4680 format represents a major innovation in cylindrical battery technology.
Typical dimensions include:
* Diameter: 46 mm
* Length: 80 mm
Common applications:
* Electric vehicles
* Utility-scale energy storage
* Advanced industrial equipment
* Higher energy output
* Reduced production costs
* Fewer cells required per pack
* Improved structural integration
Due to their larger size, 4680 cells require heat shrink tubing with enhanced dimensional consistency and mechanical performance.
Selecting the right tubing involves much more than simply matching the battery diameter.
The first consideration is selecting the correct tubing width.
Common flat widths range from:
* 29 mm to 30 mm
Common flat widths range from:
* 34 mm to 35 mm
Common flat widths range from:
* 72 mm to 74 mm
Proper sizing ensures smooth shrinkage and a professional appearance.
Shrink ratio describes the degree to which tubing contracts when heated.
Common shrink ratios include:
* 2:1
* 2.5:1
* 3:1
For cylindrical lithium-ion batteries, 2:1 shrink ratios are generally sufficient because the battery surface is relatively uniform.
* Tight fit
* Reduced wrinkles
* Consistent appearance
* Improved assembly efficiency
Wall thickness affects both protection and flexibility.
Typical battery sleeve thicknesses range between:
* 0.05 mm
* 0.12 mm
* Lower material usage
* Reduced battery weight
* Easier shrinking
* Improved abrasion resistance
* Better mechanical protection
* Increased durability
Manufacturers should balance performance requirements and production costs when determining thickness.
Heat shrink tubing should shrink efficiently without damaging battery components.
Typical characteristics include:
* Initial shrink temperature: 70°C to 90°C
* Full shrink temperature: 100°C to 150°C
The ideal tubing provides rapid and uniform shrinkage while maintaining dimensional stability.
Longitudinal shrinkage refers to dimensional changes in the tubing length during heating.
Lower longitudinal shrinkage provides:
* Better coverage consistency
* Improved appearance
* Easier manufacturing control
Excessive longitudinal shrinkage can create exposed metal areas near the cell ends.
Battery insulation materials must provide excellent electrical protection.
Dielectric strength measures the ability of a material to withstand electrical stress.
High dielectric strength helps:
* Prevent short circuits
* Improve battery safety
* Increase product reliability
For lithium-ion batteries, dielectric performance is one of the most important selection criteria.
High insulation resistance minimizes electrical leakage and contributes to long-term stability.
Manufacturers should verify insulation properties through routine testing and quality control procedures.
Battery sleeves are frequently exposed to handling, transportation, and operational stresses.
Strong tensile properties help tubing resist tearing and damage during installation.
Good elongation allows tubing to stretch without cracking during processing.
Abrasion resistance is especially important in:
* Electric vehicle battery packs
* Industrial equipment
* Energy storage systems
Durable tubing helps maintain insulation integrity throughout the battery lifecycle.
Battery safety standards continue to become more stringent worldwide.
Although heat shrink tubing cannot prevent thermal runaway events, flame-retardant materials can help limit flame propagation and improve overall battery safety.
Many battery manufacturers prefer PET heat shrink tubing that meets:
* UL94 V-0
* Customer-specific safety requirements
Flame-retardant sleeves are particularly important in electric vehicle and energy storage applications.
Color plays an important role in battery identification and branding.
Common options include:
* Blue
* Green
* Black
* Red
* Orange
* Yellow
* White
* Gray
* Transparent
Color coding can help identify:
* Cell chemistry
* Production batches
* Customer specifications
* Capacity classifications
* Product series
This improves traceability and production efficiency.
Many manufacturers use custom-printed PET heat shrink tubing.
Printed sleeves may include:
* Company logos
* Product names
* Safety warnings
* Certification marks
* Date codes
* QR codes
* Serial numbers
Printed battery sleeves provide:
* Improved branding
* Enhanced traceability
* Product differentiation
* Better inventory management
High-quality printing should remain legible after shrinking and throughout the battery's service life.
Electric vehicle batteries operate under demanding conditions that require superior insulation performance.
EV battery manufacturers typically require:
* Strict dimensional control
* High dielectric strength
* Flame retardancy
* Consistent shrinkage behavior
Electric vehicle batteries experience repeated heating and cooling cycles.
High-quality PET tubing should maintain:
* Structural integrity
* Color consistency
* Mechanical strength
* Electrical insulation
Vehicle movement creates continuous vibration.
The tubing must remain securely attached throughout years of operation without cracking or peeling.
The growing popularity of 4680 cells has introduced new challenges for heat shrink tubing manufacturers.
The larger circumference requires:
* Wider tubing
* More precise expansion control
* Uniform shrinkage characteristics
As tubing shrinks around larger cells, stresses become more significant.
Manufacturers should select materials with:
* Strong tensile strength
* Excellent elongation
* Stable shrink performance
Because many 4680 applications involve electric vehicles and energy storage systems, customers often demand higher quality standards than those used for traditional consumer batteries.
Reliable PET heat shrink tubing depends on rigorous quality control throughout production.
Raw materials should be inspected for:
* Purity
* Moisture content
* Consistency
* Color stability
Manufacturers should monitor:
* Extrusion conditions
* Expansion ratios
* Thickness uniformity
* Printing quality
Finished tubing should undergo testing for:
* Shrink ratio
* Tensile strength
* Elongation
* Dielectric strength
* Flame retardancy
* Appearance quality
Consistent testing helps ensure reliable field performance.
The lowest-cost option is not always the most economical solution.
Poor-quality tubing may lead to:
* Production defects
* Increased rejection rates
* Customer complaints
* Safety concerns
Even minor dimensional variations can create assembly issues.
Consistent width and thickness are essential for automated production lines.
Actual shrink testing should always be performed before approving production materials.
Laboratory data alone may not fully reflect real manufacturing conditions.
A reliable supplier should provide:
* Technical support
* Quality documentation
* Consistent production standards
* Responsive customer service
Supplier reliability is often as important as material performance.
As battery energy density increases, insulation materials must continue to evolve.
Future products are expected to offer:
* Better flame resistance
* Improved electrical performance
* Enhanced durability
Environmental concerns are driving interest in:
* Recyclable materials
* Reduced production waste
* Lower carbon footprints
Advanced battery sleeves may incorporate:
* Digital traceability systems
* Enhanced QR coding
* Automated manufacturing integration
As battery manufacturers develop new cylindrical cell designs, heat shrink tubing technology will continue adapting to meet evolving requirements.
PET heat shrink tubing is a critical component in the manufacture of cylindrical lithium-ion batteries. Whether used for 18650, 21700, or 4680 cells, the right tubing provides essential electrical insulation, mechanical protection, safety enhancement, and product identification.
When selecting PET heat shrink tubing, manufacturers should carefully evaluate dimensions, shrink ratio, wall thickness, shrink temperature, dielectric strength, flame retardancy, mechanical performance, color consistency, and supplier reliability. A well-chosen battery sleeve not only improves product appearance but also contributes significantly to long-term safety and operational reliability.
As battery technologies continue advancing, the demand for high-performance PET heat shrink tubing will grow alongside the industry's increasing focus on safety, efficiency, and sustainability.
Answer: PET heat shrink tubing provides electrical insulation, mechanical protection, product identification, and improved safety by covering the conductive metal surface of battery cells.
Answer: The primary difference is size. 21700 cells have a larger diameter and require wider heat shrink tubing to ensure proper fit and shrink performance.
Answer: Yes. Manufacturers can customize dimensions, thickness, colors, logos, safety warnings, QR codes, serial numbers, and other printed information.
Answer: For many battery applications, especially electric vehicles and energy storage systems, flame-retardant tubing is strongly recommended to enhance safety performance.
Answer: Typical thicknesses range from approximately 0.05 mm to 0.12 mm, depending on the desired balance between flexibility, insulation performance, and mechanical protection.
Answer: Quality is typically verified through testing of dimensions, shrink ratio, tensile strength, dielectric strength, elongation, flame retardancy, and appearance.
Answer: Their larger diameter requires wider tubing, more uniform shrinkage, better mechanical strength, and tighter manufacturing controls to ensure consistent performance.
