Scalable High-Performance Graphene Films Over Hundreds Micrometer Thickness via Sheargraphy.

Area of Science:

• Materials Science
• Nanotechnology
• Thermal Engineering

Background:

• High-performance graphene films offer significant potential for thermal management due to their heat-carrying capacity.
• Existing thick graphene films (hundreds of microns) have limited thermal conductivity (<1000 W m⁻¹ K⁻¹) primarily due to internal wrinkle defects.

Purpose of the Study:

• To develop a novel strategy for producing thick graphene films with enhanced in-plane thermal conductivity.
• To overcome the limitations imposed by sheet defects in achieving high thermal performance in thick graphene materials.

Main Methods:

• A sheargraphy strategy utilizing microscale shearing fields (5 µm) generated by a horizontally moved wire array was employed.
• This method precisely regulated the sheet arrangement of graphene oxide liquid crystals, flattening wrinkles and eliminating polycrystallinity.

Main Results:

• Achieved 215 µm thick graphene films with a record in-plane thermal conductivity of 1380 W m⁻¹ K⁻¹.
• The sheargraphy process resulted in uniform liquid crystals, leading to highly ordered, densified, and flat stacked graphitic crystallites.
• The maximum thermal flux reached 0.3 W K⁻¹, demonstrating superior long-distance heat spreading capabilities.

Conclusions:

• The sheargraphy strategy effectively regulates the ordering of 2D sheets in thick graphene films.
• This approach enables the production of high heat-flux graphene films, offering solutions for demanding thermal management applications.
• The developed methodology provides a pathway to overcome limitations in graphene-based thermal management materials.