Increase In Cell Voltage Research Articles

Rational design of chromium-doped NiFe phosphide/phosphate heterostructures for inhibiting chloride ion adsorption and achieving alkaline seawater splitting at industrial-level current density

Electrocatalysts with high activity and corrosion resistance, tailored for industrial-grade current densities, played a crucial role in seawater electrolysis. Here, we synthesized a petal-like Cr-doped NiFe phosphate 'semi-coated' phosphide heterostructure electrocatalyst grown on nickel foam (Cr-NiFeP/PO3@NF). This catalyst demonstrated superior catalytic performance in natural seawater, maintaining stability and only a slight increase in cell voltage after operating continuously for 100 h at a current density of 1 A cm−2. The incorporation of Cr introduced a significant number of unpaired electrons, which enhanced the conductivity of the catalyst, facilitated the creation of electron depletion regions around Ni and Fe, and improved the interaction with adsorption intermediates. Furthermore, the high activity and corrosion resistance during the oxygen evolution reaction (OER) were due to the interaction between the in-situ formed high-valent phosphate and NiFeCrOOH during the anodization process.

Charge Transfer in n-FeO and p-α-Fe2O3 Nanoparticles for Efficient Hydrogen and Oxygen Evolution Reaction.

This study aims to explore the n-FeO and p-α-Fe2O3 semiconductor nanoparticles in hydrogen (HER) and oxygen (OER) evolution reactions and a combined full cell electrocatalyst system to electrolyze the water. We have observed a distinct electrocatalytic performance for both HER and OER by tuning the interplay between iron oxidation states Fe2+ and Fe3+ and utilizing phase-transformed iron oxide nanoparticles (NPs). The Fe2+ rich n-FeO NPs exhibited superior HER performance compared to p-α-Fe2O3 and Fe(OH)x NPs, which is attributed to the enhancement in n-type semiconducting nature under HER potential, facilitating the electron transfer for the reduction in H+ ions. In contrast, p-α-Fe2O3 NPs demonstrated excellent OER activity. An H-cell constructed using n-FeO||p-α-Fe2O3 NPs as cathode and anode achieved a cell voltage of 1.87 V at a current density of 50 mA/cm2. The cell exhibited remarkable stability after 30 h of activation and maintained the high current density of 100 mA/cm2 for 80 h with a negligible increase in cell voltage. This work highlights the semiconducting properties of n-FeO and p-α-Fe2O3 for the electrochemical water splitting system using the band bending phenomenon under the applied potential.

The Effect of Water Quality on PEM Electrolyzer Performance

There has been growing interest in the use of removable, clean, and sustainable energy sources as a solution to eliminate environmental problems caused by fossil fuels. In particular, the electrolysis of water to produce green hydrogen is one of the most promising technologies. Among various electrolysis techniques, proton exchange membrane water electrolyzer (PEMWE) stands out as the most promising for mobility and large-scale energy-storage applications (1). Hydrogen production by PEMWEs requires approximately 45 kg of high-quality water to produce 5 kg of hydrogen. It has been estimated that about 22% of the total cost of a state-of-the-art PEMWE system is for water deionization treatment (2). This water purity requirement is not only an economic barrier, but also a constraint for the use of this system in areas where high-quality water is not accessible or in areas where water for human consumption is a scarce resource. Therefore, studying the effect of water quality on PEMWE performance is an important first step in identifying key degradation mechanisms on the path to discovering new PEMWE architectures that are more tolerant of poor-quality feed waters.In this work, the effect of common impurities, such as Na+ and Mg2+, in feed water on the performance of common PEMWE architectures is studied. The main goals of the work are: 1) to understand the tolerance range for long term operation, 2) to identify major degradation mechanisms when the failure occurs. Experiments were carried out in an electrolyzer equipped with platinized Ti electrodes, IrO2 and Pt/C as anodic and cathodic catalysts, respectively, and a 115 Nafion® membrane. Durability studies of 100-hour duration and electrochemical characterization of the electrolyzer at different time intervals (polarization curves and impedance spectroscopy) were performed. The membrane/electrode assembly was probed by SEM /EDX before and after the experiments and cation concentrations in the water were monitored by ICP. An electrochemical model is proposed to explain the observed behavior of the electrolyzer with DI water and in the presence of impurities.The results show that the presence of cations affects the performance of the electrolyzer at different levels depending on the concentration of the cation and its valence (Mg2+ > Na+ >DI water). Mg+2 had the same effect as Na+ even at 5 times lower concentration. Cations have higher affinity than protons for sulfonic acid groups (-SO3 -), leading to a displacement of protons and a consequent reduction in the membrane proton conductivity. However. according to the polarization curves, there are effects beyond the ohmic potential due to the increase in membrane resistance. The major effect of cations is on the reaction kinetics, which is the primary reason for the observed increase in cell voltage. The presence of cations within the membrane blocks the transport of protons, which creates a lack of protons at the cathode, resulting in the kinetic change from proton reduction to reduction of water. Moreover, the EDX results showed that Na+ and Mg2+ ions transfer from anode to cathode and deposit on the membrane and catalyst layers, which may cover the active catalyst sites, block the proton transport inside the membrane and degrade the catalyst ionomer layers.References Sazali N. Emerging technologies by hydrogen: A review. International Journal of Hydrogen Energy. 2020 (45): 18753-18771Becker H, Murawski J, Shinde DV, Stephens IEL, Hinds G, Smith G. Impact of impurities on water electrolysis: A review. Sustainable Energy & Fuels. 2023;7(7):1565-603.

High-voltage and dendrite-free zinc-iodine flow battery

Zn-I2 flow batteries, with a standard voltage of 1.29 V based on the redox potential gap between the Zn2+-negolyte (−0.76 vs. SHE) and I2-posolyte (0.53 vs. SHE), are gaining attention for their safety, sustainability, and environmental-friendliness. However, the significant growth of Zn dendrites and the formation of dead Zn generally prevent them from being cycled at high current density (>80 mA cm−2). In addition, the crossover of Zn2+ across cation-exchange-membrane also limits their cycle stability. Herein, we propose a chelated Zn(P2O7)26- (donated as Zn(PPi)26-) negolyte, which facilitates dendrite-free Zn plating and effectively prevents Zn2+ crossover. Remarkably, the utilization of chelated Zn(PPi)26- as a negolyte shifts the Zn2+/Zn plating/stripping potential to −1.08 V (vs. SHE), increasing cell voltage to 1.61 V. Such high voltage Zn-I2 flow battery shows a promising stability over 250 cycles at a high current density of 200 mA cm−2, and a high power density up to 606.5 mW cm−2.

Poly(Dibenzothiophene-Terphenyl Piperidinium) for High-Performance Anion Exchange Membrane Water Electrolysis.

The anion exchange membrane water electrolysis is widely regarded as the next-generation technology for producing green hydrogen. The OH- conductivity of the anion exchange membrane plays a key role in the practical implementation of this device. Here, we present a series of Z-S-x membranes with dibenzothiophene groups. These membranes contain sulfur-enhanced hydrogen bond networks that link surrounding surface site hopping regions, forming continuous OH- conducting highways. Z-S-20 has a high through-plane OH- conductivity of 182±28 mS cm-1 and ultralong stability of 2650 h in KOH solution at 80 °C. Based on rational design, we achieved a high PGM-free alkaline water electrolysis performance of 7.12 A cm-2 at 2.0 V in a flow cell and demonstrated durability of 650 h at 2 A cm-2 at 40 °C with a cell voltage increase of 0.65 mV/h.

Poly(Dibenzothiophene‐Terphenyl Piperidinium) for High‐Performance Anion Exchange Membrane Water Electrolysis

AbstractThe anion exchange membrane water electrolysis is widely regarded as the next‐generation technology for producing green hydrogen. The OH− conductivity of the anion exchange membrane plays a key role in the practical implementation of this device. Here, we present a series of Z−S‐x membranes with dibenzothiophene groups. These membranes contain sulfur‐enhanced hydrogen bond networks that link surrounding surface site hopping regions, forming continuous OH− conducting highways. Z−S‐20 has a high through‐plane OH− conductivity of 182±28 mS cm−1 and ultralong stability of 2650 h in KOH solution at 80 °C. Based on rational design, we achieved a high PGM‐free alkaline water electrolysis performance of 7.12 A cm−2 at 2.0 V in a flow cell and demonstrated durability of 650 h at 2 A cm−2 at 40 °C with a cell voltage increase of 0.65 mV/h.

Non-precious high entropy alloys and highly alkali-resistant composite membranes based high performance anion exchange membrane water electrolyzers

Cost-effective highly efficient and stable catalysts and alkali-resistant anion exchange membranes (AEMs) are critical for practical applications of anion exchange membrane water electrolyzers (AEMWEs). Here, bifunctional non-precious FeCoNiCuMo high entropy alloys (HEAs), electrochemically deposited on nickel mesh as an anode (FeCoNiCuMo/NM) and on carbon paper as a cathode (FeCoNiCuMo/CP), together with a NiFe layered double hydroxide (LDH) loaded AEM (AEM/LDH), were developed for high performance AEMWEs. The AEMWE thus fabricated delivered an ultrahigh current density of 1777 mA cm−2 at 2 V and exhibited remarkable stability with a less than 0.1% cell voltage increase after a 100-hour operation at 100 mA cm−2 at 50 °C, largely outperforming those of the precious metal based AEMWE, composed of IrO2/NM as the anode and Pt/C/CP as the cathode, 1231 mA cm−2@2 V and 4.57% increase in cell voltages. Composition of the alkali-resistant, hydrophilic, and water electrolysis active NiFe LDH into the AEM improved not only the electrolyte uptake and operational stability, but also the efficiency of the AEMWE, with a 10% boost in current density achieved at 2 V and a reduction in cell voltage increases from 2.94% to 0.0951%. The present development demonstrates the practicality of AEMWEs toward green hydrogen production.

Enhanced stability of bipolar membrane water electrolysis with FeCoNi layered double hydroxides electrocatalyst in a frequently-inverted electrolyte mode

The aim of this study was to synthesize a novel, non-noble metal-based layered double hydroxides (LDH) bifunctional catalyst for bipolar membrane water electrolysis (BPMWE) and to improve the stability of BPMWE with forward bias BPM. The FeCoNi-LDH/NF catalyst was successfully prepared using an electrodeposition method and tested in BPMWE. Low overpotentials for both the HER and OER were observed in the FeCoNi-LDH/NF electrode. Significant changes in pH and conductivity occurred in the anolyte and catholyte of BPMWE without frequently-inverted electrolyte within 192 h, resulting in an increase of cell voltage for hydrogen production. However, in the frequently-inverted electrolyte mode, where the electrolyte was periodically shifted every 24 h, excess H+ in the anolyte and OH– in the catholyte of BPMWE were effectively neutralized by electrolyte shifting, resulting in stable pH and conductivity in the electrolytes and maintaining a stable cell voltage within 192 h. With 1 M KOH as the electrolyte, the cell voltage of BPMWE was only 1.58 V under a current density of 20 mA·cm−2 at 90 °C. Our study should provide insights into efficient bifunctional catalyst synthesis and operational stability control in BPMWE.

Stainless Steel Activation for Efficient Alkaline Oxygen Evolution in Advanced Electrolyzers.

Designing robust and cost-effective electrocatalysts for efficient alkaline oxygen evolution reaction (OER) is of great significance in the field of water electrolysis. In this study, an electrochemical strategy to activate stainless steel (SS) electrodes for efficient OER is introduced. Bycycling the SS electrode within a potential window that encompasses the Fe(II)↔Fe(III) process, its OER activity can be enhanced to a great extent compared to using a potential window that excludes this redox reaction, decreasing the overpotential at current density of 100mA cm-2 by 40mV. Electrochemical characterization, Inductively Coupled Plasma - Optical Emission Spectroscopy, and operando Raman measurements demonstrate that the Fe leaching at the SS surface can be accelerated through a Fe → γ-Fe2O3 → Fe3O4 or FeO → Fe2+ (aq.) conversion process, leading to the sustained exposure of Cr and Ni species. While Cr leaching occurs during its oxidation process, Ni species display higher resistance to leaching and gradually accumulate on the SS surface in the form of OER-active Fe-incorporated NiOOH species. Furthermore, a potential-pulse strategy is also introduced to regenerate the OER-activity of 316-type SS for stable OER, both in the three-electrode configuration (without performance decay after 300h at 350mA cm-2) and in an alkaline water electrolyzer (≈30mV cell voltage increase after accelerated stress test-AST). The AST-stabilized cell can still reach 1000 and 4000mA cm-2 at cell voltages of 1.69 and 2.1V, which makes it competitive with state-of-the-art electrolyzers based on ion-exchange membrane using Ir-based anodes.

Direct ammonia SOFC – A potential technology for green shipping

International shipping carries about 90% of the global trade, thereby emitting significant amounts of greenhouse gasses by using fossil based fuels. Zero-emission technologies using green fuels are crucial to reduce the environmental impact of this important transport sector. Among the considered concepts is green ammonia in a solid oxide fuel cell (SOFC).The present study investigated SOFCs fueled with ammonia regarding cracking, electrochemical performance and durability. Ammonia cracking was for the first time directly measured over a planar, anode supported SOFC at open circuit voltage and during operation, as well as in presence of several balance of plant components. At temperatures around 700 °C, ammonia is significantly cracked when passing over hot metallic low surface area components (like Ni current collectors) even in the absence of the SOFC. The Ni/YSZ SOFC anode is active for the cracking as well. The area specific resistance of the SOFC is larger when using ammonia as compared to a H2/N2 mixture, due to two origins, (i) a decrease of the cell temperature due to the endothermal cracking, which leads to larger ohmic resistance and (ii) presence of unconverted ammonia, which increases the polarisation resistance in the low frequency region. Durability tests reveal increased cell voltage degradation when using ammonia fuel at 700 °C, mainly due to increase of the ohmic contributions. Micro structural analysis suggests nitridation as cause of this degradation. A stable SOFC operation is possible at 750 °C.

Mechanistic enhanced cell voltage based on halides doped metal oxide fullerenes for use in Li-ion batteries: Insights from DFT intuition

Designing of anode nanomaterials with an optimum cell voltage is an important challenge for high-performance lithium (Li) ion batteries. In this study, we have investigated the electrochemical potential of pristine and Li-doped magnesium oxide (Mg12O12) and zinc oxide (Zn12O12) fullerenes through density functional theory (DFT) simulations, with a focus on their potential applications in lithium-ion batteries. Specifically, we investigated the halide ion encapsulated oxide nanocages as a means to achieve this improvement. We examined both unaltered and halide encapsulated Mg12O12 and Zn12O12 with Li atom/lithium cation (Li/Li+). Our investigation delves into the geometric and electrochemical characteristics of Li/Li+ interactions with Mg12O12 and Zn12O12 nanocages. We analyzed adsorption energies (Ead) and frontier molecular orbitals (FMOs) of Li/Li+ ions with these nanocages to gain insights into how neutral or ionic Li affects their geometric and electrochemical properties. The initial cell voltages of bare Mg12O12 and Zn12O12 are found to be 0.61 and 0.57 V, primarily due to marginal distinctions in the adsorption energies of Li and Li+ bound systems. Notably, the encapsulation of various halides into Mg12O12 and Zn12O12 nanocages significantly enhanced the cell voltage. Among the considered halides, the encapsulation of fluoride anion (F−) into Mg12O12 and Zn12O12 stands out, leading to a remarkable increase in cell voltage of 4.05 and 3.55 V for lithium-ion batteries, respectively. Moreover, the use of toluene solvent further increased the Ead values of Li cation with pure and halides encapsulated oxides (Mg12O12 and Zn12O12) nanocages. Ultimately, the Gibb's free also decreased along with the decrease in the cell voltage which is encountered in the acceptable range. The most suitable anode nanomaterial is suggested to be Li doped F−@Mg12O12 which has the most acceptable cell voltage of 1.59 V. The work also leads to more research work on the designing of halides encapsulated oxides fullerenes based secondary batteries for use in electrochemical energy storage devices. This work is a full-length guideline for the experimentalist to synthesize such systems to overcome the energy crises.

Single Cell Performance and Durability of Pt and Pt-Based Catalysts Supported on Mesoporous Carbon

Introduction In Japan, an extremely high cell performance, i.e., 0.84 V at 0.2 A/cm2 and 0.70 V at 3.0 A/cm2, is required for polymer electrolyte fuel cells (PEFCs) used in fuel cell electric vehicles after 2030 [1]. In addition to high oxygen reduction reaction (ORR) activity of the Pt and the Pt-based cathode catalysts for increasing cell voltage in the low current density (LCD) region, high oxygen diffusivity is crucial for achieving the cell voltage in the high current density (HCD) region [2]. Therefore, it is considered that carbon supports for the catalyst NPs would play an important role for realizing the high cell performance. In this study, a mesoporous carbon (MPC) was selected as the support for Pt and Pd@Pt core-shell structured catalyst NPs and cell performance of the catalysts were compared with that of the catalyst supported on a conventional Ketjen Black (KB). Furthermore, durability of the MPC support against a high potential range was investigated. Experimental KB-600JD (SBET: 1,335 m2/g, LION) and MPC (CNovel MH-18, SBET 1,334 m2/g, TOYO TANSO [3]) were used as carbon supports. The Pt/MPC catalyst, Pt diameter of 2.5 nm and metal loading of 50 wt.%, was synthesized through impregnation of Pt(NO2)2(NH3)2 followed by thermal reduction in N2 at 400oC. Pt/Pd/KB and Pt/Pd/MPC core-shell catalysts were synthesized by a direct displacement reaction (DDR) method [4]. Diameter of Pd@Pt NPs was 5.8 nm and Pt and Pd metal loading were 20 wt.% and 30 wt.%, respectively. Cyclic voltammogram was recorded in Ar-saturated 0.1 M HClO4 at 25oC with a scan rate of 50 mV/s and ORR activity was evaluated in O2-saturated 0.1 M HClO4 at 25oC with a positive potential scan rate of 10 mV/s at 1,600 rpm. Fuel cell performance was evaluated by using a single cell with an active area of 1 cm2. Nafion DE2020 was used as an ionomer for the catalyst ink preparation (I/C ratio was set to 0.83-1.2) and Nafion NRE 211 with 25 µm in thickness was used as a membrane. Pt loading in the cathode catalyst layer was set to 0.1 mg/cm2. H2 and air were supplied to the anode and the cathode by 418 NmL/min. and 988 NmL/min., respectively, and pressurized to 150 kPa at gas outlets. The cell temperature was set to 80oC and humidified from 35% to 95% relative humidity (RH). H2 utilization was 5% at a current density of 3.0 A/cm2. Durability of the carbon supports was evaluated by using the single cell. H2 and N2 were fed to anode and cathode, respectively, and cathode potential was swept from 1.0 to 1.5 V vs. RHE with a scan rate of 500 mV/s for 1,000 cycles. Results and Discussion Pore size distribution of the carbon supports is shown in Figure 1. Both KB-600JD and MPC (CNovel MH-18) carbon supports have mesopores, and the MPC exhibits a narrower pore size distribution centered at 4 nm. Figure 2 demonstrates I-V performance of Pd@Pt core-shell catalysts, indicating that Pt/Pd/MPC catalyst shows a higher cell voltage in HCD region (> 2 A/cm2) than that of Pt/Pd/KB-600JD catalyst. Interconnectivity of the mesopores analyzed by 3D-TEM observation of the carbon supports is depicted in Figure 3. It is clear that density of interconnected mesopores is much higher in the MPC support, which is considered to contribute to the higher cell voltage in HCD region of the Pt/Pd/MPC catalyst. Figure 4 displays cross-sectional SEM image of the Pt/Pd/MPC catalyst. In addition to the well-interconnected mesopores (Figure 3), macropores coexist in the MPC support, which is also considered to contribute to the higher cell voltage in HCD region.A high potential durability test was performed by using potential cycling of 1.0-1.5 V vs. RHE for 1,000 cycles at 80oC. Thickness of Pt/MPC cathode catalyst layer was decreased by 36% after the durability test, while the decrease was mitigated to 14% with a heat treatment of the MPC support at 2,200oC in Ar. (Figures 5). As is well known, it was demonstrated that the high temperature heat treatment has a positive effect for durability improvement of the carbon support against the high potential range.This study was partly supported by NEDO, Japan.

Solvent-Driven Degradation of Ni-Rich Cathodes Probed by Operando Gas Analysis

High-capacity Ni-rich layered metal oxide cathodes are highly desirable to increase the energy density of lithium-ion batteries. However, these materials suffer from poor cycling stability, which is exacerbated by increased cell voltage due to higher interfacial reactivity than their lower Ni-content analogues. Here, we study the pivotal role of electrolyte solvents in determining the interfacial reactivity at charged LiNi0.33Mn0.33Co0.33O2 (NMC111) and LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes by using both single-solvent model electrolytes and the mixed solvents used in commercial cells (1, 2). Operando gas analysis reveals that the solvent-dependent reactivity for Ni-rich cathodes is related to the extent of lattice oxygen release and accompanying electrolyte oxidation. We demonstrate here the detrimental effect of ethylene carbonate (EC), a core component in conventional electrolytes, when NMC811 is charged above 4.3 V vs Li/Li+ - the observed onset potential for lattice oxygen release. Oxygen loss is enhanced by EC-containing electrolytes and correlates with more electrolyte oxidation/breakdown and cathode surface degradation, which increase concurrently above 4.4 V. The gas analysis also reveals the crosstalk effect caused by the products of the nascent oxygen from the NMC811 lattice and the electrolyte solvent, showing anodic reactivity. In contrast, NMC111, which does not release oxygen up to 4.6 V, shows a similar extent of degradation irrespective of the electrolyte. Higher lattice oxygen release with EC-containing electrolytes is coupled with higher interfacial impedance, a thicker oxygen-deficient rock-salt surface reconstruction layer, more electrolyte solvent and salt breakdown. Oxygen loss is suppressed in the EC-free electrolyte, highlighting the incompatibility between Ni-rich cathodes and conventional electrolyte solvents. W. M. Dose et al., Onset Potential for Electrolyte Oxidation and Ni-Rich Cathode Degradation in Lithium-Ion Batteries. ACS Energy Letters 7, 3524-3530 (2022).W. M. Dose et al., Electrolyte Reactivity at the Charged Ni-Rich Cathode Interface and Degradation in Li-Ion Batteries. ACS Applied Materials & Interfaces 14, 13206-13222 (2022). Figure 1

Microporous structure flowing integrated with electrolytic water splitting based on stacked mesh electrode for hydrogen production

In order to promote gas bubble transport during water splitting for hydrogen production, stacked mesh electrodes integrated microporous structure flowing and electrolytic water splitting have been fabricated by electrodepositing CoFe alloy. The average size of the bubble on the mesh electrode surface is 40 μm and the release time of trapped bubbles in the pores of the electrode is 2.11 s during the process of water splitting at 50 mA cm−2 and 1 M KOH. The electrodes show excellent performance in both hydrogen evolution reaction (HER, 247 mV at 1000 mA cm−2) and oxygen evolution reaction (OER, 350 mV at 1000 mA cm−2). The required cell voltage at 1000 mA cm−2 for flow-through electrolyzer assembled with the stacked mesh electrodes is only 2 V under the condition of 6 M KOH, and 343 K. The voltage caused by the bubble in the flow-through electrolyzer assembled with stacked mesh electrodes is just about 50 mV at the current density of 1000 mA cm−2. The energy required for hydrogen production is only 4.04 kWh Nm−3 and 4.78 kWh Nm−3 under the current density of 200 mA cm−2 and 1000 mA cm−2, respectively. Besides, the flow-through electrolyzer assembled with the stacked mesh electrodes shows excellent stability with only a 60 mV increase in cell voltage after continuing electrolytic water splitting for 100 h at 1000 mA cm−2.

Effect of Water Vapor and Hydrogen Concentration on Power Generation Characteristics of Protonic Ceramic Fuel Cell

The proton and hole conductivities of BaZrO3-based perovskites depend on partial pressures of oxygen and water vapor. These conductivities affect the power generation characteristics of Proton Ceramic Fuel Cells (PCFCs) using the perovskite as an electrolyte. In this study, the effect of humidification conditions on the power generation characteristics of an anode-supported PCFCs was investigated.The configuration of the anode-supported PCFC was La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode/BaZr0.8Yb0.2O3-δ(BZYb) electrolyte/Ni-BZYb anode. The diameter of the effective cathode area was approx. 10 mm. The cathode gas composition was fixed at 97% concentration of air and 3% concentration of water vapor. The concentration of water vapor in the anode gas was controlled to be 3-69%. The current density-voltage characteristics and AC impedance were measured by Bio-Logic SP-150.In all water vapor concentration conditions, the cell showed the highest OCV (approximately 1 V) at 3% concentration of water vapor. However, the maximum power density was highest at 30% concentration of water vapor (346 mW/cm2). The highest maximum power density at 30% concentration of water vapor can be explained by the following reason. The OCV values decrease with increasing the concentration of water vapor because of decreasing the concentration of hydrogen. On the other hand, from the results of impedance measurements, the ohmic resistance of the cell decrease with increasing the concentration of water vapor because of increase of proton conductivity of the cell. Thus, the increase of cell voltage by increase of proton conductivity should be higher than the decrease of OCV values.【Acknowledgements】This presentation is the result of the research and development of ultra-efficient proton-conducting ceramic fuel cell devices, JPNP20003, funded by the New Energy and Industrial Technology Development Organization (NEDO), Japan. We would like to express our gratitude to all parties involved.

Green Electrochemical Complexation of Fluconazole, Itraconazole, Voriconazole, Ketoconazole and Clotrimazole with Silver, Copper and Zinc Cations

Electrochemical complexation of azole antifungal drugs fluconazole (FCZ), itraconazole (ITZ), ketoconazole (KTZ), voriconazole (VCZ) and clotrimazole (CTZ) with silver, copper and zinc cations was carried out galvanostatically in an undivided electrolytic cell equipped with a sacrificial anode and a stainless steel cathode under green conditions. In this work, we synthesized twenty different complexes of these drugs by a simple method in water (containing a strong acid)/ethanol mixtures with high yield (average 67%) and purity. The effective synthetic parameters, including the applied current, electricity consumption, acid concentration, cell voltage, energy consumption and cell design were optimized. Our results indicate that the applied current and acid concentration have no significant effects on the yield and purity of azole complexes. But these factors have a significant effect on cell voltage and energy consumption in such a way that by increasing the applied current or decreasing the acid concentration, the cell voltage and energy consumption increase. The Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) techniques have been used for the characterization of synthesized complexes. In addition, cyclic voltammetry analysis has been used to investigate the reaction mechanism. This method provides an efficient and green strategy for the complexation of azole drugs in one step without the need for metal salts.

CO2 electroreduction to multicarbon products from carbonate capture liquid

CO2 electroreduction to multicarbon products from carbonate capture liquid

Onset Potential for Electrolyte Oxidation and Ni-Rich Cathode Degradation in Lithium-Ion Batteries.

High-capacity Ni-rich layered metal oxide cathodes are highly desirable to increase the energy density of lithium-ion batteries. However, these materials suffer from poor cycling performance, which is exacerbated by increased cell voltage. We demonstrate here the detrimental effect of ethylene carbonate (EC), a core component in conventional electrolytes, when NMC811 (LiNi0.8Mn0.1Co0.1O2) is charged above 4.4 V vs Li/Li+—the onset potential for lattice oxygen release. Oxygen loss is enhanced by EC-containing electrolytes—compared to EC-free—and correlates with more electrolyte oxidation/breakdown and cathode surface degradation, which increase concurrently above 4.4 V. In contrast, NMC111 (LiNi0.33Mn0.33Co0.33O2), which does not release oxygen up to 4.6 V, shows a similar extent of degradation irrespective of the electrolyte. This work highlights the incompatibility between conventional EC-based electrolytes and Ni-rich cathodes (more generally, cathodes that release lattice oxygen such as Li-/Mn-rich and disordered rocksalt cathodes) and motivates further work on wider classes of electrolytes and additives.

Preparation of ZrB2 coatings by electrophoretic deposition in NaCl–KCl–AlCl3 molten salts

Fabrication of transition metal diboride coatings via electrophoretic deposition in molten salts has been recently proposed, however, the influence of the process parameters on the coating has not yet been studied extensively. In this paper, the effects of cell voltage as well as deposition time on the produced ZrB2 coatings by electrophoretic deposition of ZrB2 nanoparticles in NaCl–KCl–AlCl3 molten salts at 710 °C were investigated. The micromorphologies of the surface and the cross-section of the ZrB2 coatings were characterized by SEM. It was found that with the increase of cell voltage from 1.3 V (i.e., electric field 0.87 V/cm) to 1.8 V (1.2 V/cm), the thickness of the ZrB2 coating increased under the cell voltages from 1.3 V to 1.5 V and decreased from 1.5 V to 1.8 V. We assume that during the electrophoretic deposition process, the viscosity of molten salt containing high concentration ZrB2 nanoparticles close to the depositing electrode, which is influenced by the motion rate of nanoparticles governed by the electric field, probably plays an essential role for electrophoretic deposition process of nanoparticles on the electrode. In addition, under the cell voltage of 1.5 V the growth of ZrB2 coating was studied as a function of deposition time. As the deposition time was increased, the thickness and coherence of the coating were elevated.

Study on the Cathodic Behavior of Impurities in the Process of Aluminum Extraction by Soluble Anode Electrolysis

The preparation of coarse Al–Si alloys by carbon-based electrothermal reduction is a viable means of recycling scrap aluminum on an industrial scale to allow the high-value utilization of this resource. However, the presence of impurities on the cathode can have significant effects on the product purity. The present study explored the behavior of impurity elements on the cathode and the reasons for the decreased purity of aluminum deposited at the cathode with increases in electrolysis time. X-ray diffraction, scanning electron microscopy and inductively coupled plasma-atomic emission spectroscopy were used to study the compositions of the molten salt electrolyte and of the cathode product, as well as the phases and element distribution on the working electrode. With increasing cell voltage, the elements added as impurities were found to precipitate in the order of Fe > Al > Si > Mn > Ti > Mg > Ca. Increasing the concentration of these elements in the molten salt electrolyte was determined to increase the cell voltage, with Mg and Ca having the greatest effect.