Anodic Deposition Research Articles

New Process to Recycle Precious Metals Using Electrochemical Anodic Deposition

New Process to Recycle Precious Metals Using Electrochemical Anodic Deposition

Fabrication and properties of MEMS compatible energetic arrays based on carbon-based copper azide

Copper azide is a promising primary explosive with low toxicity and high energy density. However, due to the extreme electrostatic sensitivity, it does not have many practical applications in the miniaturized pyrotechnics. In this work, we constructed an energetic composite, embedding in oriented carbon nanotubes (CNTs) arrays grown on a silicon substrate, which is compatible with the microfabrication technique of Micro-Electro-Mechanical Systems (MEMS). Since it has excellent electrical conductivity and mechanical strength, oriented CNTs, as nano-containers of Cu(N3)2, can availably reduce the electrostatic sensitivity and bring about the directional output of detonation energy. The oriented CNTs arrays were prepared by magnetron sputtering, anodization and chemical vapor deposition successively. Electrochemical deposition was used to deposit copper nanoparticles in the cavities of CNTs, which were converted into copper azide by subsequent in-situ azide reaction. The electrostatic sensitivity test, thermal performance analysis and laser ignition experiment were conducted on the energetic composite, respectively. The results show that the energetic composite kept safe under an electrostatic stimulation of 3.18 mJ, while original copper azide exploded when subjected to stimulation of 0.05 mJ. The energetic composite opens a new route of introducing hazardous primary explosives into micro-initiators and modern pyrotechnics.

Enhanced electrocatalytic degradation of bisphenol A by graphite/β-PbO2 anode in a three-dimensional electrochemical reactor

In this study, the electrocatalytic synergy of the graphite/β-PbO2 anode and granular activated carbon (GAC) particles electrodes for bisphenol A (BPA) degradation are investigated in a three-dimensional electrochemical reactor (3DER). The graphite/β-PbO2 anode was prepared by anodic deposition method and the electrocatalytic properties of lead oxide film were studied by FESEM, XRD, EDX-mapping, linear sweep voltammetry and accelerated lifetime test techniques. The effect of five independent variables including pH, Na2SO4 concentration, current density, GAC amount, and reaction time on the system response was optimized by an orthogonal central composite-genetic algorithm (OCCD-GA). The results showed that β-PbO2 crystals were deposited as completely compact pyramidal clusters on the graphite surface. In addition, the service life and oxygen evolution potential (OEP) for the electrocatalytic layer of β-PbO2 were 90 h and 2 V, respectively. Based on the developed quadratic model (R2 > 0.99 and p-value < 0.0001), the optimal points for pH, Na2SO4 concentration, current density, GAC amount, and reaction time were predicted to be 4.6, 0.074 mol L−1, 35.7 mA cm−2, 25 g, and 80 min, respectively. Under optimal conditions, BPA removal efficiency in 3DER system and separate application of electrocatalytic degradation and GAC were obtained 98.8%, 72.2% and 9.75%, respectively. Thus, the electrocatalytic synergy of 3DER system due to lead oxide layer and GAC particle electrodes in BPA degradation was calculated to be 35.5%. LC-MS analysis was used to identity the intermediates formed during BPA degradation. The final degradation intermediates were short-chain acids including adipic acid, malonic acid and, acetic acid.

Evaluation of mechanical behaviour of graphene oxide grafted CFRP composites: a comparison of anodic and cathodic EPD

ABSTRACT In this work, graphene oxide (GO) was grafted on carbon fibre (CF) surface using anodic and cathodic electrophoretic deposition (EPD). Twelve-layer carbon fibre–reinforced polymer (CFRP) composite laminates were fabricated using the modified CFs. Morphology study of modified CFs revealed that cathodic EPD has resulted in dense and uniform deposition of nanofiller. Flexural and Short Beam Shear (SBS) tests were conducted to evaluate their flexural and interlaminar properties. Both anodic and cathodic CFRP composites have shown better mechanical performance than neat CFRP composite, with cathodic CFRP composite showing the best performance due to uniform deposition of nanofiller. Cathodic CFRP composite has shown an improvement of 7.57% and 16.12% in flexural and ILSS responses, respectively, with respect to neat CFRP composite. Differential scanning calorimetry (DSC) and fractography analysis using scanning electron microscope (SEM) were carried out to know the thermal behaviour and failure mechanism of all fabricated composites, respectively.

Novel electrochemical deposition of Co(CO3)0.5(OH)∙0.11H2O nano-needles with folded umbrella-like architecture onto nickel foam for supercapacitors

Here, we developed a novel anodic hydrothermal electrochemical deposition technology capable of directly growing a film of Co(CO3)0.5(OH)∙0.11H2O∙0.11H2O onto nickel foam for supercapacitors. The resultant film exhibited a morphology of nano-needles with folded umbrella-like architecture, different from the smooth needle-like morphology in reported articles, and could deliver a specific capacitance of 2.455 F·cm−2 (1227F·g−1) at 5 mA∙cm−2, a rate capability of 58.9% after a 6 fold increase in the charge/discharge current density and a capacity retention of 93.7% after 10,000 cycles in a three-electrode electrolytic cell. When packaged as a two-electrode asymmetric supercapacitor (ASC) device with the Co(CO3)0.5(OH)∙0.11H2O film electrode as the positive electrode and active‑carbon as the positive electrode, the ASC device exhibited specific capacitances of 1.46(112.3), 1.38(106.2), 1.36(104.6), 1.25(96.2) and 1.11 F·cm−2 (85.4 F·g−1) at 5, 8, 10, 20 and 30 mA∙cm−2, and the capacitance retention rate of 72.9% after 10,000 cycles at 8 mA∙cm−2. The results demonstrate the potential of anodic hydrothermal electrochemical deposition in fabricating the film of active electrode materials on conductive substrates for next-generation supercapacitor with high performance.

Evidence of Solid-State Polymerization in Regioregular Poly-3′,4′-Didodecyl-2,2′:5′,2′′-Terthiophene During Electrochemical Cycling

The electrochemical oxidation of 3′,4′-didodecyl-2,2′:5′,2′′-terthiophene (3′4′-DDTT) at applied potential values lower than 0.8 V vs Ag/Ag+ leads to the formation of an anodic deposit that is prevalently constituted by the products of monomer coupling at positions 5 and 5′′. Upon electrochemical cycling poly-3′4′-DDTT manifests three phenomena: the cathodic shift of the main peak of poly-3′4′-DDTT oxidation, the bathochromic shift of 60 nm for the main UV–vis absorption peak, and the IR spectral evolution consisting of the progressive increase of the signals of 2,5-substituted thiophenes at expense of the signals from 2-substituted thiophenes. The observed behavior was interpreted in terms of the presence of reactive oligomers trapped in pristine as-deposited poly-3′4′-DDTT, with the oligomers undergoing further coupling in the polymeric phase upon electrochemical cycling. This combination of findings led us to conclude that poly-3′4′-DDTT manifests solid-state polymerization. After voltammogram stabilization poly-3′4′-DDTT was electrochemically stressed. The system showed a reversible electrochemical behavior up to 0.9 V vs Ag/Ag+. A depiction of the evolution of the electronic bands in poly-3′4′-DDTT when passing from the pristine state to the electrochemically cycled state has been proposed, taking into account the combination of electrochemical and optical data.

Electrophoretic deposition of nickel ferrite anode for lithium-ion half cell with superior rate performance

We report the use of nickel ferrite (NFO) with different morphologies as a superior anode material for lithium-ion batteries. The NFO nanoparticles are synthesized using simple auto-combustion process (CNFO) and micron-sized faceted particles are synthesized through pyrolysis of a nickel and iron metal-organic framework (MOF-NFO). Facile electrophoretic deposition (EPD) technique is employed to fabricate electrodes from a stable suspension of the active material (NFO) and conducting carbon-black. The EPD grown electrodes are uniform, porous and well adhered to the copper current collector. The CNFO and MOF-NFO electrodes retain a reversible capacity of 560 and 650 mAhg−1, respectively, after 150 cycles at a specific current of 0.5 Ag−1. Such EPD grown electrodes exhibit excellent rate capability delivering a capacity of 150 and 275 mAhg−1 at a high specific current of 8 Ag−1 for CNFO and NFO-MOF electrodes, respectively. The role of pseudocapacitance in enhancing the rate performance has been explained with the help of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. It is observed that even with significantly different particle size and morphology, the method of electrode fabrication plays a key role in accommodating the large volumetric changes during cycling and thereby improves the electrochemical properties of the electrode.

(Invited) Metal Oxides and Composites for Chemical Sensing

In the field of advanced sensor technology, metal oxide nanostructures are promising materials due to their high charge carrier mobility, easy fabrication and excellent stability. In particular, most of them exhibit a reversible interaction between their surfaces and the surrounding atmosphere. This interaction may lead to a change of some different properties of the material, such as electrical conductance, capacitance, work function or optical characteristics. All metal oxides are in principle sensitive to gases if they are prepared in a sufficiently porous form (high surface to volume ratio and electrical properties controlled by surface states), but in order to be active material in chemical sensors they need to fulfill specific requirements such as sensitivity, selectivity, stability, fast response and recovery time.Further conductometric sensors are the cheapest devices that could be integrated into portable olfaction systems, due to their easy readout, small size and low cost. Depending on the materials they are based on, they could offer high sensitivity, but they often lack selectivity between different chemical species. Moreover, they sometimes have stability issues, due to high temperature required during normal operation (200-400°C). Furthermore, one dimensional (1D) semiconductor metal oxides such as nanowires (NWs) have been attracted great deal of attention in the field of chemical sensors due to their unique chemical/physical properties. In chemical sensor, surface of the active materials determines the sensor sensitivity toward specific gas analyte. The enhancement in the sensor response can be achieved by increasing the active surface area of the sensor. But there is still a lot of work going on regarding the preparation of nanostructured oxides, like controlling their morphology and position at the nanoscale level. Moreover, a major challenge is the reliable integration of quasi-1D nanostructures on specific transducers used to fabricate chemical sensors, assuring stable electrical contacts over long-term operation.Various strategies have been used to increase the gas response and selectivity, including modulating the sensing temperature, morphological control, catalyst doping/loading and catalytic filtering of interference gases. Another effective strategy to enhance the sensor response and selectivity is to construct the heterojunction between two different oxides that enables the control of conductivity at p-p, p-n, and n-n interfaces, and synergistic catalytic effects between different materials.The results of bringing together the properties of two different nanostructure materials into a single sensing platform by using a common, simple, low cost and high yield growth method will be presented. Herein, we report on the novel preparation and characterization of different nanostructures and hetrostructures morphologies such as NiO, WO3, Bi2O3 and ZnO NWs, (fig. 1)TiO2 nanotubes and NiO/ZnO branched 1D-1D nano-heterostructures and NiO/SnO2, CuO/ZnO Core-shell, SnO2/Go and WO3-doped with Nb (fig. 1). Several growth techniques have been used for the growth of different nanostructures: vapour phase evaporation and condensation, thermal oxidation, electrochemical anodization, hydrothermal synthesis and atomic layer deposition. The surface morphology of the nanostructures was investigated by using scanning electron microscopy (SEM) while, for structural characterization GI-XRD, the transmission electron microscopy (TEM), and XPS, Raman spectroscopy, UV-Vis spectroscopy. Finally, heterostructures based conductometric gas sensing devices have been fabricated and tested towards different gases spices such as (NO2, H2, CO, VOC’s) and their performance have been compared with literature and the host materials. Further in our recent work, the sensing properties of ZnO NWs were improved by functionalizing with 3-aminopropyl) trimethoxysilane (APTES). The whole process creates the amino (-NH2) terminated ZnO surface (SAM). These functionalized conductometric sensing devices showed excellent performance toward acetone and ethanol as compared to the pristine ZnO NWs. Acknowledgments This work was partially funded by the NATO Science for Peace and Security Programme under grant No. G5634 "Advanced Electro-Optical Chemical Sensors" and by MIUR “Smart Cities and Communities and social innovation” project titled "SWaRM Net/Smart Water Resource Management – Networks”.

Electrochemically Grown Energy and Power Dense Cathodes for Li and Na Ion Batteries

Electrochemical synthesis of materials has contributed to significant breakthroughs in materials processing by replacing high temperature, cost and energy intensive pyrometallurgical processes. Although electrodeposition as a technology for reduction of elements and alloys has been practiced since at least the 1940s, a current key and exciting question is to identify and develop electrodeposition strategies for the growth of secondary battery cathodes. Specifically, we focus on anodic electrolytic deposition methods to grow alkali-ion intercalated, layered/spinel transition metal oxide intercalation cathode systems. State-of-the-art synthesis for layered oxide cathodes for Li and Na-ion battery involves prolonged high temperature (>700°C) processing for long reaction times (~24 hours) under high oxygen pressure, followed by slurry casting after mixing with binders and additives. Here, we demonstrate an intermediate temperature (250-350°C) electrodeposition process to grow alkali ion (Li+, Na+) intercalated transition metal oxides across multiple transition metal chemistries of the Li system (orthorhombic LiMnO2, Li2MnO3, LiNixMn1-xO4, LiMn2O4, LiCoO2) and Na system (O3 and P2 NaxCoO2, O’3 NaxMnO2) in thick film form factors. Even though our cathodes are electrochemically grown at the lowest reported synthesis temperature and reaction times, they retain the key structural and electrochemical performance of the high temperature bulk synthesized analogues. The key features of this alternate high throughput cathode manufacturing technique include formation of binder-and-additive-free, tens of microns thick, >75% dense electrodeposits exhibiting near theoretical gravimetric capacity, low tortuosity, and chemical diffusion coefficient of Li+/Na+ ions. Our findings highlight the influence of the unique molten hydroxide-based solution chemistry platform and electrochemical processing parameters, on regulating the phase assemblage, designing the microstructure, and controlling crystallographic orientation during electrocrystallization.

Correlation between Manganese Dissolution and Dynamic Phase Stability in Spinel-Based Lithium-Ion Battery

Historically long accepted to be the singular root cause of capacity fade, transition metal dissolution and its subsequent anode deposition have been reported to interfere with Li intercalation and destroy the anode solid electrolyte interphase. However, as a vital battery component, cathode behavior under transition metal dissolution still remains unclear. Here we report an unequivocal relationship between capacity fade and both dynamic phase stability and surface chemical stability of the cathode. With spinel LiMn2O4 as a model system and a Li-rich LiMn2O4 control sample, clear evidence gathered through in-situ/ex-situ high energy X-ray diffraction and scanning transmission electron microscopy reveal, for the first time, that a combination of dynamic structural transformation and surficial transition metal dissolution are the dominant factors of cathode capacity fade. LiMn2O4 exhibits irreversible phase transitions driven by Mn(III) disproportionation and Jahn-Teller distortion, which in conjunction with particle cracks formed during repeated charge/discharge result in severe Mn dissolution. Meanwhile, fast Mn dissolution in turn triggers irreversible structural evolution. These two processes form a detrimental chemical-cycle that constantly consumes the capacity of spinel. Furthermore, we are able to reproduce the atomic structural advantages of Li-rich LiMn2O4 with Li/Mn disorder and surface reconstruction, effectively suppressing the irreversible phase transition and Mn dissolution. These findings, predominately caused by transition metal dissolution and a newly discovered irreversible phase transition, close the loop of understanding capacity fade mechanisms in spinel-based cells. This insight helps elucidate structure stability improvements found from Li enrichment and cation doped cathodes, allowing for development of longer life batteries.

Promising corrosion-resistant and pre-osteoblast growth promotion performance in vitro of hydroxyapatite/TiO2 nano-porous composite coatings

The inertness of titanium alloys restricts the high intensity of the biological bonding between artificial implants and human skeletons, and there is residual stress in hydroxyapatite (HA) coatings fabricated by the frequently applied plasma spraying method. With the intention to address the aforementioned two issues, combined utilization of constant current anodization and pulsed laser deposition (PLD) was conducted to fabricate HA/TiO2 nano-porous composite coatings, and the as-fabricated samples were heat-treated under the selected appropriate conditions. The oxygen bubble mold theory has made a persuasive explanation for the growth mechanism of TiO2 nano-porous arrays. The morphologies and composition of the composite coatings including the heat-treated ones were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), grazing incidence X-ray diffraction (GI XRD) and X-ray photoelectron spectrometer (XPS). Through comprehensive analysis of the corrosion resistance in modified simulated body fluid (m-SBF) and growth efficiency of cocultured MC3T3-E1 cells in vitro, together with the characterization results, it is concluded that the sample heat-treated at 450 °C shows the most satisfactory performance in general. Therefore, the HA/ TiO2 nano-porous composite coatings have broad application prospect in the osseointegration and bone repairing abilities of artificial implants.

Highly Ordered SnO2 Nanopillar Array as Binder-Free Anodes for Long-Life and High-Rate Li-Ion Batteries.

SnO2, a typical transition metal oxide, is a promising conversion-type electrode material with an ultrahigh theoretical specific capacity of 1494 mAh g−1. Nevertheless, the electrochemical performance of SnO2 electrode is limited by large volumetric changes (~300%) during the charge/discharge process, leading to rapid capacity decay, poor cyclic performance, and inferior rate capability. In order to overcome these bottlenecks, we develop highly ordered SnO2 nanopillar array as binder-free anodes for LIBs, which are realized by anodic aluminum oxide-assisted pulsed laser deposition. The as-synthesized SnO2 nanopillar exhibit an ultrahigh initial specific capacity of 1082 mAh g−1 and maintain a high specific capacity of 524/313 mAh g−1 after 1100/6500 cycles, outperforming SnO2 thin film-based anodes and other reported binder-free SnO2 anodes. Moreover, SnO2 nanopillar demonstrate excellent rate performance under high current density of 64 C (1 C = 782 mA g−1), delivering a specific capacity of 278 mAh g−1, which can be restored to 670 mAh g−1 after high-rate cycling. The superior electrochemical performance of SnO2 nanoarray can be attributed to the unique architecture of SnO2, where highly ordered SnO2 nanopillar array provided adequate room for volumetric expansion and ensured structural integrity during the lithiation/delithiation process. The current study presents an effective approach to mitigate the inferior cyclic performance of SnO2-based electrodes, offering a realistic prospect for its applications as next-generation energy storage devices.

Extraction of Selenium and Tellurium from CaCl2–LiCl-Based Molten Chlorides Containing Na2Se, Na2Te, and CaO

This study was conducted considering the separation of long-lived fission products of 79Se from vitrified high-level radioactive wastes. The redox behavior of Se on various electrodes was investigated in CaCl2 melts containing Na2Se and CaO at 1093 K. Se2− ions were anodically oxidized to form selenide compounds on Cu and Ni electrodes, which were not affected by presence of O2− ions. Potentiostatic electrolysis using a Ni anode yielded liquid Ni–Se alloy and Ni was thus evaluated as a suitable anode material for extracting Se. A chemical reaction using NiO and Ni metal was investigated for the extraction of Se as an alternative to electrodeposition. In addition, anodic deposition behaviors of Te and Se on Ni in an equimolar CaCl2–LiCl melt containing Na2Se, Na2Te, CaO, BaCl2, SrCl2, CsCl, KCl, and EuCl2 were investigated. The potential difference between the Ni telluride and selenide formations was about 0.20 V, indicating that Te can be extracted prior to Se. The NiO/Ni apparatus consisting of a Ni rod immersed in NiO powder placed in a MgO crucible was used to extract Te and Se in two steps. Most of Te was first extracted. Then, the remaining Te and Se were almost completely extracted.

Preparation and Application of ZIF-8 Thin Layers

Herein we compare various preparation methods for thin ZIF-8 layers on a Cu substrate for application as a host material for omniphobic lubricant-infused surfaces. Such omniphobic surfaces can be used in thermal engineering applications, for example to achieve dropwise condensation or anti-fouling and anti-icing surface properties. For these applications, a thin, conformal, homogeneous, mechanically and chemically stable coating is essential. In this study, thin ZIF-8 layers were deposited on a Cu substrate by different routes, such as (i) electrochemical anodic deposition on a Zn-covered Cu substrate, (ii) doctor blade technique for preparation of a composite layer containing PVDF binder and ZIF-8, as well as (iii) doctor blade technique for preparation of a two-layer composite on the Cu substrate containing a PVDF-film and a ZIF-8 layer. The morphology and topography of the coatings were compared by using profilometry, XRD, SEM and TEM techniques. After infusion with a perfluorinated oil, the wettability of the surfaces was assessed by contact angle measurements, and advantages of each preparation method were discussed.

A review on the preparation of anode materials and anode films for solid oxide fuel cell applications

The primary components of SOFCs are the anode, cathode, and the electrolyte. Anode is critical in achieving the effective electrochemical oxidation of fuel; thus, its performance can be improved using homogenous powder synthesized through an appropriate method. Various synthesis methods, including solid-state reaction and wet chemical methods have been used to synthesize anode materials. However, each technique has several advantages and disadvantages. Given that anode is a porous electrode, few criteria, such as high conductivity, tolerance towards carbon deposition, chemical stability, and thermal stability, must be fulfilled. Researchers also modified the existing synthesis method to improve the performance of the anode. In addition, various anode fabrication techniques including physical and colloidal deposition techniques are briefly discussed to understand their effect on the performance of the deposited layers. The aim of this review is to discuss the various anode synthesis and deposition techniques and their influence on the properties and performance of SOFCs.

Comparative Study on Electrochemical Treatment of Cyanide Wastewater.

The electrochemical treatment of wastewater is widely used for cleaning due to its efficiency. In this paper, two-dimensional (2D) and three-dimensional (3D) electrochemical systems were used to treat cyanide wastewater. The effect of the applied voltage and the material of the main electrode on the removal of various ions and the characteristics of chemical reactions were mainly studied. The results show that the applied voltage was the key effect of the electrochemical treatment process. The removal of ions from the wastewater at 2 V is mainly due to the effect of electro adsorption and enrichment precipitation, while at 4 V, it is mainly due to anodization and cathodic deposition. The treatment effect of the 3D electrode system was significantly better than the 2D system. The 3D electrode system by used granular activated carbon as the particle electrode, with the carbon filled stainless mesh (CM) and coal based electrode (CB) as the main electrode, the treatment effect were better than main electrode of stainless steel mesh (M). The 3D system with CB as the main electrode had an applied voltage of 4 V, a treatment time of 5 h, plate spacing of 10 mm, and the dosage of activated carbon particles was 2 g. The removal rates of CNT, Cu, Zn, CN−, and SCN− were 94.14, 94.53, 98.14, 98.55, and 93.13%, respectively. The main reaction in anode was the electroly oxidation of CN− and SCN−, while the electrolytic deposition of Cu, Zn, and other metal ions in the cathode surface. There were not only adsorption and electric adsorption of various ions, but also an electrolytic deposition reaction of Cu, Zn, and other metal ions on the surface of the activated carbon particle electrode. During the electrochemical reaction, the concentration of hydrogen ions near the anode increases locally, which produces the precipitation of CuSCN, Cu2Fe(CN)6, and Zn2Fe(CN)6, etc. in the solution, which are helpful for the removal of cyanide and heavy metal ions in cyanide wastewater.

Electrocatalytic degradation of diuron herbicide using three-dimensional carbon felt/β-PbO2 anode as a highly porous electrode: Influencing factors and degradation mechanisms

Traditional planar PbO2 anodes have been used extensively for the electrocatalytic degradation process. However, by using porous PbO2 anodes that have a three-dimensional architecture, the efficiency of the process can be significantly upgraded. In the current study, carbon felt (CF) with a highly porous structure and a conventional planar graphite sheet (G) were used as electrode substrate for PbO2 anodes. Both CF/β-PbO2 and G/β-PbO2 anodes were prepared by the anodic deposition method. The main properties of the electrodes were characterized by XRD, EDX-mapping, FESEM, and BET-BJH techniques. The electrocatalytic degradation of diuron using three-dimensional porous CF/β-PbO2 anode was modeled and optimized by a rotatable central composite design. After optimizing the process, the ability of porous CF/β-PbO2 and planar G/β-PbO2 anodes to degrade and mineralize diuron was compared. The electrocatalytic degradation of the diuron was well described by a quadratic model (R2 > 0.99). Under optimal conditions, the kinetics of diuron removal using CF/β-PbO2 anode was 3 times faster than the G/β-PbO2 anode. The energy consumed for the complete mineralization of diuron using CF/β-PbO2 anode was 2077 kWh kg−1 TOC. However, the G/β-PbO2 anode removed only 65% of the TOC by consuming 54% more energy. The CF/β-PbO2 had more stability (115 vs. 91 h), larger surface area (1.6287 vs. 0.8565 m2 g−1), and higher oxygen evolution potential (1.89 vs. 1.84 V) compared to the G/β-PbO2. In the proposed pathways for diuron degradation, the aromatic ring and groups of carbonyl, dimethyl urea, and amide were the main targets for HO• radical attacks.

Strategies to suppress the shuttle effect of redox mediators in lithium-oxygen batteries

Various strategies can be used to suppress the shuttle effect of redox mediators in non-aqueous Li-O 2 batteries, including electrolyte additives, protective separators, anode coating and cathode modification. Rechargeable lithium-oxygen (Li-O 2 ) batteries are the next generation energy storage devices due to their ultrahigh theoretical capacity. Redox mediators (RMs) are widely used as a homogenous electrocatalyst in non-aqueous Li-O 2 batteries to enhance their discharge capacity and reduce charge overpotential. However, the shuttle effect of RMs in the electrolyte solution usually leads to corrosion of the Li metal anode and uneven Li deposition on the anode surface, resulting in unwanted consumption of electrocatalysts and deterioration of the cells. It is therefore necessary to take some measures to prevent the shuttle effect of RMs and fully utilize the soluble electrocatalysts. Herein, we summarize the strategies to suppress the RM shuttle effect reported in recent years, including electrolyte additives, protective separators and electrode modification. The mechanisms of these strategies are analyzed and their corresponding requirements are discussed. The electrochemical properties of Li-O 2 batteries with different strategies are summarized and compared. The challenges and perspectives on preventing the shuttle effect of RMs are described for future study. This review provides guidance for achieving shuttle-free redox mediation and for designing Li-O 2 cells with a long cycle life, high energy efficiency and highly reversible electrochemical reactions.

Binder free Cu2O/CuO/Cu/Carbon-polymer composite fibers derived from metal/organic hybrid materials through electrodeposition method as high performance anode materials for lithium-ion batteries

Design of Cu2O/CuO nanocomposites as anode materials for lithium-ion batteries has attracted extensive attention because of their potential applications in the energy field. Herein, in this work, the coordination polymers of Cu2+ and flexible chain-like α, ω-dicarboxylate (succinate and sebacate) are synthesized by a facile anodic electrochemical deposition method, in which succinic acid/sebacic acid is used as electrolyte and the copper foil is used as electrodes. The obtained Cu(α, ω-dicarboxylate) polymers grown on copper foil substrate are decomposed and oxidized to prepare a Cu2O/CuO/Cu/Carbon-polymer composite fibers, in which the nanoparticles of Cu2O/CuO/Cu are uniformly incorporated into a fibrous carbon-polymer, which can facilitate Li+ ion diffusion to active sites in the electrodes and alleviate the volume expansion during the charge and discharge process. As a result, the Cu2O/CuO/Cu/Carbon-polymer composite fibers can be used as novel binder free anode materials for lithium-ion batteries, which displays high capacity, excellent cycle stability and rate performance. The initial discharge capacity of composite fibers electrode derived from Cu (sebacate) polymers (Cu-C10) is as high as 508.9 mAh/g at the current densities of 50 mA·g−1. After 150 cycles, the capacity can still remain at 479.9 mAh/g with capacity retention rate of 94.3%. The preparation of electrodes by novel electrochemical deposition in this work would provide a new insight for preparing advanced binder free metal oxide/carbon-based anodes for LIBs with environmental friendliness and inexpensive.

Quantitative manganese dissolution investigation in lithium-ion batteries by means of X-ray spectrometry techniques

The manganese deposition of an aged anode has been investigated with K-edge and L-edge NEXAFS to determine the manganese species. In addition, the absolute amount of manganese could be revealed with reference-free X-ray fluorescence analysis.