Optimal Anode Research Articles

Corrosion-resistant NiFe anode towards kilowatt-scale alkaline seawater electrolysis

Development of large-scale alkaline seawater electrolysis requires robust and corrosion-resistant anodes. Here we propose engineering NiFe layered double hydroxide (LDH)-based anodes by incorporating a series of anions into the LDH interlayers. The most optimal NiFe LDH anode with intercalated phosphates demonstrates stable operation at a high current density of 1.0 A cm−2 for over 1000 hours in a 2 W-scale alkaline seawater electrolyzer (ASWE). Fundamental studies indicate that the basicity, indicated by pKa values, of the intercalated anions in NiFe LDH governs its oxygen evolution reaction activity and corrosion resistance. Highly basic anions (i.e., phosphates) securely anchor Fe sites and facilitate proton transfer to boost both durability and activity. Notably, we demonstrate the proof-of-concept for the NiFe anode in an industrial 1 kW-scale ASWE stack (1,081.2 cm2 anode area in total). This unit achieves a stable operating current density of 0.5 A cm−2 at about 2.0 V, twice that of the commercial alkaline pure water electrolyzer, contributing to an economically competitive hydrogen production cost of US$ 1.96 kgH2−1.

Performance and Durability of Metallic Aerogel Anode Catalyst in Pure-Water-Fed Hydroxide Exchange Membrane Electrolyzers

Hydrogen holds significance as a versatile energy carrier that can be used in various sectors. Recently, hydroxide exchange membrane electrolyzers (HEMELs) towards clean hydrogen production have gained intensive attention, due to the possibility to use low-cost platinum group metal (PGM)-free electrocatalysts and cheaper membranes, ionomers.1 Although a variety of PGM-free catalysts have shown promising activities towards the alkaline oxygen evolution reaction (OER), few of them delivered sufficient stability in the pure-water-fed HEMELs.2 In this work, metallic aerogel, featured with high porosity and amorphous metal oxide shells, was deployed as platform to study the structural-performance relationship in HEMELs. A poly(aryl piperidinium) membrane and ionomer with high hydroxide conductivity were integrated to study the evolution in the composition and structure of PGM-free anode catalysts.3 Owing to unique properties of the 3D metallic aerogel, the optimal aerogel anode outperformed the Ir-based anode in the KOH-fed HEMELs. A transition in the HEMEL performance with different anode catalyst was observed when shifting from alkaline electrolyte to pure water, implying a steering in the rate limiting steps in the different anode feedings. The limiting factor of pure-water-fed HEMEL was probed by deconvoluting the contributions from ohmic resistance, electrode kinetic, and mass transport. The optimal metallic aerogel anode showed no performance loss during the 580-hour stability test at an industrial electrolyzer-relevant current density of 1 A cm−2 in pure water feeding. The HEMEL performance was monitored, revealing the degradations of critical components in the membrane-electrode-assembly. The structural performance relationship in HEMEL was probed by linking the physical properties of the catalysts with HEMEL performance. The gained insight will shed light on the development of highly efficient PGM-free anode catalysts for viable pure-fed HEMELs.References R. Abbasi, B. P. Setzler, S. Lin, J. Wang, Y. Zhao, H. Xu, B. Pivovar, B. Tian, X. Chen, G. Wu and Y. Yan, Advanced Materials, 31, 1805876 (2019).M. Chatenet, B. G. Pollet, D. R. Dekel, F. Dionigi, J. Deseure, P. Millet, R. D. Braatz, M. Z. Bazant, M. Eikerling, I. Staffell, P. Balcombe, Y. Shao-Horn and H. Schäfer, Chemical Society Reviews, 51, 4583 (2022).J. Wang, Y. Zhao, B. P. Setzler, S. Rojas-Carbonell, C. Ben Yehuda, A. Amel, M. Page, L. Wang, K. Hu, L. Shi, S. Gottesfeld, B. Xu and Y. Yan, Nature Energy, 4, 392 (2019).

(Invited) Design Strategy of High-Performance Hard Carbon Anodes for Sodium-Ion Storage

The advancement of hard carbon anodes with high sodium plateau capacities (SPCs) is currently hindered by a paucity of clear materials design principles. Although the pore volume ratio of hard carbon defines the thermodynamic constraints on the theoretical sodium plateau capacities (T-SPCs), exclusive reliance on pore architecture falls short in predicting viable SPCs. In response, our research explores a pivotal kinetic parameter of hard carbons that influences the coefficient of capacity utilization (CCU) of SPCs. We employ a suite of polymeric hard carbons (PHCs) with varied microstructures to achieve our research objectives. Our systematic investigation reveals a pronounced correlation between the intensity ratio of the 2D to G band (I 2D /I G ) in the Raman spectrum and the internal kinetic barrier impeding sodium-ion migration. Leveraging these insights, and by considering both thermodynamic and kinetic facets, we introduce a novel structural gauge – the SPC factor – which serves to quantify the CCU for SPCs. This SPC factor identifies an optimal hard carbon anode configuration that combines a high closed pore volume ratio with a minimized I 2D /I G ratio. By implementing straightforward microstructural modifications to the PHCs guided by our proposed criteria, we have realized significant achievements. Notably, we have attained an SPC of approximately 400 mA h g-1, underscoring the practicality and impact of our strategy in engineering superior hard carbon anodes for sodium-ion batteries. This investigation constitutes a meaningful leap forward, providing a strategic direction for materials design aimed at augmented SPCs and fostering the progression of future sodium-ion battery technologies.

Facile Synthesis of Highly Supercapacitive Mo‐doped Titanium Nanotube Arrays and Effect of Anodization Voltage

AbstractDesigning potential architectures by the modification of conventional electrode materials is an effective approach in the development of high performance supercapacitor electrodes. The present study investigated the effect of varying anodization voltages (50, 75, and 100 V) on the morphology and electrochemical properties of titanium nanotubes (TNT). Molybdenum was doped onto TNT using a simple hydrothermal procedure, followed by thermal treatment at 450 °C. The study effectively demonstrated control over the dimensions of the nanotube structure by adjusting the anodization voltage. Additionally, it was found that the tube diameters were increased due to etching during the hydrothermal treatment with the Mo precursor, which potentially enhanced the supercapacitive performance of Mo‐doped TNT. Further, structural analysis revealed that Mo doping improved both crystallinity and electrode stability. With an optimal anodization voltage of 100 V, TNT and Molybdenum‐doped TNT could exhibit capacitance value of 13.34 and 326.54 mF cm−2 respectively, at a current density of 1 mA cm−2. Furthermore, the electrode demonstrated good cyclic stability with 88% capacitance retention and 97% coulombic efficiency after 5000 cycles. An impressive energy density of 87.03 µWh cm−2 and a power density of 799.99 µW cm−2 could be achieved with this sample in an asymmetrical device.

Li-Si alloy pre-lithiated silicon suboxide anode constructing a stable multiphase lithium silicate layer promoting Ion-transfer kinetics

Enhancing the initial Coulombic efficiency (ICE) and cycling stability of silicon suboxide (SiOx) anode is crucial for promoting its commercialization and practical implementation. Herein, we propose an economical and effective method for constructing pre-lithiated core-shell SiOx anodes with high ICE and stable interface during cycling. The lithium silicon alloy (Li13Si4) is used to react with SiOx in advance, allowing for improved ICE of SiOx without compromising its reversible specific capacity. The pre-lithiated surface layer contains uniform multiphase lithium silicates (L2SiO3, Li4SiO4, and Li2Si2O5) in the nanoscale. This multiphase lithium silicate layer exhibits mechanical robustness against variation of micro-stress, which can act as a buffer layer to relieve volume variation. In addition, analysis of dynamic electrochemical impedance spectroscopy (dEIS) and distribution of relaxation time (DRT) confirm that the multiphase lithium silicate layer enhances Li-ion diffusion kinetics and contributed to constructing stable SEI. As a result, the optimal L10-850 anode shows a high ICE of 85.3%, together with a high specific capacity of 1771.5mAh mg-1. This work gives a perspective strategy to modify SiOx anodes by constructing a pre-lithiated surface layer with practical application potentials.

Recent Advances in Developing High-Performance Anode for Potassium-Ion Batteries based on Nitrogen-Doped Carbon Materials.

Owing to the low potential (vs K/K+), good cycling stability, and sustainability, carbon-based materials stand out as one of the optimal anode materials for potassium-ion batteries (PIBs). However, achieving high-rate performance and excellent capacity with the current carbon-based materials is challenging because of the sluggish reaction kinetics and the low capacity of carbon-based anodes. The doping of nitrogen proves to be an effective way to improve the rate performance and capacity of carbon-based materials as PIB anode. However, a review article is lacking in systematically summarizing the features and functions of nitrogen doping types. In this sense, it is necessary to provide a fundamental understanding of doped nitrogen types in nitrogen-doped(N-doped) carbon materials. The types, functions, and applications of nitrogen-doped carbon-based materials are overviewed in this review. Then, the recent advances in the synthesis, properties, and applications of N-doped carbon as both active and modification materials for PIBs anode are summarized. Finally, doped nitrogen's main features and functions are concluded, and critical perspectives for future research in this field are outlined.

Concentric circular flow field to improve mass transport in large-scale proton exchange membrane water electrolysis cells

Concentric circular flow field to improve mass transport in large-scale proton exchange membrane water electrolysis cells

Construction of a superhydrophobic surface with long-term durability on 5052 Aluminium for corrosion protection

Construction of a superhydrophobic surface with long-term durability on 5052 Aluminium for corrosion protection

Manipulating micropore structure of hard carbon as high‐performance anode for Sodium-Ion Batteries

Manipulating micropore structure of hard carbon as high‐performance anode for Sodium-Ion Batteries

Manipulating Interfacial Renovation via In Situ Formed Metal Fluoride Heterogeneous Protective Layer toward Exceptional Durable Sodium Metal Anodes

AbstractSodium metal is regarded as an optimal anode material for high‐energy‐density sodium‐ion batteries (SIBs). However, during the processes of sodium deposition and stripping, the failure of the solid electrolyte interphase (SEI) film leads to the continuous accumulation of inactive sodium, thereby compromising the cycling reversibility of the battery. Here, a novel metal fluoride heterointerface layer is generated and constructed through in situ manipulation of the continuous reaction between TiF4 and metal Na. The reconstructed NaF/TiF3 interface layer, which tightly anchors the sodium metal, effectively suppresses the formation of sodium dendrites during the charge‐discharge process. The highly sodium‐philic TiF3 component exhibits strong binding with Na ions, while NaF reduces the Na+ diffusion energy barrier, significantly enhancing the reaction kinetics. Due to the successful artificial construction of this interface layer, the Na/TiF4 composite electrode demonstrates an exceptional ultra‐long cycling stability of 2370 h in symmetric cells (0.5 mAh cm−2). Density functional theory (DFT) calculations further validate the functionality of each component in the Na/TiF4 protective layer. When paired with NaNi1/3Fe1/3Mn1/3O2 cathode in a pouch cell, it exhibits stability up to 2000 cycles at current densities of 2 C and 4 C, with a maximum energy density output of 483.1 Wh kg−1 (power density: 320.8 W kg−1).

Engineering multiple heterogeneous Co/CoSe/MoSe2 embedded in carbon nanofibers with Co/Mo–Se–C bonding towards high performance sodium ion capacitors

Engineering multiple heterogeneous Co/CoSe/MoSe2 embedded in carbon nanofibers with Co/Mo–Se–C bonding towards high performance sodium ion capacitors

Morphological Modulation of TiO2 Nanotube via Optimal Anodization Condition for Solar Water Oxidation

Morphological Modulation of TiO2 Nanotube via Optimal Anodization Condition for Solar Water Oxidation

DFT study of lithium adsorption on silicon quantum dots for battery applications

DFT study of lithium adsorption on silicon quantum dots for battery applications

Enhancing ammonium-ion storage in Mo-doped VO2 (B) nanobelt-bundles anode for aqueous ammonium-ion batteries.

The recent surge in interest in aqueous ammonium ion rechargeable batteries (AAIBs) has been fueled by their eco-friendliness, efficiency, safety, and sustainability. However, finding the optimal anode material for effective ammonium ion (NH4+) storage remains a nascent and significant challenge. The research presented here focuses on the enhancement of aqueous ammonium rechargeable batteries by incorporating Mo atoms into VO2 (B) (denote as MVO), a material that has shown promise as an anode for NH4+ storage. The introduction of Mo ions was found to optimize the electronic structure and morphology of pristine VO2 (B) (label as PVO), resulting in the transformation of its nanobelts into thin nanobelt-bundles. This alteration exposes more active sites and increases oxygen vacancies, which in turn improve the conductivity and diffusion rate of NH4+ ions, thereby enhancing the overall electrochemical performance of the material. The MVO material demonstrates a high initial capacity of 283.5 mA h g-1 at 0.3 A g-1, and maintained 86.7% of its capacity after 4500 cycles, indicating excellent long-term stability. To further validate the practical application, a full cell was garnered utilizing MVO as the anode and Cu3[Fe(CN)6]2 (CuHCF) as the cathode. The resulting AAIB displays remarkable cycling stability, with 81.5% capacity preservation after 1000 cycles and large energy density of 57.9 W h kg-1. The study reveals that the doping of Mo ions can significantly improve both the stability and NH4+ storage capacity of PVO, offering a promising new direction for the exploitation of efficacious and sustainable NH4+ host materials for rechargeable batteries.

Topological proton regulation of interlayered local structure in sodium titanite for wide‐temperature sodium storage

AbstractDeveloping high‐capacity and high‐rate anodes is significant to engineering sodium‐ion batteries with high energy density and high power density. Layered Na2Ti3O7 (NTO), with an open crystal structure, large theoretical capacity, and low working potential, is recognized as one of the prospective anodes for sodium storage. Nevertheless, it suffers from sluggish sodiation kinetics and low (micro)structure stability triggered by a high Na+ diffusion barrier and weak adhesion of [Ti3O7] slabs. Herein, the interlayered local structure of NTO is regulated to solve the above issues, in which parts of interlayered Na+ sites are substituted by H+ (Na2−xHxTi3O7 [NHTO]). Theoretical calculations prove that the NHTO offers lower activation energy for Na+ transports and low interlayer spacings with alleviated Na–Na repulsion and relatively flexible [Ti3O7] slabs to reduce fractural stress. In situ and ex situ characterizations of (micro)structure evolution reveal that NHTO goes through transformation between H‐rich and Na‐rich phases, resulting in high structure stability and microstructure integrity. The optimal NHTO anode delivers a high capacity of 190.6 mA h g−1 at 0.5 C after 300 cycles and a superior high‐rate stability of 90.6 mA h g−1 at 50 C over 10,000 cycles at room temperature. Besides, it offers a capacity of 50.3 mA h g−1 after 1800 cycles at a low temperature of −20°C and 195.7 mA h g−1 after 500 cycles at a high temperature of 40°C at 0.5 C. The developed topologically interlayered local structure regulation strategy would raise the prospect of designing high‐performance layered anodes.

Lithiophilic ZnCu alloy sites on copper current collector for high performance Li metal anode

Lithiophilic ZnCu alloy sites on copper current collector for high performance Li metal anode

Hard anodizing of AK9ch high silicon aluminum alloy

This work is devoted to anodic oxidation at low temperatures in the sulfuric acid electrolyte of the foundry aluminum alloy AK9ch, with a high silicon content. Optimal anodizing conditions were chosen for obtaining coatings with a hardness of more than 300 HV and a thickness of about 40 microns. With an increase in the thickness of the coatings by increasing the current density or anodizing time, their hardness begins to decrease. The resulting hard coatings are planned to be used on large parts obtained by casting aluminum alloy AK9ch.

Experimental study on the discharge of a xenon-assisted krypton Hall thruster

Experimental study on the discharge of a xenon-assisted krypton Hall thruster

Solid Oxide Fuel Cell Anode Porosity and Tortuosity Effect on the Exergy Efficiency

Improving the efficiency of solid oxide fuel cells (SOFCs) is critical for advancing clean energy solutions on a global scale. One major challenge in enhancing SOFC efficiency is reducing anode diffusion polarization, which can significantly hinder performance. This study addresses this issue by investigating the effects of anode tortuosity and porosity on the exergy efficiency of SOFCs. The novelty of this research lies in its comprehensive numerical model, which uniquely incorporates detailed material properties and their impact on SOFC performance—specifically focusing on anode tortuosity and porosity. Using advanced Multiphysics software, we developed a model that solves mass, electron transfer, and energy equations discretized via the finite differences method. The study meticulously examines how variations in these parameters influence SOFC efficiency, providing new insights into optimal anode design. Our methodology involves simulating different anode configurations to pinpoint the key parameters that affect exergy efficiency, thereby minimizing the experimental costs and time associated with traditional approaches. The quantitative results of this study are significant. We found that an anode tortuosity of 5.5 and a porosity range of 0.05–0.1 optimize exergy efficiency, achieving a 15% improvement compared to conventional designs. Additionally, a mean pore radius between 15 and 20 µm was identified as optimal for enhancing cell voltage. These findings elucidate the critical relationship between anode material properties and SOFC performance, offering a practical pathway to improving efficiency. This research provides a novel numerical approach to understanding and optimizing anode characteristics in SOFCs. By highlighting the importance of specific material properties, such as tortuosity and porosity, and demonstrating their impact on exergy efficiency, this study offers valuable guidance for future SOFC design and development.

Electrochemical performance of Cu6Sn5 alloy anode materials for lithium-ion batteries fabricated by controlled electrodeposition.

Combining electrodeposition and heat treatment is an effective method to successfully fabricate Cu6Sn5 alloy materials, in which the S2 alloy electrode is electrodeposited at 1.2 A dm-2 current density with uniform and compact morphology. The characterization results show that monoclinic η'-Cu6Sn5 and hexagonal η-Cu6Sn5 phases fabricated at the appropriate current density exhibit excellent electrochemical performance. The optimal Cu6Sn5 alloy anode material boasts not just a significantly high discharge specific capacity of 890.2 mA h g-1 with an initial coulombic efficiency (ICE) of 73.96%, but also achieves an adequate discharge specific capacity of 287.1 after 50 cycles at 100 mA h g-1. Moreover, the electrodeposited Cu6Sn5 alloy materials also possessed a lower transfer resistance of 42.45 Ω and an improved lithium-ion diffusion coefficient of 2.665 × 10-15 cm2 s-1 at the current density of 1.2 A dm-2. Therefore, preparing the Cu6Sn5 alloy thin-film electrode could be a cost-effective and straightforward method by electrodeposition from cyanide-free plating baths to develop anode components suitable for lithium-ion battery applications.