Electrochemistry Communications最新文献

This study presents the fabrication of LiFePO₄ (LFP)-coated carbon fibers (CFs) as a positive electrode component for structural batteries, utilizing a spray coating technique. The successful coating of CFs through this method demonstrated their usefulness as efficient current collectors. The electrodes obtained using this method underwent electrochemical evaluations. Throughout the extended cycling tests at C/7, the maximum specific discharge capacity reached 146 mAh/g, maintaining a 77% capacity retention after 100 cycles. In rate performance assessments at the faster C-rate of 1.5C, the capacity measured 123 mAh/g, with a retention of 96%. The application of spray coating emerges as a promising technique for electrode production in structural batteries, showcasing its potential for optimizing performance in multifunctional energy storage systems.

In conventional Li-CO₂ batteries, Li₂CO₃ is an intractable discharge product due to its wide bandgap. To this end, researchers have focused more attention on the decomposition of Li₂CO₃ in order to reduce the high charge potential. However, even the kinetics of CO₂ evolution process can be accelerated, Li₂CO₃ will still passivate the cathodes, which in turn affects the cycle life of Li-CO₂ batteries. Here, we designed a CO₂ partly-absent Li-CO₂ battery, the concentration of CO₂ involved during the discharge process is reduced, then the discharge potential of this battery can be moved to 2.1 V. Furthermore, the discharge product of this CO₂ partly-absent Li-CO₂ battery is proved to be LiOH instead of Li₂CO₃, it can be recharged at a low potential of 3.5 V benefit from the readily degradable product (LiOH). In this Li-CO₂ battery, the effect of gas concentration on discharge process is studied firstly, and totally different results are discussed, offering new insights into the material design and the development of reliable rechargeable Li-CO₂ batteries in the future.

A numerical simulation of photocurrent transient was proposed to estimate properties of passive films and anodic films formed on pure Ti. To simulate photocurrent transient, partial differential equations describing the change in the concentration and positions of photoexcited charge carriers with time were developed based on the generation, recombination, and transports of the carriers. Simulations were performed by screening several parameters. The electron mobility, donor density, recombination coefficient and interfacial reaction rate coefficient were estimated by fitting simulated photocurrent transients to experimentally obtained transients.

This study fabricated an OER electrocatalyst with a hierarchical structure by electrodepositing Ni-Fe on NiO. The prepared electrocatalyst exhibited high activity and stability. Furthermore, the OER characteristics of the NiFe/NiO electrode were investigated by changing the metal (Ni and Fe) concentration and Ni:Fe ratio in the plating bath. As the plating bath concentration decreased, NiFe-layered double hydroxide was prominently formed due to an increase in local pH. The electrode obtained using a relatively low plating bath concentration of 130 mM demonstrated high activity with an overpotential of 245 mV and Tafel slope of 27.6 mV dec^-1 at a current density of 10 mA/cm². When the Ni:Fe ratio in the plating bath was adjusted, OER activity increased as the Fe content of the electrode increased to approximately 20.9 at.%, and as the Fe content increased beyond that, the activity gradually decreased. Fe inhibits Ni oxidation and acts as an active site owing to Fe³⁺ substitution in the γ-NiOOH structure, resulting in increased OER activity. However, when the Fe content was > 29 at.%, the inactive phase γ-FeOOH predominantly grew and the OER activity decreased.

Mg is the lightest structural metal on earth; hence, applications of its alloys have attracted attention from researchers. However, these alloys have poor corrosion resistance, which impedes their use in practice. Many researchers have investigated protective coatings for Mg alloys, but current methods consume much energy, use hazardous substances, or are complex (such as anodizing and micro-arc oxidation). This paper proposes a novel method of creating a durable and protective coating on Mg alloy substrates. The AZ91D Mg alloy was selected for investigation, and a Mn-V-P conversion coating treatment in which voltage of only 5 V was applied for 1 min to enhance the alloy’s corrosion resistance. A compact, single-layer film with uniform thickness was created; the average thickness was 1750 nm. The corrosion resistance of alloys treated with the method and through anodizing treatment was compared. For the novel coating, the corroded area fraction after a 168-h salt spray test was less than 5 %, superior to that for the coating produced through anodizing treatment. The feasibility and potential applications of the novel process are discussed.

Heteroatom-doped carbons have attracted increasing attention in recent years as inexpensive high-performance electrocatalytic materials owing to their electrical properties. A precisely controlled synthesis method for heteroatom-doped carbons is important to improve their performance and expand their applications. In this study, we developed a fluoropyridine-medicated zeolite templating method for Nitrogen/Fluorine (N/F) co-doped carbons. The N/F co-doped carbons showed better catalytic performances for oxygen reduction reaction (ORR) than N-doped carbon prepared using pyridine. In particular, the optimized N/F co-doped carbon exhibited a higher half-wave potential (0.87 V vs. RHE) than commercial Pt-loaded carbon black and N/F co-doped carbons reported in the literature. The comparative studies using various N/F co-doped carbons revealed that semi-ionic bonded C-F might improve ORR activity. In contrast, the contribution from covalent or ionic C-F to improving ORR activity would be negligible.

The urgent demand for stable electrode materials, especially for the anode, arises in the pursuit of high-energy Li-ion batteries. This research focuses on bismuth oxide (Bi₂O₃) and uncovers its performance through a straightforward, commercially viable synthesis route, along with the optimization of binders and electrolytes. By employing a sodium carboxymethyl cellulose binder and fluoroethylene carbonate additives, the Bi₂O₃ anode demonstrates significantly enhanced performance compared to prior studies. It attains an impressive initial capacity of approximately 750 mA h g⁻¹, exhibits excellent rate capability at 1000 mA g⁻¹ and maintains stable cycling performance over 6000 cycles.

Two-dimensional (2D) MXenes are promising materials for a variety of sustainable energy-related applications such as photoelectrochemical water splitting and energy storage devices. Among the MXene family, the Ti₃C₂T_x is mostly prepared by selective etching of Al from the Ti₃AlC₂ MAX phase using hydrofluoric acid (HF) or in-situ produced HF as an etchant. However, the severe toxicity, handling of HF acid as well as the oxidation and degradation of freshly synthesized MXenes when stored as aqueous suspensions obstruct the large-scale production of MXenes. 3D printing is an innovative and versatile technology utilized for a plethora of applications in the field of energy applications. Thus, integration of 3D printing technology with the synthesis procedure of MXene will provide a new outlook for large-scale production and the long-storing capability of MXene. Herein, we fabricated a novel MAX (Ti₃AlC₂)/polylactic acid (PLA) filament for fused deposition modeling (FDM) 3D printing followed by etching of the 3D-printed MAX/PLA electrode into 3DP-etched-MAX employing chronoamperometry technique consecutively in 9 M HCl and 4 M NaOH as electrolytes. The 3D printed electrochemically etched MAX (3DP-etched-MAX) electrode shows promising behaviour for the photoelectrochemical hydrogen evolution reaction (HER) and capacitive performance. In general, this work demonstrates a path of production of large-scale manufacturing of MAX/PLA filament and 3DP-etched-MAX electrodes without using toxic HF for energy conversion and energy storage applications. This work paves the way to fabricate other novel MAX filaments and electrodes for several applications beyond energy conversion and storage.

A model for impedance of a PEM fuel cell cathode catalyst layer under simultaneous application of potential and oxygen concentration harmonic perturbations is solved. The solution demonstrates strong lowering of the layer impedance under increase in the amplitude of oxygen concentration perturbation. Small in–phase oscillations of the overpotential and oxygen concentration lead to formation of a sub–layer with negligible oxygen transport loss. Working as an ideal non–polarizable electrode, this sub–layer dramatically reduces the system impedance.

In this work, we study the oxygen reduction reaction (ORR) properties of Pt-containing 3d transition-metal high-entropy alloy (Pt-HEA) surfaces, focusing on the constituent alloying elements. The surface Pt and underlying Cr-Mn-Co-Ni(1 1 1) (Pt/Cr-Mn-Co-Ni(1 1 1)) stacked lattice layers, which are synthesized through the vacuum deposition of the underlying alloy and surface Pt stacking layers on Pt(1 1 1) substrate, exhibit high pristine ORR activity and structural stability under potential-cycle loading, compared to Pt/Cr-Co-Ni, Pt/Mn-Co-Ni, and Pt/Co-Ni(1 1 1) surfaces. The outperformed ORR properties are attributed to the effective suppression of the surface segregation of Cr. This study demonstrates that not only the “high-entropy” effect induced by increasing the numbers of constituent elements but also the “chemical affinity” of Pt and the individual HEA constituent elements determine the ORR performances of Pt-HEA.