Light-weight, flexible, low-voltage electro-thermal film using graphite nanoplatelets for wearable/smart electronics and deicing devices

Abstract

Recently, graphene and graphene-based materials used as heating materials have attracted more and more attention due to their outstanding performance. However, a relatively high voltage of 12–60 V has to be applied for heating because of their high sheet resistance of 43–2600 Ω sq−1. In this paper, light-weight and flexible electro-thermal films using graphite nanoplatelets (GNP) by gap coating and plastic packaging method were present, which were more suitable for wearable/smart electronics and can work at a high heating rate of 25–65 °C/min and a high cooling rate of 24–32 °C/min under a low voltage of 3–5 V, due to the low electrical resistivity (8.9 mΩ cm), low sheet resistance (1.51 Ω sq−1) and high in-plane thermal conductivity (∼50 W (m K)−1) of GNP films. The high electrical and thermal conductance of GNP films was attributed to the obvious orientation of GNPs in microstructure, which could be controlled by the gap-coating process, the solid content of GNP dispersions and the quality of GNPs fabricated by ultrasonic exfoliation. The GNP electro-thermal (E-GNP) films exhibit outstanding heating capacity, including good heating uniformity & repeatability, good heating stability under bending and fast heating response. Moreover, the E-GNP is easily preparared with low cost, and the preparation method is green. It is experimentally demonstrated that as-prepared E-GNP films can be used as wearable devices for thermal therapy, ultra-thin heaters for smart phones, and even deicing devices in cold winter. The E-GNP films would have a wide range of applications in automobile, healthcare, wearable and smart electronics as heaters, due to their excellent heating performance and good flexibility.