A low-cost and eco-friendly strategy to improve the electrothermal performance of laser-induced graphene for electrical heaters

Flexible electrical heaters have drawn significant attention in the field of wearable electronics. A large number of studies have concentrated on improving their electrothermal performance with high heating temperatures, fast temperature response, and good thermal stability. However, the strategy of elemental modification on the electrothermal properties has rarely been explored. In this paper, the electrothermal properties of the modified laser-induced graphene (LIG) fabricated by a facile two-step process are investigated for its application as flexible electrical heaters. NOMEX polyimide composite paper is proposed as a substrate to fabricate LIG via a simple laser-writing method. Doped atoms are introduced by an eco-friendly approach of laser engraving the sodium lignosulfonate coated on the substrate. The modified LIG-based heater exhibits excellent electrothermal performance. It reaches a high steady-state temperature of 160.2 °C under a low operating voltage of 5 V, mainly due to a significantly decreased electrical resistance. Moreover, the fabricated LIG-based heater shows outstanding heating stability, ensuring reliability in practical applications. This research offers a green and low-cost approach for preparing high-performance flexible electrical heaters.