Hierarchical, Vertically‐Oriented Carbon Nanowall Foam Supercapacitor using Room Temperature Ionic Liquid Mixture for AC Line Filtering with Ultrahigh Energy Density

Abstract

Supercapacitors have been considered as a promising alternative of aluminum electrolytic capacitors (AECs) for AC line filtering applications. However, realizing supercapacitors with fast frequency response and superior energy density still remains an open issue. Herein, we demonstrate a hierarchical, vertically‐oriented carbon nanowall foam (CWF) supercapacitor using mixed room temperature ionic liquids (RTILs) for high‐performance AC line filtering. Hierarchical CWF exhibits macrospores as electrolyte reservoirs to shorten ion transport distance, vertically‐oriented, open channels to enable fast ion diffusion and consecutive scaffolds to promote electron transfer. CWF supercapacitor using RTIL mixture realizes a recorded‐high areal energy density of 1.23 μWh cm−2 at 120 Hz (almost ∼2.0 times/∼10.0 times larger than those of organic/aqueous electrolytes, respectively) and fast frequency response (RC time constant=∼1.3 ms). More importantly, CWF supercapacitor achieves a capacitance advantage over commercial AECs up to 1,000 V, substantially larger than those reported in state‐of‐the‐art literatures (maximum of ∼250 V).

Tungsten‐Disulfide/Polyaniline High Frequency Supercapacitors

“…Yet, SCs display rapid decrease in capacitive behavior in high frequencies. [ 4–6 ] The pioneering study by Miller et al. demonstrated a SCs comprising vertically oriented graphene sheets that featured good AC line filtering at 120 Hz with a resistance–capacitance (RC) time constant of 200 µs.…”

“…demonstrated a SCs comprising vertically oriented graphene sheets that featured good AC line filtering at 120 Hz with a resistance–capacitance (RC) time constant of 200 µs. [ 1 ] Other reports in recent years have demonstrated electric double layer capacitance (EDLC)‐based SCs consisting of carbon nanotube carpets, [ 2 ] coordination polymer framework, [ 3 ] printable graphene, [ 4 ] vertically‐oriented carbon nanowall foam, [ 5 ] and others. Practical applicability of EDLC‐based high frequency SCs has been restricted, however, because of their complex and expensive synthetic procedures.…”

“…Yet, SCs display rapid decrease in capacitive behavior in high frequencies. [4][5][6] The pioneering study by Miller et al demonstrated a SCs comprising vertically oriented graphene sheets retention [30] and complex multilayer hybrid architectures have been introduced to overcome this limitation. [31] Here we demonstrate for the first time a WS 2 -based high frequency SCs exhibiting excellent electrochemical properties.…”

N-Graphene Nanowalls via Plasma Nitrogen Incorporation and Substitution: The Experimental Evidence

“…The nucleation and growth of nanosized structures on the substrate are influenced by temperature, plasma power and pressure, which are controlling the thickness of self-aligned nanowalls in the range of few nanometres to a few tens of nanometres with an interlayer spacing of few nanometres [6][7][8][9]. Catalyst-free synthesis, large surface area, sharp edges with open boundaries and ease of functionalisation of CNWs can be suitable for numerous applications such as field emission [10,11], electrochemical and energy storage applications [12][13][14][15][16][17][18] and novel electronic devices [19,20]. Thus, tailoring the electrical characteristics of CNWs/nanocarbons for achieving application-specific properties has attracted wide attention, specifically by incorporating a heterogeneous atom for controlling the surface properties [21], tuning the bandgap [22] and tailoring the electrical properties [23][24][25].…”

Investigations on the effect of process parameters on the growth of vertically oriented graphene sheet in plasma‐enhanced chemical vapour deposition system

“…[1] These properties have led graphene to offer significant potential in plethora of industrial applications such as sensors, supercapacitors, ion acceleration, aerospace technology, and many others. [2][3][4][5] The vertically oriented graphene sheets (VOGS) are more promising for many specific applications as compared to its horizontal counterpart due to exposed edges and F I G U R E 1 Geometry constructed in the computational model using COMSOL Multiphysics 5.2 modelling suite. All the domains are assigned numbers, and their descriptions are given adjacent to the geometry high surface-to-volume ratio of VOGS.…”