Stretchable electronics find widespread uses in a variety of applications such as wearable electronics, on-skin electronics, soft robotics and bioelectronics. Stretchable electronic devices ...conventionally built with elastomeric thin films show a lack of permeability, which not only impedes wearing comfort and creates skin inflammation over long-term wearing but also limits the design form factors of device integration in the vertical direction. Here, we report a stretchable conductor that is fabricated by simply coating or printing liquid metal onto an electrospun elastomeric fibre mat. We call this stretchable conductor a liquid-metal fibre mat. Liquid metal hanging among the elastomeric fibres self-organizes into a laterally mesh-like and vertically buckled structure, which offers simultaneously high permeability, stretchability, conductivity and electrical stability. Furthermore, the liquid-metal fibre mat shows good biocompatibility and smart adaptiveness to omnidirectional stretching over 1,800% strain. We demonstrate the use of a liquid-metal fibre mat as a building block to realize highly permeable, multifunctional monolithic stretchable electronics.
High‐performance supercapacitors (SCs) are promising energy storage devices to meet the pressing demand for future wearable applications. Because the surface area of a human body is limited to 2 m2, ...the key challenge in this field is how to realize a high areal capacitance for SCs, while achieving rapid charging, good capacitive retention, flexibility, and waterproofing. To address this challenge, low‐cost materials are used including multiwall carbon nanotube (MWCNT), reduced graphene oxide (RGO), and metallic textiles to fabricate composite fabric electrodes, in which MWCNT and RGO are alternatively vacuum‐filtrated directly onto Ni‐coated cotton fabrics. The composite fabric electrodes display typical electrical double layer capacitor behavior, and reach an ultrahigh areal capacitance up to 6.2 F cm−2 at a high areal current density of 20 mA cm−2. All‐solid‐state fabric‐type SC devices made with the composite fabric electrodes and water‐repellent treatment can reach record‐breaking performance of 2.7 F cm−2 at 20 mA cm−2 at the first charge–discharge cycle, 3.2 F cm−2 after 10 000 charge–discharge cycles, zero capacitive decay after 10 000 bending tests, and 10 h continuous underwater operation. The SC devices are easy to assemble into tandem structures and integrate into garments by simple sewing.
A multiwall carbon nanotube/reduced graphene oxide composite fabric electrode with an ultrahigh areal capacitance of 6.2 F cm−2 is obtained by alternating filtration on Ni‐coated cotton fabric. With simple textile sewing and sealing techniques, these high‐performance electrodes are assembled into all‐solid‐state fabric‐type supercapacitor devices, which possess record‐breaking initial capacitance (2.7 F cm−2) and excellent retention, remarkable flexibility, and are waterproof.
Lightweight and flexible energy storage devices are urgently needed to persistently power wearable devices, and lithium-sulfur batteries are promising technologies due to their low mass densities and ...high theoretical capacities. Here we report a flexible and high-energy lithium-sulfur full battery device with only 100% oversized lithium, enabled by rationally designed copper-coated and nickel-coated carbon fabrics as excellent hosts for lithium and sulfur, respectively. These metallic carbon fabrics endow mechanical flexibility, reduce local current density of the electrodes, and, more importantly, significantly stabilize the electrode materials to reach remarkable Coulombic efficiency of >99.89% for a lithium anode and >99.82% for a sulfur cathode over 400 half-cell charge-discharge cycles. Consequently, the assembled lithium-sulfur full battery provides high areal capacity (3 mA h cm
), high cell energy density (288 W h kg
and 360 W h L
), excellent cycling stability (260 cycles), and remarkable bending stability at a small radius of curvature (<1 mm).
Liquid metal (LM) has recently been used as an advanced stretchable material for constructing stretchable and wearable electronics. However, due to the poor wettability of LM and the large ...dimensional change during stretching, it remains very challenging to obtain a high conductivity with minimum resistance increase over large tensile strains. To address the challenge, an LM‐superlyophilic and stretchable fibrous thin‐film scaffold is reported, on which LM can be readily coated or printed to form permeable superelastic conductors. In contrast to conventional LM‐based conductors where LM particles are filled into an elastic matrix or printed on the surface of an elastic thin film, the LM can quickly infuse into the LM‐superlyophilic scaffold and form bi‐continuous phases. The LM‐superlyophilic scaffold shows unprecedented advantages of an extremely high uptake of the LM and a conductivity‐enhancement characteristic when stretched. As a result, the LM‐based conductor displays and ultrahigh conductivity of 155 900 S cm−1 and a marginal resistance change by only 2.5 fold at 2 500% strain. The conductor also possesses a remarkable durability over a period of 220 000 cycles of stretching tests. The printing of LM onto the LM‐superlyophilic scaffold for the fabrication of various permeable and wearable electronic devices is demonstrated.
A liquid‐metal‐superlyophilic fibrous scaffold is reported, on which liquid metal can be readily coated or printed to fabricate permeable superelastic conductors. Such a liquid‐metal‐superlyophilic scaffold enables high mass loading of liquid metal and possesses a smart conductivity‐strain‐enhancing feature.
The booming development of wearable and on‐skin electronics has driven increased interest in flexible and stretchable conductors, which serve as the indispensable building blocks for these electronic ...devices. However, conductors for such soft electronics are mostly fabricated with impermeable elastic thin films, which not only affect the long‐term wearing comfort but also limit the device's multifunctionality. In recent years, permeable conductors, conducting materials that are fabricated based on breathable materials and structures with deformability, have shown great promise for applications in wearable and skin‐mountable electronics. Herein, a specific perspective on the development of permeable conductors that can simultaneously display conductivity, flexibility or stretchability, and permeability to air, moisture, and liquid is provided. Key design considerations of permeable conductors, as well as the state‐of‐the‐art strategies to endow flexible and stretchable conductors with permeability, are discussed. Finally, key challenges and future directions of permeable conductors and electronic devices are discussed along with the analysis of possible solutions.
Herein, key design considerations for developing conductors for wearable and on‐skin electronics are discussed. The state‐of‐the‐art strategies to simultaneously enable the conductors conductive, flexible or stretchable, and permeable to air, moisture, and liquid are summarized. Challenges and prospects of permeable electronics are also discussed.
The facile and low-cost fabrication of free-standing magnetic catalysts with high catalytic efficiency, rapid reaction rate and excellent recoverability has been pursued for various catalysis ...applications, e.g., treating aqueous organic 4-nitrophenol pollutants. Here, we design and fabricate a free-standing nickel-coated hyperporous polymer foam (Ni-HPF) with adjustable shapes and sizes, hierarchical multiscale porous structures, abundant catalytical interfaces and excellent super-paramagnetic properties. Due to the synergistical effect of abundant binding sites and highly catalytic reduction, the as-prepared Ni-HPF has demonstrated high conversion efficiency (> 90% at extremely low concentration of 7.5 μM) and rapid reaction rate (2.58 × 10−3 s−1) for the reduction of organic 4-nitrophenol. Moreover, the magnetic catalyst also holds excellent recoverability (>80% conversion rate even after 1000 cycles) and good reproducibility (>80% conversion rate after 3 months of storage). As such, this work with novel material design and working principle could provide a wide range of potential applications in water purification, chemical catalysis and energy storage devices.
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•A nickel-coated hyperporous polymer foam (Ni-HPF) was designed by simple processes.•Ni-HPF exhibited stable hierarchical porous structure and abundant catalytic sites.•Ni-HPF showed high catalytic efficiency and reaction rate for 4-NP reduction.•The magnetic catalyst held outstanding reusability and excellent reproducibility.
Permeable electronics possess the capability of permeating gas and/or liquid while performing the device functionality when attached to human bodies. The permeability of wearable electronics can not ...only minimize the thermophysiological disturbance to the human body but also ensure a biocompatible human-device interface for long-term, continuous, and real-time health monitoring. To date, how to simultaneously acquire high permeability and multifunctionality is the major challenge of wearable electronics. Here, a critical discussion on the future development of wearable electronics toward permeability is presented. In this perspective, the critical metrics of permeable electronics are discussed, and the historical evolution of wearable technologies is reviewed with highlights of representative examples. The materials and structural strategies for developing high-performance permeable electronics are then analyzed.
Abstract
We demonstrate a rechargeable zinc-ion battery with high energy density and cyclability using MnO
2
and reduced graphene oxide (MnO
2
/rGO) electrode. The flexible and binder free electrode, ...with high MnO
2
mass ratio (80 wt% of MnO
2
), is fabricated using vacuum filtration without any additional additives other than rGO. Compared to batteries with conventional MnO
2
electrodes, the Zn–MnO
2
/rGO battery shows a significant enhanced capacity (332.2 mAh g
-1
at 0.3 A g
-1
), improved rate capability (172.3 mAh g
-1
at 6 A g
-1
) and cyclability. The capacity retention remains 96% after 500 charge/discharge cycles at 6 A g
-1
. The high MnO
2
mass ratio makes MnO
2
/rGO electrode advantageous when the capacity is normalized to the whole electrode, particularly at high rates. The calculated gravimetric energy density of Zn–MnO
2
/rGO battery is 33.17 W h kg
-1
, which is comparable to the existing commercial lead-acid batteries (30–40 W h kg
-1
). Furthermore, the discharge profile and capacity of our Zn–MnO
2
/rGO battery shows no deterioration during bending test, indicating good flexibility. As a result, zinc-ion battery is believed to be a promising technology for powering next generation flexible electronics.
Textile-based wearable electronics have attracted intensive research interest due to their excellent flexibility and breathability inherent in the unique three-dimensional porous structures. However, ...one of the challenges lies in achieving highly conductive patterns with high precision and robustness without sacrificing the wearing comfort. Herein, we developed a universal and robust in-textile photolithography strategy for precise and uniform metal patterning on porous textile architectures. The as-fabricated metal patterns realized a high precision of sub-100 µm with desirable mechanical stability, washability, and permeability. Moreover, such controllable coating permeated inside the textile scaffold contributes to the significant performance enhancement of miniaturized devices and electronics integration through both sides of the textiles. As a proof-of-concept, a fully integrated in-textiles system for multiplexed sweat sensing was demonstrated. The proposed method opens up new possibilities for constructing multifunctional textile-based flexible electronics with reliable performance and wearing comfort.
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