Ultrahigh‐Areal Capacitance Flexible Supercapacitors Based on Laser Assisted Construction of Hierarchical Aligned Carbon Nanotubes

Abstract

Electrochemical energy storage is a key technology for a clean and sustainable energy supply. In this respect, supercapacitors (SC) have recently received considerable attention due to their excellent performance, including high-power density and long-cycle life. However, the poor binding strength between the active materials and substrate, the low active material loading, and small specific capacitance hinder the overall performance improvement of the device. In this study, an ultrahigh-areal capacitance flexible SC based on the Al micro grid-based hierarchical vertically aligned carbon nanotubes (VACNTs) is studied. Interestingly, the Al micro grid-based VACNTs exhibit ultrahigh loading (13 mg cm −2 ), and the as-fabricated VACNTs electrode display outstanding electrochemical performance, including an impressive areal capacitance of 1,300 mF cm −2 at the current density of 13 mA cm −2 and excellent stability with a retention ratio of 90% after 20,000 cycles at the current density of 130 mA cm −2 . Furthermore, the hierarchical VACNT electrodes show excellent mechanical flexibility when assembled into quasisolid-state SC using Na 2 SO 4 -PVA gel as the electrolyte. The capacitance of this device is hardly changed bending different angles, even 180°. This study demonstrates the tremendous potential of Al micro grid-based hierarchical VACNTs as electrodes for high-performance flexible and wearable energy storage devices.

Al Foil-Supported Carbon Nanosheets as Self-Supporting Electrodes for High Areal Capacitance Supercapacitors

“…The Nyquist plots of CNS-30, CNS-60, and CNS-120 are shown in Figure 6 , which is beneficial to understanding the capacitive behaviors of all of the samples. All of the plots contain a semicircle in the high-frequency region and a line perpendicular to the real axis in the low-frequency region, which reflect the charge transfer resistance (R ct , the diameter of semicircle) and the diffusion resistance (R d ) [ 25 , 66 , 67 ], respectively. The equivalent series resistance (ESR), the real axis intercept of the semicircle in the high-frequency region, reflects the inner resistance of materials, the interface contact resistance of the electrode and electrolyte, as well as the electrolyte ionic resistance [ 68 , 69 ].…”

“…In the reported literature works, the metal substrates commonly used for the preparation of self-supporting electrode materials are gold (Au) [ 20 ], silver (Ag) [ 21 ], copper (Cu) [ 22 ], nickel (Ni) [ 23 ], iron (Fe) [ 24 ], and aluminum (Al) [ 25 , 26 ], among others. An ideal metal substrate used to prepare a self-supporting electrode is supposed to have the advantages of high electrical conductivity, low cost, and a simple synthesis processes.…”

“…Moreover, the density of Al is much lower than that of other metal substrates, which is beneficial to decrease the total mass of the energy storage devices. In recent years, many Al-based self-supporting electrode materials have been prepared by hydrothermal reactions [ 15 ], CVD [ 25 , 27 ], wet chemical methods [ 28 ], and so on, and possess high electrochemical performance. Therefore, Al substrates are promising candidates to prepare self-supporting electrode materials for the application of supercapacitors.…”

Floating Catalyst Chemical Vapor Deposition Patterning Nitrogen‐Doped Single‐Walled Carbon Nanotubes for Shape Tailorable and Flexible Micro‐Supercapacitors

“…[1][2][3][4][5][6] 2D planar micro-supercapacitors (MSCs) are such energy storage devices due to their flexibility, high integration, fast charging and discharging, ultra-long cycle life, and excellent compatibility. [7][8][9][10] Carbon-based materials, such as activated carbon fiber, [11] carbon nanotubes (CNTs), [12][13][14] graphene, [15,16] onion carbon [17] and MXene composites with carbon material [2,18] are promising candidates for electrode materials of MSCs due to their chemical stability, controlled pore structure, and low cost. [19,20] Among them, CNTs have excellent mechanical properties, high electrical conductivity and are easily functionalized, making them ideal candidates for MSCs.…”

Constructing Flexible All‐Solid‐State Supercapacitors from 3D Nanosheets Active Bricks via 3D Manufacturing Technology: A Perspective Review

“…can also be used to produce high-performance patterning microelectrodes, which play a key role in the construction and application of flexible all-solid-state supercapacitors. [37,42,43] To sum up, the above mentioned 3D manufacturing technologies bring unprecedented new opportunities for the development and application of intensive and flexible energy storage devices.…”