Highly concentrated electrolytes (HCEs), created simply by increasing the lithium salt concentration from the conventional 1 M to 3–5 M, have been suggested as a path towards safer and more stable lithium batteries. Their higher thermal and electrochemical stabilities and lower volatilities are usually attributed to the unique solvation structure of HCEs with not enough solvent available to fully solvate the Li+ ions—but much remains to be understood. Here the structural features that characterize the behavior of electrolytes in general and HCEs in particular, and especially the transition from conventional to highly concentrated behavior, are reported for lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in acetonitrile (ACN), a common HCE system. We analyze four different salt concentrations using ab initio molecular dynamics (AIMD) and the CHAMPION software, to obtain trends in global and local structure, as well as configurational entropy, to elucidate what truly sets apart the highly concentrated regime.

A highly sensitive respirometric method is presented that allows real-time monitoring of reaction rates involving H2 and O2 during electrochemical polarization. The measurement approach is based on simultaneous monitoring of the changes in the total pressure and the O2 partial pressure inside a closed chamber. Hence, it is possible to quantify the rates resulting from reactions such as HER, ORR and OER as a function of the applied potential. As a result, deconvolution of the net electric current into cathodic and anodic partial reaction rates during electrochemical polarization can be obtained. It was demonstrated that the respirometric monitoring approach can reveal superfluous cathodic reactions from Al during cathodic polarization as well as during anodic polarization of Al and Mg AZ31. Thus, the true metal oxidation rate could be determined from the electric current and the cathodic reaction rates. Furthermore, the rate of the HER during cathodic electrodeposition of Zn was measured. Through respirometric monitoring of Ni and stainless steel at high anodic potentials, the rate of O2 evolution could be distinguished from electrode oxidation processes.

Voltammetry studies of electrodeposition are growing rapidly. Yet, relations for the analysis of electrodeposition reactions in voltammetry remain relatively obscure in the literature. The existing cyclic and square wave voltammetry relations for electrodeposition and their limitations are discussed to increase awareness. A retrospective analysis is performed to demonstrate the impact of model selection in improving the analysis of electrodeposition behavior with voltammetric data. A repository for voltammetry models of electrodeposition is proposed to further increase familiarity and application of the most appropriate models, which would support a rapidly growing area of research and technological development.

Anodic oxidation of PhTeR (R = CF3CH2, CF2H, Me, Ph) was carried out in methanol containing various supporting electrolytes (YO− M+) such as p-tosylate, benzenesulfonate, acetate, and benzoate salts using a divided cell to provide the corresponding hypervalent tellurium compounds such as monomeric PhRTe(OY)2 and dimeric PhR(OY)Te–O–TePhR(OY) predominantly in moderate to good yields.

Novel bifunctional polyhedral oligomeric silsesquioxane (Vi-POSS-SO3Na) and a surface densification method to fabricate the composite membrane based on sulfonated poly (fluorenyl etherketone) (SPFEK) was firstly reported for the application in direct methanol fuel cells (DMFCs). Firstly, the synthetic Vi-POSS-SO3Na implants on the SPFEK surface by swelling-filling process. Afterward, the vinyl groups on POSS are cross-linked to form a dense X-POSS layer on the membrane surface by a simply thermal treatment which is called surface densification. The crosslinked dense X-POSS with sulfonated groups on the composite membrane surface can effectively prevent the permeation of methanol and enhance the oxidative stability without the sacrificing proton conductivity. The SPFEK/POSS-0.09 membrane with an area loading of 0.09 mg cm−2 POSS exhibits enhanced oxidative stability and the lowest methanol permeability (2.12 × 10−8 cm2 s−1). Direct methanol fuel cell was assembled and its performance was evaluated. The peak power density using SPFEK/POSS-0.03 membrane reaches 65.1 mW cm−2 that is much higher than the one (24.8 mW cm−2) using pristine SPFEK membrane at 80 °C. The results demonstrate that the surface densification is an effective method to suppress methanol crossover and surface-densified SPFEK/POSS proton exchange membrane with X-POSS layer has improved the comprehensive performance of composite membrane.

Electric vehicle batteries must possess fast rechargeability. However, fast charging of lithium-ion batteries remains a great challenge. This paper develops a feature-driven closed-loop optimization (CLO) methodology to efficiently design health-conscious fast-charging strategies for batteries. To avoid building an early outcome predictor, the feature highly related to battery end-of-life is used as the optimization objective instead of using the predicted lifetime. This feature is extracted from the battery’s early cycles and the experimental cost is thus reduced. By developing closed-loop multi-channel experiments with Bayesian optimization (BO), the optimal charging protocols with long cycle lives are located quickly and efficiently among 224 four-step, 10 min fast-charging protocols. Experimental results show that BO performs well with different acquisition functions, and a minimum of 12 paralleled channels for each round of experiments are recommended to obtain stable optimization results. Compared with the benchmark, the developed method recommends similar fast-charging protocols with long cycle lives based on much less experimental cost.

Electrolytic reduction technology plays a significant role in industrial metal production. In present work, cyclic voltammetry (CV) and square wave voltammetry (SWV) were applied to study the electrochemical behaviors of ZnO cathode in the CaCl2-NaCl melt at 873 K. During the experiment, we found that the dissolution-electrodeposition mechanism (ZnO = Zn2+ + O2−, Zn2+ + 2e− = Zn) dominates the electrolytic reduction of ZnO, and the contribution of the direct-reduction from solid phase (ZnO + 2e− = Zn + O2−) is small. Furthermore, the electro-reduction of ZnO was conducted by potentiostatic electrolysis. The peak potential of ZnO to Zn was −0.48 V vs Ag/Ag+. Therefore, the metallic Zn can be obtained at an applied potential of −0.80 V (vs Ag/Ag+). When the applied potential increased to −2.00 V (vs Ag/Ag+), the Zn and CaZn3 alloy were formed simultaneously. The electrolytic products were confirmed by X-ray diffraction (XRD) analysis. This study proved the feasibility of electro-reduction technology to prepare Zn metal through the reduction of ZnO material.

This work applies machine learning to holistically interrogate the influence of metallurgical factors, such as chemical composition, heat treatment, and mechanical properties, on the stress corrosion cracking resistance of corrosion-resistant alloys. Particularly, we explored the effect of nickel in reducing the stress corrosion cracking susceptibility in boiling magnesium chloride, arguably a controversial topic since Copson’s 1959 seminal publication. This paper offers insights into the synergies of nickel with other alloying elements that ultimately impact the resistance to stress corrosion cracking. Furthermore, a more detailed description of statistical patterns in the so-called Copson curve is provided.

Anodized aluminum oxide (AAO) has been used as nanotemplates for nanomaterials and nanodevice fabrications. Microfabrication techniques are attracting attention for nanodevice synthesis. However, AAO requires a microfabrication-compatible substrate due to its brittleness. While there are studies that already show AAO on compatible substrates, the pore sizes may not be applicable for multicomponent nanodevices. In this study, wide pore AAOs with ohmic bottom contacts are fabricated on 76 mm Si wafers. Sputtering was used to deposit Al along with supporting layers to achieve this goal. A quiescent electropolishing technique was used to smooth the surface of Al. Standard photolithography was used to define the active area on the Al for anodization. Then 195 V two-step anodization was performed to fabricate wide pore AAOs with pore diameters ranging from 130 ± 32 nm to 400 ± 31 nm with interpore distance of 480 ± 47 nm. It also showed that the ordering of the pores depended on the current density over the more conventional anodization time.

The discharge process of Nb(IV) complexes to Nb was studied by cyclic voltammetry. A galvanostatic electrolysis with the cathodic current density of 1.5·10−2 A cm−2 in the NaCl–KCl–NaF–K2NbF7 melt in contact with Nb anode was used for deposition of niobium coatings on the cryogyroscope rotor at temperature 1023 K, and time of process from 8 to 12 h. The coatings were continuous and smooth due to the special design of the cathode. The rotation speed of the stirrer was set to 35 rpm and did not change in all experiments. Such conditions made it possible to obtain coatings with the thickness up to 150 μm. The main characteristics of the niobium coatings such as purity, roughness, nonsphericity, and superconductivity were investigated.

Recent years, electric vehicles gradually become popular, but their cruising range has become one of the main problems that plague car companies and users. The lithium-rich manganese-based cathode material batteries with higher energy density stand out. The state of charge is an important parameter. This paper selects a 19Ah lithium-rich manganese-based cathode material battery for research, using extended Kalman filter based on second-order Equivalent circuit model estimate its state of charge. However, the impedance spectrum of lithium-rich manganese battery is different from that of 18650 lithium-ion battery, and the second-order equivalent circuit model will have errors, resulting in the low accuracy of SOC estimation. In order to solve this problem, this paper proposes two schemes: EKF-LSTM and LSTM-EKF. The whale optimization algorithm (WOA) is used to select the preset parameters. The results show that the LSTM-EKF method has the highest estimation accuracy, with a maximum error of 1.46%.

An integrated combinatorial synthesis, characterization, and testing methodology and platform is proposed and developed for high-throughput exploration of Li-ion rechargeable battery cathode chemistries. This article describes the design of the platform’s combinatorial synthesis part and its prototype performance. A key design element is a multi-gear powertrain with a unique milling-force adjustable pestle that ensures high compatibility with varying types of electrode materials. To demonstrate the prototype, LiNiO2 was prepared via a solid-state route under various operating conditions. We evaluated the effects of processing parameters, including milling force and mixing speed, on the synthesized electrode’s physical properties and electrochemical behavior. The synthesized LiNiO2 materials show excellent electrochemical performance comparable to manually synthesized LiNiO2.

Electromotive force (emf) measurements made using a combination of solute- and solvent-based electrodes were used to determine the activity of NiF2 in molten FLiNaK eutectic at 823 K across a concentration range of x NiF2 = 5.2 × 10–4–1.0 × 10–2. The solute emf values were measured using electrodes consisting of Ni wires immersed in FLiNaK with dissolved NiF2 contained in graphite crucibles. The measured emf values were then converted to the FLiNaK Eutectic Potassium Electrode (FEKE) potential and used to quantify the activity of dissolved NiF2. This quantification was based upon comparative measurements of a reference solvent electrode consisting of a K-Bi alloy immersed in pure FLiNaK contained in a boron nitride crucible and a solute electrode. Short cell lives were characteristic of the measurements due to the corrosive nature of the fluoride salts. Quantifying the activity of NiF2 will improve the utility of Ni2+/Ni reference electrodes in molten fluoride salts, which are notoriously difficult electrolytes to work with because of their reactivity. This work demonstrates the general nature of the solute-solvent approach as a repeatable, easily employed method for measuring the activity values of electroactive species in a variety of molten salts to improve understanding of the electroactive species behavior in these systems.

The battery state of charge (SOC) and capacity are important state management indicators of the battery management system, and their estimation accuracy directly affects the safety of power battery use and the driver’s driving experience. Since the increment change rate of the estimated variable can reflect the changing trend of the estimated variable, an extended Kalman filter algorithm based on the increment change rate is proposed in this paper, on this basis, an adaptive double-extended Kalman filter algorithm based on incremental change rate is constructed for the co-estimation of SOC and capacity of batteries. The tests under various operating conditions show that the target algorithm proposed in this paper has greater advantages over the traditional adaptive double-extended Kalman filter algorithm, and the maximum absolute error value (MAE) and root mean square error (RMSE) of the target algorithm can be reduced by 36.3% and 74.4% (SOC), 95.5% and 97.6% (capacity) compared with the traditional adaptive double-extended Kalman filter algorithm under DST operating conditions; The MAE and RMSE of the target algorithm can be reduced by 79.1% and 92.3% (SOC), 95.4% and 96.2% (capacity) under BBDST operating conditions.

Two-dimensional (2D) perovskite light emitting diodes (LEDs) with violet emission were demonstrated with areal sizes in the centimeter scale. High-quality and uniform 2D BA2PbBr4 thin film was synthesized via combined thermal evaporation, spin-coating, and anti-solvent techniques. The perovskite film was authenticated by X-ray diffraction, scanning electron microscopy, and atomic force microscopy and exhibited high in crystallinity and morphology. The absorption spectrum fitted using Tauc plot revealed a bandgap of ∼3.0 eV, which agrees well with the photoluminescence spectrum. A p-i-n diode structure with a BA2PbBr4 active area of ∼2 cm2 was fabricated using LiF, TmPyPb, and PEDOT:PSS as the electron injection, electron, and hole transport layers, respectively. The device displayed a diode behavior with a turn-on voltage at 1.75 V and a saturation current of 65 mA cm−2. The electroluminescence of LEDs was centered at ∼406 nm with full width at half maximum of 13.6 nm, a color purity of 83.9%, and CIE coordinates of (0.18, 0.07). The optimum external quantum efficiency and luminance of 0.083% and 112 cd m−2 were achieved at current density of 59 mA cm−2. To our best knowledge, this investigation first realized 2D BA2PbBr4 perovskite LEDs with the shortest emission wavelength and high color purity in violet.

The development of high efficiency energy storage systems is increasingly important as these systems enable utilize energy from renewable sources and reduce greenhouse gas evolution caused by fuel combustion technologies at the same time. Electrochemical characteristics of Zn-ion hybrid supercapacitor (ZIHS) cells based on 1 M acetonitrile and propylene carbonate electrolytes in zinc tetrafluoroborate (Zn(BF4)2), zinc di[bis(trifluoromethylsulfonyl)imide] (Zn(TFSI)2) and zinc trifluoromethanesulfonate (Zn(OTf)2) have been studied using cyclic voltammetry, constant current charge/discharge and electrochemical impedance methods. The Ragone plots have been calculated from constant power measurement data. Very high energy and power densities (80 Wh kg−1 and 21.2 kW kg−1) have been calculated for 1 M Zn(BF4)2/AN based Zn-ion hybrid supercapacitor. Some assembled ZIHSs had shown excellent cycling and energy stability over 20000 cycles.

Scalable energy conversion/storage by water splitting is significantly hindered by the slow kinetics of oxygen evolution reaction (OER). Implementation of electrochemical catalysts with low cost and high turn-over efficiency, or application of a photoanode in photoelectrochemical (PEC) cell using a semiconductor with proper protection layer are two possible solutions. Herein, two binary Iron-group alloy films (Ni-Co and Ni-Fe) and one ternary Iron-group alloy film (Ni-Co-Fe) under self-limiting deposition condition are investigated and continuous ultrathin films with various composition are generated. The self-limiting deposition, corroborated by XPS depth profile, is caused by the precipitation of hydroxide/oxyhydroxide species under high local pH, enabled by the privation of pH buffer species. Each binary and ternary Iron-group mutual alloy films exhibits improved water oxidation kinetics compared to pure i or Co film. In particular, an overpotential of 0.314 V at 10 mA cm−2 and a Tafel slope of 34.7 mV dec−1 are obtained on the Ni-Fe-Co film. The Iron-group mutual alloy deposited GaAs is further investigated for photoelectrochemical water oxidation. The stability towards photocorrosion under the light in an aqueous solution containing K3Fe(CN)6/K4Fe(CN)6 is significantly improved by electrodepositing the mutual alloy films while the optimum stability property is found on the ternary alloy film.

Herein, we report the investigations on the electrochromic properties of nebulized-spray deposited Mn3O4 thin films in Na2SO4 aqueous solution as a function of molar concentration, for the first time. Phase analysis reveals that the films possess a tetragonal structure. From the Raman study, strong Mn2+ breathing vibration (in Mn–O) occurred in tetrahedral sites (of spinel Mn3O4). At 0.02 M, the film surface is covered with very-tiny particles with 84% highest optical transparency average. Both transmittance and absorbance related properties of electrochromic states are consider here, while introducing the notions of transmittance modulation (ΔT), absorbance modulation (ΔA), transmittance modulation efficiency (TME) and absorbance modulation efficiency (AME (or) coloration efficiency). When the concentration increases, the red shift was occurred at highest peaks of ΔT, ΔA, TME and AME with respect to the decrease in optical band gap. The maximum AME and TME of 25.064 cm2 C−1 (at 369.1 nm) and 17.542 cm2 C−1 (at 438.6 nm) were obtained for prepared samples. After the 100th cycle, the average AME (and TME) values in the UV and visible regions are decreases from 18.910 to 2.783 cm2 C−1 (2.884 to 1.060 cm2 C−1) and from 11.089 to 4.772 cm2 C−1 (11.346 to 4.684 cm2 C−1), respectively, indicating that the film is electrochromically active in the visible region even after the 100th cycle.

Zinc metal has emerged as seeded anode material in the field of high-efficiency aqueous metal-air battery system due to the advantages of abundant reserves, strong reversibility and high capacity. Unfortunately, the conventional zinc electrodes commonly adopt a flat structure, and the dendrite accumulation and corrosion during the cycle process lead to sub-optimal efficiency and performance. Herein, the zinc electrode is designed as a three-dimensional (3D) spiral structure to improve the utilization efficiency of zinc and the quality of the battery. Compared with the zinc plate, the 3D spiral zinc electrode can shorten the movement distance of the particles in space and the operation period in time, increase the specific surface area of the reaction, reduce the resistance of mass and charge transfer, and achieve the effect of optimizing the performance of the battery system. The results show that the aqueous zinc-air battery made of 3D spiral zinc electrode exhibits better charge-discharge characteristics, higher power density and narrower voltage windows. This study demonstrates a zinc anode with simple feasibility properties and a special structure, aiming to provide a new research direction and innovation strategy for the development of high-performance rechargeable zinc-air battery systems.

Plasma electrolytic polishing (PEP) is widely used in the finishing process of metallic parts. Some parts with narrow structures always suffer from surface quality deterioration in the PEP process. In this paper, the deterioration of surface quality was studied to reveal the vapor film evolution mechanism during the polishing. The conditions for the bump defects generation were investigated with the comparison of polished surface morphology under different voltages and immersion depths. The reasons for the bump defects generation were analyzed through the compositions, the chemical states of the elements, and the microstructure of bump defects. The relationship between the current density, the thickness of the vapor film, and the heat to maintain the vapor film was discussed. The vapor film was maintained by Joule heat generated by itself. During the PEP process, excessive current density on the anode surface made the vapor film thickness greater than the critical value of heat could maintain, leading to the collapse of the vapor film. The anode then came into partial contact with the electrolyte, resulting in bump defects. As a result, it is suggested that the thickness of the vapor film be reduced to prevent the surface quality of narrow structures from deteriorating.