Commercial Capacitors Research Articles

Lead-free piezoelectric nanogenerator using lightweight composite films for harnessing biomechanical energy

Highly desirable to exploit the ultrathin, lightweight, and flexible composite films (CFs) and alternative lead-free piezoelectric materials for biomechanical energy harvesting applications, also gained a huge interest in recent days for various smart sensing applications. Here, Bi4Ti3O12 nanoparticles (BiTO NPs), BiTO NPs/PDMS CFs were prepared by simple sol-gel technique and low-cost spin-coating process. Lightweight composite piezoelectric nanogenerator (LW-CPNG) having 20 wt% of BiTO NPs generates higher electrical responses (12.5 V, 100 nA and 562 μW/cm2) as compared to the other LW-CPNGs upon 10 N force. The intrinsic functional properties of BiTO NPs, CFs, LW-CPNGs were evaluated by considering the hysteresis loop test, weight ratio analysis of BiTO in CFs, switching polarity, stability, commercial capacitors charging analysis, load resistance and external force dependent analysis. Further, LW-CPNGs output was tested for real time applications such as powering commercial light-emitting diodes and monochromatic display devices. The LW-CPNG (20 wt%) generates (10 V, 60 nA) by the biomechanical foot tapping suggest that the proposed device is a thin, cost-effective and potential candidate to harness the waste biomechanical energy in our daily life.

Simultaneous realization of broad temperature stability range and outstanding dielectric performance in (Ag+, Ta5+) co–doped TiO2 ceramics

Effects of sintering condition on dielectric properties and microstructure were systematically investigated in (Ag1/4Ta3/4)0.005Ti0.995O2 ceramics. A giant dielectric constant of ∼9831 (1 kHz) and a relatively low dielectric loss of ∼0.041 (1 kHz) were realized at the optimal sintering condition of 1330 °C with a holding time for 10 h. Notably, stable temperature coefficient (within −6.8% to 8.8%) of the dielectric constant at 10 kHz was achieved in a broader temperature range (-200–200 °C), which shows superior temperature stability of our sample than the application requirements (−55–200 °C and Δεr/ε25 °C < ±15%) of commercial X9R capacitor.

Biocompatible and sustainable power supply for self-powered wearable and implantable electronics using III-nitride thin-film-based flexible piezoelectric generator

Energy harvesters that scavenge biomechanical energy are promising power supply candidates for wearable and implantable electronics. Of the most widely used energy harvesters, piezoelectric generators can generate more electric charge than their triboelectric counterparts with similar device size, thus are more suitable to make compact wearable devices. However, most high-power piezoelectric generators are made from lead zirconate titanate, making them undesirable for wearable applications due to the toxic lead element. In this study, a flexible piezoelectric generator (F-PEG) is fabricated with chemically stable and biocompatible Group-III-nitride (III-N) thin film by a layer-transfer method. The III-N thin-film F-PEG can generate an open-circuit voltage of 50 V, a short-circuit current of 15 µA, and a maximum power of 167 µW at a load resistance of 5 MΩ. Applications of the III-N thin-film F-PEG are demonstrated by directly powering electronics such as light-emitting diodes and electric watches, and by charging commercial capacitors and batteries to operate an optical pulse sensor. Furthermore, the III-N thin-film F-PEG shows good durability and a stable output after being subjected to severe buckling tests of over 30,000 cycles.

Superior response in ZnO nanogenerator via interfaced heterojunction for novel smart gas purging system

A novel direct way to synthesis Zinc oxide-tin dioxide heterojunction (ZTH) using a simple grinding technique without employing successive processes has been introduced. A facile, rapid and economical fabrication strategy was studied using various characterization tools. The underlining mechanism of adhesion was studied using finite elemental simulation tools. The heterojunction was further processed into PDMS based composite for the realization of nanogenerator. The ZTH showed a 4 fold improved response compared to intrinsic ZnO which is based on novel n–n bulk heterojunction principle. The peak to peak voltage was around 12 V with a current of 60–70 nA. The calculated power density was 1.7 mW/m2 and load sensitivity was around 1.5 V/N. The device was further demonstrated to charge the commercial capacitors and is used for biomechanical energy harvesting. Finally, a novel piezoelectric smart gas purging system (P-SMGP) was demonstrated using the device which may find applications in chemistry lab and food industry.

Enhanced specific capacitance by a new dual redox-active electrolyte in activated carbon-based supercapacitors

Commercial electrochemical capacitors exhibit high power density and long cycle life but suffer from low energy density due to low specific capacitance of activated carbon (<200 F g−1). Redox-enhanced electrochemical capacitors achieve higher specific energy by adding redox-active ingredients to the electrolyte, which provide additional faradaic pseudo-capacitance. Here, high-performance and stable aqueous redox electrochemical capacitors using a new dual-active electrolyte is developed, and the specific capacitance of activated carbon increases to 885 F g−1 after adding 0.05 M FeBr3 with no degradation over 10,000 cycles in a two-electrode cell, which is more than four-fold of the original capacitance of 204 F g−1. In addition, PVA was introduced to the electrolyte and proved to be a useful way to increase the coulombic efficiency. Moreover, this new energy storage system delivers high specific energy of 40 Wh kg−1 in 0.5 M Na2SO4 based on the mass of electrodes.

Operation of a Superconducting Nanowire in Two Detection Modes: KID and SPD

We present the performance of a superconducting nanowire that can be operated in two detection modes: i) as a kinetic inductance detector (KID) or ii) as a single-photon detector (SPD). Two superconducting nanowires developed for use as single-photon detectors (SNSPDs) are embedded as the inductive (L) component in resonant inductor/capacitor (LC) circuits coupled to a microwave transmission line. The capacitors are low loss commercial chip capacitors and limit the internal quality factor of the resonators to approximately $Q_i = 170$. The resonator quality factor, $Q_r \simeq 23$, is dominated by the coupling to the feedline and limits the detection bandwidth to on the order of 1MHz. When operated in KID mode, the detectors are AC biased with tones at their resonant frequencies of 45.85 and 91.81MHz. In the low-bias, standard KID mode, a single photon produces a hot spot that does not turn an entire section of the line normal but only increases the kinetic inductance. In the high-bias, critical KID mode, a photon event turns a section of the line normal and the resonance is destroyed until the normal region is dissipated. When operated as an SPD in Geiger mode, the resonators are DC biased through cryogenic bias tees and each photon produces a sharp voltage step followed by a ringdown signal at the resonant frequency of the detector which is converted to a standard pulse with an envelop detector. We show that AC biasing in the critical KID mode is inferior to the sensitivity achieved in DC-biased SPD mode due to the small fraction of time spent near the critical current with an AC bias.

The Generated Entropy Monitored by Pyroelectric Sensors.

Entropy generation in irreversible processes is a critical issue that affects the failure and aging of electrical, chemical or mechanical systems. The promotion of energy conversion efficiency needs to reduce energy losses, namely to decrease entropy generation. A pyroelectric type of entropy detector is proposed to monitor energy conversion processes in real time. The entropy generation rate can be derived from the induced pyroelectric current, temperature, thermal capacity, pyroelectric coefficient and electrode area. It is profitable to design entropy detectors to maintain a small thermal capacity while pyroelectric sensors minimize geometrical dimensions. Moreover, decreasing the electrode area of the PZT cells could avoid affecting the entropy variation of the measured objects, but the thickness of the cells has to be greatly reduced to promote the temperature variation rate and strengthen the electrical signals. A commercial capacitor with a capacitance of 47 μF and a maximum endured voltage of 4 V were used to estimate the entropy to act as an indicator of the capacitors’ time-to-failure. The threshold time was evaluated by using the entropy generation rates at about 7.5 s, 11.25 s, 20 s and 30 s for the applied voltages of 40 V, 35 V, 30 V and 25 V respectively, while using a PZT cell with dimensions of 3 mm square and a thickness of 200 μm.

Self-powered hybrid flexible nanogenerator and its application in bionic micro aerial vehicles

With the successive advent of piezoelectric nanogenerator (PENG) and triboelectric nanogenerator (TENG), the harvest of ambient mechanical energy has become more high-efficient, low-lost and simpler for self-powered systems. Introducing lightweight alternative power source to bionic micro aerial vehicle (BMAV) which is widely used for military surveillance or monitoring air pollution and so on, is the forefront of the research hotspots. However, there is still no design applying the two kinds of nanogenerator (NG) together in BMAV to collect the flapping mechanical energy more efficiently. In this paper, we demonstrate a hybrid flexible nanogenerator (HFNG) based on the combination of triboelectric and piezoelectric devices in BMAV. It not only can solve the problem of power supply, but also make the BMAV intelligent to monitor the changes of specific environmental factors. The newly designed HFNG can produce a maximum open-circuit voltage of 80 V, short-circuit current of 3.0 μA with the instantaneous output power density of 34.1 mW/m2 when the flapping frequency of BMAV (f) is 14 Hz. The rectified output of HFNG has been applied to charge the commercial capacitor, rechargeable battery and drive light-emitting diodes. It was also demonstrated that HFNG can be used for testing the lift force (L) of BMAV. Moreover, the output performances of HFNG have been proved to be sensitive to temperature, humidity, alcohol concentration and PM2.5 in the environment.

A Ru–Pt alloy electrode to suppress leakage currents of dynamic random-access memory capacitors

Rutile TiO2, a high temperature phase, has attracted interest as a capacitor dielectric in dynamic random-access memories (DRAMs). Despite its high dielectric constant of >80, large leakage currents caused by a low Schottky barrier height at the TiO2/electrode interface have hindered the use of rutile TiO2 as a commercial DRAM capacitor. Here, we propose a new Ru–Pt alloy electrode to increase the height of the Schottky barrier. The Ru–Pt mixed layer was grown by atomic layer deposition. The atomic ratio of Ru/Pt varied in the entire range from 100 at.% Ru to 100 at.% Pt. Rutile TiO2 films were inductively formed only on the Ru–Pt layer containing ≤43 at.% Pt, while anatase TiO2 films with a relatively low dielectric constant (∼40) were formed at Pt compositions > 63 at.%. The Ru–Pt (40–50 at.%) layer also attained an increase in work function of ∼0.3–0.4 eV, leading to an improvement in the leakage currents of the TiO2/Ru–Pt capacitor. These findings suggested that a Ru–Pt layer could serve as a promising electrode for next-generation DRAM capacitors.

An air-cushion triboelectric nanogenerator integrated with stretchable electrode for human-motion energy harvesting and monitoring

Harvesting energy from human-motion can be a viable solution for developing self-powered wearable and portable electronic devices. This work presents an air-cushion triboelectric nanogenerator (ACTNG) which is entirely made of stretchable materials. ACTNG can efficiently harvest mechanical energy from intense movements like walking, running and jumping without any ambient influence. Systematic testing of different parameters like diameter (20–60 mm), frequency (1–5 Hz), and applied force (20–60 N), reveals an optimal peak power density of 44.6 mW m−2. The output performance is further validated by charging commercial capacitors, lighting LEDs, and operating as a power supply for a scientific calculator and digital thermometer. In addition, this device can operate as a human motion sensor with a detection sensitivity of 33.8 μA MPa−1 for instantaneous force. This device has potential for a wide range of applications in biocompatible, wearable, and smart sensing technologies.

Coaxial Hybrid Triboelectric Nanogenerator for Scavenging Multidirectional Mechanical Energy

AbstractScavenging mechanical energy from ambient environment has been one of the most promising approaches to tackle global energy shortage for its marvelous abundance over the world. Yet harvesting such energy finely is rather challenging because of highly fragmentary property. Recently, efforts based on triboelectric nanogenerator (TENG) made it no longer a dream to promote this progress. In this paper, a novel coaxial hybrid TENG (CH‐TENG) with the integration of rubber core and elastic wavy shell is demonstrated, which can run in two distinguishing working modes to collect the mechanical energy from multiple directions. While operated by researchers manually, a maximum instantaneous output of 150 and 48 V of open‐circuit voltage (VOC), 2 µA and 145 nA of short‐circuit current (ISC) can be reached under continuous off‐axial pressing as well as axial stretching, respectively, sufficing to charge commercial capacitors and drive 20 light‐emitting diode bulbs. Attributing to the elaborate design of structure, as‐fabricated CH‐TENG shows lots of merits such as remarkable durability, high portability, outstanding sensitivity, and superb directivity. All of these manifest its great competitiveness in upcoming green future.

Effects of Sc2O3 and MgO additions on the dielectric properties of BaTiO3-based X8R materials

In the present study, dielectric formulations compatible with the base-metal electrode process, using a host material (BaTiO3 + 0.05 mol% MnCO3 + 1.37 mol% BaSiO3) with 0.3–0.6 mol% Sc2O3 and 0–2.0 mol% MgO, were examined. The addition of Sc2O3 and MgO led to the formation of a grain core-shell structure and therefore gave rise to temperature-stable dielectric properties, while the TEM and EDS results revealed the chemical inhomogeneity of the Sc3+ ions across the grains. The Sc2O3 content played an important role in the reducing the dielectric constant (K), improving the electrical resistivity, and flattening the TCC curve of the ceramics by inhibiting grain growth. Meanwhile, the existence of MgO was proven to enhance the densification, affect the room-temperature electrical resistivity, reduce the tanδ value, and improve the TCC value at - 55 °C. The optimum formulation derived in the present study involved adding 0.45 mol% Sc2O3 and 1.0 mol% MgO to the host material. This yielded the following dielectric properties: K = 1,744, tanδ = 0.58%, TCC = - 3.9% (- 55 °C) and - 8.5% (150 °C), and electrical resistivity = 2.8 × 1012 Ω cm (25 °C) and 1.7 × 1011 Ω cm (150 °C). These dielectric properties satisfied the requirements of the EIA-X8R specification, thus validating the material's potential for application to commercial capacitors.

Versatile Core–Sheath Yarn for Sustainable Biomechanical Energy Harvesting and Real‐Time Human‐Interactive Sensing

AbstractThe emergence of stretchable textile‐based mechanical energy harvester and self‐powered active sensor brings a new life for wearable functional electronics. However, single energy conversion mode and weak sensing capabilities have largely hindered their development. Here, in virtue of silver‐coated nylon yarn and silicone rubber elastomer, a highly stretchable yarn‐based triboelectric nanogenerator (TENG) with coaxial core–sheath and built‐in spring‐like spiral winding structures is designed for biomechanical energy harvesting and real‐time human‐interactive sensing. Based on the two advanced structural designs, the yarn‐based TENG can effectively harvest or respond rapidly to omnifarious external mechanical stimuli, such as compressing, stretching, bending, and twisting. With these excellent performances, the yarn‐based TENG can be used in a self‐counting skipping rope, a self‐powered gesture‐recognizing glove, and a real‐time golf scoring system. Furthermore, the yarn‐based TENG can also be woven into a large‐area energy‐harvesting fabric, which is capable of lighting up light emitting diodes (LEDs), charging a commercial capacitor, powering a smart watch, and integrating the four operational modes of TENGs together. This work provides a new direction for textile‐based multimode mechanical energy harvesters and highly sensitive self‐powered motion sensors with potential applications in sustainable power supplies, self‐powered wearable electronics, personalized motion/health monitoring, and real‐time human‐machine interactions.

Disk-based triboelectric nanogenerator operated by rotational force converted from linear force by a gear system

A triboelectric nanogenerator (TENG) is an energy harvester which converts ambient mechanical energy into electrical energy. A disk-based rotational TENG converts rotational mechanical energy into electrical energy with advantages over a vertical contact-separation based TENG. Since the disk-based TENG operates in grating-based sliding mode, its electrical output is advantageous in terms of prolonged continuous energy harvesting. However, rotational mechanical energy is less abundant than linear mechanical energy in typical environments. In this work, a new disk-based TENG which converts linear mechanical energy into electrical energy through the use of a gear system (linear-to-rotational TENG, LR-TENG) was fabricated as an experimental device. A TENG based on a vertical contact-separation mode (V-TENG), composed of identical triboelectric materials, was also fabricated as a control device. Here, it is experimentally demonstrated that the electrical output of the LR-TENG was superior to that of the V-TENG at the same magnitude of applied force and at an identical level of applied mechanical energy, as the surface charge density of the LR-TENG is much greater than that of the V-TENG. The LR-TENG can effectively provide power to numerous small electronic devices. Examples include charging a commercial capacitor and lighting commercial LEDs.

Triboelectric\u2013Electromagnetic Hybrid Generator for Harvesting Blue Energy

Progress has been developed in harvesting low-frequency and irregular blue energy using a triboelectric–electromagnetic hybrid generator in recent years. However, the design of the high-efficiency, mechanically durable hybrid structure is still challenging. In this study, we report a fully packaged triboelectric–electromagnetic hybrid generator (TEHG), in which magnets were utilized as the trigger to drive contact–separation-mode triboelectric nanogenerators (CS-TENGs) and coupled with copper coils to operate rotary freestanding-mode electromagnetic generators (RF-EMGs). The magnet pairs that produce attraction were used to transfer the external mechanical energy to the CS-TENGs, and packaging of the CS-TENG part was achieved to protect it from the ambient environment. Under a rotatory speed of 100 rpm, the CS-TENGs enabled the TEHG to deliver an output voltage, current, and average power of 315.8 V, 44.6 μA, and ~ 90.7 μW, and the output of the RF-EMGs was 0.59 V, 1.78 mA, and 79.6 μW, respectively. The cylinder-like structure made the TEHG more easily driven by water flow and demonstrated to work as a practical power source to charge commercial capacitors. It can charge a 33 μF capacitor from 0 to 2.1 V in 84 s, and the stored energy in the capacitor can drive an electronic thermometer and form a self-powered water-temperature sensing system.

High Energy Density Dielectrics Based on PVDF‐Based Polymers

AbstractMany applications, such as hybrid vehicles, pulsed power generators, and power factor correction, require capacitors with high energy density to reduce the size or weight of the related systems. For these applications, dielectric film capacitors are often used because of their fast discharge speed and high power density. The energy density of commercial available film capacitors is relatively low and cannot meet the demands for those applications. In the past decade, different polymer‐based dielectric materials have been intensively investigated to improve the energy density of the materials. Here, the progress in developing high energy density polymer‐based dielectric materials is reviewed, and strategies to improve the energy density of dielectric polymers are summarized and discussed. Because polyvinylidene fluoride (PVDF)‐based polymers have relatively high dielectric properties and have been intensively studied for the energy storage applications, the discussion focuses mainly on PVDF‐based polymers and composites. An outlook for the future directions and problems that will be tackled to further improve the energy density of dielectrics is also provided.

Studies on Electrochemical Properties of Ni-Mn-Oxides for Advance Energy Storage Application

INTRODUCTION Recently, supercapacitors have been widely studied through all over the world as a new class of energy storage devices to fulfill the need of increasing clean and renewable energy demand. Over many energy storage devices (batteries, commercial capacitors etc) supercapacitors have their remarkable advantages such as fast charge-discharge ability, long cycling stability and comparatively high power density which enable them to be used as a promising energy sources for various portable electric vehicles and electronic gadgets. According to the charge storage mechanism the supercapacitors can be categorized into two distinct groups. One is the electrochemical double layer capacitors (EDLCs) which can store charge by non-faradic process i.e. there is no charge transfer occurs at the interface of electrode material and electrolyte solution and the other mechanism is pseudocapacitors in which charge can be stored within the electrode material by the redox reaction or Faradic process. In the both charge storage mechanisms, surface of the electrode material takes a leading role. Porous, interconnected, conducting materials with high surface to volume ratio such as nanocrystal can offer high specific capacitance value and can act as high performance supercapacitors. Generally, carbon based materials like carbon nano tube (CNT), carbon aerogel, activated carbon etc. are used as electrode materials for EDLCs whereas various metal oxides, conducting polymers are used as materials for pseudocapacitor electrode1,2. From last few decades’ various metal oxides (RuO2, NiO, Fe2O3, MnO2, V2O5, Co2O3 etc) have drawn considerable attention as promising electrode materials due to their excellent theoretical capacitance values. But their low electrical conductivity and poor stability are the main problem which are still yet to be resolved. Thus, people are working to search new advance electrode materials to improve the low electrochemical conductivity as well as poor cycling stability. It was observed that many binary and ternary metal oxides and combination of metal oxides with Carbon based materials or conducting polymers can improve electrochemical performance. Among many binary and ternary metal oxides Ni-M-oxide (M= Mn, Co, Fe, Zn etc.) have attracted great attentions due to their natural abundance, low cost, easy synthesis technique, environmental friendliness and excellent electrochemical performance. In this work, we have synthesized Ni-Mn-Oxides with different molar ratios (Ni:Mn= 1:1, 1:2, 1:3 and 1:4) using easy sol-gel route and studied the overall electrochemical properties of these electrode materials. We have achieved a high specific capacitance value (1215 Fg-1 at scan rate 2mVs-1) along with low charge transfer resistance and long cycle life for the composite having Ni:Mn =1:3. This composite shows high surface area (127 m2 g-1) and large pore size (8.2 nm) distribution along with high electrical conductivity which can provide easy path for charge transport. RESULTS AND DISCUSSION Nanostructure studies of Ni-Mn-Oxides with different molar ratios (Ni:Mn = 1:1, 1:2, 1:3 and 1:4) were performed using XRD and FTIR spectroscopy. The morphological and surface areas with pore size studies have also been performed by field emission scanning electron microscopy (FESEM) and Brunauer–Emmett–Teller (BET) method. The electrochemical performance like CV, galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) of all electrode materials were carried out using three electrodes set up in 1 M Na2SO4 solution. The specific capacitance (Cm) for all electrode materials are calculated from the CV profiles, following the equation Cm = i/ 2mν, where m and ν are the mass of the electroactive material and potential scan rate and current (i) is obtained by integrating the area of the curves as it is defined by eq.(1), i=∫i(V)dv/(Vc -Va) , where va and vc are the lowest and highest voltage of the potential range. The electrochemical studies were shown in fig. 1. It was observed that the surface area as well as specific capacitance values of the materials increase with increase of Mn molar ratio upto (Ni:Mn= 1:3) and next decreased with increase of Mn. Morphological changes also observed with change of Fe-molar ratio. The maximum specific capacitance 1215 Fg-1 is achieved in 1M Na2SO4 solution in 2mVs-1 scan rate with molar ratio of Ni:Mn= 1:3. CONCLUSION The synthesized Ni-Mn-Oxides exhibit excellent electrochemical performance with high surface area and good stability. The overall studies on the electrochemical properties of the materials suggest that it can be used as energy storage application in future. ACKNOWLEDGMENTS Author A. Ray wish to thank Department of Science and Technology (D.S.T), INSPIRE, Govt. of India for financial support. REFERENCES S. Periyasamy et al., ACS Appl. Mater. Interfaces, 8, 12176–12185 (2016).B. E. Conway, J. Electrochem. Soc., 138, 1539 (1991) http://jes.ecsdl.org/cgi/doi/10.1149/1.2085829. Figure 1

Dielectric Polymers Prepared By Electropolymerizing of Nitrile-Based Anions

Electropolymerized dielectric polymer coats conductive surfaces like no other technique is capable of and thus various applications can be proposed, such as making a uniform dielectric coating for complex micro- or nanowires or even coating porous carbon. It is shown here that electrolytes containing nitrile-based anions, such as dicyanamide (DCA), tetracyanoborate (TCB), tricyanomethanide (TCM), or cyanate OCN are capable of producing thin polymeric layers when electropolymerized at positive voltages onto carbon, aluminum or other inert electrodes. Interestingly, reaction mechanisms are quite different, but all the polymers are inorganic nitriles, are insoluble in water or acetone, have no melting point and decompose only at temperatures > 300 oC. [1-3] The advantage of preparing a dielectric polymer by electrochemical deposition method was indicated in our paper [2], where large surface area graphene-based electrodes in 1-butyl-1-methylpyrrolidinium dicyanamide (BMPDCA) ionic liquid were coated with a thin polydicyanamide dielectric layer and used as high voltage supercapacitor electrodes. The new capacitor technology offers more than order of magnitude higher energy densities, compared to commercial tantalum and aluminum capacitors in the 4-10 V cell voltage range [2]. The protective self-healing nanolayer formed is a new carbon-nitrogen material polyDCA with dielectric constant value of 6 and dielectric strength of 250 MV m-1 (at 10 V). Good stability (>10000 cycles) and high efficiency (>99.8% coloumbic) have been demonstrated for the passivated reduced graphene oxide (RGO) electrodes. In the second paper [3] it was demonstrated that TCB-based electrolytes could be used as safe supercapacitor/battery electrolytes as these are protected against overvoltage by two mechanisms: Firstly, voltage (E) more positive than 2.2 V (vs. Ag|AgCl reference electrode) kills the conductivity of single layer graphene and electrochemical reactions stop. Secondly, at E > 2.2 V tetracyanoborate anion polymerizes to a dielectric polymer polyTCB, which electrically isolates graphite or porous carbon grains from current collectors. Differently from polyDCA, polyTCB forms faster and without formation of gasses at anode. Acknowledgments Authors would like to thank Estonian Ministry of Education and Research (institutional research project IUT20-13) and European Regional Development Fund (The Centres of Excellence TK117 and, TK141) for financial support.

(Invited) All-Solid Hybrid Energy Fabric for Wearable Electronics

The demand for wearable power sources has been growing rapidly in the modern era of portable electronics. It is essential to make these power sources more comfortable and fit for the human body, especially for some medical applications in which case we need to wear it day and night. Energy harvesting and storage devices in the form of a common-looking fabric is thus of a great interests in recent years. Herein, we have successfully woven out a type of micro-cable power textile for simultaneously harvesting energy from ambient sunshine and mechanical movement. Solar cells fabricated from lightweight polymer fibers into micro cables are then woven via a scalable shuttle-flying process with fiber-based triboelectric nanogenerators to create a hybrid energy harvesting fabric. The hybrid power fabric is just 320 µm thick, fabricated with a size of 4 cm by 5 cm, was demonstrated to charge a 2 mF commercial capacitor up to 2 V in 1 min under ambient sunlight in the presence of mechanical excitation, such as human motion and wind blowing. Based on the similar strategy, a novel solid solar energy harvesting and storage hybrid textile combining both photovoltaic cells and super-capacitors were also designed and realized, in order to provide power at dark condition within a single textile. With such features as low-cost, thinness, light-weight, being flexible and wearable, as well as colorful appearance, this work represents a significant step towards the development of large scale energy harvesting and storage for wearable electronics and self-powered home technology. Some recent publications were selected as “Research Highlights” by Nature and the “9 most impressive social innovation goods from October” of Yahoo News in 2016.

Electrocaloric effects in multilayer capacitors for cooling applications

Abstract