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Understanding how lithium-ion dynamics affect the (de)lithiation mechanisms of state-of-the-art nickel-rich layered oxide cathodes is crucial to improve electrochemical performance. Here, we directly observe two distinct kinetically induced lithium heterogeneities within single-crystal LiNixMnyCo(1−x−y)O2(NMC) particles using recently developed operandooptical microscopy, challenging the notion that uniform (de)lithiation occurs within individual particles. Upon delithiation, a rapid increase in lithium diffusivity at the beginning of charge results in particles with lithium-poor peripheries and lithium-rich cores. The slow ion diffusion at near-full lithiation states—and slow charge transfer kinetics—also leads to heterogeneity at the end of discharge, with a lithium-rich surface preventing complete lithiation. Finite-element modeling confirms that concentration-dependent diffusivity is necessary to reproduce these phenomena. Our results demonstrate how kinetic limitations cause significant first-cycle capacity losses in Ni-rich cathodes.

The mitigation of decomposition reactions of lithium-ion battery electrolyte solutions is of critical importance in controlling device lifetime and performance. However, due to the complexity of the system, exacerbated by the diverse set of electrolyte compositions, electrode materials, and operating parameters, a clear understanding of the key chemical mechanisms remains elusive. In this work, operandopressure measurements, solution NMR, and electrochemical methods were combined to study electrolyte oxidation and reduction at multiple cell voltages. Two-compartment LiCoO2/Li cells were cycled with a lithium-ion conducting glass–ceramic separator so that the species formed at each electrode could be identified separately and further reactions of these species at the opposite electrode prevented. One principal finding is that chemical oxidation (with an onset voltage of ∼4.7 V vs Li/Li+for LiCoO2), rather than electrochemical reaction, is the dominant decomposition process at the positive electrode surface in this system. This is ascribed to the well-known release of reactive oxygen at higher states-of-charge, indicating that reactions of the electrolyte at the positive electrode are intrinsically linked to surface reactivity of the active material. Soluble electrolyte decomposition products formed at both electrodes are characterized, and a detailed reaction scheme is constructed to rationalize the formation of the observed species. The insights on electrolyte decomposition through reactions with reactive oxygen species identified through this work have a direct impact on understanding and mitigating degradation in high-voltage/higher-energy-density LiCoO2-based cells, and more generally for cells containing nickel-containing cathode materials (e.g., LiNixMnyCozO2; NMCs), as they lose oxygen at lower operating voltages.

Inorganic surface coatings such as Al2O3are commonly applied on positive electrode materials to improve the cycling stability and lifetime of lithium-ion cells. The beneficial effects are typically attributed to the chemical scavenging of corrosive HF and the physical blockage of electrolyte components from reaching the electrode surface. The present work combines published thermochemistry data with new density functional theory calculations to propose a new mechanism of action: the spontaneous reaction of the LiPF6electrolyte salt with Al2O3-based surface coatings. Using 19F and 31P solution nuclear magnetic resonance spectroscopy, it is demonstrated that the storage of LiPF6-containing electrolyte solution with Al2O3produces LiPO2F2, a well-known electrolyte additive. The production of LiPO2F2is also observed for electrolyte solutions that were stored for 14 days at 40 °C with Al2O3-coated LiNi0.6Mn0.2Co0.2O2(NMC622) and LiNi0.8Co0.15Al0.05O2(NCA) materials. Given the beneficial nature of this species for the lifetime and stability of lithium-ion cells, this reaction is here proposed to similarly benefit the performance of cells that use Al2O3-coated cathode materials.

Electrolyte additives are a practical route to improving the lifetime and performance of lithium-ion cells. It is not well understood what makes a good additive; thus, the discovery of new additives poses a significant challenge. Computational methods have the potential to streamline the search for new additives, but it is important to compare predicted additive behavior with experimentally measured results. A new electrolyte additive, 1,3-dimethyl-2-imidazolidinone (DMI), has been evaluated in LiNi1-x-yMnxCoyO2 (NMC)/graphite pouch cells as a single additive and with the co-additive vinylene carbonate (VC). This work compares the density functional theory (DFT)-predicted behavior of DMI with experimental results, including differential capacity analysis (dQ/dV), electrochemical impedance spectroscopy (EIS), high-temperature storage, gas chromatography-mass spectrometry (GC-MS) and long-term cycling tests. The DFT-calculated reduction potential of DMI is [?]0.63 V vs Li/Li+, consistent with the experimental observation that it reduces at a lower potential than ethylene carbonate (EC), [?]0.80 V vs Li/Li+. Although DMI turns out not to be a competitively useful additive, the good match between many aspects of the experimental results and theoretical predictions is a good indication that it is possible to understand aspects of the behavior of additives. This can guide future researchers.

Eventual rapid capacity loss or "rollover" failure of lithium-ion cells during long-term cycling (>3000 cycles in many cases) at room temperature was studied with Li[Ni0.5Mn0.3Co0.2]O2/graphite pouch cells. The effects of positive electrode material coating, electrolyte additives, upper cutoff voltage, LiPF6 concentration, cell rest periods, electrode thickness, graphite type and electrolyte solvent formulation were probed. Cells were tested under 1C charge and discharge with "rate maps" (discharges at C/20, C/2, 1C, 2C, 3C) applied every 100 cycles. The loss of high rate capability (3C) is shown to be an early warning of impending rollover failure. Electrochemical impedance spectroscopy (EIS) and studies of symmetric cells made using electrodes from disassembled cells demonstrate that impedance growth at the positive electrode and associated DC resistance growth is responsible for rollover failure in these cells. Ultra-high precision coulometry (UHPC) shows that cells that were charged to higher voltages, which increase the rate of electrolyte oxidation, or show higher rates of electrolyte oxidation at the same cutoff potential due to changes in electrolyte formulation, normally are more prone to eventual rollover failure. In order to avoid rollover and extend the cycling life of Li-ion cells, it is important to choose optimal cell chemistries, some of which are enumerated in this report.

The development of new positive electrode materials is on route to increase the energy density of lithium-ion batteries (LIBs) for electric vehicle and grid storage applications. The performance of new materials is typically evaluated using hand-made half coin cells with the new material as the positive electrode and a piece of lithium foil for the negative. Whereas half coin cells are easy to make and can give reproducible data, they can fail to accurately predict how a material would perform in a full cell. The present work develops methods to prepare full coin cells, using graphite as the negative electrode material. Detailed instructions are provided to enable researchers to prepare their own high quality full coin cells with good reproducibility between cells. The precision of the hand-made full coin cells is compared with and found to approach the quality of machine-made, commercially produced full cells.

The use of electrolyte additives is an important method to improve lithium-ion cell lifetime and performance without significantly affecting costs. This work evaluates two organic anhydrides, glutaric anhydride (GA) and citraconic anhydride (CA), as additives in Li(Ni0.6Mn0.2Co0.2)O2 (NMC622)/graphite and Li(Ni0.5Mn0.3Co0.2)O2 (NMC532)/graphite pouch cells, using ultrahigh precision coulometry and high-temperature storage. The additives were tested singly and in binary blends. GA-based additive blends give high coulombic efficiencies (CEs) and good storage performance. However, GA leads to substantial impedance during formation. Most notably, GA is extremely effective at suppressing gas during cell formation and storage. Whereas CA-containing blends yield good CEs, they show rapid voltage drop during storage. Both additives may provide specific benefits for target applications. Long-term cycling data indicates that GA is a negative electrode SEI-forming additive that is useful for capacity retention and limiting cell impedance growth when used as a binary blend with vinylene carbonate or lithium difluorophosphate. These results are also intended to facilitate comparison between chemically related additives in order to better understand the underlying chemistry behind their function in lithium-ion cells.

Fast-charging lithium-ion cells require electrolyte solutions that balance high ionic conductivity and chemical stability. The introduction of an organic ester co-solvent is one route that can improve the rate capability of a cell. Several new co-solvent candidates were identified based on viscosity, permittivity (dielectric constant), and DFT-calculated electrochemical stability windows. Several formate, nitrile, ketone, and amide co-solvents are shown to increase the ionic conductivity of lithium hexafluorophosphate in conventional organic-carbonate-based solutions. Based on gas production during the first formation cycle in Li[Ni1-x-yCoxAly]O2/graphite-SiO pouch cells, five candidates were identified: methyl formate (MF), ethyl formate (EF), propionitrile (PN), isobutyronitrile (iBN), and dimethyl formamide (DMF). High temperature storage (60degC), long-term cycling, and ultrahigh-precision coulometry results indicate that MF offers the greatest balance between conductivity increase and cell lifetime. Future work is encouraged to develop more stable solution chemistries that incorporate MF. PN may prove useful for low temperature (< 40degC) applications.

Electrolyte additives are used in lithium-ion cells to achieve higher energy densities and longer lifetimes for electric vehicle and grid storage applications. This work tests a recently developed electrolyte additive, MDO (3-methyl-1,4,2-dioxazol-5-one) and introduces two new additives, PDO (3-phenyl-1,4,2-dioxazol-5-one) and BS (benzonitrile sulfite, 5-phenyl-1,3,2,4-dioxathiazole 2-oxide). The cell formation, high temperature storage and long-term cycling performance of lithium-ion NMC/graphite pouch cells prepared with these additives and binary blends thereof are presented. Differential capacity results indicate that MDO and PDO form passive solid-electrolyte interphase layers on the graphite electrode during cell formation, whereas BS does not. It is demonstrated that PDO is a highly promising new additive, especially when used as a binary blend with lithium difluorophosphate or ethylene sulfate. Future work is encouraged to explore the interactions between these additives and develop optimized solution chemistries, for example by adjusting the ratio of primary and secondary additives or through introducing ternary blends.

Electrolyte additives are a promising route to stable solution chemistries needed for improved and next-generation lithium-ion cells. Yet the underlying chemistry remains unknown for most additives and additive blends in use. This work presents possible reaction pathways for solid-electrolyte interphase formation in lithium-ion cells from ethylene sulfate (DTD), prop-1-ene-1,3-sultone (PES) and the binary PES/DTD blend. Pathways are supported by theoretical calculations (density functional theory) and experimental results (electrochemistry, gas chromatography thermal conductivity detection, X-ray photoelectron spectroscopy, isothermal microcalorimetry). A hypothesis to understand the synergistic chemistry of the blend is proposed: Reduction of PES, the 'primary additive', at the negative electrode forms a nucleophile that reacts with electrophilic DTD, the 'secondary additive', to produce a passive solid-electrolyte interphase that inhibits direct reduction of DTD or the solvent. The results are further discussed in the contexts of future mechanistic studies, computational additive discovery, and the development of improved lithium-ion cell chemistries.

Solid-state NMR spectroscopy was used to characterize the solid-electrolyte interphase (SEI) formed on the graphite electrode surface from the electrolyte additive pyridine pentafluorophosphate (PPF). The PPF-derived SEI was prepared in a full Li(Ni0.4Mn0.4Co0.2)O2/graphite cell, rather than in a coin cell or using a bench-top synthesis approach. 19F and 19F-31P cross-polarization measurements provide direct evidence that F atoms and P-F bonds are present at the graphite surface. By comparing rinsed and unrinsed samples, an insoluble SEI component was differentiated from residual LiPF6 from the dried electrolyte. The SEI species contains F and P chemical environments that are similar to, but distinct from, the additive starting material and the lithium hexaflurophosphate (LiPF6) electrolyte salt used in this work. The results are consistent with the previously proposed formation of a dilithium 4,4'-bipyridine-N,N'-bis(pentafluorophosphate) salt. LiF was also observed and is attributed to decomposition of the PPF-derived surface layer and/or the LiPF6 electrolyte salt.

Single crystal, Ni-rich layered lithium metal oxides are promising candidates for next-generation cathodes in lithium-ion batteries. However, these Ni-rich materials display anisotropic swelling and contraction during cycling, and this may lead to the generation of internal stresses and thereby to fracture and capacity loss. In this work, the spatio-temporal evolution of lithium concentration and stress state within a LiNi0.8Mn0.1Co0.1O2(NMC811) single crystal are predicted using a fully coupled chemo-mechanical model. The stress state in the crystal arises from a spatially non-uniform distribution of Li concentration, and from a non-linear dependence of intercalation strain upon lithium concentration. The peak tensile stress is greatest near top-of-charge, due to the high sensitivity of intercalation strain upon lithium occupancy at low concentrations, and the peak tensile stress increases with both cycling rate and particle dimension. Significantly, the predicted peak tensile stress is insufficient to cause basal plane fracture of single crystals when their diameter is below 2.5 μm and the charging and discharging rates are below 5C. This suggests that intraparticle fracture is not a significant degradation mode for well-designed NMC811 single crystals.

The use of electrolyte additives to form a passive solid-electrolyte interphase (SEI) at one or both electrodes is a common method for improving lithium-ion cell lifetime and performance. This work follows the chemical and electrochemical processes involved in SEI formation on graphite electrodes for two Lewis acid-base adducts, pyridine boron trifluoride (PBF) and pyridine phosphorus pentafluoride (PPF). The combination of experimental methods (electrochemistry, in situ volumetric measurements, gas chromatography, isothermal microcalorimetry, and X-ray photoelectron spectroscopy) with quantum chemistry models (density functional theory) provides new insight into the interfacial chemistry. PBF and PPF are reduced at [?]1.3 V vs. Li/Li+ and [?]1.4 V, respectively. This is followed by radical coupling to form 4,4'-bipyridine adducts, hydrogen transfer to ethylene carbonate solvent molecules, and reduction of the solvent to produce lithium ethyl carbonate. The reduced bipyridine adducts, Li2(PBF)2 and Li2(PPF)2, are shown to compose part of the SEI at the negative electrode surface.

This work reports measurements of the dielectric constants of ethylene carbonate (EC)/ethyl methyl carbonate (EMC) blends between 25 and 60 °C. Dielectric constants were measured using a cylindrical capacitance cell and a frequency response analyzer. EC and EMC form nonideal mixtures that cannot be described by a simple linear mixing model. A quadratic mixing rule was instead adopted, and the mixing parameter is reported for 25–60 °C. The results of this research may be used to calculate the dielectric constant of any EC/EMC mixture over this temperature range with ≤4% estimated error. By modeling the ionic dissociation of lithium hexafluorophosphate (LiPF6) in various solvents, the significance of the dielectric constant on quantum chemistry simulations of chemical processes is explored. The effect of the dielectric constant accuracy on electrochemical processes was similarly evaluated by calculating the solvation energy of neutral and singly oxidized vinylene carbonate in various solvents. It is demonstrated that the exact value of the dielectric constant can significantly affect calculation accuracy when ε < 40, which is the case for the most commonly used EC/EMC blends.

The article discusses case studies concerning challenges faced by scientists attempting to evaluate the environmental and social impacts of water policy. It mentions about designing of the Tasang Dam in Myanmar on the Nu/Salween River, which is being done without an environmental impact assessment (EIA), and the series of EIAs involving the Yali Falls Dam the Sesan River Basin in Vietnam. Also discussed is about scientific findings and protests in the case of the Pak Mun Dam in Thailand.

The applications of in situ vibrational spectroscopy for identifying bulk and surface Ni(OH)2are discussed. Raman spectra from α- and β-Ni(OH)2samples immersed in water are generally similar to those collected from comparable dry samples. However, the Raman scattering intensities vary, and dry β-Ni(OH)2additionally exhibits a surface O–H stretching mode at 3690 cm–1. Using in situ Raman spectroscopy, the spontaneous transformation of α-Ni(OH)2to β-Ni(OH)2in room-temperature water was monitored. Such transformations are conventionally performed in high-temperature alkaline media. An intralayer OH-diffusion model is proposed. Internal stresses at the α/β-phase boundary caused shifted peaks, higher order vibrational modes, and a new water peak at 3520 cm–1. We conclude that Raman spectroscopy may be applied to observe Ni(OH)2materials in situ during chemical and electrochemical treatments. Such measurements provide information on the proportions of α- and β-Ni(OH)2and their fine structural details with high sensitivity.

This work establishes a new method to measure the electrochemically active surface area (AECSA) of nickel electrodes, in situ. The addition of 0.08 mol L[?]1 of an oxalate salt to an alkaline electrolyte solution shifts the half-wave potential of the Ni(II)/Ni(III) redox pair by about [?]80 mV. Further, these peaks are very narrow. The sharpest peak in this work has a full width at half maximum (FWHM) of just 11 mV. This unusual sharpness is attributed to the layered structure of nickel hydroxides and the adsorption of oxalate from the solution on the (001) surface. This is supported by attenuated total reflectance infrared (ATR-IR) peaks measured at 1265 cm[?]1, 1655 cm[?]1, and 1713 cm[?]1, which correspond to mononuclear bidentate oxalate bonded to nickel. At sufficiently fast potential scan rates ([?]150 mV s[?]1), the adsorbed oxalate limits growth of the surface hydroxide to a single layer. During the reverse scan, the surface NiOOH/Ni(OH)2 reduction peak is well-separated from other electrochemical processes and may be used to accurately and precisely measure the AECSA. The error of this method is estimated at < 10%.

Electrolyte additives, as a small proportion of the electrolyte, greatly affect the performance of lithium-ion cells. This work performs a comparative study to reveal the difference between commercial 99.8% pure 3-phenyl-1,4,2-dioxazol-5-one (PDO) additive and lab-made 95% pure PDO in NMC622/graphite cells. In addition, a set of experiments were conducted to evaluate the performance of 99.8% pure PDO and its binary blends with vinylene carbonate (VC), 1,3,2-dioxathiolane-2,2-dioxide (DTD) or lithium difluorophosphate (LFO) in NMC811/graphite cells. 99.8% Pure PDO and 95% pure PDO show little difference in the NMC622 cells, with the latter presenting relatively better performance in the best-performing blends for long-term cycling and high-temperature storage tests. Considering all the tests including ultra high precision coulometry (UHPC) cycling, long-term cycling, and high-temperature storage, the NMC811 cells with 2%PDO+ 1%LFO outperformed the other PDO-containing cells. The PDO-based blends were confirmed to be more promising in cells with higher nickel content; that is, PDO could be a useful additive in high-nickel content cells.

An experimental protocol is developed to measure the shear strength of NMC811 single crystals within the cathode of a lithium-ion cell. The cathode is placed upon a set of thick metallic substrates that possess a wide range of indentation hardness. For each choice of substrate, the top surface of the cathode is indented by a Vickers indenter to a sufficient depth that the cathode layer is subjected to an approximately spatially uniform compressive normal traction equal to the hardness of the substrate. The sensitivity of plastic flow and fracture of the single crystals to substrate hardness is determined by observation of the particles in the indented top surface of the cathode using a scanning electron microscope. It is found that the shear strength of fully lithiated NMC811 single crystals along their basal plane is 86 ± 12 MPa, and decreases to 39 ± 5 MPa upon cell charging (delithiation of the cathode). This implies that particle slip and fracture will occur under mild mechanical loading, for example by calendering during manufacture and by electrical cycling of the compacted cathode. The indentation protocol developed here has application to a wide range of single crystal cathode materials.

Ni-based catalysts in aqueous alkaline media are low-cost electrode materials for electrolytic hydrogen generation, a renewable method of producing fuel and industrial feedstock. However, Ni cathodes show a significant decrease in their hydrogen evolution reaction (HER) activity after several hours of electrolysis. Further, industrial electrolysers are often subjected to transient anodic currents, the effects of which on Ni-based catalysts are not well-known. We consider the source of electrode deactivation and the effects of temporary anodic currents on smooth metallic Ni electrodes in alkaline solutions by cyclic voltammetry (CV), galvanostatic and potentiostatic polarization, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Polished surfaces are covered by a bilayer composed of a-Ni(OH)2 underlaid by non-stoichiometric NiOx. Below the reversible hydrogen electrode (RHE) potential, the air-formed layer mostly reduces to Ni metal and H atoms incorporate deep into the electrode material. Under industrial conditions, i.e., concentrated NaOH/KOH solutions and large cathodic current densities, a-NiHx and b-NiHx can form at the electrode surface. Above the RHE potential, NiOx, a-Ni(OH)2, b-Ni(OH)2 and b-NiOOH form reversibly and mostly reduce back to Ni on subsequent cathodic polarization. However, repeated oxidation and reduction will introduce strain on a catalyst material, which may lead to its mechanical failure.

The fabrication of mixed-metal oxide films holds promise for the development of practical photoelectrochemical catalyst coatings but currently presents challenges in terms of homogeneity, cost, and scalability. We report a straightforward and versatile approach to produce catalytically active zirconium-based films for electrochemical and photoelectrochemical water oxidation. The mixed-metal oxide catalyst films are derived from novel single-source precursor oxide cage compounds containing Zr with first-row transition metals such as Co, Fe, and Cu. The Zr-based film doped with Co on fluorine-doped tin oxide (FTO)-coated glass exhibits the highest electrocatalytic O2evolution performance in an alkaline medium and an operational stability above 18 h. The deposition of this film onto a BiVO4photoanode significantly enhances its photoelectrochemical activity toward solar water oxidation, lowering the onset potential by 0.12–0.21 V vs reversible hydrogen electrode (RHE) and improving the maximum photocurrent density by ∼50% to 2.41 mA cm–2for the CoZr-coated BiVO4photoanodes compared to that for bare BiVO4.

Nickel-rich layered oxides are promising positive electrode materials for lithium-ion batteries due to their high capacity and decreased cobalt content. The application of surface coatings is a common approach to slowing or potentially stopping deleterious reactions at the electrode–electrolyte interface of lower-Ni content layered oxides. However, their efficacy on Ni-rich LiNi0.8Mn0.1Co0.1O2(NMC811) is less certain, and knowledge on how to design effective coatings with favorable properties is sparse. In this work, we develop a convenient solution-based deposition method for the synthesis of aluminum oxide coated NMC811 secondary particles and we study the effects of annealing temperature on their structure and electrochemical lifetime in lithium-ion batteries. Using energy-dispersive X-ray spectroscopy and X-ray fluorescence spectroscopy, we quantify the amount and distribution of aluminum oxide on the cathode particles. Changes in the coating phase and composition as a function of annealing temperature are tracked with solid-state nuclear magnetic resonance and X-ray photoelectron spectroscopy. 27Al NMR spectroscopy at very high fields (23.5 T) provides direct evidence that after annealing up to 400 °C, 4-, 5-, and 6-coordinate aluminum is present, here assigned to an amorphous alumina coating, but after annealing to 600 °C, a γ-LiAlO2-like coating is observed. We further differentiate between Al in the bulk and surface phase and identify, for the first time, the critical temperature at which doping occurs in NMC811. Surface/bulk doping starts to occur in the range of 500–600 °C, with considerable bulk doping being found at 800 °C. The onset of Al diffusion coincides with the decrease in capacity retention, contradicting previous studies and giving new insight into the relationship between lifetime and lithium-ion conductivity.

A review of literature focusing upon geographic accessibility to health facilities indicates that while distance has been the traditional measure, travel time may now be a more meaningful indicator. Applying a 30-minute travel time standard to general hospitals, as advocated by various health plans, this paper illustrates an approach to the determination of geographic accessibility through a combination of a travel time file and sociodemographic profiles. Focusing upon all residents of West Virginia, the study identifies the number and characteristics of persons who reside within and beyond the 30-minute standard. More than 10 per cent of the entire population and nearly 20 per cent of the rural residents live in areas which are, by this standard, inaccessible to general hospitals. The “inaccessible” populations are characterized as having sociodemographic attributes associated with high medical needs. Other applications of travel time data are discussed.

The finding of an evaluative study of an experimental pediatric unit in which routine nursing care is accomplished by parent and physician, effects of hospitalization on the patient and his family, and the impact of the unit on medical students. In general, both parents and physicians were satisfied with the communications but “errors” were uncovered, especially in regard to the child's diagnosis, prognosis, and after-care. Also, parents were pleased with their other experiences on the unit and with the opportunity it provided for them to stay with their children. Disruptions of family life were minimal. Most medical students expressed approval of the unit as a care facility and preferred it to the more traditional pediatric ward as a teaching experience.

Finding new electrolyte additives could help create lithium-ion batteries with better performance at high voltage, allowing higher energy density. However, finding the perfect additive remains a tremendous challenge, since researchers still don’t understand how to predict their performance. A new group of dioxazolone electrolyte additives have been tested in lithium-ion batteries alone or in combination with well-known co-additives. The new additives consist of a 3-phenyl-1,4,2-dioxazol-5-one (PDO) parent structure with or without (methoxy, fluoro and nitro) functional groups on the para position of the phenyl ring. It is found that PDO (no functional group) and p-(4-nitrophenyl)-1,4,2-dioxazol-5-one (pNDO) are the best performing dioxazolones overall and show promising results.

The supersonic solar wind possesses a variety of simple small scale (<10-min observation duration) phenomena, including discontinuities1–3and magnetic holes4,5. We report here recent AMPTE-UKS6(Active Magnetospheric Particle Tracer Explorer–UK Satellite) observations, however, which reveal a dramatic new complex structure within the solar wind flow. In the plasma and field observations of this magnetic hole/current sheet system, the layers surrounding the strong rotation in the magnetic field contain compressed and heated solar wind, an enhanced field strength and considerable wave activity. The interior region shows strong ion heating but with ambient densities and a fluctuating magnetic field which dips to low values. The bulk flow velocity inside is deflected sharply from the anti-sunward direction, but not in the direction predicted by magnetic stresses across the boundary. The structure is expanding in thickness and is relatively young. The source of momentum and energy for this event remains unclear, and could even be magnetospheric.

Hydrogen generation by water electrolysis is a renewable method of producing fuel and industrial feedstock. Ni-based H2-evolution catalysts in alkaline media are low-cost alternatives to the noble-metal-based electrode materials used in acidic media. However, Ni cathodes show a significant decrease in their hydrogen evolution reaction (HER) activity after several hours of electrolysis. We consider the source of electrode deactivation on smooth metallic Ni electrodes by cyclic voltammetry (CV), galvanostatic and potentiostatic polarization, and X-ray diffraction (XRD). Below the reversible hydrogen electrode (RHE) potential, H atoms incorporate deep into the electrode material. Under industrial conditions, i.e., concentrated NaOH/KOH solutions and large cathodic current densities, α-NiHxand β-NiHxcan form at the electrode surface.