From smartphones and high-rate UAVs to medical devices, lithium polymer batteries are the unsung heroes. They can be molded into any shape and provide a stable power supply. So, what are lithium polymer batteries? How do they work? How can you customize your battery? This guide will provide a comprehensive overview.
The core reason why lithium polymer batteries have become the preferred choice for electronic products lies in their unique chemical properties and physical structure.
1. High energy density: LiPo batteries achieve up to 250Wh/kg in the same volume, storing significantly more energy than traditional batteries.
2. Flexible form factor: Lithium polymer cells can be manufactured in rectangular and curved shapes to fit tablet batteries, smart wearables, and wristbands, conforming to the internal space of various products.
3. Lightweight: They weigh approximately 20%-40% less than steel-cased lithium batteries of the same capacity, meeting the weight requirements of portable devices and drones.
4. Safety: In extreme situations, LiPo batteries will only swell and will not catch fire or explode.
Lithium Polymer Battery Structure
The LiPo battery structure employs advanced lamination processes and colloidal polymer technology:
Positive electrode: Primarily composed of LiCoO2 and NMC, it directly determines the battery’s specific energy and cycle life.
Negative electrode: Primarily composed of graphite, its main function is to insert and extract lithium ions, store electrical energy, and ensure efficient charge-discharge cycles.
Electrolyte: Primarily in colloidal form, it acts as a medium for lithium-ion transport, enabling efficient ion migration between the positive and negative electrodes.
Tab: A metal conductive sheet connecting the battery electrodes to external circuitry; the positive electrode is aluminum, and the negative electrode is nickel.
Lithium Polymer Battery Classification
To meet the needs of different application areas, we roughly classify lithium polymer cells into the following categories.
Classified by shape and packaging
Soft pack batteries: These are the most commonly used Standard LiPo batteries. We can customize the length, width, thickness, capacity, and voltage to meet your specific end-product needs.
Irregularly shaped batteries: We can produce Round, Curved, Triangular, or Ultra-thin batteries to fit smart rings or curved wearable devices.
Classified by discharge rate (C rating)
General rate batteries: primarily 0.5C to 1C, suitable for devices with stable power consumption, such as GPS tracking systems, laser devices, and portable medical devices.
High discharge rate batteries: 5C to 130C, capable of instantly delivering high power, suitable for UAVs (unmanned aerial vehicles), RC models, and jump starters.
Classified by electrolyte physical form
Gelled Polymer Electrolyte: Currently the most commonly used type, mainly composed of PEO, PVDF, and LiPF6. It combines the high conductivity of liquid electrolytes with the safety of solid electrolytes.
Solid Polymer Electrolyte: Completely liquid-free, extremely safe, but its conductivity is more than 10 times lower than that of gel electrolytes.
How Lithium Polymer Batteries Work
Lithium-ion polymer batteries operate according to a typical lithium-ion migration mechanism, the core of which lies in the back-and-forth insertion and extraction of lithium ions between the positive and negative electrodes.
Charging process: When the battery is connected to an external power source, Li+ ions are extracted from the positive electrode material, pass through the electrolyte and separator, and embed into the graphite of the negative electrode. At this time, electrons from the external circuit flow to the negative electrode, thus converting electrical energy into chemical energy.
Discharging process: When the battery is connected to an external load, Li+ ions on the negative electrode pass through the electrolyte back to the positive electrode. Simultaneously, electrons flow through the external circuit, generating current to power your device.
Lithium Polymer Battery Pros & Cons
The biggest advantage of lipo batteries is their high degree of customization, allowing them to meet the needs of various consumer electronics, wearable devices, and medical products.
The biggest disadvantage is their high cost, being 20% more expensive than 18650 batteries. 18650 li-ion batteries are standard products, with initial production capacities reaching 100W units. They also have weaker physical strength, lacking a steel casing for protection, making pouch cells susceptible to punctures or crush damage.
Lithium Polymer Battery Applications
With its flexibility and high power output, Lithium polymer technology has been widely adopted in all industries with stringent space and weight requirements.
Consumer Electronics: From smartphones, tablets, and headphones to smart wearables, it’s the only option for achieving compact designs.
Drones and Model Aircraft: With its extremely high power-to-weight ratio and high discharge rate, polymer lithium batteries are the core power source for FPV racing drones, professional surveying drones, and remote-controlled models.
Medical Devices: Portable ventilators, pulse oximeters, and monitors utilize the portability of LiPo batteries to enable true mobile healthcare, while also offering long standby times.
Smart Home and IoT: Robot Vacuum Cleaners, smart locks, and sensors. The low self-discharge characteristics of polymer batteries ensure long-term stability of these devices in standby mode.
How to Custom Lipo Batteries
As a leading Lithium Polymer Battery Manufacturer in China, we offer a one-stop customized service from cell R&D to Battery Pack assembly. Below is our customized polymer battery process:
1. Size Parameter Determination: We can precisely customize the battery’s Thickness, Width, and Length according to your device’s casing.
2. Electrochemical Performance Matching: Based on your load requirements, we adjust the active positive and negative electrode material formulations to match specific Capacity and charge/discharge rates.
3. PCM and BMS Customization: Each Lipo battery pack is equipped with a high-performance Protection Circuit Board (PCB/BMS) integrating overcharge, over-discharge, short-circuit protection, and temperature monitoring.
4. Connectors and Housings: We offer a variety of connector types (such as JST, Molex, Hirose) and wire specifications. In addition to standard PVC heat shrink, plastic housings are also available.
We support rapid small-batch prototyping from the prototype stage to large-volume production, ensuring you receive batteries with high consistency in voltage and internal resistance. Contact us now to start to custom polymer batteries.
FAQs About Li-polymer Battery
This largely depends on your specific application.
Lipo batteries are suitable for: devices with limited space, high-rate discharge, and special shapes.
Standard 18650 Li-ion batteries are suitable for: devices with ample internal space and low purchase budgets.
Yes, your polymer battery is safe as long as it operates within our specified parameters. Even in extreme cases, it will only swell, not catch fire.