Yarn supercapacitors have great potential in future portable and wearable electronics because of their tiny volume, flexibility and weavability. However, low-energy density limits their development in the area of wearable high-energy density devices. How to enhance their energy densities while retaining their high-power densities is a critical challenge for yarn supercapacitor development. Here we propose a coaxial wet-spinning assembly approach to continuously spin polyelectrolyte-wrapped graphene/carbon nanotube core-sheath fibres, which are used directly as safe electrodes to assembly two-ply yarn supercapacitors. The yarn supercapacitors using liquid and solid electrolytes show ultra-high capacitances of 269 and 177 mF cm−2 and energy densities of 5.91 and 3.84 μWh cm−2, respectively. A cloth supercapacitor superior to commercial capacitor is further interwoven from two individual 40-cm-long coaxial fibres. The combination of scalable coaxial wet-spinning technology and excellent performance of yarn supercapacitors paves the way to wearable and safe electronics.

Continuous, ultrastrong graphene fibers are achieved by wet-spinning of giant graphene oxide liquid crystals, followed by wet-drawing and ion-cross-linking. The giant size and regular alignment of graphene sheets render the fibers with high mechanical strength and good conductivity. Such graphene fibers promise wide applications in functional textiles, flexible and wearable sensors, and supercapacitor devices.

Kilometer-scale continuous graphene fibers (GFs) with outstanding mechanical properties and excellent electrical conductivity are produced by high-throughput wet-spinning of graphene oxide liquid crystals followed by graphitization through a full-scale synergetic defect-engineering strategy. GFs with superior performances promise wide applications in functional textiles, lightweight motors, microelectronic devices, and so on.

As a reliable and scalable precursor of graphene, graphene oxide (GO) is of great importance. However, the environmentally hazardous heavy metals and poisonous gases, explosion risk and long reaction times involved in the current synthesis methods of GO increase the production costs and hinder its real applications. Here we report an iron-based green strategy for the production of single-layer GO in 1 h. Using the strong oxidant K2FeO4, our approach not only avoids the introduction of polluting heavy metals and toxic gases in preparation and products but also enables the recycling of sulphuric acid, eliminating pollution. Our dried GO powder is highly soluble in water, in which it forms liquid crystals capable of being processed into macroscopic graphene fibres, films and aerogels. This green, safe, highly efficient and ultralow-cost approach paves the way to large-scale commercial applications of graphene.

Fiber-based asymmetric micro-supercapacitor (F-asym-mSC) is assembled by core–sheath graphene fiber decorated by MnO2as the positive electrode and graphene-carbon nanotubes hybrid fiber as the negative electrode. The F-asym-mSC shows the highest energy density (11.9 μWh cm−2) for fiber-based supercapacitors and paves the way to high energy density, wearable, and flexible electronic devices.

A novel all graphene coaxial fiber supercapacitor (GCS) was fabricated, consisting of a continuously wet-spun core graphene fiber and facilely dip-coated graphene sheath. GCS is flexible, lightweight and strong, and is also accompanied by a high specific capacitance of 205 mF cm(-2) (182 F g(-1)) and high energy density of 17.5 μW h cm(-2) (15.5 W h kg(-1)). The energy density was further improved to 104 μW h cm(-2), when an organic ion liquid electrolyte was used.

provide an incessant highway for electron transportation, further reducing the electrochemical polarization. The large theoretical specific surface area [13] (2630 m 2 g −1 ) and unstuck graphene surface contribute to better loading and distribution of nanosized active materials. In addition, the remarkable mechanical properties of graphene [14] can preserve the integrity of electrode in the volume expansion/ shrink process during battery operation. [7] Nevertheless, it is worth mentioning that these supreme properties are only achieved in the highest quality graphene: a single-layer, defect-free graphene sheet as large as possible. Hence, improving the quality of graphene, especially three major parameters of defect concentration, stacking degree, and lateral size of graphene sheets, is of crucial importance. [2] Actually, the large-scale production of high-quality graphene has been generally regarded as the most ambitious challenge to address before practical application of graphene materials. [1,2,15] In this respect, chemical exfoliation of graphite especially oxidation into graphene oxide (GO), has been commercialized, and large size single-layer GO can be produced in ton-level scale with relatively low cost. [16,17] GO is generally reduced into chemically converted graphene (CCG) for further applications in electrodes. However, CCG still contains abundant defects, greatly limiting the vital electric conductivity and other properties. Hence, reducing the defect concentration is the basic concern for real applications of GO and CCG in EES technologies. [1,2,13] Even though methods such as heteroatom doping, [18] chemical vapor deposition, [19] and deliberate design of microsized morphology [7,20] have been utilized to improve electrochemical properties of graphene-based materials, respectively, [21][22][23] whereas their productivity, precise controllability, high reproducibility, and compatibility with the industrial cast-coating technology (particularly for those monolithic graphene bulks) are challenges hard to be resolved. Therefore, it is urgent to find a new production method of graphene, especially powder-formed graphene material that accords with requirements in both quality and quantity to satisfy the demands from EES applications.Here, we propose a new facile and highly controllable strategy to produce high-quality graphene powder, that is, crumpled graphene microflower (GmF), in large scale. Through our design, three parameters of high-quality graphene are simultaneously achieved in GmF: (i) raw materials of ultralarge Poor quality and insufficient productivity are two main obstacles for the practical application of graphene in electrochemical energy storage. Here, highquality crumpled graphene microflower (GmF) for high-performance electrodes is designed. The GmF possesses four advantages simultaneously: highly crystallized defect-free graphene layers, low stacking degree, sub-millimeter continuous surface, and large productivity with low cost. When utilized as carbon host for sulfur cathode, the ...

Graphene aerogel has attracted great attention due to its unique properties, such as ultralow density, superelasticity, and high specific surface area. It shows huge potential in energy devices, high-performance pressure sensors, contaminates adsorbents, and electromagnetic wave absorbing materials. However, there still remain some challenges to further promote the development and real application of graphene aerogel including cost-effective scalable fabrication and miniaturization with group effect. This study shows millimeter-scale superelastic graphene aerogel spheres (GSs) with group effect and multifunctionality. The GSs are continuously fabricated on a large scale by wet spinning of graphene oxide liquid crystals followed by facile drying and thermal annealing. Such GS has an unusual core-shell structure with excellent elasticity and specific strength. Significantly, both horizontally and vertically grouped spheres exhibit superelasticity comparable to individual spheres, enabling it to fully recover at 95% strain, and even after 1000 compressive cycles at 70% strain, paving the way to wide applications such as pressure-elastic and adsorbing materials. The GS shows a press-fly behavior with an extremely high jump velocity up to 1.2 m s . For the first time, both free and oil-adsorbed GSs are remotely manipulated on water by electrostatic charge due to their ultralow density and hydrophobic properties.