Ultrahigh Thermal Conductive yet Superflexible Graphene Films

Abstract

Electrical devices generate heat at work. The heat should be transferred away immediately by a thermal manager to keep proper functions, especially for high-frequency apparatuses. Besides high thermal conductivity (K), the thermal manager material requires good foldability for the next generation flexible electronics. Unfortunately, metals have satisfactory ductility but inferior K (≤429 W m K ), and highly thermal-conductive nonmetallic materials are generally brittle. Therefore, fabricating a foldable macroscopic material with a prominent K is still under challenge. This study solves the problem by folding atomic thin graphene into microfolds. The debris-free giant graphene sheets endow graphene film (GF) with a high K of 1940 ± 113 W m K . Simultaneously, the microfolds render GF superflexible with a high fracture elongation up to 16%, enabling it more than 6000 cycles of ultimate folding. The large-area multifunctional GFs can be easily integrated into high-power flexible devices for highly efficient thermal management.

Recent Advances in Graphene-Based Free-Standing Films for Thermal Management: Synthesis, Properties, and Applications

“…Thermal annealing in a proper temperature may partially reduce GO to rGO, thus leading to the higher thermal conductivity of the GFs. Previous studies have corroborated that the thermal annealing temperature exerts a significant impact on the thermal conductivity of the GFs [28,37,38,40]. Renteria et al [38] studied the effect of thermal annealing temperature on the thermal conductivity of the rGO films.…”

“…Recently, Peng et al [28] scraped a GO suspension (10-20 mg·mL −1 ) with a thickness of 0.5-5 mm on copper foil and kept evaporating the water at room temperature for 24 h. The as-prepared GO film was carbonized at 1300 • C for 2 h and graphitized at a high temperature of 3000 • C for 1 h under argon flow. After cooling slowly to room temperature, the GF was compressed under a pressure of 50 MPa for 15 min, 100 MPa for 30 min, and 300 MPa for 1 h to form a dense GF.…”

“…Peng et al obtained the GO films through a scrape coating and direct evaporation [28]. After carbonized at 1300 • C and graphitized at 3000 • C, as well as compressed at 50-300 MPa, the rGO films exhibited a thermal conductivity as high as 1940 ± 113 W/m·K.…”

The effect of doping graphene oxide on the structure and property of polyimide-based graphite fibre

“…3,4 Graphite lms derived from PMDA-ODA-type PI lms can obtain an ultrahigh thermal conductivity of 1700 W m À1 K À1 in the plane direction. 5 Many researchers have studied the inuence of chemical structure, 6,7 drawing ratio, 8,9 and heat-treating 10 conditions on the performance of graphite lms. Various identication methods 11,12 have been used to illustrate the mechanism of pyrolysis strategy of polyimide lms, and the behaviour of polyimide lms has also been examined.…”

Electrically insulating POE/BN elastomeric composites with high through-plane thermal conductivity fabricated by two-roll milling and hot compression

“…Substantial researches have focused on fabricating paper-like composites with high in-plane thermal conductivity and low through-plane thermal conductivity [29][30][31][32][33]. For example, pure graphene films with a high in-plane thermal conductivity of 1940±113 W m −1 K −1 have been fabricated [31]. [47][48][49], and constructing a segregated structure [5,[50][51][52].…”