ChemElectroChem最新文献

Poly(oxyethylene) (POE) is frequently used as suitable component to prepare solid polymer electrolytes (SPEs), due to its: (i) ability to coordinate and dissociate doping salts; (ii) good mechanical properties; and (iii) high chemical and electrochemical stability. With the aim to obtain calcium secondary batteries, here we describe the preparation and studies of crosslinked Ca-polycondensate (NPCY) electrolytes with formula NPCY/(CaTf₂)_x based on fragments of POE chains and CaTf₂. The molecular weight of POE precursors is Y=400 and 1000 g ⋅ mol⁻¹. The effect of POE molecular weight on the thermal, structural, and electrical properties of NPCY/(CaTf₂)_x is investigated revealing that in mesoscale this materials show: (i) two different nanodomains with polyether chains both “free” (not coordinating the cation) and involved in 4–4 coordination cages of Ca²⁺ metal ions; (ii) f_α-fast, f_α-cross and f_α-slow relaxation modes of polyether chains, detected by broadband electrical spectroscopy, which are coupled with the long-range charge migration pathways of SPEs; (iii) that triflate (Tf⁻) anions, which act as plasticizers, modulate the inter-chain migration processes of Ca²⁺ between polyether coordination sites. Finally, the conductivity values of NPCY/(CaTf₂)_x, which is up to 10⁻⁴ S ⋅ cm⁻¹ at 80 °C, classify NPCY/(CaTf₂)_x as promising SPEs for the development of calcium secondary batteries.

Promoting safer and more cost-effective lithium-ion battery manufacturing practices, while also advancing recycling initiatives, is intrinsically tied to reducing reliance on fluorinated polymers like polyvinylidene difluoride (PVDF) as binders and minimizing the use of hazardous and expensive solvents such as N-methyl pyrrolidone (NMP). In pursuit of this objective, olefin- and rubber-based polymers have been investigated as promising alternatives for binder materials in high-energy Ni-rich LiNi_xCo_yMn_zO₂ (NCM, x≥0.8) cathodes for lithium-ion batteries (LIBs). Alternative binders such as polyisobutylene (PIB), poly(styrene-butadiene-styrene) (SBS), nitrile butadiene rubber (NBR), and its hydrogenated version (HNBR) offer versatile solutions. These polymers can be dissolved in industrial solvents, such as toluene, and have been further processed into homogeneous cathode slurries, thus facilitating the manufacturing of high-energy Ni-rich NCM cathodes for lithium-ion batteries. The evaluation of NCM811 cathodes obtained from PIB, SBS, NBR, and HNBR has involved a thorough assessment of their physical and chemical properties, electrochemical performance, and production expenses, compared with NCM811 cathodes based on PVDF. Notably, cathodes employing PIB and HNBR have exhibited outstanding qualities, showcasing high specific capacity and remarkable electrochemical stability akin to PVDF-based counterparts. Furthermore, the alternative binders′ superior adhesion, elasticity, and thermal stability have facilitated obtaining uniform and mechanically stable cathode films. Furthermore, using toluene, with its low vapor pressure, has significantly reduced energy costs associated with drying processes, thereby enhancing the overall cost-effectiveness of the NCM811 cathodes.

Covering approximately 71 % of Earth's surface and absorbing almost 70 % of the solar radiation energy, water presents a tremendous opportunity for hydropower generation, revealing considerable promise for future applications. Benefited from the low cost, negligible pollution, and the characteristic of solely utilizing ambient thermal energy, hydrovoltaic (HV) technology has garnered significant attention in recent years for its substantial contributions to energy harvesting and conversion. While traditional hydrovoltaic generators (HVGs) have predominantly utilized two-dimensional (2D) structures, the emergence of three-dimensional (3D) HV materials signifies a pivotal shift due to superior specific surface areas, intricate porous architectures and enhanced mechanical strength. Herein, we summarized the development of 3D HVGs, categorizing them into flow-induced, moisture-induced, and evaporation-induced types. We explored their working mechanisms, evolutions, strategies for electricity output enhancement and the limitations they face. Moreover, we discussed the integration of HVGs with other energy conversion technologies and the development of comprehensive HVG systems that exploit various water sources for energy generation. At last, we highlighted the challenges confronting 3D HVGs and anticipated future directions for this burgeoning field.

The electrochemical deposition of iron hexacyanoruthenate (Fe−HCR) on gold electrodes was studied in electrolytes prepared with light and heavy water. Cyclic voltammetry of the material during preparation and after transfer to a precursor-free solution exhibits two reductions peaks in H₂O-based electrolytes but only one reduction peak in D₂O-based electrolytes. The voltammetric behavior changes reversibly upon transfer of the material between D₂O-based and H₂O-based 1 mol L⁻¹ KCl solutions. No clear structural differences between samples prepared in D₂O and H₂O were detected by means of X-ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection absorption spectroscopy (PM IRRAS). We noted a relatively slow exchange of coordinated water and a fast exchange of zeolitic water. Using voltammetric experiments we could rule out simple effects of solution conductivity for K⁺, participation of H⁺/D⁺ in the charge compensation and surface effects on the observed dependence of the peak splitting on the isotopic composition of the solvent. The most likely reason for the observed behavior is the different structure of the H-bonded water network of coordinated H₂O and zeolitic H₂O/D₂O which is supported by the PM IRRAS data.

We investigated the corrosion properties and transpassive behavior of CrMnFeCoNi and CrCoNi multi-principal element alloys (MPEAs) in a 0.1 M NaCl electrolyte at pH 12. By using SECM-based tip substrate voltammetry (TSV) in combination with the chemical analysis of the electrolyte, we were able to differentiate between anodic metal dissolution and oxygen evolution in the transpassive range. Our investigations have shown that CrCoNi has a significantly higher corrosion resistance compared to CrMnFeCoNi. In the studied alkaline environment, a transpassive oxide film is formed on the surface of CrCoNi during secondary passivation. This transpassive oxide film appears to play a significant role in oxygen evolution, as the increase in TSV currents at the microelectrode coincides with the corresponding current density plateau of the voltametric current trace. The formation of the transpassive oxide film was not observed in previous studies conducted in acidic environments. Moreover, the alkaline electrolyte induced a positive hysteresis and mild pitting corrosion, in addition to intergranular corrosion, which was the sole corrosion process observed at acidic pH levels. These findings enhance the understanding of the processes governing the transpassivity of CrMnFeCoNi and CrCoNi MPEAs in alkaline environments and have potential implications for the development of application-tailored corrosion-resistant MPEAs.

The current goals for implementing the hydrogen economy have highlighted a need to further optimize water-splitting technologies for clean hydrogen production. Proton exchange membrane water electrolysis (PEMWE) is a leading technology, but further optimizations of anode materials including the porous transport layer (PTL) and the adjacent catalyst layer (CL) are required to increase overall cell performance and reduce cost. This literature review describes advances in PTL development and characterization, highlighting early PTL characterization work and most common methods including capillary flow porometry and mercury intrusion porometry, optical imaging, neutron and x-ray radiography, and x-ray computed tomography. The article also discusses PTL protective coatings and their characterizations, focusing on platinum group metal (PGM)-based coatings, alternative non-PGM-based coatings, post-treated PTLs, and investigations into thin PGM-based coatings. Furthermore, it highlights the integration of the PTL and the adjacent CL along with associated characterization challenges. Lastly, this review discusses future developments in the characterization needed to improve PEMWE's performance and long-term durability are discussed.

The front cover picture illustrates the dissolution of gold lattice in various pH environments, highlighting the electrochemical interaction with different electrolytes. Gold dissolution is minimal at neutral pH and increases at acidic and alkaline extremes, influenced by the formation of gold oxides and the rate and mechanism of the oxygen evolution reaction. The pH scale highlights the range from acidic to alkaline, reflecting the study′s examination of gold′s structural stability across pH levels. Cover design by Kateryna Streltsova. More details can be found in the Research Article by Kevin Stojanovski, Serhiy Cherevko, and co-workers (DOI: 10.1002/celc.202400373).

The inside cover picture highlights the ability of cobalt(II) tellurium oxide (CTO) to intercalate electrolytic potassium ions upon photo-induced charge separation, thereby stabilising the excited electron, whilst also driving the oxygen evolution reaction by oxidising hydroxide ions. It is shown that the photo-electrocatalytic (PEC) current is about double that of the electrocatalytic (EC) current while the EC current, subsequent to the termination of illumination, is almost as high as the PEC current. This exhibits the ability of CTO to deintercalate and release charge after the termination of illumination. More details can be found in the Research Article by Roelof Jacobus Kriek and co-workers (DOI: 10.1002/celc.202400047).

Silicon (Si) anode is of considerable interest in Li-ion batteries due to its high theoretical capacity (4200 mAh g⁻¹), abundant reserves in the earth, and environmentally friendly nature. Although Si anode has significant advantages, the electrode is prone to cracks due to large volume changes in its structure during discharge cycles in Li-ion batteries. Rapid capacity degradation occurs as a result of deterioration of the structural integrity of the electrode. Although binders are known to contribute to improving the electrochemical performance of anode materials, polyvinylidene fluoride (PVdF) used in commercial Li-ion batteries cannot maintain the mechanical stability of the Si anode during cycles due to weak Van der Waals interactions, which also dissolves in the flammable, explosive and volatile solvent N-Methyl-2-pyrrolidone (NMP). In this study, low cost, sustainable and environmentally green psyllium gum (PG) was extracted from psyllium husk and tested for the first time as a water-soluble binder for Si anode. According to galvanostatic charge/discharge tests, the Si-PG anode exhibits a capacity of 1415 mAh g⁻¹ after 100 cycles at a voltage range of 0.01–1.5 V and current density of C/2, which is almost 3 times higher than the Si-PVdF anode (494 mAh g⁻¹).

Copper is an active electrocatalyst for various energy conversion reactions, but its performance depends on the structure of the active surface sites. In this work, we propose a simple strategy to tailor both the roughness and the active site's geometry of copper. To modify the surface of copper, we oxidize and reduce a copper polycrystalline electrode in 0.1 M solutions containing both sodium fluoride and sodium chloride with different chloride/fluoride molar ratios: (0.1-x) M NaF+x M NaCl. To address the anion effect on the changes in surface geometry, we recorded the voltammetric fingerprints of the modified electrodes using lead underpotential deposition (UPD). The voltammetric analysis suggested that while chloride induces (n10) sites, fluoride promotes an increase in the active surface area and the growth of low-coordinated sites with (110) or (111) geometry. Solutions containing both fluoride and chloride anions induced (n10) motifs covered by nanometric clusters, as observed by scanning electron microscopy, forming a highly defect-rich surface. Our work provides a direct link between electrochemical response and ex-situ structural characterization, and compares, in detail, the effect of chloride and fluoride on the surface nanostructuring of copper.