Process for producing continuous graphene fibers from functionalized graphene sheets

A process for producing a graphene-based continuous or long fiber from chemically functionalized graphene sheets, said process comprising:

• (a) preparing a graphene dispersion having chemically functionalized graphene sheets dispersed in a liquid medium wherein said chemically functionalized graphene sheets contain chemical functional groups attached thereto and a non-carbon element content of 0.1% to 47% by weight;
• (b) dispensing and depositing at least a continuous or long filament of said graphene dispersion onto a supporting substrate, wherein said dispensing and depositing procedure includes mechanical shear stress-induced alignment of said chemically functionalized graphene sheets along a filament axis direction, and partially or completely removing said liquid medium from said filament to form a continuous or long fiber comprising aligned chemically functionalized graphene sheets;
• (c) using heat, electromagnetic waves, UV light, high-energy radiation, or a combination thereof to induce chemical reactions or chemical bonding between chemical functional groups attached to adjacent chemically functionalized graphene sheets to form said long graphene fiber, wherein said continuous or long graphene fiber comprises chemically functionalized graphene sheets that are chemically bonded with one another having an inter-planar spacing d002 from 0.36 nm to 1.5 nm as determined by X-ray diffraction and a non-carbon element content of 0.1% to 47% by weight and wherein said functionalized graphene sheets contain a combination of sp2 and sp3 electronic configurations, are substantially parallel to one another and parallel to a fiber axis direction, and said fiber contains no core-shell structure, have no helically arranged graphene domains, and have a length no less than 0.5 cm and a physical density from 1.5 to 2.2 g/cm3;
• (d) further comprising an optional step of compressing said continuous or long fiber to increase a degree of graphene sheet orientation and physical density or to improve contact between chemically functionalized graphene sheets;
• and
• (e) further comprising an optional step of reducing said non-carbon content to less than 20% by weight using chemical, thermal, UV, or radiation means.