Fiber-Based All-Solid-State Flexible Supercapacitors for Self-Powered Systems

Abstract

All-solid-state flexible supercapacitors based on a carbon/MnO(2) (C/M) core-shell fiber structure were fabricated with high electrochemical performance such as high rate capability with a scan rate up to 20 V s(-1), high volume capacitance of 2.5 F cm(-3), and an energy density of 2.2 × 10(-4) Wh cm(-3). By integrating with a triboelectric generator, supercapacitors could be charged and power commercial electronic devices, such as a liquid crystal display or a light-emitting-diode, demonstrating feasibility as an efficient storage component and self-powered micro/nanosystems.

A General Electrode Design Strategy for Flexible Fiber Micro‐Pseudocapacitors Combining Ultrahigh Energy and Power Delivery

“…Various carbonaceous materials like activated carbon,9, 10 carbon nanotubes (CNTs),11, 12, 13 reduced graphene oxide (rGO),14, 15, 16 and our recently developed rGO/CNT hybrids17, 18 were exploited as active materials for fiber m‐SCs, yet their applications are restricted by the low capacitance of <200 mF cm −2 . Alternatively, incorporating pseudocapacitive materials into fiber m‐SCs is a superior solution to achieve high‐density energy due to 10–100 times higher theoretical capacitance than carbon materials 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36. Due to the poor conductivity for pseudocapacitive materials, composite electrode design by depositing active materials on one‐dimensional (1D) conductive scaffolds including carbon‐based fibers19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or metal‐based wires,31, 32, 33, 34, 35, 36 was employed to improve the electron transport.…”

“…Alternatively, incorporating pseudocapacitive materials into fiber m‐SCs is a superior solution to achieve high‐density energy due to 10–100 times higher theoretical capacitance than carbon materials 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36. Due to the poor conductivity for pseudocapacitive materials, composite electrode design by depositing active materials on one‐dimensional (1D) conductive scaffolds including carbon‐based fibers19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or metal‐based wires,31, 32, 33, 34, 35, 36 was employed to improve the electron transport. Despite some progresses, the improvements in the areal energy density for these fiber m‐SCs are still too modest to cater for many practical requirements and often come at the expense of sacrificing their rate capability or power density 1, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36.…”

“…Due to the poor conductivity for pseudocapacitive materials, composite electrode design by depositing active materials on one‐dimensional (1D) conductive scaffolds including carbon‐based fibers19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or metal‐based wires,31, 32, 33, 34, 35, 36 was employed to improve the electron transport. Despite some progresses, the improvements in the areal energy density for these fiber m‐SCs are still too modest to cater for many practical requirements and often come at the expense of sacrificing their rate capability or power density 1, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36. This impedes their broad practical applications where both high power and energy densities are required.…”

“…The widely employed scaffolds in the literature are mainly carbonaceous fibers such as CNT yarns, rGO fibers, and their composite fibers. But their conductivity is unsatisfactory for long‐range electron transport along the fiber 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. Unlike macroscopic planar SCs, effective long‐distance electron transport is highly required for fiber m‐SCs due to the lack of extra metal current collectors within slender fiber electrodes.…”

“…Unlike macroscopic planar SCs, effective long‐distance electron transport is highly required for fiber m‐SCs due to the lack of extra metal current collectors within slender fiber electrodes. However, such crucial design concern is often ignored in previous carbon‐based fiber m‐SCs, thus leading to a major bottleneck in performance (typically <200 mF cm −2 and <1 mW cm −2 ) 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. As compared, metallic scaffold was recognized as the best candidate for long‐range electron transport 31, 32, 33, 34, 35, 36.…”