Wrinkled Hollow Carbon Spheres with Adjustable Diameter for High‐Performance Supercapacitors

Abstract

Creating more pleated and collapsed structures for carbon‐based electrode materials is an important measure to enhance the performance of supercapacitors. Herein, a polymer formed by the aldimine reaction of terephthalaldehyde and aminopropyltriethoxysilane was utilized as the carbon source, and tetraethoxysilane was added as a silica additive to achieve the wrinkled structure on hollow carbon spheres. The silica had a significant modulating effect on the structure of the obtained wrinkled hollow carbon sphere (WHCS), which displayed a visible pleated structure, hollow structure, high specific surface area, and pore volume. As an electrode material for supercapacitors, WHCS exhibits excellent performance with a capacitance of 312 F ⋅ g−1 and remarkable cycle life stability, demonstrating its great potential for use in supercapacitors.

Coral-Shaped NiO@Graphene Composite Derived from Spent Zinc–Carbon Batteries: Geometric Structure and Electrochemical Studies of Supercapacitors

“…The TEM images at low magnification of GNs (Figure a) show the formation of graphene sheets with the random curving of a few overlapping the large thin sheets. At higher TEM magnification (Figure b), the graphene sheets depict a wrinkled morphology, which is characteristic of the electro-exfoliation method used to prepare graphene. − Moreover, the wrinkled and overlapped morphology of graphene sheets could increase the interlayer spacing, which facilitates the use of other compounds to make a good composite. High-resolution TEM analysis of GNs (Figure c) apparently shows the thickness of some graphene sheets overlap due to wrinkle morphology after the electro-exfoliation process.…”

“…The XRD pattern of the GN-NiO sample shows clear peaks at 37.1°, 43.1°, 62.8°, and 76°, corresponding to (111), (200), (220), and (311) planes of the NiO phase in the GN-NiO composite, respectively. − The structure and quality of the graphene nanosheets and the composite were examined by Raman spectroscopy and are illustrated in Figure b. The graphene nanosheet structure shows three peaks: The D peak at 1347 cm –1 is associated with the defect structures in the graphene network of the sp 3 -disorder mode of C, and the G peak at around 1570 cm –1 is related to the vibrational mode of the sp 2 bond of the graphitic carbon phase . Moreover, the Raman spectroscopy analysis depicts a symmetric 2D peak at 2696 cm –1 , indicating the presence of exfoliated graphene nanosheets.…”

“…This (002) peak of graphene nanosheets indicates the expansion of graphene layers in the sample. 14 Moreover, the GNs illustrate a laminar structure after exfoliation, which provides a good framework for highly conductive composites. In comparison with the GNs sample, the peak (002) at 26.5°of graphene nanosheets appears with the appearance of other peaks of the metal oxide NiO in the GN-NiO sample.…”

“…Figure 4b clearly illustrates images of a few layers of graphene with overlapped morphology and also the increase in interlayer spacing. 14 Figure 4 panels c and d show the high-resolution SEM of the GN-NiO composite. These images indicate that the NiO-coated GNs make a coral structure with corrugated morphology on the surface.…”

“…However, among all of the various methods, electrochemical exfoliation is the easiest and experimentally safest (using a low DC electrical source), uses high-purity raw materials (graphite sources), and is low-cost. Electrochemical exfoliation can produce high-quality graphene sheets from graphite rods, graphite sheets, or pencil cores. , …”