1D Supercapacitors for Emerging Electronics: Current Status and Future Directions

Abstract

considering their potential for performing even more complex functions. In particular, the recent booming of the "internet of things" and "artificial intelligence" further encourages the development of a new generation of wearable devices. [4] Accordingly, we need reliable and compact yet high-performance energy storage systems to power emerging electronics. Plus, the mechanical characteristics of the systems should support a pleasant user experience in terms of wearability. Recently, the 1D energy storage devices, especially 1D supercapacitors (SCs), have emerged as a promising candidate. [5][6][7][8][9][10][11] 1D SCs are elongated (fiber/yarn/wire/ cable-like) structures with dimensions typically ranging from tens to hundreds of micrometers in diameter, and several millimeters to meters in length. Their 1D structures offer various advantages over their conventionally rigid and bulky counterparts: 1) they show a higher degree of mechanical flexibility (which helps withstand long-term and repetitive deformations); 2) allow easy scaling up by self-integration (which is useful for meeting a wide range of power requirements); 3) are easily packed into small spaces with diverse shapes (which brings design versatility); and 4) have shape advantage for integrating with other 1D devices (which is preferable for the fabrication of multifunctional wearable systems). [5,9,10,12] Further, 1D SCs also have several potential advantages over other emerging 1D energy storage devices, especially, 1D batteries. 1) 1D SCs have unique energy storage characteristics. They can provide superior power density and faster charging/discharging rates than 1D batteries. Also, their energy density is gradually catching up that of 1D batteries with the uses of intercalative and extrinsic pseudocapacitive materials in electrodes. [13] 2) 1D SCs are often superior in their safety and environmental friendliness. Batteries, e.g., Li-ion batteries, typically comprise of hazardous, organic electrolytes, which is harmful to the human body if they leak. Organic electrolytes are also prone to fire or even explosion. In contrast, 1D SCs based on aqueous polymer gel electrolytes are much safer and more environmentally friendly. 3) 1D SCs may work in a wider operating temperature window when suitable electrolytes are used, which extends their potential usages in emerging electronics at different environmental conditions. In contrast, redox reactions in batteries often can only work in a narrow temperature window. 4) 1D SCs may offer longer lifespan to avoid frequent battery replacement in practical application. [14,15] 1D supercapacitors (SCs) have emerged as promising candidates to power emerging electronics in recent years because of their unique advantages in energy storage and mechanical flexibility. There are four main research fronts in the development of 1D SCs: 1) enhancing mechanical characteristics, 2) achieving superior electrochemical performance, 3) enabling multiple device integration, and 4) demonstrating multifunctionality. Here, a brief...

Engineering MoS2 Nanosheets on Spindle‐Like α‐Fe2O3 as High‐Performance Core–Shell Pseudocapacitive Anodes for Fiber‐Shaped Aqueous Lithium‐Ion Capacitors

“…The wide-spread use of portable and wearable electronics has dramatically accelerated the development of fiber-shaped energy-storage devices owing to their attractive advantages of small sizes and feasible integration and weaveability. [1][2][3][4][5][6][7][8] In particular, fiber-shaped lithium-ion batteries (LIBs) and supercapacitors (SCs) are currently dominating such wearable energy-storage devices. [9][10][11][12][13][14] Fiber-shaped SCs can provide high powder density, fast charge-discharge capability and long cycle life, however, the inferior energy density restricts their extensive practical application.…”

Mechanically and Electronically Robust Transparent Organohydrogel Fibers

“…In contrast, porous and breathable fabric electronics can be worn for a long time without causing skin discomfort. Accordingly, supercapacitors, batteries, triboelectric nanogenerators, smart textiles, and heaters have been developed based on conductive fibers or conductive textiles.…”

“…[2] In contrast, porous and breathable fabric electronics can be worn for a long time without causing skin discomfort. Accordingly, supercapacitors, [3] batteries, [4] triboelectric nanogenerators, [5] smart textiles, [6] and heaters [7] have been developed based on conductive fibers or conductive textiles.However, most conductive fibers are based on the transmission of electrons. Electron-conductive solid fibers prepared by doping conductive materials into fibers may significantly change the Young's moduli and reduce their stretchability and transparency.…”

Hierarchical Transition Metal Oxide Arrays Grown on Graphene‐Based Fibers with Enhanced Interface by Thin Layer of Carbon toward Solid‐State Asymmetric Supercapacitors

“…Due to their prominent advantages of fast charge‐discharge and high power‐density, flexible fiber‐based supercapacitors have drawn considerable attention as long cycle life energy storage and conversion devices in many fields including portable and wearable electronics . However, their low energy‐density restricts their wide practical applications .…”