PTC composites are expected to be the heating material with great development potential. A heating system is necessary for thermal management. Under low temperature, batteries suffer from poor performance such as low charging and discharging rate and low charge and discharge capacity.

Lithium-ion batteries are the dominant type of battery used in portable electronic devices, electric vehicle, and large-scale energy storage system for their high-energy density, long cycle life, and fast charging and discharging rate. Besides, some are seen in safety batteries. Up to now, they are still widely used in these fields. As early as the 1950s, the PTC effect was found in carbon black-filled polyolefin composites, which was first suggested by Frydman to be used in electrical circuit protection, self-regulating heaters, and temperature sensors.

In general, conductive polymer composites (CPCs) exhibit a sharp electrical resistivity increase when the temperature is close to the melting point of the polymer, which is called the positive temperature coefficient (PTC) effect. This work provides a new method of fabricating PTC composites with balanced electrical and mechanical properties. The incorporation of 18 wt.% POE significantly increases the elongation at break, reaching an ultrahigh value of 980 wt.%, which means great flexibility has been achieved in HDPE/POE/CB composites. Meanwhile, the PTC switching temperature shifts down to a lower temperature. When the CB content is 30 wt.%, the room temperature resistivity gradually increases with the increasing content of POE because of the barrier effect of POE phase, and the PTC intensity is gradually enhanced. The results show that the incorporation of 18 wt.% POE can decrease the percolation threshold of conductive carbon black from 22.5 wt.% to 16 wt.%. SEM was conducted to reveal phase morphology and filler dispersion, and DSC was conducted to research crystallization behavior. Micro morphology and crystallization behavior are closely related to PTC properties. The effects of POE and CB content on the PTC performance and flexibility were investigated. In order to expand its applications to fields that need good flexibility, polyolefin elastomer (POE) was incorporated into HDPE/CB composites as a secondary thermoplastic elastomer phase to provide flexibility.

High-density polyethylene (HDPE)/carbon black (CB) is widely used in positive temperature coefficient (PTC) composites.

Poe atoll 3.1