Abstract
NiO is a promising electrode material for supercapacitors. Herein, the novel vertically standing nanosized NiO encapsulated in graphene layers (G@NiO) are rationally designed and synthesized as nanosheet arrays. This unique vertical standing structure of G@NiO nanosheet arrays can enlarge the accessible surface area with electrolytes, and has the benefits of short ion diffusion path and good charge transport. Further, an interconnected graphene conductive network acts as binder to encapsulate the nanosized NiO particles as core–shell structure, which can promote the charge transport and maintain the structural stability. Consequently, the optimized G@NiO hybrid electrodes exhibit a remarkably enhanced specific capacity up to 1073 C g−1 and excellent cycling stability. This study provides a facial strategy to design and construct high‐performance metal oxides for energy storage.
Highlights
nickel oxide (NiO) is a promising electrode material for supercapacitors
The nanosheets have a smooth surface with about 30 nm thickness and about 2 μm height (Figure 2b,c), where such high surface– volume ratio can provide sufficient surface areas with electrolytes
With extend the plasma exposing time, it can be found that the whole nanosheet morphology was maintained (Figure S2, Supporting Information)
Summary
Supercapacitors, including electrical double-layer capacitors still need to be solved.[11,12] To address these problems, one (EDLCs) and pseudocapacitors, have become a research focus effective strategy is to hybridize with carbonaceous materials, recently owing to their desirable properties, such as fast charge such as amorphous carbon, graphene, and carbon nanotubes, and discharge, high power densities, excellent cycling perfor- which can improve the conductivity and improve the strucmance and safety.[1,2,3,4,5] Compared with carbon nanomaterials tural stability.[19,20,21] For example, Feng et al synthesized peapod for EDLCs, pseudocapacitor materials, especially transition NiO nanoparticles in carbon fibers, which shows the high spemetal oxides (TMOs), can provide higher specific capacity and cific capacitance and good cycling stability.[15] due to energy density due to the efficient reversible redox reaction.[6,7,8,9] the aggregation and limited mutual connections, traditional. An asymmetric supercapacitor (G@NiO//NGH) using G@NiO as positive electrode and nitrogen-doped graphene hydrogels (NGHs) as negative electrode can show a high energy density of 52.6 Wh kg−1 at the power density of 800 W kg−1, and good cycling stability
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