Nitrogen-doped amorphous carbon-silicon core-shell structures for high-power supercapacitor electrodes

Abstract

We report successful deposition of nitrogen-doped amorphous carbon films to realize high-power core-shell supercapacitor electrodes. A catalyst-free method is proposed to deposit large-area stable, highly conformal and highly conductive nitrogen-doped amorphous carbon (a-C:N) films by means of a direct-current plasma enhanced chemical vapor deposition technique (DC-PECVD). This approach exploits C2H2 and N2 gases as the sources of carbon and nitrogen constituents and can be applied to various micro and nanostructures. Although as-deposited a-C:N films have a porous surface, their porosity can be significantly improved through a modification process consisting of Ni-assisted annealing and etching steps. The electrochemical analyses demonstrated the superior performance of the modified a-C:N as a supercapacitor active material, where specific capacitance densities as high as 42 F/g and 8.5 mF/cm2 (45 F/cm3) on silicon microrod arrays were achieved. Furthermore, this supercapacitor electrode showed less than 6% degradation of capacitance over 5000 cycles of a galvanostatic charge-discharge test. It also exhibited a relatively high energy density of 2.3 × 103 Wh/m3 (8.3 × 106 J/m3) and ultra-high power density of 2.6 × 108 W/m3 which is among the highest reported values.

Recent Progress in Some Amorphous Materials for Supercapacitors

“…It is worth noting that the synthesis of N‐doped amorphous carbon networks requires a relatively long process (about a week), which is worth exploring in future studies. In addition, compared to several techniques, the new and uncatalyzed plasma enhanced chemical vapor deposition technique employed by Tali et al to prepare N‐doped amorphous carbon films achieved an excellent specific capacity and density (42 F g −1 , 8.5 mF cm −2 ) and a wonderful cycling stability (retaining ≈94% after 5000 cycles), as shown in Figure d. The as‐prepared composites also showed a great energy density (2.3 × 103 Wh m −3 ) and superhigh power density (2.6 × 108 W m −3 ).…”

Nanoimprinted conducting nanopillar arrays made of MWCNT/polymer nanocomposites: a study by electrochemical impedance spectroscopy

“…Figure 4A illustrates the equivalent circuit we used for fitting the EIS spectra, where R 1 ' is the electrolyte resistance, between MWCNT/polymer composites and the electrolyte. 31,32 The diffusion of ions in porous structure does not obey Fick's laws and thus cannot be modeled as a standard Warburg impedance term. By modifying Fick's equations and solving the differential equations under nanoporous boundary conditions, the anomalous diffusion impedance Ma 3 can be express as: 33 (2),…”

Carbon Nanofibers Functionalized with Active Screen Plasma-Deposited Metal Nanoparticles for Electrical Energy Storage Devices

“…6 Regardless of the manufacturing process, the architecture consisting of a conductive or electroactive material deposited on the carbon nano-fibers was found to facilitate the diffusion of electrolyte ions, maximize the surface area for the electrochemical reaction and improve the charge percolation efficiency. 11 Several multi-step processes use some kind of plasma technology to grow or etch nanostructures on carbon scaffolds, [16][17] or to modify the surface chemistry by reaction with gas species. [18][19] In this study, a simpler one-step surface engineering process, based on the advanced composite active screen technology, was used for the first time to functionalize carbon nanofibers.…”