Electrolytic Environment Research Articles

New Redox Chemistries of Halogens in Aqueous Batteries.

Halogen-based redox-active materials represent an important class of materials in aqueous electrochemistry. The existence of versatile halogen species and their rich bonding coordination create great flexibility in designing new redox couples. Novel redox reaction mechanisms and electrochemical reversibility can be unlocked in specifically configurated electrolyte environments and electrodes. In this review, the halogen-based redox couples and their appealing redox chemistries in aqueous batteries, including redox flow batteries and traditional static batteries, that have been studied in recent years are discussed. New aqueous electrochemistry provides hope to outperform the state-of-the-art materials and systems that are facing resources and performance limitation, and to enrich the existing battery chemistries.

High-Resolution Distance Dependence Interrogation of Scanning Ion Conductance Microscopic Tip-Enhanced Raman Spectroscopy Enabled by Two-Dimensional Molybdenum Disulfide Substrates.

Scanning ion conductance microscopy (SICM) is a powerful surface imaging tool used in the electrolytic environment. Tip-enhanced Raman spectroscopy (TERS) can give more information in addition to the morphology provided by the SICM by utilizing label-free Raman spectroscopy aided by the localized plasmonic enhancement from the metal-coated probes. In this study, the integration of SICM with TERS is demonstrated through employing a silver-coated plasmonic nanopipette. Leveraging a two-dimensional (2D) molybdenum disulfide (MoS2) as a model system, the SICM-TERS enhancement factor was estimated to be ∼105, supported by finite-difference time-domain (FDTD) simulation. Moreover, the subnanometer distance dependence SICM-TERS study reveals the tensile stress and structural changes caused by the nanopipette. These findings illustrate the potential of SICM-TERS for providing comprehensive morphological and chemical insights into electrolytic environments, paving the way for future investigations of electrocatalytic and biological systems.

NiCoMn phosphides-based 3D nanoflowers as universal electrocatalyst towards hydrogen evolution reaction at all pH values

In addressing the pH constraints encountered in real-world electrolyte environments, it is of great practical significance to establish a universal electrocatalyst capable of facilitating the hydrogen production reaction (HER) across all pH levels. Herein, non-precious metals NiCoMn were incorporated into a nickel foam skeleton and subjected to phosphorization treatment, yielding the NiCoMn-O-P@NF catalyst suitable for HER across the entire pH spectrum. Leveraging the synergistic effects of these three metals and phosphating regulation, the synthesized NiCoMn-O-P@NF demonstrates efficient HER catalytic performance in acidic (−0.05 VRHE at 10 mA cm−2), alkaline (−0.17 VRHE at 10 mA cm−2), and neutral (−0.25 VRHE at 10 mA cm−2) electrolytes, with exceptional stability. This study presents a cost-effective electrocatalyst with robust and enduring catalytic performance for HER over the full pH range, offering an environmentally friendly solution to the challenges of practical hydrogen generation.

Corrosion behavior of 70/30 cupronickel in electrolytic seawater antifouling environment

Available chlorine is most commonly used in seawater cooling systems to eliminate biofouling. The corrosion behavior of 70/30 cupronickel alloy after exposure to seawater with different concentrations of available chlorine was studied by electrochemical and immersion tests. The electrochemical measurements show that 100 ppm available chlorine accelerates the corrosion of 70/30 cupronickel alloy in seawater. The corrosion rate of 70/30 cupronickel sample in seawater with 100 ppm available chlorine is 3–4 times higher than that in seawater with 0–10 ppm available chlorine. Scanning Kelvin probe (SKP) and scanning vibrating electrode technique (SVET) results demonstrate that the local electrochemical reaction of 70/30 cupronickel alloy is more active after soaking in seawater with 100 ppm available chlorine. Energy dispersive spectroscopy (EDS) results reveal that Cl element in the corrosion products is enriched after exposure to seawater with 100 ppm available chlorine. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the corrosion product of 70/30 cupronickel sample contains more Cu2(OH)3Cl after being immersed in seawater with 100 ppm available chlorine.

Optoelectronic synapses with chemical-electric behaviors in gallium nitride semiconductors for biorealistic neuromorphic functionality

Optoelectronic synapses, leveraging the integration of classic photo-electric effect with synaptic plasticity, are emerging as building blocks for artificial vision and photonic neuromorphic computing. However, the fundamental working principles of most optoelectronic synapses mainly rely on physical behaviors while missing chemical-electric synaptic processes critical for mimicking biorealistic neuromorphic functionality. Herein, we report a photoelectrochemical synaptic device based on p-AlGaN/n-GaN semiconductor nanowires to incorporate chemical-electric synaptic behaviors into optoelectronic synapses, demonstrating unparalleled dual-modal plasticity and chemically-regulated neuromorphic functions through the interplay of internal photo-electric and external electrolyte-mediated chemical-electric processes. Electrical modulation by implementing closed or open-circuit enables switching of optoelectronic synaptic operation between short-term and long-term plasticity. Furthermore, inspired by transmembrane receptors that connect extracellular and intracellular events, synaptic responses can also be effectively amplified by applying chemical modifications to nanowire surfaces, which tune external and internal charge behaviors. Notably, under varied external electrolyte environments (ion/molecule species and concentrations), our device successfully mimics chemically-regulated synaptic activities and emulates intricate oxidative stress-induced biological phenomena. Essentially, we demonstrate that through the nanowire photoelectrochemical synapse configuration, optoelectronic synapses can be incorporated with chemical-electric behaviors to bridge the gap between classic optoelectronic synapses and biological synapses, providing a promising platform for multifunctional neuromorphic applications.

Physical insight into the enhanced urea electrooxidation using Ni and Fe-based LDH, LDO, and hydroxides under different dissolved gas saturation conditions in electrolyte

The production of green hydrogen is one of the most demanding and challenging for modern technology. A promising and an effective approach is electrocatalytic anodic urea oxidation reaction to generate hydrogen at cathode under alkaline electrolysis condition. However, it remains crucial for the development of active and stable electrocatalysts for efficient urea oxidation. In this study, we employed the hydrothermal synthesis route for NiFe LDH, NiFe LDO, and Ni(OH)2. The superior performance of NiFe LDH compared to other catalysts is observed due to easy charge transfer facilitated by Fe ions. Moreover, Fe incorporation prevents surface poisoning of the electrocatalyst, resulting in increased activity and stability for electrocatalytic urea oxidation reaction. The influence of different electrolyte environments on the performance of urea-based electrolyzers for sustainable hydrogen production and management of urea-rich wastewater has been measured for the first time by varying oxygen saturation and nitrogen purging conditions. In cyclic voltammetry studies, O2-saturated and purging conditions outperformed N2 gas saturation or purging. The findings of this study provide valuable insight into the design of practical and environmentally friendly urea electrooxidation systems.

Investigation into the Electrochemical Corrosion Characteristics of As-Built SLM Ti-6Al-4 V Alloy in Electrolytic Environments

Investigation into the Electrochemical Corrosion Characteristics of As-Built SLM Ti-6Al-4 V Alloy in Electrolytic Environments

Revealing Ion Adsorption and Charging Mechanisms in Layered Metal-Organic Framework Supercapacitors with Solid-State Nuclear Magnetic Resonance.

Conductive layered metal-organic frameworks (MOFs) have demonstrated promising electrochemical performances as supercapacitor electrode materials. The well-defined chemical structures of these crystalline porous electrodes facilitate structure-performance studies; however, there is a fundamental lack in the molecular-level understanding of charge storage mechanisms in conductive layered MOFs. To address this, we employ solid-state nuclear magnetic resonance (NMR) spectroscopy to study ion adsorption in nickel 2,3,6,7,10,11-hexaiminotriphenylene, Ni3(HITP)2. In this system, we find that separate resonances can be observed for the MOF's in-pore and ex-pore ions. The chemical shift of in-pore electrolyte is found to be dominated by specific chemical interactions with the MOF functional groups, with this result supported by quantum mechanics/molecular mechanics (QM/MM) and density functional theory (DFT) calculations. Quantification of the electrolyte environments by NMR was also found to provide a proxy for electrochemical performance, which could facilitate the rapid screening of synthesized MOF samples. Finally, the charge storage mechanism was explored using a combination of ex-situ NMR and operando electrochemical quartz crystal microbalance (EQCM) experiments. These measurements revealed that cations are the dominant contributors to charge storage in Ni3(HITP)2, with anions contributing only a minor contribution to the charge storage. Overall, this work establishes the methods for studying MOF-electrolyte interactions via NMR spectroscopy. Understanding how these interactions influence the charging storage mechanism will aid the design of MOF-electrolyte combinations to optimize the performance of supercapacitors, as well as other electrochemical devices including electrocatalysts and sensors.

Electrochemical, Structural, and Hyperspectral Imaging Investigation of Bifunctional Zn-Air Battery Gas-Diffusion Electrodes

Rechargeable Zinc-air batteries (RZAB) emerge as highly promising solutions for electrochemical energy storage (EES) applications. Nevertheless, a noteworthy drawback in the existing generation of these batteries lies in the air gas-diffusion electrode (GDE). This component grapples with issues related to both efficiency and durability. In response to this challenge, our research is concentrated on the creation of a novel GDE, accompanied by an in-depth examination of its electrochemical, structural, and compositional characteristics. The primary objective is to comprehensively assess the physico-chemical factors that exert an influence on its efficiency and durability. In the case of the present research, two different catalysts were chosen for the ORR (discharge) and OER (charge) electrocatalysis, namely α-MnO2 nanorods (NR) and Ni nanoparticles (NP), respectively. The GDEs were produced by applying a water-based catalyst ink, augmented with PTFE and C-black, through spray-coating onto a carbon paper support, which serves as the gas diffusion layer (GDL). Initially, the ideal proportion of OER/ORR catalyst was determined by conducting electrochemical tests on both the individual material (via RRDE studies) and the gas diffusion electrode using a rapid screening protocol. The material extracted from the GDEs, in pristine state and after ageing under operating conditions, was then characterized with electrochemical methods, SEM microscopy, HRTEM/SAED microscopy/electron diffraction, as well as with direct- and Fourier-space soft x-ray transmission microscopy (STXM) at the Mn, Ni and Zn L-edges. The electrochemical tests conducted in this study demonstrated a progressive improvement in performance as the nickel nanoparticle content increased, until a plateau is reached after 23% wt. Specifically, lower overpotentials were observed alongside increased cyclic stability for the combined ORR/OER processes. These assessments were conducted in two distinct electrolyte environments: pure KOH and KOH with the inclusion of Zn2+. The inclusion of Zn2+ aimed to replicate and understand the potential impact of anode chemistry on the cathode's overall performance. The investigation employed HRTEM and SAED analyses to meticulously monitor alterations in the crystal structure of the α-MnO2 electrocatalyst under diverse aging conditions. Notably, during ORR cycling, the manganese nanorods underwent amorphization. However, cyclic processes between oxygen OER and ORR revealed the recovering of the original crystalline phase. The introduction of Zn2+ into the system resulted in the formation of a partially amorphous Zn-Mn mixed oxide. To delve further into the nuanced changes, soft-X ray hyperspectral imaging, both in direct and Fourier space was employed. By spectral imaging at the Mn and Ni L-edges, we could assess the space-dependent valence alterations of Manganese and Nickel at different stages of aging with space resolution down to a few tens of nanometers. The integration of diverse analytical techniques, including electrochemical assessments, STXM, HRTEM/ SAED imaging, along with space-resolved structural analyses, has provided a comprehensive, molecular-level understanding of the performance and degradation of bifunctional ORR/OER electrocatalysts within the realistic context of gas diffusion electrodes. Of particular significance is the capability of this combined approach to meticulously trace and correlate the changes in the chemical state of the manganese ORR electrocatalyst. This shift, notably away from the optimal 3+/4+ mixed valence state, was observed in response to aging and Zn2+ contamination. The correlation of this chemical state drift with electrochemical conditions and the evolution of crystal structure adds a nuanced layer of insight into the intricate interplay of factors influencing the performance and degradation of these electrocatalysts. In particular, the control of the oxidative stress under OER, enabled by addition of Ni NPs, was correlated with preservation of α-MnO2 crystallinity, GDE operation in the presence of Zn2+ was proved to give rise to the formation of ZnMn2O4, poisoning the electrocatalyst. Lastly, the role of hydrophobicity of the active layer of the GDE was proven to be of crucial importance in the stability of the Mn-based catalyst, as PTFE-surrounded clusters were observed to be less affected by cycling with respect to others which clearly underwent electrolyte flooding. Figure 1

Supercapacitive investigation of polyazomethine incorporating electron-withdrawing Nitro Group: Room temperature synthesis

A polyazomethine, designated as NAZ, was synthesized effortlessly at room temperature via a highly efficient polycondensation route employing 5,5′-(4-nitro-1,2-phenylene)bis(furan-2-carbaldehyde) (III) as a monomer, along with a diverse array of diamines meticulously selected for engineering the NAZ polyazomethine. The resulting NAZ material underwent a comprehensive characterization employing cutting-edge techniques including X-ray diffraction (XRD), the random morphology of polyazomethine has revealed in FESEM and TEM images, energy dispersive X-ray analysis (EDAX), and a suite of advanced spectroscopic methods. In the realm of Fourier-transform infrared spectroscopy (FTIR), the emergence of the distinctive –CHN– peak at 1608 cm−1 unequivocally validated the triumphant conversion of dicarbaldehyde (III) and diamines into the desired polyazomethine structure. XRD diffractograph unveiled the tantalizingly amorphous disposition of NAZ, while the FESEM images elegantly revealed its enigmatic and inherently random morphology. The EDAX analysis, meanwhile, provided an exquisite insight into the intricate chemical composition and elemental distribution meticulously orchestrated on the surface of NAZ. Delving into the electrochemical domain, the synthesized polyazomethine electrodes were subjected to a rigorous battery of tests including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and the formidable electrochemical impedance spectroscopy (EIS). The superlative supercapacitive prowess of the NAZ electrodes were fervently evaluated across a plethora of electrolytic environments encompassing NaOH, LiCl, NaNO2, and the venerable KOH, spanning an impressive range of concentrations. Noteworthy is the awe-inspiring performance of the NAZ electrode in the hallowed 1 M KOH electrolyte, boasting an unprecedented specific capacitance (Cp) of 860 Fg−1, specific energy (SE) soaring to an impressive 6.14 Whrkg−1, and specific power (SP) scaling the summit at a staggering 74 KWkg−1, thus epitomizing optimal performance in every facet.Furthermore, the indomitable NAZ electrode exhibited an unparalleled degree of stability, steadfastly retaining a remarkable 69.25 % of its initial capacitance even after being subjected to the rigorous crucible of successive 1000 cycles within the exacting confines of the 1 M KOH electrolyte.

Exploring Flower-Structured Bifunctional VCu Layered Double Hydroxide and its Nanohybrid with g-C3N4 for Electrochemical and Photoelectrochemical Seawater Electrolysis.

Seawater electrolysis holds great promise for sustainable green hydrogen generation, but its implementation is hindered by high energy consumption and electrode degradation. Two dimensional (2D) layered double hydroxide (LDH) exhibits remarkable stability, high catalytic activity, and excellent corrosion resistance in the harsh electrolytic environment. The synergistic effect between LDH and seawater ions enhances the oxygen evolution reaction, enabling efficient and sustainable green hydrogen generation. Here, we report a synthesis of low cost, novel 2D Vanadium Copper (VCu) LDH first time in the series of LDH's as a highly efficient bifunctional electrocatalyst. The electrochemical (EC) and photoelectrochemical (PEC) study of VCu LDH and VCu LDH/Graphite Carbon Nitride (g-C3N4) nanohybrid was performed in 0.5 M H2SO4 (acidic), 1 M KOH (basic), 0.5 M NaCl (artificial seawater), 0.5 M NaCl+1 M KOH (artificial alkaline seawater), real seawater and 1 M KOH+real seawater (alkaline real seawater) electrolyte medium. It was found that VCu LDH shows a remarkable lower overpotential of 72 mV hydrogen evolution reaction (HER) and 254 mV oxygen evolution reaction (OER) at current density of 10 mA/cm2 under alkaline real seawater electrolysis exhibiting bifunctional activity and also showing better stability.

Organization оf Electrochemical Protection оf Steel Underground Pipelines Against Corrosionin the Gas Distribution Industry of the Republic of Belarus

Steel underground gas pipelines occupy a significant share of the total length of gas distribution pipelines, and therefore their maintenance in proper condition is a constant and very urgent task. Due to its global nature, the main influencing factor affecting the technical condition of any steel underground pipelines, including gas pipelines, is corrosion, primarily soil corrosion. To protect against it on pipeline networks, along with insulating coatings, electrochemical protection (ECP) is applied, that is, following the definition of STO [Standard of Organization] 17330282.27.060.001–2008, protection of metal against corrosion in an electrolytic environment, carried out by establishing a protective potential on it or eliminating the anodic potential shift from the stationary potential. In the gas distribution industry of the country, methods and means of electrochemical protection have been applied since the beginning of gasification and the construction of the first gas pipelines. All gas supplying organizations of the State Production Association for Fuel and Gasification “Beltopgaz” (six regional and Minsk city), which operate gas distribution facilities, have specialized corrosion protection services. These services provide maintenance of available ECP equipment, conduct electrical measurements on gas pipelines and corrosion studies of soils, and have certified laboratories. This paper is devoted to the analysis of domestic experience in organizing electrochemical protection of steel underground gas distribution pipelines, searching for promising directions for its improvement and increasing efficiency through the implementation of a unified industry technical policy, automation and telemechanization of ECP equipment in the general context of digital transformation, optimization of the timing and volume of maintenance.

Interfacial optical anisotropy of Cu(110) electrochemistry using singular value decomposition

Understanding surface/interface states (SIs) in metal–electrolyte environments is crucial for diverse scientific and technological fields. This work investigates the reflectance anisotropy spectroscopy (RAS) of Cu(110) in HCl solution to gain deeper insights. Using the singular-value decomposition (SVD) method, we extract three distinct RAS features that track electrochemical changes. We argue that these features stem from surface-induced bulk optical anisotropies and Cl− adsorption. Their correlation with cyclic voltammetry (CV) further supports this interpretation. Specifically, we link these lineshapes to HCl adsorption, and microscale surface roughness resembling a lamellar grating, as verified by electrochemical scanning tunneling microscopy (EC-STM), and another one correlated to ab initio calculations bearing transitions between bulk and surface states of Cu(110). Our findings shed light on SIs behavior in metal–electrolyte interfaces. The combination of SVD and RAS establishes a robust methodology for studying metallic surfaces in electrochemical systems, enabling comparisons with ab initio predictions.

Investigating the expansion behavior of silicon nanoparticles and the effects of electrolyte composition using a graphene liquid cell

Understanding the volume expansion behavior of Si anodes and their interaction with electrolyte environments is crucial for developing high-performance lithium-ion batteries (LIBs). This study utilizes a graphene liquid cell for in situ imaging to systematically investigate the volume expansion and etching behavior of Si anode nanoparticles in different electrolyte environments. Comparative experiments on Si@C core-shell nanoparticles assess their volume expansion dynamics. The findings reveal significant variation in the expansion rate of nano Si depending on the electrolyte environment, with chemical etching observed under specific conditions. Conversely, Si@C core-shell structures show mitigated expansion due to the confinement effect of the carbon matrix. Battery performance experiments validate these results, demonstrating the excellent cycling stability of Si@C anodes. Various coating agents are explored to optimize Si@C structures, with dopamine thin layer coating exhibiting the best cycling stability. This study offers fundamental insights into Si anode expansion, electrolyte effects, and carbon coating impacts, advancing LIB technology.

Graphene Quantum Dots as Hole Extraction and Transfer Layer Empowering Solar Water Splitting of Catalyst-Coupled Zinc Ferrite Nanorods.

Despite the narrow band gap energy, the performance of zinc ferrite (ZnFe2O4) as a photoharvester for solar-driven water splitting is significantly hindered due to its sluggish charge transfer and severe charge recombination. This work reports the fabrication of a hybrid nanostructured hydrogenated ZnFe2O4 (ZFO) photoanode with enhanced photoelectrochemical water-oxidation activity through coupling N-doped graphene quantum dots (GQDs) as a hole transfer layer and Co-Pi as a catalyst. The GQDs not only reduce the surface-mediated nonradiative electron-hole pair recombination but also induce a built-in interfacial electric field leading to a favorable band alignment at the ZFO/GQDs interface, helping rapid photogenerated hole separation and serving as a conducting hole transfer highway, improve the hole transportation into the Co-Pi catalyst for enhanced water oxidation reaction kinetics. The optimized ZFO/GQD/Co-Pi hybrid photoanode delivers a 23-fold photocurrent enhancement at 1.23 V versus the reversible hydrogen electrode (RHE) and a significant 360 mV reduction in the onset potential, reaching 0.65 VRHE compared with the ZFO photoanode under 1 sun illumination in a neutral electrolytic environment. This investigation underscores the mechanism of synergistic interplay between the hole transport layer and cocatalyst in boosting the solar-illuminated water-splitting activity of the ZFO photoanode.

Binder-free phosphor-coated multiphase bismuth cobalt-selenide electrode for solar-charged quasi-solid-state hybrid supercapacitors

The enormous utilization of fossil fuels and the accelerated progression of global warming have irreversible destructive consequences on Earth's biodiversity. In response to this concern, there is a growing need to adopt green and renewable energy sources as effective strategies for mitigating environmental challenges. Herein, we report the novel synthesis and electrochemical properties of a binder-free phosphorus-coated multiphase bismuth-cobalt selenide/nickel foam (P@BCS/NF) electrode. Phosphorization was performed under an N2 atmosphere in a tube furnace to cover the electrodes. The synthesized electrode exhibited a porous nanorod morphology, which enhanced its electrochemical and energy storage properties. The P@BCS/NF electrode delivered a high areal capacity value of 836.4 µAh cm−2 in 1 M KOH electrolytic solution with excellent cycling stability, 81.4 % capacity retention, and 98.8 % coulombic efficiency over 10,000 cycles. A quasi-solid-state hybrid supercapacitor (QHSC) device was constructed using P@BCS/NF as the positive electrode and activated carbon as the negative electrode. The QHSC device showed maximum areal energy and power density values of 384.37 μWh cm−2 and 21750 μW cm−2, respectively, together with high stability of 94.4 % capacitance retention after 10,000 cycles. The practical application of the QHSC device was demonstrated in a PVA-KOH electrolytic environment by powering various electronic devices.

Knittable Electrochemical Yarn Muscle for Morphing Textiles.

Morphing textiles, crafted using electrochemical artificial muscle yarns, boast features such as adaptive structural flexibility, programmable control, low operating voltage, and minimal thermal effect. However, the progression of these textiles is still impeded by the challenges in the continuous production of these yarn muscles and the necessity for proper structure designs that bypass operation in extensive electrolyte environments. Herein, a meters-long sheath-core structured carbon nanotube (CNT)/nylon composite yarn muscle is continuously prepared. The nylon core not only reduces the consumption of CNTs but also amplifies the surface area for interaction between the CNT yarn and the electrolyte, leading to an enhanced effective actuation volume. When driven electrochemically, the CNT@nylon yarn muscle demonstrates a maximum contractile stroke of 26.4%, a maximum contractile rate of 15.8% s-1, and a maximum power density of 0.37 W g-1, surpassing pure CNT yarn muscles by 1.59, 1.82, and 5.5 times, respectively. By knitting the electrochemical CNT@nylon artificial muscle yarns into a soft fabric that serves as both a soft scaffold and an electrolyte container, we achieved a morphing textile is achieved. This textile can perform programmable multiple motion modes in air such as contraction and sectional bending.

Interfacial "Double-Terminal Binding Sites" Catalysts Synergistically Boosting the Electrocatalytic Li2S Redox for Durable Lithium-Sulfur Batteries.

Catalytic conversion of polysulfides emerges as a promising approach to improve the kinetics and mitigate polysulfide shuttling in lithium-sulfur (Li-S) batteries, especially under conditions of high sulfur loading and lean electrolyte. Herein, we present a separator architecture that incorporates double-terminal binding (DTB) sites within a nitrogen-doped carbon framework, consisting of polar Co0.85Se and Co clusters (Co/Co0.85Se@NC), to enhance the durability of Li-S batteries. The uniformly dispersed clusters of polar Co0.85Se and Co offer abundant active sites for lithium polysulfides (LiPSs), enabling efficient LiPS conversion while also serving as anchors through a combination of chemical interactions. Density functional theory calculations, along with in situ Raman and X-ray diffraction characterizations, reveal that the DTB effect strengthens the binding energy to polysulfides and lowers the energy barriers of polysulfide redox reactions. Li-S batteries utilizing the Co/Co0.85Se@NC-modified separator demonstrate exceptional cycling stability (0.042% per cycle over 1000 cycles at 2 C) and rate capability (849 mAh g-1 at 3 C), as well as deliver an impressive areal capacity of 10.0 mAh cm-2 even in challenging conditions with a high sulfur loading (10.7 mg cm-2) and lean electrolyte environments (5.8 μL mg-1). The DTB site strategy offers valuable insights into the development of high-performance Li-S batteries.

Design and Fabrication of a Sensors-integrated Silicon Electrode for Gap Status Monitoring in Micro Electrochemical Machining

Abstract The monitoring of micro machining gap and the control of machining status within the gap have become bottlenecks in the research and development of micro electrochemical machining (ECM). General electrical signals are difficult to reflect the status of micro machining gap. Electrolytic products in micro machining gap are prone to precipitation and retention, leading to unstable material removal process. Micro ECM urgently requires gap status monitoring and feedback control. To realize gap status monitoring, a sensors-integrated silicon electrode, with a micro temperature sensor and a micro conductivity sensor on the silicon electrode near-front sidewall, is proposed innovatively in this study. Based on bulk silicon process and electroplating process, sensors-integrated silicon electrodes are designed and fabricated. Based on the signal processing system built for the temperature and conductivity sensor, the temperature and conductivity detection functions are verified and the sensors are calibrated. Micro ECM experiments with sensors-integrated silicon electrodes are carried out and micro holes with 200 μm depth are machined. For the conductivity sensor on the sensors-integrated silicon electrode, due to the affection of electrolytic environment, the function surface is contaminated and damaged, and the structural design needs to be further improved. For the temperature sensor, it is not affected by the electrolytic environment due to insulation-film’s protection, and reliable temperature monitoring is achieved in micro ECM. The detection results indicate that the temperature inside the machining gap has increased by 20 ℃ due to the electrochemical thermal effect and resistance thermal effect in micro ECM, and the temperature shows an increasing trend while machining depth increasing. The feasibility of process monitoring with sensors-integrated silicon electrode in micro ECM is preliminarily verified.

Monitoring the Electrochemical Failure of Indium Tin Oxide Electrodes via Operando Ellipsometry Complemented by Electron Microscopy and Spectroscopy.

Transparent conductive oxides such as indium tin oxide (ITO) are standards for thin film electrodes, providing a synergy of high optical transparency and electrical conductivity. In an electrolytic environment, the determination of an inert electrochemical potential window is crucial to maintain a stable material performance during device operation. We introduce operando ellipsometry, combining cyclic voltammetry (CV) with spectroscopic ellipsometry, as a versatile tool to monitor the evolution of both complete optical (i.e., complex refractive index) and electrical properties under wet electrochemical operational conditions. In particular, we trace the degradation of ITO electrodes caused by electrochemical reduction in a pH-neutral, water-based electrolyte environment during electrochemical cycling. With the onset of hydrogen evolution at negative bias voltages, indium and tin are irreversibly reduced to the metallic state, causing an advancing darkening, i.e., a gradual loss of transparency, with every CV cycle, while the conductivity is mostly conserved over multiple CV cycles. Post-operando analysis reveals the reductive (loss of oxygen) formation of metallic nanodroplets on the surface. The reductive disruption of the ITO electrode happens at the solid-liquid interface and proceeds gradually from the surface to the bottom of the layer, which is evidenced by cross-sectional transmission electron microscopy imaging and complemented by energy-dispersive X-ray spectroscopy mapping. As long as a continuous part of the ITO layer remains at the bottom, the conductivity is largely retained, allowing repeated CV cycling. We consider operando ellipsometry a sensitive and nondestructive tool to monitor early stage material and property changes, either by tracing failure points, controlling intentional processes, or for sensing purposes, making it suitable for various research fields involving solid-liquid interfaces and electrochemical activity.