Anodic Corrosion Research Articles

Experimental study on soil improvement by electrochemical injection coupled with anode movement technique

An improved electroosmotic method which involves coupling anode movement with injection of calcium chloride (CaCl2) solution into soils during the electroosmotic process was proposed in this paper. The laboratory-based experimental study was conducted in a custom-designed test set-up to assess the effectiveness of the proposed method. During the electroosmotic process, the drained water, drainage rate, electric current, electric resistance, power consumption, settlement, and penetration resistance were monitored. The experimental study showed that after treatment, the drainage volume was about 3.5 times that of the pure electroosmotic, 1.6 times that of the electroosmotic process with injection only, and 2.4 times that of the electroosmotic process with anode movement only. Further, electrochemical injection coupled with anode movement can significantly reduce the non-uniform electrochemical changes in the treated samples, resulting in a relatively uniform settlement and considerable cementation area throughout the sample. The results demonstrate that using this method can effectively alleviate anode corrosion, double the voltage gradient and mitigate the electric resistance increase, further enhancing electroosmotic treatment efficiency.

Biopolymer‐Based Gel Electrolytes for Advanced Zinc Ion Batteries: Progress and Perspectives

AbstractIn recent years, aqueous zinc ion batteries (ZIBs) with ultra‐high safety and environmental friendliness have emerged as a promising candidates for energy storage and energy conversion devices. However, the severe side reactions and dendrites issues discourage the practical application of ZIBs. Recently, biopolymer‐based gel electrolytes have disclosed large potential in tackling these challenges of ZIBs, with numerous advancements reported. Their advantages lie in suppressing side reactions including hydrogen evolution and Zn metal anode corrosion, as well as inhibiting the growth of Zn dendrites. This review comprehensively examines the classification, structures and properties of biopolymer‐based gel electrolytes, with a focus on hydrogel electrolytes derived from various natural macromolecular biopolymers, along with a brief discussion on non‐hydrogel electrolytes using ionic liquids or organic solutions as solvents. Subsequently, the preparation of biopolymer‐based gel electrolytes with physical and chemical methods are summarized. Furthermore, the practical applications of biopolymer‐based gel electrolytes in ZIBs with diverse cathodes materials are introduced. Finally, it highlights the environmental benefits and excellent electrochemical performance of biopolymer‐based gel electrolytes, outlining their prospects for the next generation of ZIBs and proposing future perspectives.

Inspired corrosion resistance of copper mediated by multiple ethoxy units linker included indazole based bis-Schiff base dyes in NaCl solution

In this study, hydrophilic multiple ethoxy units linkage chain included bis-Schiff base dyes (SBs 1–3) were designed and synthesized for strengthening corrosion resistance of copper in NaCl solution. The corrosion resistance and corrosion inhibition mechanism of the target dyes for copper were investigated in 3.0 wt% NaCl solution. The adsorption of these dyes on copper surface was revealed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) revealed the adsorption of these dyes containing CN double bonds on copper surface, achieving excellent corrosion inhibition efficiency. The electrochemistry shows that the dyes were able to inhibit the corrosion of copper in sodium chloride solution, and the corrosion inhibition efficiency reached the peak value at a concentration of 1.00 mM. It is noted that the corrosion inhibition efficiency increased with the number increase of ethoxy units. The kinetic potential polarization curves indicate that the dyes were anodic corrosion inhibitors, which could inhibit the anodic reaction process of corrosion. The adsorption of corrosion inhibitor these dyes on copper surface followed Langmuir isothermal adsorption model.

Development of NiFeSx for Selective Oxygen Evolution Reaction (OER) in Alkaline Seawater: Mitigating Chlorine Evolution in Next-Gen Seawater Electrolysis Devices

Efficient seawater electrolysis for hydrogen production faces challenges like active site poisoning, chloride oxidation, and anode corrosion, necessitating the development of effective oxygen evolution reaction (OER) electrocatalysts[1]. Strategies such as enhancing OER kinetics, mitigating chloride oxidation, bolstering corrosion resistance, and integrating multifunctionality into electrocatalysts are being pursued. Researchers explore internal and external cultivation methods to optimize electrocatalyst properties while understanding structural evolution and OER mechanisms remains crucial. Seawater electrolysis, tapping into Earth's abundant seawater resources, offers a scalable solution for green hydrogen production, especially when paired with renewable energy sources[2]. It holds promise for providing energy and water to offshore areas and mobile maritime systems, crucial for addressing energy and environmental challenges. In this study, we have fabricated a PGM (platinum group metal) free anode that shows promising performance in alkaline seawater. The material consists of nanoclusters of FeNiSx.This study applied a polyol-assisted hydrothermal synthesis strategy to describe an advanced procedure for synthesising NiFeSx. Several physical and chemical characterisation tools are applied to investigate the anode electrode for alkaline seawater oxidation XRD, SEM, TEM and electrochemical characterisation. The outcomes of these characterisations were displayed as graphs. The catalysts reveal nanocluster morphologies. The figure below depicts the preliminary findings, illustrating the electrochemical performance and the physical characterisations. Figure 1 (a) and (b) depict the morphological evaluation by electron microscopy revealing the nanostructure-based clusters of the produced materials with the scanning and transmission electron microscopy, respectively. In. Polarisation curves of the oxygen evolution activity of the synthesised NiFeiSx electrocatalysts on Ni foam working electrodes, in a three-electrode configuration with Pt wire serving as the counter and Hg/HgO serving as the reference electrode in 0.1M KOH + 0.5 NaCl electrolyte. The best-performing catalysts obtained a high current exchange density close to 225 mAcm-2 shown in Figure 1(c). In addition, we are evaluating the efficacy of this high-performance anode electrocatalyst in a single-cell electrolyser and the best and most stable catalyst will be tested in stacks we are developing with our partners in the ANEMEL project.Our research methodology encompasses a comprehensive array of ex-situ and in-situ characterization techniques to delve into the intricacies of seawater electrolysis for hydrogen production. We will utilize impedance spectroscopy to dissect electrochemical behaviour, including resistance, capacitance, and charge transfer resistance. Additionally, chronopotentiometry/chronoamperometry will assess the catalyst's long-term stability, while real-time examination of catalyst crystal structure during OER will be facilitated by Powder X-ray diffraction (XRD). Surface chemistry and elemental composition analysis will be conducted using X-ray photoelectron spectroscopy (XPS), while in-situ Raman spectroscopy will offer insights into electronic structure changes during the reaction, shedding light on the OER mechanism. Furthermore, FTIR spectroscopy will unveil reaction intermediates and mechanisms, providing a detailed understanding of the reaction pathway. Post-mortem catalyst analysis post-electrochemical testing will evaluate degradation, ultimately aiding in optimizing catalyst design for long-term stability and high-performance OER. Acknowledgements The authors acknowledge the ANEMEL Project funded by the Horizon Europe (European Innovation Council) Grant agreement 101071111. Figure 1

Crafting a Reversible Zinc Metal Anode: The Impact of Organic Electrolyte Additives in Solid Electrolyte Interface Formation

Li ion batteries are appealing for their high energy density and high working potential, however, concerns regarding their expense, access to raw materials and safety have steered researchers towards exploring new sustainable, clean, cost effective and efficient energy storage system.1 Within this domain, aqueous zinc metal battery has emerged as potential candidate due to its impressive specific capacity, low redox potential, environmental sustainability, and cost-effectiveness. Nevertheless, impediments such as corrosion of Zn anode, excessive dendrite formation, hydrogen evolution and dissolution of cathodes impose constraints on their applicability.2 To tackle these challenges, numerous investigations show utilization of organic molecules (Triethyl Phosphate3, Pyridine4) as additives or cosolvents. However, the use of high concentration salt and various organic additives reduces the ionic conductivity of the electrolytes and negatively impacts the cost and energy density of the battery.Along this line, we have delved into electrochemical properties of hybrid electrolyte composed of water and propylene carbonate, and their ability to form solid electrolyte interphase (SEI). Through this exploration, we've noted a remarkable improvement in battery characteristics such as high coulombic efficiency and stable capacity. By introducing a small amount of propylene carbonate, we have observed substitution of water molecules solvating Zn2+ ions with additives and triflate anions. This led to electrochemical reduction of solvated Zn ion species, forming a solid electrolyte interphase rich in ZnF2 as confirmed by XPS. Moreover, spectroscopic investigations indicate a significant interaction between the highly basic carbonyl oxygen moiety of propylene carbonate (PC) and water molecules, thereby mitigating the dissolution of the cathode.5 This phenomenon facilitates the attainment of remarkable specific capacity of approximately 300 mAh g-1 over the course of 900 cycles at a current density of 1 A g-1. Furthermore, we emphasize the significance of considering the dielectric constant and polarity of an additive or cosolvent in evaluating the performance of the electrolyte for aqueous zinc ion batteries.Reference: O. Schmidt, A. Hawkes, A. Gambhir, and I. Staffell, Nature Energy, 2, 1–8 (2017)V. Verma, S. Kumar, W. Manalastas, Jr., and M. Srinivasan, ACS Energy Lett., 6, 1773−1785 (2021).S. Liu, J. Mao, W. K. Pang, J. Vongsvivut, X. Zeng, L. Thomsen, Y. Wang, J. Liu, D. Li, and Z. Guo, Adv. Func. Mater., 31, 2104281 (2021).J. Luo, L. Xu, Y. Zhou, T. Yan, Y. Shao, D. Yang, L. Zhang, Z. Xia, T. Wang, L. Zhang, T Cheng, and Y. Shao, Angew. Chem. Int. Ed., 62, e202302302, (2023).B. Kakoty, R. Vengarathody, S. Mukherji, V. Ahuja, A. Joseph, C. Narayana, S. Balasubramanian, and P. Senguttuvan, J. Mater. Chem. A, 10, 12597–12607 (2022)

Decoupling Lithium Salt and Lithium Polysulfide Solvation By Partially-Fluorinated Ether Boosts Cycle Life of Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are regarded as one of the most promising next-generation energy storage systems due to their advantages of high energy density and low material cost. However, the conventional Li-S cell construction with ether-based electrolyte, composed of 1,2-dimethoxyethane (DME) and 1,3-dioxalane (DOL), suffers from severe shuttle effect and lithium metal anode corrosion because of soluble lithium polysulfide (LiPS) intermediates. These deficiencies further lead to limited cell calendar life and impedes Li-S batteries from practical applications. Weakening the electrolyte solvation power towards lithium polysulfide by adding hydrofluoroethers (HFEs) has been intensively explored and considered as an effective strategy to suppress LiPS dissolution and improve the electrochemical stability of electrolyte against lithium anode. Nevertheless, excessive fluorination of the current HFE cosolvents simultaneously confines the dissolution and solvation towards lithium salt, which detrimentally limits the ionic conductivity and therefore the electrochemical performance of the electrolyte. Herein, with the aim of decoupling lithium salt and LiPS solubility, we developed a partially fluorinated glyme, 1,2-bis(2,2-difluoroethoxy) ethane (F4DEE) as a novel solvent in Li-S battery electrolyte. The targeted design of F4DEE molecular structure enables F4DEE itself a considerable lithium salt solubility (> 6 M for LiTFSI) yet a confined LiPS solubility (< 100 mM for Li2S6). By combining F4DEE with conventional solvent DOL, the resulted DOL/F4DEE electrolyte realizes an extraordinary balance between reasonable ionic conductivity and suppressed LiPS dissolution. Furthermore, DOL/F4DEE electrolyte can induce a fluorine-rich solid-electrolyte interface (SEI) on Li anode surface, which is proven to be sturdy and thus benefit Li stripping/plating stability under real Li-S cycling conditions. When tested in coin cell configuration at room temperature, the Li-S cell with DOL/F4DEE electrolyte delivers a high initial specific capacity of 1081 mAh g-1 at 0.05 C and an extended lifetime of over 180 cycles before cell failure at 0.1 C. This cycle life is a threefold increase compared to the conventional DME/DOL electrolytes, highlighting the promising potential of our electrolyte design strategy.

Impact of cell design and conditioning on polymer electrolyte membrane water electrolyzer operation

Integration of polymer electrolyte membrane water electrolyzers (PEMWEs) for clean hydrogen generation requires a robust understanding of the impact cell designs and conditioning protocols have on operation and stability. Here, catalyst-coated electrode and catalyst-coated membrane cells employing Pt/C cathode catalyst layer, an IrO2 anode catalyst layer, with a platinized titanium mesh or a carbon paper with a microporous layer as the porous transport layer were developed. The impact of cell conditioning above and below 0.25 A cm−2 was investigated using advanced electrochemical impedance spectroscopy analyses and microscopic imaging, with the electrochemical response related to physicochemical processes. Operation below 0.25 A cm−2 prior to operation above 0.25 A cm−2 resulted in anode corrosion and titanium cation contamination, increasing the cell voltage at 1 A cm−2 by 200 mV compared to uncontaminated cells. Conditioning above 0.25 A cm−2 led to non-negligible hydrogen transport resistances due to cathode flooding that resulted in a ca. 50 mV contribution at 1 A cm−2 and convoluted with the anode impedance response. The presence of a microporous layer increased catalyst utilization but increased the cell voltage by 300 mV at 1 A cm−2 due to increased anodic mass transport resistances. These results yield critical insights into the impact of PEMWE cell design and operation on corresponding cell performance and stability while highlighting the need for application dependent standardized operating protocols and operational windows.

Efficacy of Andrographis paniculata leaf extract as a green corrosion inhibitor for mild steel in concentrated sulfuric acid: Experimental and computational insights

The rising demand for eco-friendly corrosion inhibitors has intensified efforts to find sustainable alternatives to hazardous chemical inhibitors widely used in industry. Mild steel, although commonly utilized in acidic environments, is prone to significant corrosion, necessitating effective solutions to prevent structural degradation. This study investigates the potential of Andrographis paniculata leaf extract (APLE) as a sustainable, green corrosion inhibitor for mild steel in concentrated sulfuric acid, a condition representative of harsh industrial environments. Using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods, APLE demonstrated a high inhibition efficiency of 95.14% at a concentration of 4000 ppm, effectively reducing both anodic and cathodic corrosion reactions. Scanning electron microscopy (SEM) revealed a protective layer formation on the steel surface, significantly reducing corrosion. The adsorption of APLE followed the Langmuir isotherm, indicating monolayer coverage, while quantum chemical calculations validated APLE's electron-donating capability, enhancing surface stability through physisorption. These findings underscore APLE as a viable, eco-friendly alternative to conventional inhibitors, offering promising applications in various acidic environments.

Constructing High‐Performance Zn‐Iodine Batteries with CuI‐PVP Composite Layer Coated Zn Anodes

AbstractAqueous zinc‐iodine (Zn‐I2) batteries featuring abundant raw materials, inherent safety, excellent cost competitiveness and environmental benignity have been identified as one kind of important electrochemical energy storage devices. However, these batteries always suffer from inferior electrochemical performance, because of dendrite growth and corrosion/passivation of the anodes. Herein, a copper iodide‐polyvinylpyrrolidone (CuI‐PVP) composite layer is proposed to suppress the parasitic reactions and protect the Zn anodes. In this layer, the CuI can spontaneously react with metallic Zn and convert into Cu and Cu5Zn8 (2CuI+Zn→2Cu+ZnI2; 5Cu+8Zn→Cu5Zn8). The highly zincophilic Cu and Cu5Zn8, as heterogeneous seeds, can guide the uniform Zn nucleation and deposition, while alleviating corrosion of the Zn anodes. At the same time, the iodide species releasing from the composite layer can be oxidized and deposited on the cathodes, contributing additional capacity. As a result, the symmetric cell prepared with the CuI‐PVP@Zn anodes demonstrates a long cycling lifetime of 1400 hours at 1 mA cm−2 and 1 mAh cm−2. Under an even higher current density of 5 mA cm−2, the CuI‐PVP@Zn cell can still stably work for more than 660 hours. The practical application of this CuI‐PVP@Zn electrode has been further demonstrated in Zn‐I2 full batteries, which achieve 60 % higher specific capacity than the untreated ones (251.4 vs. 157.1 mAh g−1 after 2800 cycles).

Polymeric Ionic Liquid-Enabled In Situ Protection of Li Anodes for High-Performance Li-O2 Batteries.

Redox mediators (RMs) have shown promise in enhancing Li-O2 battery cycling stability by reducing overpotential. However, their application is hindered by the shuttle effect, leading to RM loss and Li anode corrosion. Here, we introduce a polyionic liquid, poly (1-Butyl-3-vinylimidazolium bis(trifluoromethanesulfonylimine)) ([PBVIm]- TFSI) as an additive, showcasing a novel Li anode protection strategy for LiI-mediated Li-O2 batteries. [PBVIm]+ cations migrate to the Li anode, forming a protective cationic shield that promotes uniform Li+ deposition. The addition of [PBVIm]-TFSI enhances the cycling stability, achieving 105 cycles at 200 mA·g-1, compared to the cell with LiI which exhibited 38 cycles under the same conditions. Synchrotron X-ray tomography reveals the evolution of this protective layer, providing insights into its formation mechanism, in conjunction with XPS analysis. Our findings offer a new approach to Li anode protection in Li-O2 batteries, emphasizing the critical role of interfacial engineering for battery performance.

NiFe pyrophosphate enables long-term alkaline seawater oxidation at an ampere-level current density

Seawater electrolysis has potential for scalable hydrogen (H₂) production, yet anode corrosion by chloride ions (Cl⁻) remains a critical challenge. Herein, we present an amorphous NiFe pyrophosphate (P2O74−) on Ni foam (NiFe-PPi/NF) for long-term alkaline seawater oxidation (ASO). Ex situ and in situ characterizations demonstrate that the in situ released P2O74− can act as an anion protective layer, effectively repelling Cl⁻ and safeguarding high-valence active metal sites during ASO. Through surface-anticorrosion design, NiFe-PPi/NF demonstrates stable operation at 1000 mA cm⁻2 for over 1000 hours with no loss in activity and requires a low overpotential of just 370 mV to achieve this industrial current density in alkaline seawater. This study offers a valuable strategy for developing corrosion-resistant anodes for ASO.

Challenges and Approaches to Designing High‐Energy Density Lithium‐Sulfur Pouch Cells

AbstractLithium‐sulfur (Li−S) batteries are of great interest as next‐generation energy storage devices in a wide variety of applications, due to their high specific capacity and the environmental abundance of sulfur. However, liquid electrolyte Li−S technology faces several challenges such as polysulfide shuttling, anode corrosion and sluggish cathode kinetics. Practical deployment of Li−S batteries requires evaluation in large‐format, high energy density pouch cells. Stringent operating conditions such as high sulfur loading and operating current, low electrolyte amount, and limited anode quantity are required for high energy density pouch cells, which further curtails the electrochemical performance and cycle life. This review aims to provide an understanding of the different failure mechanisms of large‐format Li−S pouch cells and formulate key design parameters of Li−S pouch cells that have high capacity, coulombic efficiency and long cycle life. Recent developments in Li−S pouch cells are then discussed, focusing on cathode and electrolyte design for polysulfide immobilization, accelerated sulfur conversion kinetics, and Li anode protection. A review of advanced characterization techniques suitable for Li−S pouch cell studies is also provided. Finally, viewpoints are offered on the remaining challenges and prospects to guide future research in scaling up Li−S technology for real‐world applications.

Metal‐Phosphonate‐Organic Network as Ion Enrichment Layer for Sustainable Zinc Metal Electrode with High Rate Capability

AbstractZinc (Zn) metal batteries could be the technology of choice for sustainable battery chemistries owing to its better safety and cost advantage. However, their cycle life and Coulombic efficiency (CE) are strongly limited by the dendritic growth and side reactions of Zn anodes. Herein, we proposed an in situ construction of a metal‐phosphonate‐organic network (MPON) with three‐dimensional interconnected networks on Zn metal, which can act as an ion enrichment layer for Zn anodes in Zn‐metal batteries. This MPON with abundant porous structure and phosphate sites possesses ion enriching properties and high Zn2+ transference number (0.83), which is beneficial for enhancing Zn2+ migration and self‐concentrating kinetics. Meanwhile, MPON offers hydrophobicity to effectively inhibit the water‐induced Zn anode corrosion. As a result, the Zn electrode exhibits superior Zn/Zn2+ reversibility of over 4 months at 3 mA cm−2 and a high CE of 99.6 %. Moreover, the Zn/NaV3O8 ⋅ 1.5H2O and Zn/MnO2 full cells using ultrathin Zn anodes (10 μm) exhibit high‐capacity retention of 81 % and 78 % after 1400 and 1000 cycles, respectively. This work provides a unique promise to design high‐performance anode for practical Zn‐metal‐based batteries.

Metal-Phosphonate-Organic Network as Ion Enrichment Layer for Sustainable Zinc Metal Electrode with High Rate Capability.

Zinc (Zn) metal batteries could be the technology of choice for sustainable battery chemistries owing to its better safety and cost advantage. However, their cycle life and Coulombic efficiency (CE) are strongly limited by the dendritic growth and side reactions of Zn anodes. Herein, we proposed an in situ construction of a metal-phosphonate-organic network (MPON) with three-dimensional interconnected networks on Zn metal, which can act as an ion enrichment layer for Zn anodes in Zn-metal batteries. This MPON with abundant porous structure and phosphate sites possesses ion enriching properties and high Zn2+ transference number (0.83), which is beneficial for enhancing Zn2+ migration and self-concentrating kinetics. Meanwhile, MPON offers hydrophobicity to effectively inhibit the water-induced Zn anode corrosion. As a result, the Zn electrode exhibits superior Zn/Zn2+ reversibility of over 4 months at 3 mA cm-2 and a high CE of 99.6 %. Moreover, the Zn/NaV3O8 ⋅ 1.5H2O and Zn/MnO2 full cells using ultrathin Zn anodes (10 μm) exhibit high-capacity retention of 81 % and 78 % after 1400 and 1000 cycles, respectively. This work provides a unique promise to design high-performance anode for practical Zn-metal-based batteries.

Constructing Quasi-Single Ion Conductors by a β-Cyclodextrin Polymer to Stabilize Zn Anode.

Aqueous Zn-ion batteries (AZIBs) are promising for the next-generation large-scale energy storage. However, the Zn anode remains facing challenges. Here, we report a cyclodextrin polymer (P-CD) to construct quasi-single ion conductor for coating and protecting Zn anodes. The P-CD coating layer inhibited the corrosion of Zn anode and prevented the side reaction of metal anodes. More important is that the cyclodextrin units enabled the trapping of anions through host-guest interactions and hydrogen bonds, forming a quasi-single ion conductor that elevated the Zn ion transference number (from 0.31 to 0.68), suppressed the formation of space charge regions and hence stabilized the plating/striping of Zn ions. As a result, the Zn//Zn symmetric cells coated with P-CD achieved a 70.6 times improvement in cycle life at high current densities of 10 mA cm-2 with 10 mAh cm-2. Importantly, the Zn//K1.1V3O8 (KVO) full-cells with high mass loading of cathode materials and low N/P ratio of 1.46 reached the capacity retention of 94.5 % after 1000 cycles at 10 A g-1; while the cell without coating failed only after 230 cycles. These results provide novel perspective into the control of solid-electrolyte interfaces for stabilizing Zn anode and offer a practical strategy to improve AZIBs.

Constructing Quasi‐Single Ion Conductors by a β‐Cyclodextrin Polymer to Stabilize Zn Anode

AbstractAqueous Zn‐ion batteries (AZIBs) are promising for the next‐generation large‐scale energy storage. However, the Zn anode remains facing challenges. Here, we report a cyclodextrin polymer (P‐CD) to construct quasi‐single ion conductor for coating and protecting Zn anodes. The P‐CD coating layer inhibited the corrosion of Zn anode and prevented the side reaction of metal anodes. More important is that the cyclodextrin units enabled the trapping of anions through host–guest interactions and hydrogen bonds, forming a quasi‐single ion conductor that elevated the Zn ion transference number (from 0.31 to 0.68), suppressed the formation of space charge regions and hence stabilized the plating/striping of Zn ions. As a result, the Zn//Zn symmetric cells coated with P‐CD achieved a 70.6 times improvement in cycle life at high current densities of 10 mA cm−2 with 10 mAh cm−2. Importantly, the Zn//K1.1V3O8 (KVO) full‐cells with high mass loading of cathode materials and low N/P ratio of 1.46 reached the capacity retention of 94.5 % after 1000 cycles at 10 A g−1; while the cell without coating failed only after 230 cycles. These results provide novel perspective into the control of solid‐electrolyte interfaces for stabilizing Zn anode and offer a practical strategy to improve AZIBs.

Regulating the Helmholtz plane by trace ionic liquid additive for advanced Al-air battery

Al-air batteries (AABs) are the next generation of alternative energy sources due to their high theoretical energy density, low cost, and environmental friendliness. Researchers have been interested in AABs with stable discharge in alkaline solution, long discharge time, and high conductivity. However, the uncontrolled self-corrosion of the Al anode and the severe hydrogen evolution reaction in alkaline electrolytes have been two major drawbacks hindering the commercial development of AABs. These shortcomings reduce the Al anode's utilization and significantly shorten the battery's service life. Herein, the Helmholtz plane structure was reconstructed using an ionic liquid additive called 1-aminopropyl-3-methylimidazolium bromide (AMIB) to regulate the electrochemical interface between the electrolyte and the Al anode. Electrochemical tests found that when 3 mM AMIB was added, the corrosion inhibition efficiency could reach up to 60 %. Further surface analysis and theoretical calculations showed that AMIB can form a dense and uniform protective layer on the surface of the Al anode substrate, which reduces the anode corrosion, lowers the active centers for hydrogen evolution on the Al surface, and reduces the hydrogen evolution rate. The full-cell studies found that the specific capacity of the cell increased from 1227 to 2564 mAh g−1, the energy density increased from 1546 to 3359 Wh kg−1, and the Al anode utilization increased from 41.2 % to 86.1 % as the AMIB addition to the alkaline electrolyte risen from 0 to 3 mM. This method of electrolyte regulation provides an efficient strategy for the commercial development of AABs.

Weak solvation effects and molecular-rich layers induced water-poor Helmholtz layers boost highly stable Zn anode

The advancement of aqueous Zn-based energy storage systems encounters major challenges due to the occurrence of side reactions and the growth of dendrites caused by the highly active nature of water in the aqueous electrolyte. Herein, a zwitterion additive named sulfonated amphoteric betaine (referred to as DMAPS) regulates the Zn2+ electrolyte environment through a weak solvation effect to promote highly stable Zn anodes. The inherently occurring anionic (-SO3-) and cationic (-NR4+) counterions in the DMAPS chain can be effectively separated under an external electric field to enable the creation of distinct ion migration pathways, thereby significantly enhancing the transportation of electrolyte ions. Moreover, DMAPS can be adsorbed onto the surface of Zn anode to form a H2O-poor Helmholtz layer, which can serve as a protective barrier to suppress corrosion of the Zn anode by free H2O and inhibits the formation of differential electric field to facilitate the directional deposition of Zn2+. In addition, density functional theory (DFT) and molecular dynamics (MD) further assisted in demonstrating the intrinsic mechanism of the reconstruction of the solvated sheath structure of Zn2+ by DMAPS. As a result, the Zn//Zn symmetric cell in ZnSO4+DMAPS solution can be cycled steadily for 2100 h at a current density of 1 mA cm-2 and 1 mAh cm-2. The assembled Zn ion hybrid capacitor with ZnSO4+DMAPS electrolyte was stably cycled for 20,000 cycles with 90% capacity retention at 5 A g-1.

Mitigating anodic corrosion in aluminum–air batteries: Effects of alkali metal cation size on electrochemical performance

Anodic corrosion limits the performance of aluminum–air batteries (AABs) by reducing discharge capacity and hindering energy density. This study proposes a strategy to mitigate anodic corrosion by controlling electrolyte cations to decrease the activity of free water molecules in the anodic corrosion process. Alkali metal cations (Na+, K+, Rb+) are introduced into a 1mol dm−3 KOH solution to examine their solvation properties and effects on free water molecule activity. Results show that larger cations (Na+ < K+ < Rb+) enhance anode discharge capacity by promoting more stable discharge reactions. Raman spectroscopy reveals that as cation radius increases, free water molecule activity decreases due to increased hydration. X-ray photoelectron spectroscopy analysis shows that larger cations favor the formation of corrosion-resistant aluminum compounds like Al2O3 and Al(OH)3, due to their higher concentration in the electric double layer, inhibiting anodic corrosion. This study highlights the critical role of cation solvation in enhancing electrochemical performance and corrosion resistance of AAB anodes.

Anion-cation coupled electrolyte additive enhancing the performance of lithium-oxygen batteries

The rational design of electrolyte via introducing additive is an efficient strategy to improve the electrochemical performance of lithium-oxygen batteries (LOBs). In this work, coupling LiCl and Sn(TFSI)2 as the anion-cation electrolyte additive achieved the high-performance of LOBs by promoting the oxygen electrode reactions, regulating the Li+ solvation structure, and inducing the growth of the SEI protective layer. Specifically, Cl− with strong coordination affinity to Li+ could weaken the binding between Li+ and TEGDME solvent molecules, leading to the formation of an anion-dominant Li+ solvation structure, which facilitates the diffusion of Li+ in the electrolyte bulk and electrolyte/electrode interface. On the other hand, Sn2+ can serve as a redox mediator to catalyze ORR on the cathode and participate in the growth of smooth and dense SEI protective layer on Li metal anode surface, thus effectively promoting the oxygen electrode reaction kinetics and suppressing the corrosion of Li anode. As a consequence, the LOBs with coupled LiCl and Sn(TFSI)2 additive exhibited a ultra-high discharge capacity of 21517.1 mA h g−1 and an excellent cycling life of 334 cycles. This work provides a deep understanding for designing efficient electrolyte with additive for LOBs.