Fig 1

The development history of graphene fibers 31, 37-39. Adapted with permission from Ref. 37, Copyright 2012, John Wiley and Sons. Adapted with permission from Ref. 38, Copyright 2011, American Chemical Society. Adapted with permission from Ref.31, Copyright 2011, Springer Nature. Adapted with permission from Ref. 39, Copyright 2017, Royal Society of Chemistry."

Fig 2

The preparation method of graphene fibers: (a) Space-confined hydrothermal method, (b) CVD deposition method, (c) dry spray method, and (d) wet spinning method. (a) Shaping and weaving of graphene fibers by space-confined hydrothermal treatment. Adapted with permission from Ref. 38, Copyright 2012, John Wiley and Sons. (b) Film to fiber self-assembly. Preparation process of graphene fiber. Adapted with permission from Ref. 37, Copyright 2011, American Chemical Society. (c) Schematic illustration of the dry spinning process with a concentrated organic dispersion of graphene oxide (GO). Adapted with permission from Ref. 39, Copyright 2017, Royal Society of Chemistry. (d) The schematic showing the evolution of graphene fibers by wet-spinning. Adapted with permission from Ref. 36, Copyright 2020, John Wiley and Sons."

Fig 3

Various strategies to enhance the performance of graphene fibers (GFs). (a) In situ Small Angle X-ray Scattering patterns of GO fluid. Adapted with permission from Ref. 74, Copyright 2019, Springer Nature. (b) Schematic images of the molecular doping mechanism of giant graphene-Ag fibers. Adapted with permission from Ref. 82, Copyright 2013, John Wiley and Sons. (c) Schematic of the "intercalated" structure of the GO fibers and graphene fibers. Adapted with permission from Ref. 70, Copyright 2015, American Association for the Advancement of Science."

Table 1

Comparison table of strength, electrical conductivity and thermal conductivity of graphene fibers prepared by different methods."

Fig 4

Schematic diagram of the configuration of the three fiber devices. Left: parallel; middle: twisted; right: coaxial. Adapted with permission from Ref.116, Copyright 2020, John Wiley and Sons."

Fig 5

Graphene fiber-based supercapacitors. (a) Schematic of GFs via plasma treatment (left). Specific capacitance of as-prepared GFs and PGFs (right). Adapted with permission from Ref. 130, Copyright 2018, American Chemical Society. (b) Schematic illustration of the GF@3D-Gs (left). Cross-section view of a GF@3D-G (right). Adapted with permission from Ref. 131, Copyright 2013, John Wiley and Sons. (c) Schematic of the fiber activation process. Adapted with permission from Ref. 134, Copyright 2019, American Chemical Society. (d) Schematic illustration of the dot-sheet porous structure formed between CDs and graphene. Adapted with permission from Ref. 132, Copyright 2018, Royal Society of Chemistry. (e) The wet spinning process of graphene fibers (f) SEM images of the inner wall of the needle and GF electrode. Adapted with permission from Ref. 135, Copyright 2015, Royal Society of Chemistry."

Fig 6

Graphene fiber-based pseudocapacitors. (a) Schematic of wet-spinning process for MXene/GO fiber. Adapted with permission from Ref. 150, Copyright 2017, Royal Society of Chemistry. (b) The preparation process of SWCNT/GO fiber. Adapted with permission from Ref. 120, Copyright 2014, Springer Nature. (c) Schematic illustration of the preparation of N-doped GFs. Adapted with permission from Ref. 141, Copyright 2017, John Wiley and Sons."

Table 2

Electrochemical performance of GF-based supercapacitors."

Fig 7

Graphene fiber-based lithium-ion battery. (a) The fabrication process of titania/rGO fiber batteries. Adapted with permission from Ref. 164, Copyright 2017, American Chemical Society. (b) A 4 m long GO/CNT/S fiber (left). Schematic of cable lithium sulfur batteries (middle). Charge/discharge profiles determined at 0.1C (right). Adapted with permission from Ref. 165, Copyright 2017, John Wiley and Sons. (c) Schematic of fiber-shaped lithium-ion battery (LIB) with self-healable ability (left). Cyclic performance of self-healing LIB with different healing times at 0.1 A∙g?1 (right). Adapted with permission from Ref. 166, Copyright 2018, Elsevier."

Fig 8

Graphene fibers used in neural microelectrodes. (a) Fabrication Process of GF-Pt microelectrode. (b) Image of an inserted microelectrode. (c) CV of each individually addressable microelectrode assembled in one array. All microelectrodes showed very similar electrochemical responses. Adapted with permission from Ref. 105, Copyright 2019, John Wiley and Sons."

Fig 9

Graphene fibers for thermoelectric devices. (a) SEM images with different magnifications and view angles of graphene fibers. (b) Comparison of the S of graphene fiber. Adapted with permission from Ref. 107, Copyright 2016, Springer. (c) Scheme for measurement of the fiber device. Adapted with permission from Ref. 106, Copyright 2020, American Chemical Society. (d) Digital photographs of thermoelectric generators. (e) The stability with time for output performance of thermoelectric generators. Adapted with permission from Ref. 174, Copyright 2019, Elsevier."

Fig 10

Graphene based fibers for solar cells and phase change materials. (a) Schematic of the principle for graphene fiber-based solar cell. (b) Current density versus voltage curves of graphene fiber-shaped solar cell. Adapted with permission from Ref. 56, Copyright 2015, John Wiley and Sons. (c) Schematic of dye-sensitized solar cell prepared by using a Pt/graphene composite fiber. Adapted with permission from Ref.180, Copyright 2013, John Wiley and Sons. (d) Schematic of hollow graphene/CNTs/PANI fiber and TiO2/Ti wire. Adapted with permission from Ref. 181, Copyright 2020, Springer. (e) Schematic of integrated device containing solar cell and supercapacitor. Adapted with permission from Ref. 109, Copyright 2020, Elsevier. (f) The aerogel-directed smart fiber as spun. (g) Photograph (left) and IR image under light irradiation (right) of PEG-graphene fiber sewn on a white fabric. Adapted with permission from Ref. 110, Copyright 2018, John Wiley and Sons."