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The effects of locally applied zinc chloride (ZnCl

The upcoming ubiquitous electronics era, which will find widespread popularity of flexible/wearable electronics, self-powered devices, and the Internet of Things (IoT), stimulates us to develop a new concept of advanced power sources beyond currently available battery technologies. Among several approaches to reach this goal, printed power sources with various form factors and flexibility have recently garnered considerable attention as a promising system. The form factor-free, printed power sources, driven by their design diversity, shape/performance compatibility with electronics, and scalable/low-cost processability, enable monolithic/seamless integration with complex/unconventional-shaped electronic devices, in comparison to conventional rigid/bulky counterparts. Here, we review the current status and challenges of the form factor-free, printed power sources, with a focus on their materials development. Various printing techniques and their process parameters exploited for the printed power sources are briefly described. Subsequently, ink materials and chemistry of major cell components are discussed. Based on the understanding of the printing techniques and materials, applications of the printed power sources are overviewed to highlight their exceptional shape aesthetics and electrochemical characteristics in the integrated electronics. Finally, we propose development directions and outlook of the form factor-free, printed power sources as a device-customized energy storage system, along with prospects of their future applications.

Summary The forthcoming smart and ubiquitous electronics era presents significant interest in wireless interconnectivity and shape aesthetics. To fulfill this demand, a new class of advanced power sources with various form factors that are different from existing commercial ones is needed. Printed power sources have recently garnered substantial attention because of their design diversity, shape and performance compatibility with electronics, and scalable and low-cost processability. They are fabricated directly on complex-structured objects via application-customized printing techniques, enabling monolithic integration and electrochemical coupling with target devices. In this Perspective, we describe the current status and challenges of printed power sources, focusing on their role as built-in power sources. Various printing techniques and ink materials and chemistry of electrodes and electrolytes are discussed as key enabling factors. Noteworthy progress in printed built-in power sources is reviewed to highlight their design diversity and electrochemical superiority. Finally, development direction and outlook of printed built-in power sources are discussed in conjunction with their application fields.

Despite their potential as promising alternatives to current state-of-the-art lithium-ion batteries, aqueous rechargeable Zn-ion batteries are still far away from practical applications. Here, we present a new class of single-ion conducting electrolytes based on a zinc sulfonated covalent organic framework (TpPa-SO3Zn0.5) to address this challenging issue. TpPa-SO3Zn0.5 is synthesised to exhibit single Zn2+ conduction behaviour via its delocalised sulfonates that are covalently tethered to directional pores and achieve structural robustness by its β-ketoenamine linkages. Driven by these structural and physicochemical features, TpPa-SO3Zn0.5 improves the redox reliability of the Zn metal anode and acts as an ionomeric buffer layer for stabilising the MnO2 cathode. Such improvements in the TpPa-SO3Zn0.5–electrode interfaces, along with the ion transport phenomena, enable aqueous Zn–MnO2 batteries to exhibit long-term cyclability, demonstrating the viability of COF-mediated electrolytes for Zn-ion batteries., A zinc sulfonated covalent organic framework is presented as a new single-ion conducting electrolyte for aqueous rechargeable Zn-ion batteries.

Despite their potential as a next-generation alternative to current state-of-the-art lithium (Li)-ion batteries, rechargeable aqueous zinc (Zn)-ion batteries still lag in practical use due to their low energy density, sluggish redox kinetics, and limited cyclability. In sharp contrast to previous studies that have mostly focused on materials development, herein, a new electrode architecture strategy based on a 3D bicontinuous heterofibrous network scaffold (HNS) is presented. The HNS is an intermingled nanofibrous mixture composed of single-walled carbon nanotubes (SWCNTs, for electron-conduction channels) and hydrophilic cellulose nanofibers (CNFs, for electrolyte accessibility). As proof-of-concept for the HNS electrode, manganese dioxide (MnO2 ) particles, one of the representative Zn-ion cathode active materials, are chosen. The HNS allows uniform dispersion of MnO2 particles and constructs bicontinuous electron/ion conduction pathways over the entire HNS electrode (containing no metallic foil current collectors), thereby facilitating the redox kinetics (in particular, the intercalation/deintercalation of Zn2+ ions) of MnO2 particles. Driven by these advantageous effects, the HNS electrode enables substantial improvements in the rate capability, cyclability (without structural disruption and aggregation of MnO2 ), and electrode sheet-based energy (91 Wh kgelectrode-1 )/power (1848 W kgelectrode-1 ) densities, which lie far beyond those achievable with conventional Zn-ion battery technologies.

With the ever-growing interests in ubiquitous smart electronics and the Internet of Things, the demand for high-energy-density power sources with aesthetic versatility has increased tremendously. High-energy-density Li-metal batteries have attracted considerable attention for fulfilling the high-energy-density requirement of smart electronics. To obtain form factor-free Li-metal batteries with both design diversity and electrochemical reliability, printed solid-state electrolytes are required as a key component because of their viability for the printing/solidification-based fabrication process and electrode-customized chemical/physical properties. This review present an overview of printed solid-state electrolytes for form factor-free Li-metal batteries with a focus on the materials chemistry and fabrication requirements. In addition, their structural/physical/electrochemical properties were discussed in terms of compatibility with Li-metal batteries.

With the advent of the ubiquitous electronics era, high-performance power sources with aesthetic diversity are indispensably needed as a key-enabling technology. Printed batteries have recently emerged as a crispy energy storage system to address this issue. Printed batteries are fabricated through simple, low-cost, and scalable printing processes. Their salient features include various form factors, shape conformability, and monolithic integration with devices of interest. Research directions on printed batteries are currently focused on (i) the design of battery shapes and configurations, (ii) synthesis of battery component inks with tunable rheological properties and electrochemical performances, and (iii) adoption of suitable printing techniques. We describe the current status and challenges of printed batteries, with a particular focus on the form factors, battery component inks, printing techniques, cell performances, and integration with other systems. The development directions and outlook of prin...

Solid-state microsupercapacitors with ultrahigh areal-number-density are integrated on a chip via high-fidelity printing., Microsupercapacitors (MSCs) have garnered considerable attention as a promising power source for microelectronics and miniaturized portable/wearable devices. However, their practical application has been hindered by the manufacturing complexity and dimensional limits. Here, we develop a new class of ultrahigh areal number density solid-state MSCs (UHD SS–MSCs) on a chip via electrohydrodynamic (EHD) jet printing. This is, to the best of our knowledge, the first study to exploit EHD jet printing in the MSCs. The activated carbon-based electrode inks are EHD jet-printed, creating interdigitated electrodes with fine feature sizes. Subsequently, a drying-free, ultraviolet-cured solid-state gel electrolyte is introduced to ensure electrochemical isolation between the SS–MSCs, enabling dense SS–MSC integration with on-demand (in-series/in-parallel) cell connection on a chip. The resulting on-chip UHD SS–MSCs exhibit exceptional areal number density [36 unit cells integrated on a chip (area = 8.0 mm × 8.2 mm), 54.9 cells cm−2] and areal operating voltage (65.9 V cm−2).

Wirelessly rechargeable solid-state supercapacitors are studied for soft, smart contact lenses with continuous operations., Recent advances in smart contact lenses are essential to the realization of medical applications and vision imaging for augmented reality through wireless communication systems. However, previous research on smart contact lenses has been driven by a wired system or wireless power transfer with temporal and spatial restrictions, which can limit their continuous use and require energy storage devices. Also, the rigidity, heat, and large sizes of conventional batteries are not suitable for the soft, smart contact lens. Here, we describe a human pilot trial of a soft, smart contact lens with a wirelessly rechargeable, solid-state supercapacitor for continuous operation. After printing the supercapacitor, all device components (antenna, rectifier, and light-emitting diode) are fully integrated with stretchable structures for this soft lens without obstructing vision. The good reliability against thermal and electromagnetic radiations and the results of the in vivo tests provide the substantial promise of future smart contact lenses.

Recent advances in smart contact lenses are essential to the realization of medical applications and vision imaging for augmented reality through wireless communication systems. However, previous research on smart contact lens has been driven by external electrical wired systems or wireless power transfer with temporal and spatial restrictions, which can limit their continuous use. Therefore, an essential prerequisite for electronic smart contact lenses is their monolithic integration with energy storage devices. However, conventional rigid, large sized, and fixed-shaped energy storage devices are not suitable for the soft, smart contact lens. Here, we demonstrate a new class of wirelessly-rechargeable solid-state supercapacitors directly printed on smart contact lenses. Supercapacitors are known to exhibit long cycle lives and high-power density, which are suitable for consistent fast wireless charging and discharging for operating the electronic devices in the smart contact lens. The arc-shaped form factor and limited area of the printed supercapacitor require a high-precision microscale direct ink writing (DIW) process and tailored component inks. The printed solid-state supercapacitor integrated smart contact lens show great potential as an effective/scalable platform for wearable electronics with continuous operation.