Can PTC be added to polymer batteries?

PTC can be added, but not all polymer batteries require or are suitable for adding PTC, which depends entirely on the design of the battery cell, 

packaging form, and application scenario.

1.The function of PTC

PTC is an important passive protection component, and its resistance increases sharply with increasing temperature. The function in the battery is:

Overcurrent/Short Circuit Protection: When the current abnormally increases (such as a short circuit), the PTC heats up and the resistance 

increases, effectively limiting the current and acting as a "recoverable fuse".

To some extent, thermal protection: in conjunction with abnormal temperature rise, it can cut off the circuit.

2. Common forms of adding PTC to polymer batteries

There are usually two types of PTC integration methods for polymer batteries (soft pack lithium-ion batteries):

Cell level PTC: directly integrated into the terminals or interior of the cell. This design is commonly seen in cylindrical or square aluminum shell 

batteries. For typical aluminum-plastic film soft pack polymer battery cells, it is difficult and not a mainstream approach to directly integrate PTC 

inside the cell due to its thin and compact structure.

Pack level PTC: This is a more common and flexible approach. PTC, as a part of the protection circuit, is integrated on the protection board (PCB) 

of the battery. The vast majority of consumer electronic products that use polymer battery cells (such as smartphones, tablets, Bluetooth 

earphones) have their protection functions (including overcharging, overdischarging, overcurrent, and short circuit) implemented through this 

protective board, and PTC is one of the standard components on the board.

3. Key factors determining whether PTC is needed

The chemical system and safety of battery cells themselves: Some high-quality and highly stable polymer battery cells (such as those using 

lithium iron phosphate LiFePO ₄ material) have a lower risk of thermal runaway and may reduce their dependence on PTC, but overcurrent 

protection still needs to be considered.

Application scenarios and customer requirements:

Small capacity, low rate applications (such as wearable devices): Typically, overcurrent protection can be achieved by combining MOSFETs 

on the protection board with sampling resistors, and independent PTC may be omitted.

High magnification and high-power applications (such as drones and power tools): high current and high risk, it is strongly recommended to 

configure PTC in the protection circuit as a dual guarantee.

4.Suggestion

Clear requirements: Ask the battery cell or PACK factory: "What is the overcurrent and short-circuit protection mechanism of this battery cell or 

battery module? Does it include PTC components? “

Check the specification sheet: Carefully read the battery specification sheet, and in the "Protection Function" or "Safety Characteristics" column, 

it is usually clearly listed whether it includes "Overcurrent Protection (OCP)", "Short Circuit Protection (SCP)", and whether it uses "PTC".

Safety first: For any product that may experience high current discharge or have an uncontrollable usage environment, it is strongly recommended 

to use a battery solution with PTC (integrated into the protective board). This is one of the lowest cost and most effective security measures.

Conduct testing: During the sample stage, conduct actual short-circuit testing and overcharge discharge testing on the battery to verify whether its 

protection circuit (including PTC) operates quickly and effectively.

Summary:

Polymer batteries themselves (cells) may not necessarily have built-in PTC, but their complete battery pack (cells+protective plate) can and 

often should incorporate PTC as the core protective component. After selecting the plan and obtaining the specifications, please make sure to 

confirm this item. Safety is no small matter, a reliable PTC can greatly enhance the overall safety of the battery system.