Scalable production of high-performing woven lithium-ion fibre batteries

Dendrite Issues for Zinc Anodes in a Flexible Cell Configuration for Zinc-Based Wearable Energy-Storage Devices

A key application of aqueous rechargeable Zn-based batteries (RZBs) is flexible and wearable energy storage devices (FESDs). Current studies and optimizations of Zn anodes have not considered the special flexible working modes needed. In this study, we present the Zn accumulation on the folded line and curve areas of flexible anodes. The correlation between the bending radius and the lifespan of symmetric cells is proposed. The interface contact of hydrogel electrolytes when working in a bending mode is another key factor affecting cell lifespan. After detailed analysis, the ideal cell configuration is shown to be hydrogel electrolytes with suitable chemistry, satisfactory mechanical properties, and high adhesivity. Thus a water in salt (WIS) hydrogel is proposed that demonstrates a highly stable cell performance. This work provides a new perspective in Zn anode research for the development of FESDs.

Advances in High-Performance Autonomous Energy and Self-Powered Sensing Textiles with Novel 3D Fabric Structures

The seamless integration of emerging triboelectric nanogenerator (TENG) technology with traditional wearable textile materials has given birth to the next-generation smart textiles, i.e., textile TENGs, which will play a vital role in the era of Internet of Things and artificial intelligences. However, low output power and inferior sensing ability have largely limited the development of textile TENGs. Among various approaches to improve the output and sensing performance, such as material modification, structural design, and environmental management, a 3D fabric structural scheme is a facile, efficient, controllable, and scalable strategy to increase the effective contact area for contact electrification of textile TENGs without cumbersome material processing and service area restrictions. Herein, the recent advances of the current reported textile TENGs with 3D fabric structures are comprehensively summarized and systematically analyzed in order to clarify their superiorities over 1D fiber and 2D fabric structures in terms of power output and pressure sensing. The forward-looking integration abilities of the 3D fabrics are also discussed at the end. It is believed that the overview and analysis of textile TENGs with distinctive 3D fabric structures will contribute to the development and realization of high-power output micro/nanowearable power sources and high-quality self-powered wearable sensors.

Cooperative Chloride Hydrogel Electrolytes Enabling Ultralow-Temperature Aqueous Zinc Ion Batteries by the Hofmeister Effect

Aqueous zinc ion batteries have high potential applicability for energy storage due to their reliable safety, environmental friendliness, and low cost. However, the freezing of aqueous electrolytes limits the normal operation of batteries at low temperatures. Herein, a series of high-performance and low-cost chloride hydrogel electrolytes with high concentrations and low freezing points are developed. The electrochemical windows of the chloride hydrogel electrolytes are enlarged by > 1 V under cryogenic conditions due to the obvious evolution of hydrogen bonds, which highly facilitates the operation of electrolytes at ultralow temperatures, as evidenced by the low-temperature Raman spectroscopy and linear scanning voltammetry. Based on the Hofmeister effect, the hydrogen-bond network of the cooperative chloride hydrogel electrolyte comprising 3 M ZnCl₂ and 6 M LiCl can be strongly interrupted, thus exhibiting a sufficient ionic conductivity of 1.14 mS cm^-1 and a low activation energy of 0.21 eV at -50 °C. This superior electrolyte endows a polyaniline/Zn battery with a remarkable discharge specific capacity of 96.5 mAh g^-1 at -50 °C, while the capacity retention remains ~ 100% after 2000 cycles. These results will broaden the basic understanding of chloride hydrogel electrolytes and provide new insights into the development of ultralow-temperature aqueous batteries.

Industrial scale production of fibre batteries by a solution-extrusion method

Fibre batteries are of significant interest because they can be woven into flexible textiles to form compact, wearable and light-weight power solutions^1,2. However, current methods adapted from planar batteries through layer-by-layer coating processes can only make fibre batteries with low production rates, which fail to meet the requirements for real applications². Here, we present a new and general solution-extrusion method that can produce continuous fibre batteries in a single step at industrial scale. Our three-channel industrial spinneret simultaneously extrudes and combines electrodes and electrolyte of fibre battery at high production rates. The laminar flow between functional components guarantees their seamless interfaces during extrusion. Our method yields 1,500 km of continuous fibre batteries for every spinneret unit, that is, more than three orders of magnitude longer fibres than previously reported^1,2. Finally, we show a proof-of-principle for roughly 10 m² of woven textile for smart tent applications, with a battery with energy density of 550 mWh m^-2.

Batteries for wearables

This perspective article highlights the recent advances and future challenges of battery technologies for wearables.

Mxene reinforced supramolecular hydrogels with high strength, stretchability and reliable conductivity for sensitive strain sensors

Conductive hydrogels used as electronics have received much attention due to their great flexibility and stretchability. However, the fabrication of ideal conductive hydrogels fulfilling with excellent mechanical properties and outstanding sensitivity remains a great challenge until now. Moreover, high sensitivity and broad linearity range are pivotal for the feasibility and accuracy of hydrogel sensors. In this study, a conductive supramolecular hydrogel was engineered by directly mixing the aqueous dispersion of MXene with the precursor of N-acryloyl glycinamide (NAGA) monomer and then rapidly photo cross-linked by UV irradiation. The resultant PNAGA/MXene hydrogel-sensors exhibited high mechanical strength (4.8 MPa), great stretchability (630%), and excellent durability. The conductive hydrogel-based sensor presented excellent conductivity (17.3 S·m^-1 ) and a wide scope of linear dependence of sensitivity on strain (0-125%, gauge factor = 2.05). It displayed reliable detection of various motions, including repeated subtle movements and large strain. It was also showed good degradation in vitro and antifouling capability. This work may provide a simple and promising platform for engineering conductive supramolecular hydrogels with integrated high performance aiming for smart wearable electronics, electronic skin, soft robots, and human-machine interfacing. This article is protected by copyright. All rights reserved.

Cotton textile inspires MoS2@reduced graphene oxide anodes towards high-rate capability or long-cycle stability sodium/lithium-ion batteries

Textile-based electrodes show superior energy storage performances, including high-rate capability for Na-ion batteries and long-cycling stability for Li-ion batteries, as elucidated by morphology differences that sodiation/desodiation brings intense nanomachine effect.

Electronic Textiles for Wearable Point-of-Care Systems

Traditional public health systems are suffering from limited, delayed, and inefficient medical services, especially when confronted with the pandemic and the aging population. Fusing traditional textiles with diagnostic, therapeutic, and protective medical devices can unlock electronic textiles (e-textiles) as point-of-care platform technologies on the human body, continuously monitoring vital signs and implementing round-the-clock treatment protocols in close proximity to the patient. This review comprehensively summarizes the research advances on e-textiles for wearable point-of-care systems. We start with a brief introduction to emphasize the significance of e-textiles in the current healthcare system. Then, we describe textile sensors for diagnosis, textile therapeutic devices for medical treatment, and textile protective devices for prevention, by highlighting their working mechanisms, representative materials, and clinical application scenarios. Afterward, we detail e-textiles' connection technologies as the gateway for real-time data transmission and processing in the context of 5G technologies and Internet of Things. Finally, we provide new insights into the remaining challenges and future directions in the field of e-textiles. Fueled by advances in chemistry and materials science, textile-based diagnostic devices, therapeutic devices, protective medical devices, and communication units are expected to interact synergistically to construct intelligent, wearable point-of-care textile platforms, ultimately illuminating the future of healthcare system in the Internet of Things era.

Towards advanced aqueous zinc battery by exploiting synergistic effects between crystalline phosphide and amorphous phosphate

High-performance aqueous zinc batteries are expected to be realized, rooting from component synergistic effects of the hierarchical composite electrode materials. Herein, hierarchical crystalline Ni-Co phosphide coated with amorphous phosphate nanoarrays (C-NiCoP@A-NiCoPO₄) self-supporting on the Ni foam are constructed as cathode material of an aqueous zinc battery. In this unique core-shell structure, the hexagonal phosphide with high conductivity offers ultra-fast electronic transmission and amorphous phosphate with high stability, and open-framework provides more favorable ion diffusivity and a stable protective barrier. The synergistic effects of this intriguing core-shell structure endow the electrode material with outstanding reaction kinetics and structural stability, which is theoretically confirmed by density functional theory (DFT) calculations. As a result, the C-NiCoP@A-NiCoPO₄ electrode exhibits a higher specific capacity of 350.6 mA h g^-1 and excellent cyclic stability with 92.6% retention after 10 000 cycles. Moreover, the C-NiCoP@A-NiCoPO₄ is coupled with Zn anode to assemble an aqueous pouch battery that delivers ultra-high energy density (626.33 W h kg^-1 at 1.72 kW kg^-1) with extraordinary rate performance (452.05 W h kg^-1 at 33.56 kW kg^-1). Moreover, the corresponding quasi-solid flexible battery with polyacrylamide hydrogel electrolyte exhibits favorable durability under frequent mechanical strains, which indicates the great promise of crystalline/amorphous hierarchical electrodes in the field of energy storage.

Wearable E-Textiles Using a Textile-Centric Design Approach

Electronics worn on the body have the potential to improve human health and the quality of life by monitoring vital signs and movements, displaying information, providing self-illumination for safety, and even providing new routes for personal expression through fashion. Textiles are a part of daily life in clothing, making them an ideal platform for wearable electronics. The acceptance of wearable e-textiles hinges on maintaining the properties of textiles that make them compatible with the human body. Beneficial properties such as softness, stretchability, drapability, and breathability come from the 3D fibrous structures of knitted and woven textiles. However, these structures also present considerable challenges for the fabrication of wearable e-textiles. Fabrication methods used for modern electronic devices are designed for 2D planar substrates and are mostly unsuitable for the complex 3D structures of textiles. There is thus an urgent need to develop fabrication methods specifically for e-textiles to advance wearable electronics. Solution-based fabrication methods are a promising approach to fabricating wearable e-textiles, especially considering that textiles have been successfully modified using pigmented dyes in dyebaths and printing inks for thousands of years. In this Account, we discuss our research on the solution-based electroless metallization of textiles to fabricate conductive e-textiles that are building blocks for e-textile devices. Electroless metallization solutions fully permeate textile structures to deposit metallic coatings on the surfaces of individual textile fibers, maintaining the inherent textile structures and wearability. The resulting e-textiles are highly conductive, soft, and stretchable. We furthermore discuss ways to turn the challenges related to textile structures into new opportunities by strategically using the structural features of textiles for e-textile device design. We demonstrate this textile-centric approach to designing e-textile devices using two examples. We discuss how the structure of an ultrasheer knitted textile forms a useful framework for new e-textile transparent conductive electrodes and describe the implementation of these electrodes to form highly stretchable light-emitting e-textiles. We also show how the structural features of velour fabrics form the basis for an innovative "island-bridge" strain-engineering structure that enables the integration of brittle electroactive materials and protects them from strain-induced damage, leading to the fabrication of stretchable textile-based lithium-ion battery electrodes. With the vast variety of textile structures available, we highlight the opportunities associated with this textile-centric design approach to advance textile-based wearable electronics. Such advances depend on a deep understanding of the relationship between the textile structure and the device requirements, which may potentially lead to the development of new textile structures customized to support specific devices. We conclude with a discussion of the challenges that remain for the future of e-textiles, including durability, sustainability, and the development of performance standards.