Anode Surface Research Articles

Functional organic 7,7,8,8‐tetracyanoquinodimethane artificial layers for the dendrite suppressed lithium metal anodes

AbstractThe large‐scale industrialization of lithium metal (Li), as a potential anode for a high energy density energy storage system, has been hindered by dendrite growth. The construction of an artificial solid electrolyte interphase layer featuring high ionic and low electronic conductivity has been verified to be a high‐performance strategy to confine the dendrite growth and promote the Li anode stability. Therefore, a functional organic protective layer is homogeneously deposited on the Li anode surface via an in situ chemical reaction between tetracyanoquinodimethane (TCNQ) and Li. The as‐synthesized Lin‐TCNQ organic film could efficiently trap non‐uniform Li deposition and restrain dendrite propagation. Particularly, an asymmetric M‐TCNQ‐Li|Cu cell with the Lin‐TCNQ layer breezed through a high Coulombic efficiency of 91.15% after 100 cycles at 1.0 mA cm−2. The M‐TCNQ‐Li|NCM622 cell delivered a high capacity of 143.40 mAh g−1 at 0.2 C and maintained a good cyclic stability of 110.44 mAh g−1 after 160 cycles. The analysis results of spectroscopic tests further demonstrate that the Lin‐TCNQ with the enhanced absorption energy is conducive to lithiophilicity and decreases the overpotential of Li deposition.

A Dynamically Ion‐Sieved Electrolyte towards Ultralong‐Lifespan Zn‐Ion Batteries

AbstractThe practical deployment of Zn‐ion batteries faces challenges such as dendrite growth, side reactions and cathode dissolution in traditional electrolytes. Here, we develop a highly conductive and dynamically ion‐sieved electrolyte to simultaneously enhance the Zn metal reversibility and suppress the cathode dissolution. The dynamic ion screen at the electrode/electrolyte interface is achieved by numerous pyrane rings with a radius of 3.69 Å, which can selectively facilitate the plating/stripping and insertion/extraction process of [Zn(H2O)6]2+ and Zn2+ on the anode and cathode surfaces. As a proof of concept, Zn//Zn symmetric cells deliver exceptional cyclic stability for over 6,800 h and ultrahigh cumulative plated capacity of 1.95 Ah cm−2. Zn//Na2Mn3O7 cells exhibit satisfactory cycling performance with capacity retention of 82.7 % after 4,000 cycles, and the assembled pouch cells achieve excellent stability and durability. This work provides valuable insights into the development of electrolytes aimed at enhancing the interface stability of aqueous batteries.

Effects of anode geometry on DC magnetron sputtering of Copper Oxide films Deposition

Abstract Effects of anode shape are examined in a custom-made DC magnetron sputtering system. Polycrystalline copper-oxide (CuO) films are deposited using wedge, ring and disc shaped anodes. Current–voltage (I-V) characteristics of the discharge were fitted with models of plasma discharge. Above 700 V a notable rise in average plasma impedance, from approximately 2kΩ to 7kΩ was observed. Scanning electron microscope (SEM) images reveal uniform and porous film growth. The deposition increased significantly with increasing the anode surface area due to decrease in gas density in cathode sheath. For all the anode shapes tested, the deposition rates were higher in magnetron sputtering compared to DC sputtering mode. X-ray diffraction (XRD) of the films deposited with the disk anode revealed polycrystalline films with predominant CuO phase. With increasing sputtering power, average crystallite size vary from 11 nm to 21 nm, dislocation density vary from approximately 8.4×〖10〗^(-3) nm-2 to 2.3×〖10〗^(-3) nm-2 and micro strain from approximately 3.3×〖10〗^(-3) to 1.7×〖10〗^(-3). This indicate that higher sputtering at higher powers produce higher quality films. Atomic force microscopy revealed that the rms roughness of the samples is about 4 nm.

Dual zinco-phobic/-philic ferroelectric nanorods coated mesh for stable Zn anode

Aqueous Zn-ion batteries are emerging as a promising option for energy storage systems due to their safety and environmental benefits. However, their stability and reversibility are often hindered by dendrite growth and interfacial side reactions. In this study, we introduce an innovative strategy to address these issues by engineering an artificial interfacial layer (AIL) on Zn anode surface. This AIL is composed of a dual zinco-phobic/-philic ferroelectric nanorods (FE NRs) mesh, which contrasts with the traditional BaTiO3 nanoparticles. The BTO NRs, particularly those with exposed P4/mmm (100) and (211) facets enriched with oxygen vacancy, facilitate a partial phase transition from the FE tetragonal P4mm phase to the paraelectric tetragonal P4/mmm phase, thereby creating dual zinco-phobic/-philic sites. Additionally, the integration of microchannels within the FE BTO NRs mesh can efficiently modulate the electric field distribution and Zn2+ concentration, leading to a more uniform Zn deposition, as conformed by electrochemical simulations. The Zn anode coated with the FE BTO NRs mesh exhibits impressive performance, achieving an ultralong cycle life of 3050 h at 1 mA cm−2 and 1mAh cm−2. It sustains a Coulombic efficiency exceeding 99.8 % over 2000 cycles, highlighting its exceptional reversibility. These findings underscore the potential of the dual zinco-phobic/-philic FE NRs mesh in overcoming the challenges faced in aqueous metal-ion batteries, showcasing its versatility and the significant performance enhancements it can offer.

Ag-Pd nanoalloy film with ultra-high thermal and electrochemical stability for power electronic packaging

Nano-Ag paste is a popular material in power electronic packaging, while its microstructure is unstable at high temperatures and suffers from electrochemical migration. In this work, Ag-Pd nanoalloy film has been prepared by the pulsed laser deposition, and been sintered at low temperature for packaging. The thermal stability is significantly improved at 300 ℃ when Ag is alloyed with Pd. The Pd addition significantly increased the diffusion activation energy of Ag atoms and reduced the diffusion coefficient. The Ag-Pd sintered layer exhibited a stable microstructure at 300 °C or even 500 °C, which indicated that Ag-Pd nanoalloy had the potential to serve at high temperatures. Ag-Pd nanoalloy will preferentially generate a PdO passivation film and cover the anode surface, thereby slowing down the dissolution of the Ag and improving its resistance to electrochemical migration. This work provides theoretical studies and insights into the applications of Ag-Pd nanoalloys in high-reliability power electronics.

Interfacial Engineering Constructing TFSI- Ion-Sieve Protective Umbrella Guiding Li-Ion Selective Transport and Solid SEI Growth.

A novel strategy is proposed by constructing TFSI- ion-sieve interlayer to guide Li-ion selective transport and solid SEI growth. The uniform MgF2 seeds on the fiber surface reacts rapidly with Li+ in electrolyte to form Mg and LiF dual functional sites for the first charging process. Benefiting from the high affinity of LiF, the TFSI- ions is enriched near the anode forming an ion-sieve interlayer, which acts as a protective umbrella and guides priority penetration of Li+ due to the coordination reaction with Li+ and thus homogenize the Li+ flux. While the Mg sites induce Li nucleation with its strong lithiophilicity and facilitate uniform Li plating on fiber surface. Furthermore, as raw material of LiF, the TFSI- enrichment on anode surface is contribute to increasing LiF content in SEI, achieving the stability enhancement and densification of SEI. Of greater importance, the excess Li+ can spread to the adjacent Mg sites for nucleation by means of ultralow Li+ migration barrier on LiF and Mg. The combination of the ion-sieve homogenization of Li+ flux in electrolyte and the uniformity of Li+ transport in LiF/Mg solid medium achieves the purpose of uniform Li metal plating/stripping.

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.

Co-solvent electrolyte-induced zinc anode surface reconstruction for high performance zinc ion batteries

The progress of rechargeable zinc (Zn) ion batteries (RZBs) has been significantly impeded by the occurrence of side reactions and dendritic issues on Zn anodes, which are attributed to the intricate reaction kinetics observed in aqueous electrolytes. Herein, we propose a co-solvent electrolyte comprising a combination of N, N-dimethylformamide (DMF) and Dimethyl sulfoxide (DMSO). This electrolyte reconstructs the surface of the Zn anode and generates a dense and robust solid electrolyte interface (SEI), which promotes uniform Zn2+ deposition and enhances Zn2+ transport kinetics. The DFT further shows that the electrolyte has a unique solvated structure which enables uniform Zn2+ deposition and the creation of stable SEI. By utilizing these advantages, the co-solvent electrolyte is capable of enduring uninterrupted cycling for more than 4000 h at a current density of 1 mA cm−2, and for over 2000 h at a current density of 5 mA cm−2. Furthermore, the Zn||NH4V4O10 full cell demonstrated exceptional electrochemical performance with regard to charge/discharge capacity and cycle stability. This study showcases the effectiveness of non-aqueous electrolytes, which will enable the progress of secure and high-capacity RZBs.

Trace Amounts of Multifunctional Electrolyte Additives Enhance Cyclic Stability of High-Rate Aqueous Zinc-Ion Batteries.

Aqueous zinc ion batteries (AZIBs) are renowned for their exceptional safety and eco-friendliness. However, they face cycling stability and reversibility challenges, particularly under high-rate conditions due to corrosion and harmful side reactions. This work introduces fumaric acid (FA) as a trace amount, suitable high-rate, multifunctional, low-cost, and environmentally friendly electrolyte additive to address these issues. FA additives serve as prioritized anchors to form water-poor Inner Helmholtz Plane on Zn anodes and adsorb chemically on Zn anode surfaces to establish a unique in situ solid-electrolyte interface. The combined mechanisms effectively inhibit dendrite growth and suppress interfacial side reactions, resulting in excellent stability of Zn anodes. Consequently, with just tiny quantities of FA, Zn anodes achieve a high Coulombic efficiency (CE) of 99.55 % and exhibit a remarkable lifespan over 2580 hours at 5mA cm-2, 1 mAh cm-2 in Zn//Zn cells. Even under high-rate conditions (10mA cm-2, 1 mAh cm-2), it can still run almost for 2020 hours. Additionally, the Zn//V2O5 full cell with FA retains a high specific capacity of 106.95 mAh g-1 after 2000 cycles at 5 A g-1. This work provides a novel additive for the design of electrolytes for high-rate AZIBs.

An Mn-Enriched Interfacial Layer for Reversible Aqueous Mn Metal Batteries.

Aqueous manganese metal batteries have emerged as promising candidates for stationary storage due to their natural abundance, safety, and high energy density. However, the high chemical reactivity and sluggish migration kinetics of the Mn metal anode induce a severe hydrogen evolution reaction (HER) and dendrite formation, respectively. The situation deteriorates in the low-concentration electrolyte especially. Here, we propose a novel approach to construct an Mn-enriched interfacial layer (Mn@MIL) on the Mn metal anode surface to address these challenges simultaneously. The Mn@MIL acts as a physical barrier to not only suppress HER but also accelerate the Mn2+ diffusion kinetics through the Mn2+ saturated interfacial layer to inhibit dendrite growth. Therefore, in the low-concentration electrolyte (1 M MnCl2), the Mn||Mn symmetric cells and Mn||V2O5 full cells with high mass loading demonstrate promising cycling stability with minimal polarization and parasitic reactions, making them more suitable for practical applications in a smart grid.

Study on electrochemical anodization initiation and progression of binderless tungsten carbide (WC) through experimentation and simulation

This article explores the electrochemical anodization of binderless tungsten carbide (WC) using computational simulations and experimental methods. It aims to comprehend the complex relationship between anodization time, surface roughness, elemental composition, and current behavior on polished and non-polished substrates. COMSOL Multiphysics models provide the initial findings by meticulously mapping the electrolyte's potential and the current density vectors. These simulations reveal the fundamental electrochemical behaviors anticipated during anodization, particularly emphasizing the regions near the anode expected to undergo anodization. Experimental observations confirm the simulation results, showcasing how non-polished WC surfaces, replete with inherent imperfections, undergo anodization characterized by fluctuating current densities and compositional changes, highlighting the profound influence of surface defects on electrochemical processes. On the other hand, when WC substrates are polished, they show a more consistent and controlled anodization process. This suggests a close connection between the occurrence of anodization and the surface treatment, ultimately influencing the effectiveness of anodization. This comprehensive study, which combines simulation and experimentation, greatly enhances the understanding of the electrochemical anodization of WC. It suggests potential methods for enhancing surface modifications to expand the range of applications for WC, particularly in precision glass molding, aerospace, and medical industries.

Failure analysis of ternary lithium-ion batteries throughout the entire life cycling at high temperature

The operation life is a key factor affecting the cost and application of lithium-ion batteries. This article investigates the changes in discharge capacity, median voltage, and full charge DC internal resistance of the 25Ah ternary (LiNi0.5Mn0.3Co0.2O2/graphite) lithium-ion battery during full life cycles at 45 °C and 2000 cycles at 25 °C for comparison. The batteries before and after cycling were disassembled, and the structure, morphology, interface characteristics, element content of the cathode and anode plates of the battery were characterized. By analyzing the failure factors of the performance of the ternary batteries during the 45 °C cycling, a reaction mechanism for the rapid decline of high-temperature cycling performance of ternary batteries has been proposed. The results show that the performance degradation of the ternary lithium-ion batteries in the whole life operated at high temperature is characterized by slow decline in the initial stage and rapid drop in the latter stage. Further analysis of physical and chemical performance revealed irreversible damage to both the cathode and anode. The dissolution of transition metal ions from the cathode and their deposition on the anode surface catalyze the decomposition of electrolyte solvents to produce a large amount of gas. Gassing, accompanied by the deposition of Li2CO3 and the thickening of SEI, leads to an increase in the internal resistance of the battery. The coupling between gassing and increased internal resistance is responsible for the rapid drop in the performance of the ternary batteries during high-temperature cycling.

Analysis of the potential of the electroactive biofilm growth in a microbial fuel cell type H

Microbial fuel cells (MFC) constitute an attractive alternative as an environmental remediation technology since they can generate electrical current using organic waste as a substrate. Since the performance of MFCs depends on the characteristics of the biofilm on the anode surface, it is important to assess the genetic information of the microorganisms that grow on the electrode. For this purpose, a sewage sludge sample was obtained from a wastewater treatment plant and used to inoculate a type H MFC. Electrochemical characterization, on one hand, indicates that while the biofilm has a typical electrochemical performance reflected by the generated voltage (near 0.4 V) and by the electroactivity observed in cyclic voltammetry experiments, and on the other hand, the metagenomic analysis shows that the most abundant genera are Pseudomonacea, Nitrosomonas, Hyphomonas, and Opitutus. The study also indicates that the biofilm’s electroactive microorganisms can metabolize amino acids, lipids, and carbohydrates and possess genetic tools for ionic transport and energy production. Regarding the electron acceptor/donator capabilities, several oxidases, reductases, and complexes were identified, mainly terminal cytochrome C oxidase and respiratory complex I, which could be associated with the exoelectrogenic capacity of the microorganisms. Finally, the metagenomic information indicates that the biofilm can synthesize rhamnose, sialic acid, and alginate molecules, which could possibly be associated with the formation and consolidation of the microbial biofilm.

Electrolyte-Salts Regulated Hydrogen-Bonding Configuration and Interphase Formation Achieving Highly Stable Anode for Rechargeable Aqueous Sodium-Ion Batteries.

Hydrogen evolution reactions that cause the alkalization of aqueous electrolytes generally frustrate the structural stability and cycling performance of NaTi2(PO4)3/C anode material for rechargeable aqueous sodium-ion batteries (ASIBs). Herein, a novel highly concentrated electrolyte with a large hydrogen-evolution overpotential and hydroxide-capture ability is rationally established by incorporating a bifunctional Mg(Ac)2 additive into a concentrated NaAc aqueous solution. The highly concentrated electrolyte salts (4m NaAc+3m Mg(Ac)2) favor regulation on hydrogen-bonding configurations and kinetically shift the hydrogen evolution potential to a lower value of -1.37 V (vs Ag/AgCl). The Mg(Ac)2 additive plays particular roles in spontaneously capturing hydroxide ions generated during hydrogen evolution reactions on anode surfaces and simultaneously forming a protective Mg(OH)2-like interphase. As a result, the unique electrolyte significantly improves the structural stability and cycling performance of NaTi2(PO4)3/C anode (94.8% capacity retention after 100 cycles at 100 mA·g-1). The effect of salt concentration on hydrogen bonding configurations of aqueous electrolytes is investigated with Raman spectroscopy and FTIR spectroscopy. The interphase is identified by coupling EDS mapping, X-ray photoelectron spectroscopy, and X-ray diffraction. This work provides a new strategy for improving the cycling stability of aqueous sodium-ion batteries.

Effect of contact materials on the transient characteristics of vacuum arc plasma and anode erosion

In this study, the mechanisms of the anode phenomena and anode erosion with various contact materials were investigated. Arc parameters were calculated, and the anode temperature was predicted with a transient self-consistent model. The simulation results predicted a constricted arc column and obvious anode phenomena in Cu–Cr alloy contacts than in W–Cu alloy contacts. This observation could be the reason for the concentrated anode erosion in Cu–Cr alloys. For the contacts made by pure tungsten (W) and W–Cu alloy, the anode temperature increased rapidly because of the low specific heat of W. However, the maximum energy flux from the arc column to the anode surface was lower than in other cases. The simulation results were compared with experimental results.

Sieving‐type Electric Double Layer with Hydrogen Bond Interlocking to Stable Zinc Metal Anode

AbstractThe stability of aqueous zinc metal batteries is significantly affected by side reactions and dendrite growth on the anode interface, which primarily originate from water and anions. Herein, we introduce a multi H‐bond site additive, 2, 2′‐Sulfonyldiethanol (SDE), into an aqueous electrolyte to construct a sieving‐type electric double layer (EDL) by hydrogen bond interlock in order to address these issues. On the one hand, SDE replaces H2O and SO42− anions that are adsorbed on the zinc anode surface, expelling H2O/SO42− from the EDL and thereby reducing the content of H2O/SO42− at the interface. On the other hand, when Zn2+ are de‐solvated at the interface during the plating, the strong hydrogen bond interaction between SDE and H2O/SO42− can trap H2O/SO42− from the EDL, further decreasing their content at the interface. This effectively sieves them out of the zinc anode interface and inhibits the side reactions. Moreover, the unique characteristics of trapped SO42− anions can restrict their diffusion, thereby enhancing the transference number of Zn2+ and promoting dendrite‐free deposition and growth of Zn. Consequently, utilizing an SDE/ZnSO4 electrolyte enables excellent cycling stability in Zn//Zn symmetrical cells and Zn//MnO2 full cells with lifespans exceeding 3500 h and 2500 cycles respectively.

Zincophilic Tellurium Interface Layer Enables Fast Kinetics for Ultralow Overpotential and Highly Reversible Zinc Anode

AbstractCorrosion, hydrogen evolution, and dendrite formation seriously affect the Zn anode, significantly limiting the practical application of aqueous zinc ion batteries. Herein, the Zn anode surface is innovatively reconstructed by decorating a zincophilic tellurium layer (Te@Zn) to enhance the Zn deposition kinetics. Theoretical calculations and experimental characterizations demonstrate that the zincophilic Te provides an abundance of anchoring sites for Zn nucleation and homogenizes the interface electric field to suppress dendrite growth. The Te@Zn anode exhibits an ultralow overpotential of 14.8 mV at 1.0 mA cm−2 and 1.0 mAh cm−2 with high Coulombic efficiency, and maintains ultra‐stable operation for over 3600 h at 0.2 mA cm−2 and 0.2 mAh cm−2. The Te@Zn||KVOH full cells and soft–pack batteries also deliver a brilliant rate capability and long cycling stability. The interfacial manipulation strategy using the Te layer on Zn anode surface paves the way for large‐scale energy storage applications.

Symmetry Donor-Acceptor Molecule Regulating Hydrogen-Bonding Network for Improved Metal Zinc Anode.

The issues of zinc dendrites and side reactions caused by active water molecules have seriously affected the development of aqueous zinc batteries (AZBs). Herein, a symmetry hydrogen-bond donor-acceptor molecule additive named 1,3-bis(hydroxymethyl)urea (BHMU) can preferentially adsorb on the anode surface and lock up water molecules through hydrogen bonding, thus isolating water molecules and reducing side reactions caused by active water molecules. With these advantages, the mixed electrolyte containing BHMU additive impels a reversible Zn anode with a high Coulombic efficiency (99.7% over 1000 cycles at 1 mA cm-2), while it also enables a stable symmetric cell operated at 1 mA cm-2 (1 mAh cm-2, 6.89% DODZn) for 2250 h and 10 mA cm-2 (10 mAh cm-2, 68.9% DODZn) for 350 h. More importantly, the Zn||PTO full battery also delivered superior cycling stability and higher capacity after 3000 consecutive 3000 cycles of circulation at 5 A g-1. This study has great significance for the use of symmetry donor-acceptor molecules to modulate the solvation structure and the interface stability of the Zn anode in aqueous electrolytes.

Zinc-tin binary alloy interphase for zinc metal batteries

Aqueous zinc ion batteries are rapidly developing as the most propitious energy storage system due to their high security, high specific capacity and low cost, etc. However, zinc anodes suffered from dendrite growth and hydrogen evolution reactions during cycling, so it is of utmost importance to upgrade zinc anode properties. In this study, the homogeneous layer of ZnSn alloy interphase was formed by introducing metallic tin to the anode surface using an ion sputtering technique. ZnSn alloy can reduce the hydrogen evolution over-potential of anode and the corrosion current, inhibiting the occurrence of hydrogen evolution and corrosion reaction. Moreover, the ZnSn alloy anode can provide uniform nucleation sites and uniformize the electric field on the anode surface, promote the uniform deposition of Zn2+, thus inhibiting the formation of zinc dendrites. Notably, compared to the Zn foil//Zn foil cell (400 h), the ZnSn alloy symmetric cell showed excellent cycling performance by cycling for 1000 h at 0.5 mA cm−2. Furthermore, even at current density of 1 A/g, the capacity retention of the ZnSn alloy//MnO2 full cell was up to 89.5 % compared to only 32.3 % for Zn foil//MnO2 cell. The preparation of this ZnSn alloy anode may provide new ideas for future alloying strategies.

Interface Stability and Reaction Mechanisms of Li3YCl5Br with High-Voltage Cathodes and Li Metal Anode: Insights from Ab Initio Simulations.

Recent advancements in battery technology emphasize the critical role of solid electrolytes in enhancing the performance and safety of next-generation batteries. In this study, we investigate the interface stability and reaction mechanisms of Li3YCl5Br, a promising halide-based solid electrolyte, in contact with high-voltage Ni-Mn-Co (NMC) cathodes and a Li metal anode using ab initio molecular dynamics simulations. Our findings reveal that Li3YCl5Br reacts with charged NMC cathodes. This reaction involves changes in the oxidation states of Br- anions in Li3YCl5Br and d-element cations in NMC, as well as the diffusion of Li ions from the solid electrolyte to the cathode to maintain charge balance. The reaction is confined to the interface, suggesting bulk stability. Conversely, the Li/Li3YCl5Br interface exhibits significant instability, with a chemical reaction that results in substantial structural changes and the formation of LiCl and LiBr at the solid electrolyte surface and metallic Y at the Li anode surface. These insights provide valuable information for optimizing interfacial design, aiming at improving the performance and reliability of all-solid-state batteries using halide solid electrolytes.