Flexible Ti₃C₂T_x/Carbon Nanotubes/CuS Film Electrodes Based on a Dual-Structural Design for High-Performance All-Solid-State Supercapacitors

Abstract

Freestanding and bendable films fabricated by two-dimensional (2D) MXene materials have demonstrated great potential as electrodes for energy storage devices owing to their paramount flexibility, structural stability, and high conductivity. Nevertheless, the unavoidable restacking of MXene sheets substantially limits their electrochemical performance. Here, a film electrode with a sandwich-like structure was fabricated by a dual-structural design through a layer-by-layer (LbL) method with alternating filtration of the Ti 3 C 2 T x /carbon nanotube (CNT) hybrid and CuS dispersion. The introduced CNTs and pseudocapacitive CuS provide abundant active sites to augment the electrode storage capacity. The enlarged interlayer spacing facilitates the transport of electrolyte ions. As a result, the optimized Ti 3 C 2 T x /CNTs/CuS-LbL-15 film electrode (1.7 mg/cm 3 ) with a thickness of 17 μm still exhibits a high gravimetric capacitance (336.7 F/g) and volumetric capacitance (572.4 F/cm 3 ) at 1 A/g in a poly(vinyl alcohol) (PVA)/H 2 SO 4 gel electrolyte, both of which are among the highest within past reports at the same thickness. Meanwhile, the sample demonstrates an impressive rate capability with 57% capacitance retention at a current density of 9 A/g, ultrastable cycling by retaining 99.6% of the initial capacity after 5000 cycles at a high rate of 5 A/g, and good flexibility under different bending states. Besides, the all-solid-state symmetric supercapacitor exhibits an energy density of 12.72 Wh/L at a power density of 340 W/L. This work provides an effective route for assembling Ti 3 C 2 T x /CNTs and CuS hybrid electrodes for high-performance energy storage devices.

Significant improvement and mechanism of tetracycline degradation with the synergistic piezoelectric effect of ZnO/CuS Z-scheme heterojunction photocatalysts

“…For the ZnO/CuS composites, the 2 θ peak diffraction at 27.7°, 29.3° and 32.7° can be identified as the (101), (102) and (106) crystal planes corresponding to a CuS crystal (JCPDS no.06-0464). 27 Moreover, it can be clearly observed that with the increase of the mass ratio of CuS to ZnO, the characteristic diffraction peak intensity of CuS in ZnO/CuS gradually increases. In addition, no other characteristic diffraction peaks were observed, demonstrating the coexistence and good integration of ZnO and CuS in the ZnO/CuS hybrid photocatalysts.…”

Tunable construction of CuS nanosheets@flower-like ZnCo-layered double hydroxide nanostructures for hybrid supercapacitors

“…7,8 In addition, the intersection with the x -axis implies the internal resistance (marked as R s ), which includes the contact resistance between the material and the NF and the intrinsic resistance of the material and electrolyte. 22…”

“…[19][20][21] Among these MSs, copper sulfide (CuS) has attracted great attention due to its good conductivity and electrochemical performance. 22,23 For instance, Zhou et al reported CuS nanoflake arrays on carbon cloth using a solvothermal strategy, and obtained a capacity of 213.8 C g −1 with a longevity of 75.1% after 5000 cycles. 24 In another study, Li et al prepared porous CuS nanosheets via a solvothermal process, which exhibited a capacitance of 974 F g −1 and durability of 81.99% after 5000 cycles.…”

Progress of 2D MXene as an Electrode Architecture for Advanced Supercapacitors: A Comprehensive Review

“…126 The CNT in the Ti 3 C 3 T x /CNT/CuS composite avoids the restacking of MXene sheets and allows large electroactive sites to become available for the electrolyte ions. 41 Gandla et al demonstrated that Mo 2 Ti 2 C 3 MXene with larger interlayer spacing is more beneficial in ionic liquid electrolytes than conventional Ti 3 C 2 T x MXene with high specific capacitance, cycle stability, and superior energy. 127 Microsupercapacitors (mSCs) are an essential power source for portable devices.…”