ChemElectroChem最新文献

Dimethyl sulfoxide is a suitable solvent for reversible oxygen reduction in the presence of Ca²⁺, but not sufficiently stable towards the anode. Solvents suitable as anolytes tend to underperform in the context of oxygen reduction. Thus, a combined approach using different electrolytes at the cathode and anode promises superior performance. However, due to the electroosmotic drag, a cross-contamination of both electrolytes is expected. In this work, the influence of solvent mixtures of dimehtyl sulfoxide as an excellent electrolyte is investigated for the cathode with tetraglymeor tetrahydrofuran for oxygen reduction in the presence of Ca²⁺ at gold and glassy carbon electrodes using the rotating ring disc electrode assembly and oxygen solubilities and diffusivities are determined. While a high share of tetraglyme and tetrahydrofuran leads to a quick deactivation of the electrodes products, intermediate shares (1:1 mixture by volume), are beneficial for the oxygen reduction. This is due to the increased solubility of oxygen in those solvent. Even more interesting is the fact that the re-oxidizability of soluble peroxide species is eased by the addition of the ethers. While the reasons for this behavior remain elusive, the beneficial effect of other solvents is an encouraging starting point for a dual electrolyte Ca²⁺-battery.

La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ (LSCF) perovskites, in the form of in–house electrospun nanofibers and commercial powders, have been tested through synchrotron x–ray diffraction and electrochemical impedance spectroscopy in the 800–1200 K range. The former analyses make it possible to evaluate the oxygen vacancies (OV) concentration, and the latter allows to assess the electrokinetics of the oxygen reduction/evolution reaction. Equivalent circuit modeling is carried out to identify the basic electrochemical processes and evaluate the associated polarization resistance R_p. One high-frequency process and two intermediate-frequency processes are recognized. For all electrochemical processes, OV concentration and R_p behave similarly with temperature in both nanofiber and granular electrodes. This led to the proposal of a new equation. For each electrochemical process, it was shown that the activation energy is the sum of an intrinsic electrochemical activation energy, plus the formation energy of OVs. For the LSCF perovskites tested in this work, the intrinsic electrochemical activation energy was found to be independent of the preparation procedure and crystal structure. In contrast, the OV formation energy was found to be strongly dependent on the preparation procedure and crystal structure, with values ranging between 0.5 and 24.1 kJ mol⁻¹. A complete set of data is provided, which can be useful for future simulation studies.

Polymer electrolyte membrane fuel cells (PEMFCs) have attracted significant attention as next-generation clean compact power sources. In this study phosphoric-acid-doped polybenzimidazole (PBI) membranes with added itanium dioxide nanowires are prepared to afford novel hybrid membranes that improve the performance and reliability of PEMFCs. Furthermore, the electrochemical and power generation properties of membrane-electrode assemblies fabricated using the prepared hybrid electrolyte membranes are investigated. The swelling of the PBI membrane caused by phosphoric acid doping is suppressed by the titanium dioxide nanowires, thereby increasing the phosphoric acid concentration in the PBI membrane, even with very low dopant loadings. The increased proton conductivity and maximum power density are attributed to the increased phosphoric acid concentration in the membrane.

Nickel–cobalt–manganese (NCM)-based cathode materials have emerged as a prominent research focus in energy storage due to their high specific capacity and layered crystal structure, enabling synergistic integration of high-energy and power density in hybrid battery-supercapacitor devices (HBSDs). This review presents a comprehensive overview of the recent advancements and future prospects of NCM-based cathodes in such hybrid systems, with a critical emphasis on electrochemical performance optimization, energy storage mechanism elucidation, and material modification strategies. Key topics include the latest progress in NCM material design, encompassing compositional optimization, surface engineering, and nanostructural tailoring, to enhance rate capability, energy density, and cycling stability. Additionally, emerging challenges and prospective directions for NCM-based HBSDs are discussed, such as in-depth investigations into interfacial reaction mechanisms for precise regulation, cost-effective manufacturing technologies for industrial scalability, and solutions to critical issues related to safety, long-term durability, and environmental sustainability. Through systematic analysis of technological innovations and research breakthroughs, this work highlights the transformative potential of NCM-based hybrid devices in next-generation energy storage, aiming to inspire new paradigms for advancing high-performance energy storage systems.

The Front Cover Feature illustrates the linearization technique presented by Cécile Pot d’or, Fabio La Mantia, and co-workers in their Research Article (DOI: 10.1002/celc.202500134). The DEIS model receives an input voltage composed of two components—the cyclic voltammetry (CV) and the multi-sine (MS)—and simulates their effects separately. As the MS signal is a small perturbation around the CV, we can calculate its response by linearizing around the CV. The MS response can then be used to generate dynamic impedance spectra.

Transition to a sustainable energy future demands the development of alternative battery technologies beyond lithium-ion batteries, which are challenging for large-scale implementation due to inherent safety concerns and resource scarcity. Aqueous zinc-ion batteries (ZIBs) are a promising solution; however, improvement of the cathode is essential for their widespread adoption. This study investigates the structural modification of zinc hexacyanoferrate (ZnHCF) as cathode materials using ball-milling and the addition of carbon black (Vulcan XC-72R). The improved electroactivity is attributed to the phase transition from cubic to rhombohedral, the conversion of Prussian blue analogue to Prussian white analogue phases, and the synergistic effect produced by the presence of carbon material. These changes lead to the formation of [Fe(CN)₆] vacancies, which draw water molecules into interstitial sites. Carbon material plays a crucial role in preserving the crystalline structure of ZnHCF and enhancing the electrochemical performance. The sample milled in presence of carbon material (BM-ZnHCF@C sample) demonstrates superior results compared to the samples unmilled and milled samples without carbon material, achieving a capacity close to 100 mAh g⁻¹ at a current density of 0.5 A g⁻¹. However, after 50 cycles, the capacity decreases by 53.3%, but is restored by replacing the Zn anode while retaining the same cathode. The zinc anode is the primary factor hindering the long-term performance of the assembled battery, as demonstrated by the evolution of the electrode potential over time in the ZIB using a T-type electrochemical cell.

Granular carbon-based cathodes in carbon dioxide-reducing bioelectrochemical systems (CO₂-reducing BES) feature high biocompatibility and stability. Wood-based biochar is gaining popularity in (bio)electrochemical applications due to its sustainability and reduced environmental impact. Yet, previous studies primarily examined lab-scale biochars. This study investigates how heterogeneity of industrial-scale granular biochars (GBs) influences their electrocatalytic activity for hydrogen evolution reaction (HER) in the nexus of CO₂-reducing BES. Significant variations are identified in overpotentials for HER at −1 mA cm⁻² (η_-1 mA cm⁻²) among the GB-based cathodes. Beechwood-derived GB pyrolyzed at 740 °C shows the lowest η_-1 mA cm⁻²(223.6 ± 30.0 mV), outperforming birchwood-derived GB at 700 °C (503.5 ± 4.9 mV) and granular graphite (608.3 ± 19.5 mV). Despite its superior performance, beechwood-based GB shows high heterogeneity. Such heterogeneity underlies different physicochemical properties, likely due to uneven temperature distribution in industrial pyrolysis. The remarkable performance of beechwood-based GB pyrolyzed at 740 °C is attributed to its higher electrical conductivity, higher degree of carbonization, favorable H/C ratios, higher disorder in carbonaceous structure, and suitable porosity. The results highlight the influence of the wood type, the importance of systematic GB characterization, and the necessity to optimize industrial-scale biochar production to achieve homogeneous and high-performance biochar.

Moving from planar electrodes to unique surface architectures can produce significant improvements in electrochemical performance. Herein, we report the inclusions of unique microstructures fabricated onto the electrode surface through printing them onto laser-engraved print beds modified with different patterns (lines, crosses, circles, waves, and unmodified surfaces). Unique surface architectures were successfully produced on the surface of additive manufactured working electrodes printed from both commercial and bespoke conductive poly(lactic acid) and bespoke poly(propylene) (B-PP) filaments. Within both poly(lactic acid) filaments, minimal alteration in performance was seen, proposed to be due to the ingress of solution negating the surface architecture. For the B-PP, which do not suffer from solution ingress, significant improvements in peak current and electrochemical area were found for all surface architectures against both inner and outer sphere redox probes, with a cross architecture producing the largest improvement. This was corroborated in the electroanalytical application, with electrodes with crosses surface architecture producing a 3-fold improvement in sensitivity, limit of detection, and limit of quantification when compared to electrodes with no additional surface architecture for the detection of acetaminophen. This work shows improvements in the electrochemical performance of additive manufactured electrodes can be achieved through simply modifying the print bed, without alterations to print files or post-print modification methods.

Inactive lithium (Li), often referred to as dead or isolated Li, consists of electrochemically disconnected metallic Li and Li-containing compounds trapped within or beneath the solid–electrolyte interphase (SEI). It is widely recognized as a primary failure mode in lithium-metal batteries (LMBs), contributing to performance degradation, safety concerns, and limited scalability. This review outlines the sequential processes of Li nucleation, growth of high-surface-area Li, and the formation of inactive Li, while identifying the key physicochemical factors influencing each stage. Li nucleation is governed by current density, temperature, electrolyte formulation, and interfacial properties, which collectively dictate the uniformity of Li plating. High-surface-area Li growth introduces mechanical and chemical instabilities, fractures and uneven stripping of these filamentous structures lead to Li isolation and inactive Li accumulation. To address these challenges, advanced characterization techniques, including solid-state nuclear magnetic resonance spectroscopy, titration gas chromatography, inductively coupled plasma optical emission spectroscopy, and operando synchrotron X-ray diffraction, offer critical insights into the formation and progression of inactive Li. Emerging reactivation strategies, such as redox mediators and tailored cycling protocols, show promise in recovering lost capacity. This review presents key mechanistic factors, advanced diagnostic tools, and emerging reactivation strategies to support a deeper understanding and control of failure mechanisms in LMBs systems.

Zinc–air batteries (ZABs) have attracted much attention because of their high energy density, low cost, and excellent safety. However, developing inexpensive oxygen electrocatalysts with stable performance and fast reaction kinetics remains challenging. Herein, a simple and versatile dual-template-assisted pyrolysis strategy to prepare iron-nitrogen co-doped porous carbon (R-Fe-N-C) catalysts using magnesium carbonate hydroxide (Mg₂(OH)₂CO₃) as a self-generated template, ferrocene as an iron source, ethylenediaminetetraacetic acid disodium zinc salt (EDTA-Na₂Zn) as a carbon source, and 1,10-phenanthroline as a nitrogen source is proposed. During the pyrolysis process, Mg₂(OH)₂CO₃ can be decomposed to generate MgO nanoparticles as self-generated hard template embedded in the carbon skeleton, and finally removed by acid etching to form a rich mesoporous structure. Meanwhile, the Zn species in EDTA-Na₂Zn can form rich micropores after high-temperature evaporation. Thus, the R-Fe-N-C catalyst reaches a high half-wave potential of 0.874 V and good stability, which is better than commercial Pt/C. In addition, ZABs with R-Fe-N-C as air cathode exhibit high open circuit voltage of 1.52 V and a maximum power density of 122.9 mW cm⁻², as well as good cycle stability over 110 hr. The proposed synthesis strategy provides an effective way for designing metal-heteroatomic-doped porous carbon materials.