MXene‐on‐Paper Coplanar Microsupercapacitors

Abstract

coplanar interdigitated electrode architecture and shorter paths for in-plane diffusion of electrolyte ions are expected to exhibit improved power and rate capabilities over the conventional electrode designs. [4,5] Such architecture can also be simply integrated on the same substrate as other electronic components such as sensors or rectifiers. However, most of the efforts have been focused on fabricating microsupercapacitors on rigid and flexible substrates employing conventional microfabrication techniques. [1,4] For example, various carbonaceous materials including activated carbon, [6] onionlike carbon [7] carbide-derived carbons, [8] carbon nanotubes, [9] and graphene [10] were employed to demonstrate state-of-theart electrical double layer type capacitors. Furthermore, pseudocapacitive materials which store charge through fast surface redox reactions such as metal oxides, [11] hydroxides, [12] sulfides, [13] and conducting polymers [14] were employed to fabricate micropseudocapacitors. While aiming at the optimal electrochemical performance within a given foot-print area, fabricating thick coplanar electrodes on unconventional substrates such as paper and textiles could increase the amount of energy stored, however this proves to be a difficult task.Paper and textiles are among the most widely used materials, but building devices on their surfaces remains a challenge. [14][15][16] Attempts have been made to use graphite in pencils and inks for writing electrodes on paper. [17,18] Paper has a hierarchical arrangement of cellulose fibers (typical diameter of 20 μm), resulting in a porous and rough surface texture that is helpful for good adhesion of ink without any additional treatments. [17] Moreover, the capillary nature of cellulose fibers, inherent surface charge, and functional groups make the paper surface a universal platform for obtaining thick coatings up to 100 μm of various functional materials by solution processing. [17][18][19][20] For example, Hu et al. demonstrated a solution processable approach to make highly conductive paper for energy storage by integrating single-walled carbon nanotubes and metal nanowires. [19] Similarly, paper-based supercapacitors employing commonly used materials such as graphene, metal oxides, and conducting polymers have been demonstrated. [20][21][22] However, there have been no reports on direct fabrication of microsupercapacitors based on a new class of layered materials, MXenes, coated on an inexpensive paper substrate.MXenes are a new family of 2D layered transition metal carbides and nitrides, [23] which have shown great promise as potential electrode materials for electrochemical energy storage devices. [24,25] Ti 3 C 2 is the most studied member of the A simple and scalable direct laser machining process to fabricate MXeneon-paper coplanar microsupercapacitors is reported. Commercially available printing paper is employed as a platform in order to coat either hydrofluoric acid-etched or clay-like 2D Ti 3 C 2 MXene sheets, followed by laser machining to fabr...

Kirigami Patterning of MXene/Bacterial Cellulose Composite Paper for All‐Solid‐State Stretchable Micro‐Supercapacitor Arrays

“…[44] Figure 2e shows the X-ray diffraction (XRD) patterns of the Ti 3 AlC 2 MAX-phase raw powder and as-prepared 2D few-layered Ti 3 C 2 T x flakes. [53,54] Additionally, the Ti 3 C 2 T x surfaces are terminated by functional groups such as O, OH, and F. Additionally, the (002) peak shifted from ≈10° to ≈6°, and the corresponding peak intensity was stronger, indicating the successful preparation of 2D few-layered Ti 3 C 2 T x flakes.…”

“…All the curves exhibit good rectangular consistency, revealing the excellent conductivity of the electrodes and capacitive behavior of these MSC units. [51][52][53][54][55] In particular, the areal capacitance is an order of magnitude higher than that of carbon material-based planar MSCs (0.1-10 mF cm −2 ). Moreover, as shown in the GCD curves of the asfabricated standard MSC units measured at the same current charge-discharge density (Figure 4j The available areal capacitance (mF cm −2 ) and energy density (mWh cm −2 ) provided per standardized MSC unit could be calculated from the GCD curves ( Figure S4a represent 132% enhancement compared to those based on pure MXene paper (85.13 mF cm −2 and 0.00419 mWh cm −2 ).…”

“…[40][41][42] Employing a new electrode material with a high specific capacitance to design and fabricate the MSC islands is the most direct and effective method to improve the poor areal capacitance of MSCAs based on conventional carbon materials. [51][52][53][54][55] However, few works on MXene-based stretchable MSCAs with both high areal performance metrics and good elongation have been reportedly available so far. [43][44][45][46][47][48][49][50] Due to their unique 2D layered structure and metallic conductivity, MXenes exhibit a high specific volumetric capacitance, which offers great potential for improving the areal performance metrics of planar MSCs.…”

All Pseudocapacitive MXene‐RuO2 Asymmetric Supercapacitors

“…[14,15] However, symmetric supercapacitor devices based on Ti 3 C 2 T x have shown limited operating voltage windows (≈0.6 V) because Ti 3 C 2 T x is prone to oxidation at higher anodic potentials (for example, anodic oxidation was observed in a symmetric two-electrode configuration at ≥0.6 V). [19,20] Recently, it has been shown that Ti 3 C 2 T x MXene electrodes are electrochemically stable in acidic electrolyte at higher cathodic potentials when metal current collectors are replaced by hydrogen overpotential materials, such as glassy carbon or graphite foil. [9] This resulted in a wider negative potential window operation of Ti 3 C 2 T x MXene electrodes (up to −1.1 V vs Hg/Hg 2 SO 4 ), [9] unlike the previous studies with a limited potential window.…”

MXene‐Based Composites: Synthesis and Applications in Rechargeable Batteries and Supercapacitors

“…The performance of the Ti 3 C 2 T x -based microsupercapacitors SCs obtained in this way is obviously better than those from conventional methods (Figure 14e). [298] In the spray coating method, MXene-based ink is sprayed on a substrate, and the shape of the electrode is controlled by a clip of a fixed width. For example, Couly et al adjust the shape by hairpins.…”