ZJU Scientists Fabricate Ultrahigh Thermal Conductive Yet Superflexible Graphene Films

2017-06-07


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The research team, led by Prof. Gao Chao from the Department of Polymer Science and Engineering, Zhejiang University, has developed a new grapheme film marked by its superflexibility—it has more than 6,000 cycles of ultimate folding and can tolerate 10,000 bending times. This groundbreaking study has addressed a tough problem with macroscopic materials—inability to possess both ultrahigh thermal conductivity and superflexibility, thereby opening the door to wide applications in highly efficient thermal management, flexible electronic devices, astronomy and aviation.

“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. Therefore, of vital importance is to fabricate a foldable macroscopic material with a prominent K. However, this is like a ‘you cannot have a cake and eat it too’ situation,” said Gao Chao.

The discovery of grapheme may solve this problem on a theoretical level. It is the most studied 2D carbon allotropeconsisting of only one plain layer of conjugated atoms arranged in a honeycomb lattice.The low atomic mass, strong bonding, simple crystal structure, and low anharmonicity of graphene endow it with prominent thermal conductivity. Meanwhile, the single-layer structure renders graphene possible flexibility. These unique properties make graphene promising as a kind of alternative building block for fabricating ultrahigh thermal conductive yet superflexible macroscopic material. However, such graphene-based macroscopic materials including a graphemefilm, fiber, and nonwoven fabric have not been accessed yet.

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Their study solves the problem by folding atomic thin graphene into microfolds. The debris-free giant graphene sheets endow a graphene film with high conductivity. Simultaneously, the microfolds render it superflexible with a high fracture elongation up to 16%, enabling it more than 6000 cycles of ultimate folding. The large-area multifunctional grapheme films can be easily integrated into high-power flexible devices for highly efficient thermal management.

These idiosyncrasies unfold infinite imagination for a lot of applications, such as foldable cell phones, foldable laptop computers and even satellites. If this film can be applied to manmade satellites, it can effectively solve the substantial temperature gap between the phototropic side and the shady face.

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