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To maintain the downscaling of microelectronic devices with footprints less than one square millimeter, next-generation microbatteries should occupy the same area and deliver adequate energy for running a new generation of multi-functional microautonomous systems. However, the current microbattery technology fails in accomplishing this task because the micrometer-sized electrodes are not compatible with on-chip integration protocols and technologies. To tackle this critical challenge, an on-chip Swiss-roll microelectrode architecture is employed that exploits the self-assembly of thin films into ultra-compact device architectures. A twin-Swiss-roll microelectrode on a chip occupies a footprint of 0.045 mm

Understanding interactions between molecular transition and intense electromagnetic fields confined by plasmon nanostructures is of great significance due to their huge potential in fundamental cavity quantum electrodynamics and practical applications. Here, we report reorientable plasmon-enhanced fluorescence leveraging the flexibilities in densely-packed gold nanogap arrays by template-assisted depositions. By finely adjusting the symmetry of the unit structure, arrays of nanogaps along two nearly-orthogonal axes can be tailored collectively with spacing down to sub-10 nm on a single chip, facilitating distinct "inter-cell" and "intra-cell" plasmon couplings. Through engineering two sets of nanogaps, the varying hybridization-induced plasmonic bonding modes lead to adjustable splitting of the fluorescence emission peak with a width up to 81 nm and narrowing of linewidths up to a factor of 3. Besides, polarization anisotropy with a ratio up to 63% is obtained on the basis of spectrally separated local hotspots with discrepant oscillation directions. The developed plasmonic nanogap array is envisaged to provide a promising chip-scale, cost-effective platform for advancing fluorescence-based detection and emission technologies in both classical and quantum regimes.

Anionic redox reactions would achieve a high capacity than typical transition-metal-oxide cathodes, offering a low-cost chemistry to advance the energy storage capability of lithium-ion batteries. Li-Cl2 chemistry using anionic redox reactions of Cl0/−1 shows superior operation voltage (~ 3.8 V) and capacity (756 mAh g− 1). However, a redox-active and reversible chlorine cathode has not been developed in organic electrolytes-based lithium-ion batteries. Chlorine ions bonded by ionic bonding hardly dissolve in organic electrolyte, imposing a thermodynamic barrier for redox reactions. Meanwhile, chlorine gas is easily formed during oxidation. Herein, we report an interhalogen compound, iodine trichloride (ICl3), as the cathode to address these two issues. In-situ and ex-situ spectroscopy data and calculations reveal that reduced Cl− ions are partially dissolved in the electrolyte, and oxidized Cl0 is anchored by forming interhalogen bonds with I. A reversible Li-Cl2 at room temperature is developed, which delivers a specific capacity of 302 mAh g− 1 at 425 mA g− 1, and a 73.8% capacity retention at 1250 mA g− 1. The demonstration of reversible interhalogen bonds enabled rechargeable Li-Cl2 battery opens a new avenue to develop halogen compound cathodes.

Skin mountable electronic devices are in a high-speed development at the crossroads of materials science, electronics, and computer science. Sophisticated functions, such as sensing, actuating, and computing, are integrated into a soft electronic device that can be firmly mounted to any place of human body. These advanced electronic devices are capable of yielding abilities for us whenever they are needed and even expanding our abilities beyond their natural limitations. Despite the great promise of skin mounted electronic devices, they still lack satisfactory power supplies that are safe and continuous. This Perspective discusses the prospects of the development of energy storage devices for the next generation skin mountable electronic devices based on their unique requirements on flexibility and miniaturized size.

High energy density, recyclability, and manufacturing flexibility are valuable assets for batteries to drive the Internet of Things in a distributed, adaptive, and sustainable way. Aqueous zinc bat...

We propose and demonstrate a flexible surface-enhanced Raman scattering (SERS) chip as a versatile platform for femtomolar detection and real-time interfacial molecule analysis. The flexible SERS chip is composed of a flexible and transparent membrane and embedded plasmonic dimers with ultrahigh particle density and ultrasmall dimer gap. The chip enables rapid identification for residuals on solid substrates with irregular surfaces or dissolved analytes in aqueous solution. The sensitivity for liquid-state measurement is down to 0.06 molecule per dimers for 10-14 mol·L-1 Rhodamine 6G molecule without molecule enrichment. Strong signal fluctuation and blinking are observed at this concentration, indicating that the detection limit is close to the single-molecule level. Meanwhile, the homogeneous liquid environment facilities accurate SERS quantification of analytes with a wide dynamic range. The synergy of flexibility and liquid-state measurement opens up avenues for the real-time study of chemical reactions. The reduction from p-nitrothiophenol (PNTP) to p-aminothiophenol (PATP) in the absence of the chemical reducing agents is observed at liquid interfaces by in situ SERS measurements, and the plasmon-induced hot electron is demonstrated to drive the catalytic reaction. We believe this robust and feasible approach is promising in extending the SERS technique as a general method for identifying interfacial molecular traces, tracking the evolution of heterogeneous reactions, elucidating the reaction mechanisms, and evaluating the environmental effects such as pH value and salty ions in SERS.

Sluggish conversion reactions severely impair the rate capability for lithium storage, which is the main disadvantage of the conversion-type anode materials. Here, the microplatform based on a sing...

The rapid development of miniaturized electronic systems stimulates the demand for microscale power sources. Microscale rechargeable batteries (μRBs) are one promising candidate for the microscale energy storage due to high energy density, long cycling stability, and excellent compatibility with electronic devices. The progress in microscale rechargeable batteries from two-dimensional to three-dimensional configurations are first summarized. The advantage of three-dimensional configurations is extensively discussed. The growing demand for high-energy-density microdevices requires significant improvement of current μRBs, thus making it urgent to obtain an in-depth understanding of electrochemical behaviors in microbatteries. In this perspective, the in-situ/in-operando analytical platforms for efficient investigation of microelectrodes are comprehensively reviewed. Moreover, the design principle of the on-site investigation of microscale batteries is highlighted. Finally, we discuss essential challenges in both device configuration and materials optimization strategies.

The great development of lightweight and portable smart electronic devices has significantly stimulated the interests in exploring and developing miniaturized energy storage systems. High-performance micro-supercapacitors (MSCs) with three-dimensional (3D) nanostructures show a great potential to improve energy storage capability, and these types of MSCs are regarded as ideal stand-alone power sources for smart microelectronics. Here, Cu0.56Co2.44O4@MnO2 core–shell nanoflowers and carbon nanotubes are integrated into a 3D hybrid asymmetric MSC with a fast, convenient, and scalable production fashion. Due to the hierarchical structure of the 3D electrodes and active materials, the hybrid MSC exhibits an improved specific areal capacitance of 665.3 ​mF ​cm−2 at 3.2 ​mA ​cm−2 and an excellent cycling performance of 89.8% retention after 8000 cycles. The MSC also shows an ultrahigh energy density of 182.3 ​μW ​h ​cm−2, which is higher than almost all the previously reported energy density values of on-chip interdigital-electrode MSCs. The efficient fabrication methodology of both the materials and the device demonstrated in this work show great potential in developing high-performance 3D MSCs.

Efficient radiative recombination is essential for perovskite luminescence, but the intrinsic radiative recombination rate as a basic material property is challenging to tailor. Here we report an interfacial chemistry strategy to dramatically increase the radiative recombination rate of perovskites. By coating aluminum oxide on the lead halide perovskite, lead-oxygen bonds are formed at the perovskite-oxide interface, producing the perovskite surface states with a large exciton binding energy and a high localized density of electronic state. The oxide-bonded perovskite exhibits a ≈500 fold enhanced photoluminescence with a ≈10 fold reduced lifetime, indicating an unprecedented ≈5000 fold increase in the radiative recombination rate. The enormously enhanced radiative recombination promises to significantly promote the perovskite optoelectronic performance.

Improve materials and architectures to shrink microscopic devices. Improve materials and architectures to shrink microscopic devices.

Inspired by origami art, we demonstrate a tubular microsupercapacitor (TMSC) by self-assembling two-dimensional (2D) films into a “swiss roll” structure with greatly reduced footprint area. A polymeric framework consisting of swelling hydrogel and polyimide layers ensures excellent ion transport between poly(3,4-ethylenedioxythiophene) (PEDOT)-based electrodes and provides efficient self-protection of the TMSC against external compression up to about 30 MPa. Such TMSCs exhibit an areal capacitance of 82.5 mF cm–2 at 0.3 mA cm–2 with a potential window of 0.8 V, an energy density and power density of 7.73 μWh cm–2 and 17.8 mW cm–2 (0.3 and 45 mA cm–2), and an improved cycling stability with a capacitance retention up to 96.6% over 5000 cycles. Furthermore, as-fabricated TMSC arrays can be detached from their surface and transferred onto target substrates. The connection of devices in parallel/series greatly improves their capacity and voltage output. Overall, our prototype devices and fabrication methodolo...

High-performance flexible lithium-ion batteries are leading candidates for power sources of wearable and foldable electronics. As a result, it is vital to design freestanding electrodes with high capacity and stability. Herein, we develop a novel strategy to significantly improve the performance of freestanding anodes by artificially introducing an ultrathin but robust interface based on polyacrylamide/gelatin gel with excellent mechanical durability and ionic conductivity. The artificial interface suppresses the formation of a thick solid electrolyte interface, facilitates charge transfer processes and strengthens the integrity of the electrode. Benefitting from these merits, our freestanding anode made of the nano/microstructured NiFe2O4–CNTs composite achieves a high capacity of 612 mA h g−1 based on the total mass of the electrode. The high-performance freestanding anode further enables a stable output capacity of 140 mA h g−1 over 1000 charge/discharge cycles for a full battery using commercial LiMn2O4 as the cathode material. Meanwhile, the excellent rate performance of the freestanding anode guarantees high energy output up to 255 W h kg−1 at a high power density of 12 000 W kg−1 for the full battery. Moreover, the intrinsic flexibility of the freestanding electrodes enables the fabrication of a flexible lithium-ion battery, which is highly stable even under harsh mechanical deformation. This work provides a new perspective to fabricate next-generation flexible batteries with high energy density and excellent stability, further advancing the development of foldable and wearable electronics toward practical applications.

Imperceptible electronics will make next-generation healthcare and biomedical systems thinner, lighter, and more flexible. While other components are thoroughly investigated, imperceptible energy storage devices lag behind because the decrease of thickness impairs the area-specific energy density. Imperceptible supercapacitors with high area-specific capacitance based on reduced graphene oxide/polyaniline (RGO/PANI) composite electrodes and polyvinyl alcohol (PVA)/H2 SO4 gel electrolyte are reported. Two strategies to realize a supercapacitor with a total device thickness of 5 µm-including substrate, electrode, and electrolyte-and an area-specific capacitance of 36 mF cm-2 simultaneously are implemented. First, the void volume of the RGO/PANI electrodes through mechanical compression is reduced, which decreases the thickness by 83% while retaining 89% of the capacitance. Second, the PVA-to-H2 SO4 mass ratio is decreased to 1:4.5, which improves the ion conductivity by 5000% compared to the commonly used PVA/H2 SO4 gel. Both advantages enable a 2 µm-thick gel electrolyte for planar interdigital supercapacitors. The impressive electromechanical stability of the imperceptible supercapacitors by wrinkling the substrate to produce folds with radii of 6 µm or less is demonstrated. The supercapacitors will be meaningful energy storage modules for future self-powered imperceptible electronics.