Custom Ultra-Thin LiPo Batteries

Ultra-thin LiPo batteries can be made as thin as about 0.3 mm when the size, capacity, and current requirements allow.
The actual minimum thickness depends on the battery footprint, required capacity, load current, and final mechanical design. A larger length and width can help provide more usable capacity without increasing thickness.
For very thin batteries, the PCM, tabs, insulation, wires, and final assembly space should also be considered.

Usually, yes. If two LiPo batteries have the same length and width, the thinner battery will usually have less capacity because there is less space for active material.

A larger length or width can help increase capacity without increasing thickness. For ultra-thin LiPo batteries, thickness, battery size, and capacity need to be considered together.

Yes. Ultra-thin LiPo batteries can support short current pulses when the cell is designed for the required load.

Pulse performance mainly depends on internal resistance, peak current, and pulse duration. A short Bluetooth, Wi-Fi, GPS, or wireless transmission pulse may be acceptable, while continuous high-current loads are more demanding.

For pulse-load applications, check:

• Peak current
• Pulse duration
• DC internal resistance (DCIR)
• Voltage drop under load
• Temperature rise

Do not select an ultra-thin LiPo battery by capacity alone. Use pulse discharge data and voltage curves to confirm that the battery can support the actual device load.

A 3.7V LiPo battery is a standard lithium-polymer cell that is typically charged to 4.2V. A 3.8V LiPo battery is usually a high-voltage LiPo cell designed for a higher charge voltage, commonly around 4.35V.

The main difference is not simply the extra 0.1V in nominal voltage. A 3.8V high-voltage cell can provide more stored energy in the same battery size, which is useful for ultra-thin devices where space is limited.

The charger and device power system must match the selected battery. A 4.35V charging system should not be used with a standard 4.2V LiPo cell.

For ultra-thin applications, choose a 3.8V high-voltage LiPo battery when you need more energy from a limited battery volume and the device is designed for the higher charging voltage.

Yes. An ultra-thin LiPo battery can include a PCM, but the protection circuit should be considered during the battery and device design stage.

The PCM usually increases thickness only around the circuit area, not across the entire battery. Its final size depends on the PCB, protection components, insulation, tab connection, and wire routing.

To keep the finished battery thin, consider:

• PCM placement – Position the circuit where the device has available space.
• PCB thickness – A low-profile PCB or FPC may reduce the local height.
• Tab and wire routing – Poor routing can increase the finished thickness.
• Insulation – Tape and protective layers also need space.
• Final assembly size – Check the maximum thickness at the PCM area, not only the bare cell thickness.

For very thin products, request a finished battery drawing with the maximum assembled thickness before finalizing the device enclosure.

A standard ultra-thin LiPo battery should not be bent or folded. Bending can damage the internal electrode layers, separator, current collectors, or pouch structure.

If your device has a curved battery compartment, the battery should be specially designed for that shape. A custom curved or shaped battery is different from bending a standard flat pouch cell.

For a curved battery project, confirm the following details: 

Required battery shape

• Curve radius
• Curve direction
• Available battery space
• Battery thickness
• Whether the shape is fixed during use

The battery should remain in its designed shape during normal operation. It should not be repeatedly flexed, folded, or twisted.

Standard ultra-thin LiPo batteries commonly operate at about -20°C to +60°C for discharge and 0°C to +45°C for charging. The exact range depends on the cell design, electrolyte, capacity, and current load.

For applications outside the standard range, different battery designs may be required:

• Low-temperature LiPo batteries are designed for better performance in cold environments.
• High-temperature LiPo batteries are designed for applications that operate at elevated temperatures.

Charging and discharging temperature limits should always be checked separately. Charging below the specified minimum temperature can cause lithium plating and permanent battery damage.

For outdoor, medical, tracking, or industrial applications, provide the required charge, discharge, and storage temperature ranges before selecting a battery.

Do not design the battery cavity using the bare cell thickness alone. Use the maximum finished battery dimensions, including the PCM, insulation, tape, wires, connector, and assembly tolerance. This is especially important for low-profile electronic designs. 

As a general starting point, allow about 0.5–1.0 mm extra in thickness and 1–2 mm in length and width. The exact clearance depends on the battery structure and device enclosure.

For compact devices, confirm the final assembled dimensions and tolerance from the finished battery drawing before finalizing the enclosure.

Yes. Ultra-thin LiPo battery samples can be provided before mass production.

If an existing cell design can meet your requirements, the typical prototype lead time is about 2 weeks. For special dimensions, shapes, PCM designs, or other custom requirements, prototype development usually takes about 2–3 weeks.

Existing models are generally faster to prepare, while special custom design require additional engineering review, assembly, and validation.

For early-stage projects, testing the closest available model first can help confirm device fit and battery performance before moving to a fully custom design.

The thin lithium polymer battery components consist of Lithium cobalt oxide as the cathode, graphite as the anode, an extremely thin polyethylene polymer membrane as the separator, and a polymer or solid polymer electrolyte.

With the technology revolution, the thin lithium ion polymer battery is widely used in smart cards, implantable medical devices, smartwatches, wireless earbuds, IOT devices,micro-sensors, asset racking, smartwatches, earbuds, etc.

Thin batteries are commonly called lithium polymer(LiPo) batteries in a pouch cell shape, printed batteries, and thin film batteries.

The ultra-thin lipo battery is configured in Z-fold to stack the anode and cathode on top of each layer and separated by the separator. This architecture maximises the chemicals and reduces the wasted space and thickness.

A thin-film battery generates electricity by reversible electrochemical reactions. During the discharge process, the lithium ions move from the anode to the cathode through the electrolyte.
During the charging process, the cathode back to the anode and generates voltage and electricity.