Improving mass loading while maintaining high transparency and large surface area in one self-supporting graphene film is still a challenge. Unfortunately, all of these factors are absolutely essential for enhancing the energy storage performance of transparent supercapacitors for practical applications. To solve the above bottleneck problem, we produce a novel self-supporting flexible and transparent graphene film (STF-GF) with wrinkled-wall-assembled opened-hollow polyhedron building units. Taking advantage of the microscopic morphology, the STF-GF exhibits improved mass loading with high transmittance (70.2% at 550 nm), a large surface area (1105.6 m/g), and good electrochemical performance: high energy (552.3 μWh/cm), power densities (561.9 mW/cm), a superlong cycle life, and good cycling stability (the capacitance retention is ∼94.8% after 20,000 cycles).
Micro-structured interconnected ribbon-like graphene sheet hanging in polygonal graphene walls was developed; the ribbons were formed along grain boundaries during the NaCl multistage-recrystallization process.
Penetrating into the inner surface of porous metal-oxide nanostructures to encapsulate the conductive layer is an efficient but challenging route to exploit high-performance lithium-ion battery electrodes. Furthermore, if the bonding force on the interface between the core and shell was enhanced, the structure and cyclic performance of the electrodes will be greatly improved. Here, vertically aligned interpenetrating encapsulation composite nanoframeworks were assembled from Cl − /SO 3 2− -codoped poly(3,4-ethylenedioxythiophene) (PEDOT) that interpenetrated and coated on porous Fe 2 O 3 nanoframeworks (PEDOT-IE-Fe 2 O 3 ) via a onestep Fe 3+ -induced in situ growth strategy. Compared with conventional wrapped structures and methods, the special PEDOT-IE-Fe 2 O 3 encapsulation structure has many advantages. First, the codoped PEDOT shell ensures a high conductive network in the composites (100.6 S cm −1 ) and provides interpenetrating fast ion/ electron transport pathways on the inner and outer surface of a single composite unit. Additionally, the pores inside offer void space to buffer the volume expansion of the nanoscale frameworks in cycling processes. In particular, the formation of Fe−S bonds on the organic−inorganic interface (between PEDOT shell and Fe 2 O 3 core) enhances the structural stability and further extends the cell cycle life. The PEDOT-IE-Fe 2 O 3 was applied as lithium-ion battery anodes, which exhibit excellent lithium storage capability and cycling stability. The capacity was as high as 1096 mA h g −1 at 0.05 A g −1 , excellent rate capability, and a long and stable cycle process with a capacity retention of 89% (791 mA h g −1 ) after 1000 cycles (2 A g −1 ). We demonstrate a novel interpenetrating encapsulation structure to highly enhance the electrochemical performance of metal-oxide nanostructures, especially the cycling stability, and provide new insights for designing electrochemical energy storage materials.
A kind of 3D micro-structured transparent and free-standing film assembled by graphene-hollow-cubes with network-faces was developed using a micro-structured NaCl template.
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