Power Sources For Electronics Research Articles

Multi-purpose triboelectric-electromagnetic hybrid nanogenerator with a mechanical motion-controlled switch for harvesting low-frequency energy

The renewable mechanical energy is pervasive but mainly contained in diverse, low-frequency and irregular motions, making its efficient exploitation highly difficult. Here, a multi-purpose triboelectric-electromagnetic hybrid nanogenerator (M-TEHG) is developed to tackle this issue through an ingenious mechanical motion-controlled switch (MMS). Consisting of a sprung-pendulum, a stiffness-adaptive plectrum and a slideable rotor, the MMS can not only transform low-frequency motions to one-way and high-speed spin but also enable the M-TEHG to automatically switch between non-contact state and contact state under the action of the rotor gravity. The M-TEHG exhibits frequency-multiplied outputs, improved durability, and superior adaptability to various motions. When triggered by low-frequency (≤ 5 Hz) swings and vibrations, the watch-sized M-TEHG can provide milliwatt-level electric power. When the M-TEHG is exposed to irregular water waves of around 1 Hz, the output power can reach roughly 0.7 mW. By harvesting human arm motions and water waves, the M-TEHG can power an electronic watch, drive a hygrometer, and light up 120 LEDs. This work provides a prospective strategy for tapping diverse low-frequency irregular motions as a green power source for wearable electronics and environment sensing systems.

Ultrahigh‐Output Triboelectric and Electromagnetic Hybrid Generator for Self‐Powered Smart Electronics and Biomedical Applications (Adv. Energy Mater. 40/2022)

Hybrid Nanogenerators In article number 2202238, Jae Yeong Park and co-workers successfully developed ultra-high output hybridized nanogenerators based on triboelectric and electromagnetic generators to scavenge biomechanical energy and provide a self-powered system. Halbach magnet arrays improve electromagnetic generator performance by concentrating magnetic flux in the coil, while polyethylene oxide nanofibers improve triboelectric performance. The fabricated device demonstrates biomechanical energy harvesting and provides a fast-charging power source for portable electronics.

Potassium Methacrylate Additive Strategy for Improved Stability of Ultrathin Copper‐Based Perovskite Solar Cells

AbstractPerovskite solar cell (PSC) using ultrathin metal transparent electrode is a promising power source for wearable electronics and aerospace applications. However, the environmental stability of device is challenging, due to the undesirable interdiffusion of metal and halogen ions. In this work, PSCs are constructed by using ultrathin copper (Cu) electrodes with low reactivity, combined with potassium methacrylate (KMMA) additive. On one hand, carbonyl groups in KMMA interact with the perovskite and improve quality of perovskite films. As a result, the power conversion efficiency (PCE) of ultrathin Cu‐based PSC is increased from 12.49% to 14.72%. On the other hand, benefitting from the binding of K+ with halogen ion, the interdiffusion of Cu and I ions is hindered. Thus, PSCs retain 80% and 75% of the initial PCE under heating at 85 °C for 130 h and maximum power point for 300 h, respectively. To the best of the knowledge, it is one of the best thermal and operational stability for the PSCs using metal‐based electrodes. At last, the symmetric PSCs exhibit superior folding stability which maintain 85.3% of initial PCE after folding for 500 cycles. Foldable PSCs on ultrathin Cu electrodes with excellent stability are attractive power sources in wearable applications.

Soft-covered wearable thermoelectric device for body heat harvesting and on-skin cooling

The recent emergence of self-powered wearable electronics gives rise to a growing demand for flexible, sustainable, and portable power supply. Wearable thermoelectric devices (WTEDs) are promising power sources for wearable electronics through directly converting body heat into electricity. However, the output power of WTEDs is still low due to the extremely small effective temperature difference across thermoelectric pillars, which hinders their practical applications. Commonly used strategies to enlarge the effective temperature difference for WTEDs, such as introducing metallic heat sinks or increasing the length of thermoelectric pillars, usually lead to clunky devices that are not suitable for wearable electronics. Here, we report on a soft-covered WTED for body heat harvesting and on-skin cooling, which demonstrates the desirable performance and wearer comfort. Distinct from the previously reported flat soft heat spreaders, this work presents the design and fabrication of a pin–fin soft cover that can serve as a flexible heat sink for WTEDs. The pin–fin soft cover was fabricated by curing the liquid metal/elastomer composite in a meltable wax mold. Systematic theoretical and finite element analysis was conducted to optimize the output power and wearability of the soft-covered WTED. The optimized WTED achieves a power density of 6.63 μW cm−2 on a stationary human body under natural convection condition with an ambient temperature of 20 °C, which is higher than the previously reported WTEDs with flat soft covers made of high-thermal-conductivity elastomers. Furthermore, our WTED can realize a 1.5 °C temperature drop for the human skin through Peltier cooling. This work demonstrates a new route to develop soft-covered WTEDs for self-powered wearable electronics and personal thermoregulation.

High-power nanogenerator of 2D-layered perovskite in a polymer matrix for self-charging battery-powered electronics

Recently two-dimensional layered halide perovskites (2D-layered HPs) with superior piezo-/ferroelectric properties and exceptional environmental stability have become potential alternatives to 3D-HPs. Herein, air-stable 2D-layered 1,3-propanediammonium lead iodide (DAPPbI4) perovskite is introduced as a promising filler material in a poly(vinylidene fluoride) (PVDF) polymer for the development of a high-performance and mechanically robust DAPPbI4–PVDF composite triboelectric nanogenerator (TENG). The triboelectric output performance is noticeably enhanced for 15 wt% DAPPbI4 owing to its improved electro-active β-phase PVDF (∼90%), high dielectric constant (∼47.4), and high piezoelectric coefficient (∼26.6 pm/V). The TENG achieved a high output voltage of ∼662 V, current density of ∼18.7 µA/cm2, unprecedented high power-density of ∼4.28 mW/cm2, and excellent pressure sensitivity of ∼13.31 V/kPa with outstanding mechanical durability and operational stability. The application of HP-based TENG as a sustainable power source for various portable electronics is demonstrated by charging a Li-ion battery (LIB) in a short time using the TENG output.

Highly strained gold (Au)-palladium (Pd) core-shell nanobipyramids with extraordinary high activity and durability towards ethanol electrooxidation

Direct ethanol fuel cells (DEFCs) have emerged as promising power sources for mobile electronics due to their eco-friendly advantages over analogous devices fed with hydrogen. However, the ethanol oxidation reaction (EOR), the anode reaction of DEFCs, suffers from slower oxidation kinetics compared to the existing H2-fuel cells. Herein, we report a strategy based on maximum strain in Au@Pd core-shell nanobipyramid (NBP) structure where strain induced electronic effect enhances surface adsorption of ethanol towards boosted EOR. The novelty of construction of the present core-shell nanoparticle (NP) lies not only in showing up maximum tensile strain due to the lattice mismatch between the core (Au) and shell (Pd) atoms but also in introducing an additional amount of strain manifested by the 5-fold twins and stacking faults type defects, caused by the presence of an optimally size selected bipyramid shape Au core. Finally, we have discovered that such highly strained Au@Pd core-shell NBPs with the thinnest possible Pd shell exhibit extraordinary high electrocatalytic effect up to highest level of mass activity of 15.26 A mgPd−1 in the EOR under alkaline conditions which is superior to that of any Pd-based catalysts reported so far and commercial Pd/C catalysts.

Performance of Direct Formate/Sodium Persulfate Microfluidic Fuel Cells with Carbon Paper and Graphite Felt Electrodes

AbstractMicrofluidic fuel cells (MFCs) are potential micro power sources for portable electronics. MFCs utilize the co‐laminar flowing of the solutions in the microchannel and remove the membranes in the traditional fuel cells. Flow‐through electrodes exploit the internal electrode surfaces and improve the MFC performance. Carbon paper (CP) has been widely used as a flow‐through electrode with a limited specific surface area. We have also used graphite felt (GF) with a high specific surface area as the electrode and then compared the performance of the MFCs with the CP and GF as the electrodes, respectively. Firstly, we showed the SEM surface morphologies of the two electrodes with or without the Pd catalysts. Secondly, we compared the electrochemical activities of the two electrodes in the solutions, respectively. The GF electrode always showed higher electrochemical activities than the CP electrode, since the GF electrode owned its larger accessible electrochemical surface area and less electrode resistance than the CP electrode. Thirdly, we compared the performance of the MFCs with the two electrodes. The results showed that the performance of the MFC with the GF electrodes electrodes was optimum, with the peak power density of 175.60 mW cm−2 and limiting current density of 616.53 mA cm−2. Finally, we conducted the discharge performance of the MFCs with the two electrodes. There existed a minor variation in the discharge current densities of the MFCs with the CP cathodes.

Raman Effect Studies of Electrochemical Synthesized Quartz Crystal of Poly-O-Phenylenediamine for Piezoelectric Application

Microelectronics arose from the desire for miniaturization of electrical devices, while Nano-electronics arose from subsequent study. Researchers have developed and modeled energy harvesting technologies based on the conservation law of energy over the last two decades to produce an alternative power source for small size electronics (nano-electronics) and low power electronic devices that can replace traditional power sources like batteries. The ambient energy, which is typically in the form of solar, thermal, vibrational, and other types, can be converted into a variety of different forms. Electrical energy can be harvested from vibrational energy in materials and other man-made materials using piezoelectric, electromagnetic, electrostatic, and nano-electric generators. Poly-o-phenylenediamine (PoPD) Quartz (silicon dioxide) Crystals were electrochemically produced at varied percentage ratios of silicon dioxide and Poly-O-Phenylenediamine samples in this study (sample A represents 20:80 percent, sample B with 50:50 percent, and sample C has 60:40 percent respectively). The Raman Effect and Scanning Electron Microscopic (SEM) analysis were used to characterize the material and forecast its Piezoelectric effect. All of the samples have their maximum peak record at Raman shift of 2872cm-1, however the Raman intensity varies. Sample A produced a peak intensity of 1250, Sample B produced a peak intensity of 1700, and Sample C produced a peak intensity of 2700. As the doping concentration of silicon dioxide increases, the Raman peak intensity for Poly-o-Phenylenediamine doped with silicon dioxide increases. The SEM images show that Sample A forms a fine cluster with little or no distinctive morphology, Sample B is ball-shaped with grain-like structure, and Sample C shows a flat, thin leaf-like shape. From sample A to C, the intra-particle separation rises, which corresponds to an increase in SiO2 concentration.

Effects of surface properties on wall superheat at the onset of microbubble emission boiling

Boiling heat transfer (BHT) is a promising technology for cooling the high heat flux emitted from next generation electronic devices. Pool boiling represents an eco-friendly cooling technology because its pumps do not require an external electronic power source. To increase the maximum heat flux of pool boiling beyond the critical heat flux, microbubble emission boiling (MEB) can be implemented with highly subcooled water. However, conventional MEB experiments use a copper heating surface, which can easily be oxidized in air. Thus, copper heating surfaces do not retain constant surface properties, especially when the BHT boiling pool is open to air. Applying a coating to the copper surface can enable further investigations of the MEB phenomenon and improve the reliability of MEB-based cooling devices. However, it is unclear which surfaces are suitable for promoting the onset of MEB. Herein, we experimentally investigated a stable hydrophilic black chrome plating on copper by performing subcooled pool boiling with water at atmospheric pressure. The results confirmed that the black chrome plating did not interrupt the onset of MEB, but rather, it enabled constant wall superheat during repeated experiments spanning the transition from nucleate boiling to MEB. Moreover, the threshold of liquid subcooling for the onset of MEB with the black chrome plating (20 K) was similar to that with a copper heat transfer surface.

Design and Testing of Autonomous Chargeable and Wearable Sweat/Ionic Liquid-Based Supercapacitors.

This work demonstrates ionic liquid electrolyte‐inscribed sweat‐based dual electrolyte functioning supercapacitors capable of self‐charging through sweat electrolyte function under a non‐enzymatic route. The supercapacitor electrodes are fabricated from TREN (tris(2‐aminoethyl)amine), poly‐3,4‐ethylenedioxythiophene, and a graphene oxide mixture with copper‐mediated chelate, and this polymer‐GO‐metal chelate film can produce excellent energy harvest/storage performance from a sweat and ionic liquid integrated electrolyte system. The fabricated device is specifically designed to reduce deterioration using a typical planar structure. In the presence of sweat with ionic liquid, the dual electrolyte mode supercapacitor exhibits a maximum areal capacitance of 3600 mF cm−2, and the energy density is 450 mWhcm−2, which is more than 100 times greater than that from previously reported supercapacitors. The supercapacitors were fabricated/attached directly to textile fabrics as well as ITO‐PET (Indium tin oxide (ITO)‐polyethylene terephthalate (PET) film to study their performance on the human body during exercise. The self‐charging performance with respect to sweat wetting time for the sweat@ionic liquid dual electrolyte showed that the supercapacitor performed well on both fabric and film. These devices exhibited good response for pH effect and biocompatibility, and as such present a promising multi‐functional energy system as a stable power source for next‐generation wearable smart electronics.

(Digital Presentation) Thermal Acceleration Model for the Capacity Fade of a Rechargeable Li Ion Battery and Its Validation with 10+ Years of Testing Data

Rechargeable Li ion batteries have become not only a major power source for consumer electronics, but also a critical power source for high demanding applications like electrical vehicles, portable military devices and medical devices. Medtronic, one of the leading medical device companies has developed a breakthrough rechargeable Li ion battery technology-OverdriveTM to power implantable neurostimulators such as Intellis and Interstim Micro. OverdriveTM batteries have exceptional stable performance and fast charging capability. Figure 1 shows design verification test of capacity stability under two different discharge rate, C/24 and C/168; charging rate are 2C for both groups. As shown in Figure 1, there is virtually no capacity fade under C/168 discharge rate cycling and only a few percent capacity loss under C/24 rate cycling for more than 10 years of testing at 37oC.It is crucial to have a good acceleration testing model to design a rechargeable battery with reliable performance over 10 years of service and to ensure robust design with foreseeing battery material replacement over time. In the early development stage, we established a thermal acceleration capacity fade model for our OverdriveTM battery based on 2 years of testing as shown in Figure 2. Figure 2 shows capacity fade of Overdrive battery cycling at different temperatures up to 10 years. The trend of additional 8 years of data is consistent with model prediction.This presentation will highlight the performance characteristics of the OverdriveTM battery technology and provide the technical details of thermal acceleration capacity fade model. In addition, we will present how the model has been applied to understand the degradation mechanism of OverdriveTM battery and to improve the battery chemistry. Figure 1

2D Materials Integrated CNT Hybrid Paper Electrodes for Flexible All-Solid-State Supercapacitors

Flexible supercapacitors (SCs) have attracted growing interests as the power source for portable and wearable electronics. Carbon nanotubes (CNTs) are emerged as one of the promising materials for flexible SC electrodes due to their excellent high electrical conductivity, high mechanical strength, large surface area, and functionalization ability. CNTs can be assembled into several macroscopic forms based on the applications. In the present work, the CNT buckypapers integrated with 2D materials such as graphene and transition metal sulfides (TMDs) especially, tin sulfide (SnS2) nanoparticles were prepared using a simple mould casting method. The flexible and free-standing, interface-enhanced CNT paper having homogeneously dispersed 2D materials was prepared. The hybridized CNT papers were thoroughly characterized to elucidate their structural and surface properties. Finally, such hybrid CNT papers were used as binder-free, free-standing electrodes for the fabrication of flexible-all-solid-state supercapacitors. The electrochemical performance (CV, GCD, EIS) of the as obtained the symmetric and asymmetric devices were assessed to evaluate the charge storage performance and effect of 2D materials on the charge storage capability and stability were studied. Figure 1

Self-rechargeable energizers for sustainability

Electrical energy generation and storage have always been complementary to each other but are often disconnected in practical electrical appliances. Recently, efforts to combine both energy generation and storage into self-powered energizers have demonstrated promising power sources for wearable and implantable electronics. In line with these efforts, achieving self-rechargeability in energy storage from ambient energy is envisioned as a tertiary energy storage (3rd-ES) phenomenon. This review examines a few of the possible 3rd-ES capable of harvesting ambient energy (photo-, thermo-, piezo-, tribo-, and bio-electrochemical energizers), focusing also on the devices' sustainability. The self-rechargeability mechanisms of these devices, which function through modifications of the energizers’ constituents, are analyzed, and designs for wearable electronics are also reviewed. The challenges for self-rechargeable energizers and avenues for further electrochemical performance enhancement are discussed. This article serves as a one-stop source of information on self-rechargeable energizers, which are anticipated to drive the revolution in 3rd-ES technologies.

Plasticized PVC-Gel Single Layer-Based Stretchable Triboelectric Nanogenerator for Harvesting Mechanical Energy and Tactile Sensing.

Triboelectric nanogenerators have garnered significant attention as alternative power sources for wearable electronics owing to their simple structure, easy fabrication, low cost, and superior power output. In this study, a transparent, stretchable, and attachable triboelectric nanogenerator (TENG) is built with an advanced power output using plasticized polyvinyl chloride (PVC)‐gel. The PVC‐gel exhibit very high negative triboelectric properties and electrically insulating PVC became an electrically active material. It is found that a single layer of PVC‐gel can act as a dielectric and as a conducting layer. The PVC‐gel based single layer of triboelectric nanogenerator (S‐TENG) creates output signals of 24.7 V and 0.83 µA, i.e., a 20‐fold enhancement in the output power compared to pristine PVC‐based TENGs. In addition, the S‐TENG can stably generate output voltage and current under stretching condition (80%). The S‐TENG can be implemented as a tactile sensor that can sense position and pressure without combining multiple elements or electrode grid patterns. This study provides new applications of power sources and tactile sensors in wearable electronics.

High‐Performance Compressible Zinc Ion Battery Based on Melamine Foam‐Derived Electrodes

Zinc ion batteries (ZIBs) with high capacity and superior safeness represent a promising candidate as the power source for portable electronics. However, it remains a big challenge to construct high‐performance ZIBs with highly compressible capability, due to the limited compressible properties of electrodes and electrolyte. Herein, a highly compressible ZIB using a cathode of polyaniline/carbon foam (PANI/CF), an anode of Zn/CF, and a gel electrolyte containing polyvinyl alcohol and Zn(CF3SO3)2 is demonstrated. The 3D interconnection structure of the self‐supporting CF material not only can provide compressible platform to load active materials, but also can facilitate transport of ions. As desired, the newly developed ZIB exhibits high specific capacity of 215 mAh g−1 at a current density of 1 A g−1 and excellent cyclic stability (88% after 2500 charge/discharge cycles). Benefiting from the excellent mechanical compressibility and stability of CFs, the ZIBs well maintain their original electrochemical performance under a compressive strain as high as 75% and even pressing/releasing for 1000 cycles under a strain of 60%, indicating outstanding compressible capability. The compressible ZIB represents a promising candidate to be used as power supplies for portable electronics in the near future.

Sandwiched Graphene/Bi2Te3/Graphene Thermoelectric Film with Exceptional Figure of Merit for Flexibility

AbstractFlexible thermoelectrics (TEs) that fit curved human skin well, could harvest energy from skin, and thus have been considered as a promising portable power source for wearable electronics. Bi2Te3, the most popular room‐temperature TE material, is still challenging to be applied in flexible devices due to its rigid nature. Although many Bi2Te3‐based films have been reported to be flexible when made thin enough, the thermal and electrical loads across them are rather small with severe limitation on the maximum power output. This work realizes a thick Bi2Te3‐based TE film with a “graphene/Bi2Te3/graphene” sandwiched structure, which demonstrates an unprecedentedly high figure of merit for flexibility among all Bi2Te3‐based films ever reported, due to the outstanding intrinsic flexibility of graphene and a small slippage barrier. Meanwhile, graphene acts as express conducting channels as well as carrier donors, resulting in an increased electrical conductivity. The numerous graphene/Bi2Te3 heterointerfaces induce energy filtering effect, leading to an enhanced Seebeck coefficient, and thus an optimized power factor is achieved. This work offers a cost‐effective avenue to make highly flexible TE films for power supply of wearable electronics by intercalating TE nanoplates into 2‐dimensional nanosheets.

Toy-blocks-inspired programmable supercapacitors with high energy density

Diversity and individuation development of wearable electronics require their power sources to be programmable and customizable. However, how to prepare all-purpose electrodes with high designability and satisfying energy density for power sources is still a serious challenge. Herein, we propose programmable supercapacitors based on novel electrode blocks, which are inspired from toy blocks. Polyaniline/carbon nanotube strip is adopted as electrode block template, where one end of the strip is loaded with capacitive MnO2 (4.9–12.4 mg cm−2) as the cathode head, while the other end is left untreated as the anode head. These two heads are designed with opposite potential windows, forming a 2.5 V asymmetric supercapacitor with a high areal capacitance (679.0 mF cm−2). The supercapacitor reaches a remarkable energy density of 513.3 μWh cm−2, which is further utilized to power a high power-consumption fan and an E-ink display. Finally, the electrode blocks are applied to programmably construct a variety of energy devices, such as high-voltage device, stretchable device, three-dimensional supercapacitor lantern and wirelessly self-charged display system. The concept of general electrode block together with its two-head feature to increase energy density will provide a new route to fabricate programmable power sources for the booming wearable electronics.

Entangled structure morphology by polymer guest enabling mechanically robust organic solar cells with efficiencies of over 16.5%

<h2>Summary</h2> Intrinsically stretchable organic solar cells (IS-OSCs) have attracted great attention as a promising power source for wearable electronics. However, reconciling high power conversion efficiency (PCE), reasonable stretchability, and thermal stability is a grand challenge. Herein, we have successfully improved the ductility and morphological stability of the PM6:BTP-eC9 blend film through introducing polymer PY-IT to form entangled structure morphology. Compared with the binary blend, the ternary system exhibits suppressed diffusion and crystallization of BTP-eC9 acceptor and load distribution across the entangled chain networks to dissipate the local energy. As a result, high efficiencies of 16.52% were obtained for the flexible OSCs based on polyethylene terephthalate (PET) substrate. Impressively, the PCE of IS-OSCs based on the elastomer substrate also achieved 15.3%. In this work, the study about intrinsic stretchability and morphological robustness demonstrates that high-performance IS-OSCs constitute a major step toward practical utilization in malleable electronic textiles.

Design and Control of Ultra-High-Speed Sensorless Drive with Two-Input Power Source for Portable Consumer Electronics

The convenience and usability of portable consumer electronics that require a motor, such as vacuum cleaners and hair dryers, will be greatly improved if both ac and dc two-input power sources can be used. The dc input power is mostly composed of a dc battery, and single-phase voltage is used as ac input power. A converter system capable of converting ac and dc voltage with control technology is required to supply the voltage for motor driving to apply both ac and dc input to the product. Because a limited number of batteries are used to decrease the weight and size of portable products, a system such as a dc converter is necessary to supply the voltage required to operate the motor and to keep the voltage fluctuation according to the usage time constant. When ac power is used in the product, a voltage drop system that can step down the ac voltage to supply voltage to the dc link is necessary to supply the voltage required to operate the motor to the dc-link. In addition, it is important to reduce the size of the system through ultra-high-speed motor operation by increasing the rotation speed because portable consumer electronics that include a motor drive should be light and portable. This paper proposed a system that can supply a stable dc-link voltage required for ultra-high-speed motor control by applying a phase control method to the ac input side and a dc boost converter to the dc input side. Furthermore, the 1-shunt sensorless method was applied to the inverter for ultra-high-speed motor design and ultra-high-speed motor control system that contributes to product miniaturization and material cost reduction, experimental verification. The ultra-high-speed motor driving evaluation under ac and dc input power conditions and the conversion to dc power input when ac power interrupt occurs were performed to more stably verify the system according to the input power change.

Large-Scale, Lightweight, and Robust Nanocomposites Based on Ruthenium-Decorated Carbon Nanosheets for Deformable Electrochemical Capacitors.

Despite the increase in demand for deformable electrochemical capacitors as a power source for wearable electronics, significant obstacles remain in developing these capacitors, including their manufacturing complexity and insufficient deformability. With recognition of these challenges, a facile strategy is proposed to fabricate large-scale, lightweight, and mechanically robust composite electrodes composed of ruthenium nanoparticles embedded in freestanding carbon nanotube (CNT)-based nanosheets (Ru@a-CNTs). Surface-modified CNT sheets with hierarchical porous structures can behave as an ideal platform to accommodate a large number of uniformly distributed Ru nanoparticles (Ru/CNT weight ratio of 5:1) while improving compatibility with aqueous electrolytes. Accordingly, Ru@a-CNTs offer a large electrochemically active area, showing a high specific capacitance (∼253.3 F g-1) and stability for over 2000 cycles. More importantly, the exceptional performance and mechanical durability of quasi-solid-state capacitors assembled with Ru@a-CNTs and a PVA-H3PO4 hydrogel electrolyte are successfully demonstrated in that 94% of the initial capacitance is retained after 100 000 cycles of bending deformation and a commercial smartwatch is charged by multiple cells. The feasible large-scale production and potential applicability shown in this study provide a simple and highly effective design strategy for a wide range of energy storage applications from small- to large-scale wearable electronics.