High Packing Density Unidirectional Arrays of Vertically Aligned Graphene with Enhanced Areal Capacitance for High-Power Micro-Supercapacitors

Abstract

Interfacial integration of a shape-engineered electrode with a strongly bonded current collector is the key for minimizing both ionic and electronic resistance and then developing high-power supercapacitors. Herein, we demonstrated the construction of high-power micro-supercapacitors (VG-MSCs) based on high-density unidirectional arrays of vertically aligned graphene (VG) nanosheets, derived from a thermally decomposed SiC substrate. The as-grown VG arrays showed a standing basal plane orientation grown on a (0001̅) SiC substrate, tailored thickness (3.5-28 μm), high-density structurally ordering alignment of graphene consisting of 1-5 layers, vertically oriented edges, open intersheet channels, high electrical conductivity (192 S cm), and strong bonding of the VG edges to the SiC substrate. As a result, the demonstrated VG-MSCs displayed a high areal capacitance of ∼7.3 mF cm and a fast frequency response with a short time constant of 9 ms. Furthermore, VG-MSCs in both an aqueous polymer gel electrolyte and nonaqueous ionic liquid of 1-ethyl-3-methylimidazolium tetrafluoroborate operated well at high scan rates of up to 200 V s. More importantly, VG-MSCs offered a high power density of ∼15 W cm in gel electrolyte and ∼61 W cm in ionic liquid. Therefore, this strategy of producing high-density unidirectional VG nanosheets directly bonded on a SiC current collector demonstrated the feasibility of manufacturing high-power compact supercapacitors.

Recent Advances in Layered Ti3C2Tx MXene for Electrochemical Energy Storage

“…For both batteries and SCs, EES involves physical interaction and/or chemical reaction at the surface or interface . Therefore, the key to better batteries and SCs is to design advanced electrode materials with large specific surface area (SSA), high electrochemical activity, and reduced ion transport distance .…”

Biomimetic and Radially Symmetric Graphene Aerogel for Flexible Electronics

“…The supercapacitor retained its rectangular shape under a wide range of scan rates of from 50 to 1000 mV s −1 (Figure 5a), demonstrating its near ideal featured electrochemical double-layer capacitive (EDLC) behavior and fast charge storage ability under large current density, which is further confirmed by the galvanostatic charge/discharge (GCD) results in Figure 5b. This value outperformed other reported graphene-based micro supercapacitor such as vertically aligned graphene (VG, 7.3 mF cm −2 ), [45] laser rGO (0.5-2.5 mF cm −2 ), [46] rGO (2.47 mF cm −2 ) [47] and the 3D cellular graphene (≈6 mF cm −2 ). Importantly, the device presented a high areal capacity of 7.9 mF cm −2 at a current density of 0.5 mA cm −2 and kept 6.9 mF cm −2 when the current density increased tenfold ( Figure S10, Supporting Information).…”

Sputtered Titanium Nitride Films on Titanium Foam Substrates as Electrodes for High‐Power Electrochemical Capacitors

“…Regarding the electrochemical analysis, the prepared TiN‐coated Ti foam was tested under neutral, acidic and alkaline electrolytes in aqueous solutions. The obtained cyclic voltammograms (CV) show nearly rectangular shapes even at scan rates as high as 10 V s −1 (5 V s −1 for 1 M Na 2 SO 4 ) (Figure a), indicating clear capacitive behavior that possibly benefits from the good electrical conductivity, and 3D structures, of the prepared electrode. The current of the CV was found to be significantly increased after replacing the neutral electrolyte with the acidic or the basic electrolytes.…”

“…Although there has been a constant push for ECs to reach new levels of energy density, power density has been less intensively studied . In fact, power density can be even more crucial since ECs are often integrated with batteries to achieve sufficient power delivery in commercial applications, e. g. better energy recovery, shorter charging time, and so forth ,,,. Furthermore, electrochemical stability, which allows ECs to undergo 10 3 to 10 6 cycles, is always of vital importance ,…”