To date, ionic conducting hydrogel attracts tremendous attention as an alternative to the conventional rigid metallic conductors in fabricating flexible devices, owing to their intrinsic ...characteristics. However, simultaneous realization of high stiffness, toughness, ionic conductivity, and freezing tolerance through a simple approach is still a challenge. Here, a novel highly stretchable (up to 660%), strong (up to 2.1 MPa), tough (5.25 MJ m−3), and transparent (up to 90%) ionic conductive (3.2 S m−1) organohydrogel is facilely fabricated, through sol–gel transition of polyvinyl alcohol and cellulose nanofibrils (CNFs) in dimethyl sulfoxide‐water solvent system. The ionic conductive organohydrogel presents superior freezing tolerance, remaining flexible and conductive (1.1 S m−1) even at −70 °C, as compared to the other reported anti‐freezing ionic conductive (organo)hydrogel. Notably, this material design demonstrates synergistic effect of CNFs in boosting both mechanical properties and ionic conductivity, tackling a long‐standing dilemma among strength, toughness, and ionic conductivity for the ionic conducting hydrogel. In addition, the organohydrogel displays high sensitivity toward both tensile and compressive deformation and based on which multi‐functional sensors are assembled to detect human body movement with high sensitivity, stability, and durability. This novel organohydrogel is envisioned to function as a versatile platform for multi‐functional sensors in the future.
A polyvinyl alcohol/cellulose nanofibril organohydrogel with simultaneously improved strength, toughness, and ionic conductivity is rationally designed. The organohydrogel shows outstanding freezing tolerance while maintains high ionic conductivity (1.1 S m−1) at −70 °C due to the presence of high dielectric dimethyl sulfoxide‐water binary solvent. The organohydrogel demonstrates great promise in serving as multi‐functional sensors under extreme conditions.
•Crack may occur at the junction and the critical current deteriorates.•A very thin solder or a silver diffusion junction is necessary to recover it.•Trapezoid junction can reduce the stress at the ...junction.•FEM is useful to evaluate the electrical and mechanical properties at the junction.
In the present study, in order to clarify the electrical and mechanical properties of the junction of superconducting wires, a junction was numerically simulated using the finite element method, and the electrical and mechanical properties were evaluated. We used a 1 µm-thick YBa2Cu3O7−δ superconducting coated conductor to act as a superconducting wire and joined two films together for current density simulation. The magnetic field dependence of the critical current density is based on the experimental results for YBa2Cu3O7−δ. We introduced a crack in the superconducting junction and confirm that the critical current is drastically reduced by increasing the width of crack. We then attempted to reinforce the crack using solder and superconducting film. The effectiveness of reinforcement of Ic was clarified using very thin solder or a silver diffusion junction.
Many high-temperature superconductor (HTS) applications require superconducting cables with high currents while operating in an alternating magnetic field. HTS cables should be composed of numerous ...superconducting tapes to achieve the required current capacity. Alternating current and magnetic fields cause AC losses in such cables and can provoke conductor instability. AC losses and contact resistances were measured of several cable designs based on commercially available REBCO tapes at the University of Twente. The AC loss was measured under identical conditions for eight REBCO conductors manufactured according to three types of cabling methods-CORC® (Conductor on Round Core), Roebel, and stacked tape, including a full-size REBCO CICC (cable in conduit conductor). The measurements were done at T = 4.2 K without transport current in a sinusoidal AC magnetic field of 0.4 T amplitude and frequencies from 5 to 55 mHz. The AC loss was measured simultaneously by calibrated gas flow calorimeter utilizing the helium boil-off method and by the magnetization method using pick-up coils. Also, the AC loss of two CORC® conductors and a Roebel cable was measured at 77 K. Each conductor was measured with and without background field of 1 T. The measured AC coupling loss in the CORC® and Roebel conductors is negligible at 4.2 K for the applied conditions while at 77 K coupling loss was observed for all conductors. The absence of coupling loss at 4.2 K can be explained by shielding of the conductor interior; this is confirmed with measurement and calculation of the penetration field of CORC® and Roebel cables. The inter-tape contact resistance was measured for CORC® and stacked tape samples at 4.2 and 77 K. It was demonstrated that a short heat treatment of CORC® conductor with solder-coated tapes activates tape-to-tape soldering and decreases the contact resistance. The reduction of contact resistance by two orders in magnitude to tens of nΩm is comparable with the interstrand contact resistance in ITER Nb3Sn type conductors.
The lithium‐conducting, rare‐earth halides, Li3MX6 (M = Y, Er; X = Cl, Br), have garnered significantly rising interest recently, as they have been reported to have oxidative stability and high ionic ...conductivities. However, while a multitude of materials exhibit a superionic conductivity close to 1 mS cm−1, the exact design strategies to further improve the ionic transport properties have not been established yet. Here, the influence of the employed synthesis method of mechanochemical milling, compared to subsequent crystallization routines as well as classic solid‐state syntheses on the structure and resulting transport behavior of Li3ErCl6 and Li3YCl6 are explored. Using a combination of X‐ray diffraction, pair distribution function analysis, density functional theory, and impedance spectroscopy, insights into the average and local structural features that influence the underlying transport are provided. The existence of a cation defect within the structure in which Er/Y are disordered to a new position strongly benefits the transport properties. A synthetically tuned, increasing degree of this disordering leads to a decreasing activation energy and increasing ionic conductivity. This work sheds light on the possible synthesis strategies and helps to systematically understand and further improve the properties of this class of materials.
A study on the influence of the synthesis method on the occurring structural disorder demonstrates that the rare‐earth‐cation disorder within the Li3(Y, Er)Cl6 material system can be engineered to enhance the resulting ionic transport properties. Mechanochemical synthesis, when compared to classic solid‐state syntheses, increases this site disorder, leading to an enhancement of ionic transport properties.
Here, we report an oxygen ion-proton-electron-conducting nanocomposite, BaCo0.7(Ce0.8Y0.2)0.3O3-δ (BCCY), derived from a self-assembly process, as a high-performance protonic ceramic fuel cell (PCFC) ...or mixed O2−/H+ dual-ion conducting fuel cell (dual-ion FC) cathode. Self-assembly during high-temperature calcinations results in the formation of a nanocomposite consisting of a mixed H+/e− conducting BaCexYyCozO3-δ (P-BCCY) phase and mixed O2−/e− conducting BaCoxCeyYzO3-δ (M-BCCY) and BaCoO3-δ (BC) phases. The interplay between these phases promotes the oxygen reduction reaction (ORR) kinetics of this composite cathode and improves its thermo-mechanical compatibility by tempering the mismatch in thermal expansion coefficient (TEC). When tested as the cathode in anode-supported dual-ion FCs and PCFCs, peak power densities (PPDs) of 985 and 464 mW cm−2, respectively, are achieved at 650°C while maintaining a robust operational stability of 812 h at 550°C. This material is ideally suited for high-performance cathodes for PCFCs and dual-ion FCs, greatly accelerating the commercialization of this technology.
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•A multi-phase nanocomposite PCFC cathode is derived from the self-assembly process•The nanocomposite shows sufficient oxygen ion, proton, and electron conductivity•Direct experimental measurement method is shown for specific proton conductivity values•The interplay in multi-phase promotes ORR kinetics and reduces thermal expansion
Protonic ceramic fuel cells (PCFCs) have attracted more attention than solid oxide fuel cells based on oxygen-ion-conducting electrolytes that operate at intermediate temperatures due to the lower activation energy for proton conduction than for oxygen ions in oxide electrolytes. However, the practical application of PCFC technology is hindered by the lack of suitable cathode materials. Here, we report our rationally designed triple conducting nanocomposite cathode BaCo0.7(Ce0.8Y0.2)0.3O3-δ with sufficient oxygen ion-proton-electron transfer capability for PCFCs. This work develops the highly active and stable cathode material and simultaneously measures the specific values of oxygen ion, proton, and electron conductivity of the cathode material. This work also highlights the design strategy of perovskite-based electrocatalysts for other energy conversion and storage systems such as water splitting, metal-air batteries, and dye-sensitized solar cells.
A nanocomposite cathode is composed of a mixed H+/e− conducting BaCexYyCozO3-δ (P-BCCY) phase, a mixed O2−/e− conducting BaCoxCeyYzO3-δ (M-BCCY) phase, and a mixed O2−/e− conducting BaCoO3-δ (BC) phase. The P-BCCY phase could promote proton diffusion, the M-BCCY phase could facilitate oxygen ion diffusion, and the BC phase could enhance the electronic conduction of the electrode; the interfaces between the three phases in nano-domain greatly increases the number of active sites for electrochemical reactions.
Proton-conducting solid oxide electrolysis cells (H-SOECs) are attracting attentions of researchers due to their unique advantages. The proton-conducting material BaCe0·7Zr0·1Y0.1Yb0.1O3-δ (BZCYYb) ...has both the advantages of barium ceria-based and barium zirconate-based materials. BZCYYb material usually is synthesized by solid-state reaction (SSR) method, hence the densification of this electrolyte material is the key to restrict the application of H-SOECs. In this paper, effects of adding 1 wt% of different sintering aids (NiO, CuO, ZnO) to BZCYYb on the grain size and the conductivity are investigated. After adding 1 wt% of NiO and CuO sintering aids, BZCYYb electrolyte achieves ideal density. The electrical conductivity of four samples (BZCYYb without adding sintering aid, BZCYYb with 1 wt% NiO, CuO, ZnO, respectively) is tested under different steam concentrations of air, nitrogen, hydrogen, and nitrogen-hydrogen mixture. The conductivity increased after the sintering aid is added. With the increase of steam concentration, the conductivity decreased slightly and then increased due to electron holes under oxygen atmosphere with steam at high temperature. In other atmospheres, the conductivity increases with the steam concentration. In the atmosphere of 20 vol% H2O-Air and H2, the conductivity of the BZCYYb samples with 1 wt% CuO is about 1.087 × 10−2 S cm−1 and 9.02 × 10−3 S cm−1 at 650 °C, and the conductivity of the BZCYYb samples with 1 wt% NiO is 1.277 × 10−2 S cm−1 and 8.24 × 10−3 S cm−1, respectively. However, compared with NiO, CuO has advantages in promoting hydration reaction and proton conduction of BZCYYb electrolyte.
•1 wt% NiO, CuO and ZnO will be used as sintering aids during the process of BZCYYb sintering.•In the hydrogen atmosphere, BZCYYb-1%CuO and BZCYYb-1%ZnO have relatively high conductivity.•In the air atmosphere, BZCYYb-1%NiO and BZCYYb-1%ZnO have relatively high conductivity.•After adding 1 wt% of NiO and CuO sintering aids, BZCYYb electrolyte achieves ideal density.•CuO sintering aid is good choice for the electrolyte of H-SOEC.
Distribution system state estimation (DSSE) has recently been tested and experimentally deployed in some practical distribution networks. Distinct features of distribution systems, such as diverse ...and unsymmetrical configurations as well as limited real-time measurements, prohibit the direct application of mature state estimation methods for transmission systems. Targeting at three-phase four-conductor configured unsymmetrical medium-voltage distribution systems (MDS) with neutral conductors and ground resistances, this paper proposes a weighted least square-based DSSE approach, in which voltages are chosen as state variables and load pseudo measurements of low-voltage distribution systems (LDS) are considered to compensate insufficient real-time measurements in MDS. Both rectangular and polar coordinates are studied, and voltage variables of neutrals and zero-injection phases are eliminated to reduce the scale of the DSSE problem. Moreover, in order to enhance the load pseudo measurement accuracy of LDSs, a clustering and partial least square regression-based load estimation model is proposed to leverage the real-time communication ability of smart meters. Case studies on a modified IEEE 123-bus distribution system with actual smart meter data illustrate the effectiveness of the proposed approaches.
Electricity transmission is an essential intermediary linking power generation and distribution. Voltage drops or total blackouts have always characterized the transmission and distribution of ...electricity in the sub-Saharan Africa and some Asian dwellers. This has been attributed partly to faulty, defective or dilapidated transmission conductors/networks. The aim of this study is to identify the causes of those defects in the transmission conductors and proffer possible remedies to them. Studies have shown that the current production techniques of transmission conductors (TCs) generate defective products, and that the materials used have their own challenges too. This work, therefore, reviewed all the production techniques and materials used in the development of TCs. It was observed that pultrusion, extrusion, hot-rolling, and stir-casting were the techniques used in the production of transmission conductors. Defects such as shrinkage, pores, impurities, and warps were identified in those techniques and some recommendations to ameliorate the defects of those techniques were presented. Spark plasma sintering is recommended as the most promising solid- state production techniques that should be adopted in fabricating transmission conductors, though it is yet to be developed for producing long-span products. In addition, advanced TCs materials such as Al-CNTs, Al-Nb, Al-Ti, and Al-B2 were presented as better alternatives to the existing TCs materials. By producing TCs with the recommended techniques and materials, the electricity availability will be enhanced; and this will lead to sustainable industrial growth and economic stability in the third world countries and the entire world.
Lithium‐metal electrodes have undergone a comprehensive renaissance to meet the requirements of high‐energy‐density batteries due to their lowest electrode potential and the very high theoretical ...capacity. Unfortunately, the unstable interface between lithium and nonaqueous electrolyte induces dendritic Li and low Coulombic efficiency during repeated Li plating/stripping, which is one of the huge obstacles toward practical lithium‐metal batteries. Here, a composite mixed ionic/electronic conductor interphase (MCI) is formed on the surface of Li by in situ chemical reactions of a copper‐fluoride‐based solution and Li metal at room temperature. The as‐obtained MCI film acts like the armor of a soldier to protect the Li‐metal anode by its prioritized lithium storage, high ionic conductivity, and high Young's modulus. The armored MCI can effectively suppress Li‐dendrite growth and work effectively in LiNi0.5Co0.2Mn0.3O2/Li cells. The armored MCI presents fresh insights into the formation and regulation of the stable electrode–electrolyte interface and an effective strategy to protect Li‐metal anodes in working Li‐metal batteries.
A composite mixed ionic/electronic conductor interphase (MCI) is formed on the surface of lithium by in situ chemical reactions of copper‐fluoride‐based solution and Li metal at room temperature. The as‐obtained MCI film acts like the armor of a soldier to protect the Li‐metal anode by its prioritized lithium storage, high ionic conductivity, and high Young's modulus.
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