Battery pack manufacturing relies on the proper selection of battery chemistries, materials, electronic components, and enclosure designs to meet application power, safety, recharge, and storage requirements. Understanding how these standard materials and components interact can help improve performance, shorten lead times, control costs, and support regulatory compliance.
Understanding Materials and Components in Battery Pack Manufacturing
Successful battery pack development begins with a thorough understanding of the application's power requirements, recharge expectations, operating conditions, and storage needs. These requirements determine which battery chemistries, materials, and components will be used throughout the design.
Because every application is different, battery packs may incorporate a wide range of standard materials and components. These selections affect not only performance and safety, but also lead times, manufacturing complexity, and time-to-market objectives.
Battery Cell Materials and Chemistry Selection
Battery chemistry serves as the foundation of battery pack design because it influences cell construction, performance characteristics, safety requirements, and component selection.
Common battery chemistries include:
- Lithium-ion and other lithium-based chemistries
- Alkaline
- Nickel-based chemistries, including nickel cadmium
Internal Battery Cell Materials
Although all batteries contain anodes, cathodes, electrolytes, and separators, the materials used vary by chemistry.
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Inside of custom battery pack showing electronics, components, and materials.
For lithium-ion cells:
- Anodes may consist of lithium, lithium-alloying materials, graphite, intermetallic materials, or silicon.
- Cathodes may include lithium-metal oxides, rechargeable lithium oxides, olivine, and vanadium oxides.
- Electrolytes may utilize lithium bis(oxalate)borate, lithium hexafluorophosphate, or similar materials in polymer, liquid, or solid-state forms.
For alkaline batteries:
- The anode is typically a zinc powder paste.
- Potassium hydroxide serves as the electrolyte.
- The cathode consists of graphite and manganese dioxide.
Separators and Cell Construction
Separators keep anodes and cathodes isolated within the cell.
- Lithium-based cells typically use foam separators.
- Alkaline batteries utilize paper separators.
Battery cells also incorporate sealing structures and current collection components, including a center nail current collector, secondary plastic seal, and metal end cap.
Battery Interconnection Materials
Every battery pack requires both internal and external electrical interconnections. The materials selected depend largely on whether the design is intended for high-power or low-power operation.
Low-Power Battery Pack Connections
Typical low-power interconnection methods include:
- Nickel strips welded to cell terminals
- Gold-plated external contacts
- Metal tabs for pouch cells
- Flying leads for lower-power connections
High-Power Battery Pack Connections
High-power battery packs generally require more robust interconnection methods, including:
- Copper braided straps
- Copper bus bars
- Threaded metal studs for external connections
These interconnect choices help support the current requirements of the application while maintaining reliable electrical performance.
Battery Management System (BMS) Components
Electronics and software have become standard elements of many battery pack designs. Many of these functions are incorporated into the battery management system (BMS).
Common BMS-related features include:
- Protection circuits
- Monitoring circuits
- Fuel gauges
- Charge controllers
- Cell balancing functions
- Communication functions
- Indicator lights
Battery Management System Requirements
While alkaline and nickel-based batteries do not necessarily require a battery management system, incorporating BMS functionality can improve protection, monitoring capabilities, and overall battery management.
For lithium-based battery packs, a battery management system is always required.
These systems help users monitor battery status and support safe operation through integrated electronics and control functions.
Electronics, Software, and Circuit Integration
The electronic components used in the battery pack are mounted on an integrated circuit platform.
The selection of a flexible circuit, rigid-flex design, or traditional rigid circuit structure depends on factors such as:
- Available installation space
- Battery pack weight objectives
- Shock and vibration requirements
- Mechanical loading conditions
- Cost considerations
The appropriate platform is chosen based on the performance and packaging requirements of the application.
Battery Enclosure Materials and Design
Battery enclosure design is largely determined by how the battery pack will be used within the final product.
Shrink Wrap and Vacuum-Formed Packaging
If the battery pack will be completely integrated inside the product, common enclosure options include:
- Shrink wrapping
- Vacuum-formed plastic
These approaches provide a practical solution for battery packs that do not require a separate user-accessible housing.
Injection Molded Plastic Enclosures
When battery packs are mounted externally or housed in a dedicated accessible compartment, injection molded plastic enclosures are commonly used.
In applications where the battery pack enclosure is visible to the user, the enclosure's appearance may need to align with the overall product design. Color, texture, and styling considerations should be coordinated between the product manufacturer and battery pack manufacturer to help minimize delays and redesigns.
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Battery pack inside injected molded plastic enclosure.
Metal Enclosures
Metal enclosures may be required when additional protection is necessary.
These enclosures are commonly used for:
- Traction applications
- Applications exposed to extreme forces
- Environments where severe mechanical damage could occur
Metal casings provide additional protection in situations where enclosure failure could create safety concerns.
Thermal Management and Environmental Protection
Battery cells can expand and swell as a result of temperature effects and gas generation over time. This condition is especially common in lithium-based battery chemistries, where cells may swell by as much as 10% during the battery pack's lifetime.
Venting and Cooling Solutions
Standard thermal management approaches include:
- Enclosure venting
- Fans
- Pumps
- Air-cooling systems
- Water-cooling systems using heat exchangers
These solutions help manage heat and support battery pack performance.
Heating Solutions for Cold Environments
Battery packs intended for extremely cold operating environments may require heating mechanisms.
Flexible heaters can be an effective option for applications that:
- Have size restrictions
- Have weight restrictions
- Utilize curved or rounded package designs
Standard Components vs. Custom Components
Material availability often depends on customer demand trends and the manufacturer's product focus. Some manufacturers may specialize in lithium-ion battery packs, while others may focus on nickel cadmium or other chemistries.
Standard materials and components can provide several benefits:
- Lower costs
- Shorter lead times
- Faster production schedules
However, high-power applications and specialized safety requirements may necessitate custom-developed solutions.
Application-Specific Integrated Circuits
Certain battery pack designs may require custom application-specific integrated circuits (ASICs) within the management system.
ASIC development may involve:
- Full custom transistor-level design
- Customization of an existing circuit platform
- Gate-level custom development
The appropriate approach depends on the application's power, functionality, and safety requirements.
Compliance, Certification, and Industry Requirements
Battery chemistry selection can affect both regulatory requirements and certification processes.
Some industries require compliance with specific safety regulations before products can be certified and released.
Industries with demanding requirements include:
- Medical devices
- Aerospace
- Military and defense applications
Certification efforts may require registration audits, testing programs, and the production of additional battery packs for both destructive and non-destructive testing. These activities can increase development costs and lead times.
Planning for Costs and Lead Times
Battery pack costs and lead times are often underestimated during the early stages of development. The final design may require more materials, components, protection features, and testing than initially anticipated.
Providing complete application requirements before development begins helps establish:
- Material selection
- Component requirements
- Customization needs
- Project costs
- Manufacturing lead times
- Prototyping schedules
This information allows manufacturers to determine which standard materials can be used and which features require custom development.
Summary
At Epec Engineered Technologies, we provide battery design, creation, and manufacturing work to customers in a range of industries, including medical, aerospace, food service, and military defense.
We partner with our customers to learn more about their operational capabilities and the battery pack power needs. Then, we offer design solutions that can keep costs low for our customers while providing a high-quality battery pack. Contact us today to learn more about our capabilities.
Key Takeaways:
- Understanding Application Requirements is Essential: Defining power needs, recharge times, and storage requirements ensures the right materials and components are selected for optimal battery performance.
- Battery Chemistry Dictates Materials & Design: Different chemistries (lithium-ion, alkaline, nickel-based) determine anode, cathode, electrolyte, and separator materials, affecting performance and safety.
- Electronics & Battery Management Systems (BMS) Enhance Safety: Protection circuits, charge controllers, and monitoring features help prevent overheating, overcharging, and failure, particularly in lithium-based batteries.
- Enclosure Materials Impact Performance & Durability: Options range from shrink wrap and plastic casings for standard applications to metal enclosures for high-impact and high-temperature environments.
- Thermal Management Solutions Prevent Failures: Battery packs may incorporate vents, fans, heat exchangers, or flexible heaters to manage temperature fluctuations and prevent swelling or performance loss.
- Standard vs. Custom Components Affect Costs & Lead Times: While standard materials help control costs and production speed, custom designs may be necessary for high-power or safety-regulated applications like medical or military use.
