Custom Lithium Batteries for Medical Devices: Expert Guide

With the rapid development of mobile internet, the use of electronic devices is becoming increasingly widespread. The application of portable medical devices is expanding, and lithium batteries, due to their high energy density, long life, and stable performance, have become the first choice for power sources in mobile medical devices. However, the unique operating environments and specific device requirements demand enhanced safety measures and customization for lithium batteries.

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Key Takeaways:

• Custom design to meet the needs of medical lithium battery devices.
• Focus on battery safety features and environmental adaptability to ensure patient safety.
• Choose batteries that meet standards such as IEC 62133 and UN38.3.
• Consider high energy density to meet lightweight requirements.
• Cooperate with battery suppliers in the medical industry like Large Power to obtain high-quality products.
• Deliver tailored solutions through precise design.

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Part 1: Core Characteristics of Medical Device Lithium Batteries

Medical device lithium batteries must satisfy the following key characteristics:

1.1 High Safety

Safety is the foremost consideration for lithium batteries; any safety incident during use can compromise the entire product. By utilizing an aluminum laminated film packing process, these batteries—unlike liquid lithium batteries with metal casings—will merely swell rather than explode under extreme conditions such as overcharging or short-circuiting, thereby significantly reducing safety risks. Furthermore, some high-end models comply with the Exic IIB T4 Gc explosion-proof standard, making them ideal for critical applications like emergency rescue devices.

1.2 Environmental Adaptability

• Temperature Performance: Low-temperature lithium batteries can operate in environments ranging from -40℃ to 60℃ with a discharge efficiency exceeding 70%. This makes them suitable for extreme applications such as extracorporeal artificial hearts, external defibrillators and outdoor emergency rescue equipment.
• Climate Performance: These batteries maintain stability even when the host device is subjected to harsh weather conditions like salt spray corrosion, sandstorms and heavy rainfall.
• Mechanical Performance: They are engineered to withstand vibrations, impacts, and drops. For instance, an ultra-thin design (which can be customized to as thin as 1mm) ensures stable operation even when the battery is bent, thus meeting the unique structural requirements of devices such as neck ventilation systems and wearable monitors.

1.3 High Energy Density and Lightweight

Medical equipment, especially in mobile healthcare and remote medicine, typically demand prolonged power support. Therefore, batteries must possess a high energy density to maximize power output within a limited space and weight. This not only extends the operational time of the device but also reduces overall weight, enhancing portability. For the same capacity, lithium polymer batteries are 40% lighter than steel-cased batteries and 20% lighter than aluminum-cased batteries, while offering a 5-15% increase in capacity, thereby extending device endurance.

1.4 Custom Design

Due to the compact battery size constraints in many devices, particularly those requiring portability, there is a need for flexible customization in dimensions, shape, and thickness. Battery manufacturing techniques, such as battery cell winding or stacking, enable compact and durable power sources that meet the requirements of medical devices like miniature endoscopes and implantable pacemakers.

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Part 2: Types of Medical Lithium Batteries and Selection Recommendations

2.1 Comparison of Mainstream Lithium Battery Types

Type	Advantages/Applicable Scenarios	Example Equipments
Lithium Polymer Battery	High safety, customizable dimensions, thin and flexible	Portable monitors, endoscopes, wearable patches
Lithium Iron Phosphate Battery	High safety, long cycle life, excellent high-temperature stability	Large medical trolleys, fixed detection devices
NMC Lithium Battery	High energy density, superior low-temperature performance	Portable oxygen generators, outdoor diagnostic devices
High-Rate Battery	Supports high current discharges (1C–50C)	Electric surgical tools, external defibrillators

2.2 Key Selection Indicators

• Capacity and Endurance: Determine the required capacity based on the device’s power consumption (for example, an ECG chest patch may require 5 days of operation) and include an additional 20% reserve.
• Dimensions and Weight: Implantable devices demand a miniaturized design (such as button batteries), whereas mobile devices must strike a balance between capacity and portability.
• Safety Certification: Batteries must meet relevant safety certifications (e.g., IEC 62133, GB/T 28164), transportation certifications (e.g., UN38.3), and for specific requirements, pass certifications such as UL 2054 and FDA traceability standards.
• Supply Chain Reliability: Choose suppliers with recognized medical qualifications (e.g., ISO 13485) to ensure consistent quality in mass production.

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Part 3: Key Design Points for Medical Lithium Batteries

3.1 Safety Protection Design

• Intelligent BMS (Battery Management System): Modern medical devices typically feature intelligent management that allows real-time monitoring of battery status. Batteries must have integrated protection circuits for overcharge, over-discharge, short circuits, overcurrent, and abnormal temperature conditions.
• Redundant Design: Key circuits often incorporate dual protection chips (such as those from the TI BQ series) to prevent a single component failure from compromising the entire protection system.

3.2 Structural Material Optimization

• Lightweight and Space Adaptation: Techniques like stacking or using flexible printed circuit (FPC) technology enable ultra-thin (≤1mm), bendable (with a bending radius of ≥5mm), or irregularly shaped batteries that are ideal for miniature devices such as endoscopes and wearable patches.
• Biocompatibility: Batteries intended for implantable devices should use medical-grade titanium alloy casings or silver-plated packaging and must pass ISO 10993 biocompatibility tests. For instance, silver-plated casings help reduce the risk of infection.

3.3 Enhanced Environmental Adaptability

• Extreme Temperature Performance: By optimizing electrolyte formulations (including low-temperature additives), batteries can maintain a discharge efficiency of ≥70% at -40℃, making them suitable for outdoor emergency rescue and cold chain transportation. Additionally, using high-temperature-resistant separators (with ceramic coatings) allows for short-term operation at 85℃, supporting high-temperature sterilization scenarios.
• Anti-Chemical Corrosion Performance: The battery design should incorporate waterproofing (at least IP65) and use materials resistant to common medical disinfectants such as alcohol and hydrogen peroxide.

3.4 Medical Compliance Design

• Electromagnetic Compatibility (EMC): Battery packs should include shielding designs to avoid interference with sensitive equipment like ECG monitors and MRI machines, in compliance with standards such as YY 0505.
• Certification Compliance: Medical device lithium batteries must pass safety certifications (e.g., IEC 62133, GB/T 28164), transportation certifications (e.g., UN38.3), and regional certifications (e.g., CB, CE, UL, CCC), while also meeting industry-specific standards (e.g., ISO 13485).

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Part 4: Analysis of Typical Application Scenarios

4.1 Wearable Devices (e.g., ECG Chest Patches)

• Requirements: Ultra-thin (less than 3mm), waterproof sealing, and Bluetooth connectivity.
• Solution: Utilize 3V lithium manganese button batteries (CR2032) with a capacity of at least 235mAh, paired with a low-power MCU.

4.2 Implantable Devices (e.g., Pacemakers)

• Requirements: Miniaturization, long life (over 10 years), and zero leakage risk.
• Solution: Use silver oxide batteries (SR series) or custom lithium-iodine batteries, with capacities around 200mAh and a self-discharge rate of less than 1% per year.

4.3 Emergency Devices (e.g., Defibrillators)

• Requirements: High discharge rate (≥30C) and a wide operating temperature range (-40℃ to 55℃).
• Solution: Adopt lithium iron phosphate high-rate batteries that support fast charging and emergency discharge.

4.4 Batteries for Portable Ultrasound Diagnostic Instruments

• Requirements: 20W power output, 10 hours of operation, and fast charging capability.
• Solution: Employ a 200Wh battery that supports fast charging (reaching 80% charge within 1 hour) and features a shock-resistant structure tested under MIL-STD-810G.

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Part 4: Conclusion

Selecting the right lithium batteries for medical devices requires a comprehensive evaluation of safety, environmental adaptability and customization needs. Partnering with suppliers experienced in the medical industry and who offer full-process quality control—from the cell to the BMS (such as Large Power, a manufacturer specializing in custom medical device lithium batteries)—can effectively mitigate design risks and accelerate time-to-market.

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FAQs

Why do medical devices prefer lithium polymer batteries?

Their pouch pack structure provides both enhanced safety (eliminating the risk of explosion) and flexible customization, which better utilizes available space in the device. They also offer a weight reduction of 20%-40% compared to traditional batteries, making them ideal for portable devices.

How can the performance of lithium batteries be ensured in low-temperature environments?

By selecting low-temperature lithium batteries (such as the Large Power -40℃ series) and optimizing the electrolyte formulation, it is possible to maintain a discharge capacity of at least 70% even at -40℃.

Q3: What certifications do medical lithium batteries need to obtain?

Medical device lithium batteries must comply with safety certifications (e.g., IEC 62133, GB/T 28164), transportation certifications (e.g., UN38.3), and regional certifications (e.g., CB, CE, UL, CCC), as well as meet industry-specific standards (e.g., ISO 13485).