Abstract
It is crucial to align two-dimensional nanosheets to form a highly compact layered structure for many applications, such as electronics, optoelectronics, thermal management, energy storage, separation membranes, and composites. Here we show that continuous centrifugal casting is a universal, scalable and efficient method to produce highly aligned and compact two-dimensional nanosheets films with record performances. The synthesis mechanism, structure control and property dependence of alignment and compaction of the films are discussed. Significantly, 10-μm-thick graphene oxide films can be synthesized within 1 min, and scalable synthesis of meter-scale films is demonstrated. The reduced graphene oxide films show super-high strength (~660 MPa) and conductivity (~650 S cm−1). The reduced graphene oxide/carbon nanotube hybrid-film-based all-solid-state flexible supercapacitors exhibit ultrahigh volumetric capacitance (407 F cm−3) and energy density (~10 mWh cm−3) comparable to that of thin-film lithium batteries. We also demonstrate the production of highly anisotropic graphene nanocomposites as well as aligned, compact films and vertical heterostructures of various nanosheets.
Highlights
It is crucial to align two-dimensional nanosheets to form a highly compact layered structure for many applications, such as electronics, optoelectronics, thermal management, energy storage, separation membranes, and composites
The graphene oxide (GO) nanosheets were synthesized by traditional Hummers method[26], which are all monolayers with a C/O ratio of 1.7 and average lateral size of ~1 μm
The former can lead to the compaction of GO nanosheets along the radial direction of the rotating hollow tube (RHT), while the latter can align and smooth the GO nanosheets along the tangential direction of the RHT
Summary
It is crucial to align two-dimensional nanosheets to form a highly compact layered structure for many applications, such as electronics, optoelectronics, thermal management, energy storage, separation membranes, and composites. The highest strength reported for the common reduced graphene oxide (rGO) films is lower than ~300 MPa along with a small electrical conductivity of ~120 S cm−122, and the volumetric energy density of 2D nanosheets-based thin-film supercapacitors is much lower than that of the thin-film lithium batteries[23,24,25] These methods are not suitable for scalable production in terms of either time consuming, complicated procedure, high cost, or specific requirements on the 2D nanosheets and their dispersion. We demonstrate the synthesis of highly aligned and compact GO films, super-strong and highly conductive rGO films, rGO/single-walled carbon nanotubes (SWCNTs) hybrid films for flexible supercapacitors (SCs) with record volumetric energy density, highly anisotropic graphene nanocomposites as well as various 2D nanosheet films and vertical heterostructures, by CCC method. The influence of alignment and compaction degree on the properties of films as well as the high efficiency, easy scalability and good controllability of CCC method are demonstrated and discussed
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