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The current work delivers preparation of MXene-based magnetic nanohybrid coating for flexible electronic applications. Herein, we report carbon dot-triggered photopolymerized polynorepinepherene (PNE)-coated MXene and iron oxide hybrid deposited on the cellulose microporous membrane via a vacuum-assisted filtration strategy. The surface morphologies have been monitored by scanning electron microscopy analysis, and the coating thickness was evaluated by the gallium-ion-based focused ion beam method. Coated membranes have been tested against uniaxial tensile stretching and assessed by their fracture edges in order to assure flexibility and mechanical strength. Strain sensors and electromagnetic interference (EMI) shielding have both been tested on the material because of its electrical conductivity. The bending strain sensitivity has been stringent because of their fast 'rupture and reform' percolation network formation on the coated surface. Increased mechanical strength, solvent tolerance, cyclic deformation tolerance, and EMI shielding performance were achieved by decreasing interstitial membrane porosity. Considering a possible application, the membrane also has been tested against simulated static and dynamic water flow conditions that could infer its excellent robustness which also has been confirmed by elemental analysis via ICP-MS. Thus, as of nurturing the works of the literature, it could be believed that the developed material will be an ideal alternative of flexible lightweight cellulose for versatile electronic applications.

Li and Mn-rich nickel cobalt manganese oxide (LMR-NCM) is one of the most promising cathode materials for realizing next-generation Li-ion batteries due to its high specific capacity of >250 mA h g-1 and operating potential > 4.5 V. Nevertheless, being plagued by severe capacity fading and voltage decay, the commercialization of LMR-NCM appears to be a distant goal. The anionic activity of oxygen and associated phase transformations are the reasons behind the unstable electrochemical performance. The tendency of LMR-NCM to react with CO2 and moisture further makes it prone to interfacial instability and degradation. Here, we report a neoteric method to mitigate the stability issues and improve the electrochemical performance of LMR-NCM by changing the electronic configuration of constituting O and transition metals via diethylzinc-assisted atomic surface reduction (Zn-ASR) using an extremely facile protocol. With the proposed Zn-ASR, a 2-3 nm thin layer of a reduced surface enriched with complex ZnOx or ZnOxRy was obtained on the LMR-NCM particles. X-ray photoelectron spectroscopy suggested the transfer of ethyl groups of diethylzinc to O atoms on the LMR-NCM surface, which ultimately led to the reduction of near-surface Mn and Ni atoms and impeded irreversible anionic activity. The presence of ZnOx/ZnOxRy also resulted in superior charge transfer and resistance against HF. As a result, in contrast to LMR-NCM, the Zn-ASR-treated sample exhibited substantially improved rate capabilities, facilitated charge transfer, enhanced capacity retention, reduced parasitic reactions, and long-term stability as reflected from in-depth electrochemical analysis, in operando gaseous evolution studies, and post-mortem microscopic analysis.

The current work presents a facile and green synthesis of carbon quantum dots (C-dots), which could serve as initiators for polymerization. Herein, C-dots have been synthesized from an easily available green herb, dill leaves, by a single-step hydrothermal method. These C-dots were efficiently utilized as initiators for the photopolymerization of the polymer poly(norepinephrine) (PNE) for the first time. The photopolymerization is discussed by a factorial design, and the optimized synthesis conditions were evaluated by a third-order regression model of three reaction parameters: monomer concentration, C-dots concentration, and UV exposure time. The sign convention of the factorial design mode indicated that monomer concentration and time of exposure are the most important factors for polymerization. The photopolymerized poly(norepinephrine) was extensively studied using Fourier transform infrared (FTIR) analysis, X-ray photoelectron spectroscopy (XPS), mass spectra, scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurement, and thermogravimetric analysis (TGA). UV-assisted deposition of PNE on six different types of substrates was performed, and their water contact angle and surface morphology were studied to evaluate the coating. This UV-triggered polymerization technique was further applied to fabricate sandwich-like composite catalyst MXene/poly(norepinephrine)/copper nanoparticles. This catalyst displayed good performance in the reduction of 4-NP (4-nitrophenol) at ambient temperature, and the first-order rate constant of the catalysis was 9.39 × 10-3 s-1. The reusability of the catalyst was evaluated in terms of the conversion factor. After 10 catalytic cycles, the conversion to catalyze 4-NP was still greater than 91%. The catalytic performance was also evaluated in the continuous flow condition through a membrane, fabricated from a cellulose filter paper coated with MXene/poly(norepinephrine)/copper nanoparticles. This composite catalyst not only offers a practical mode for the catalytic reaction of MXene-based materials but also lays down the foundation for the development of new catalysts.

The commercialization of the high energy, lithium, and manganese-rich NCM (LMR-NCM) is impeded by its complex interfacial electrochemical processes, oxygen release, and surface degradation. Here, we introduced t-butyl-dimethylsilyllithium as a single-source precursor for depositing LixSiyOz with an integrated network of siloxane moieties as an artificial cathode/electrolyte interphase (ACEI) which stabilizes LMR-NCM by mitigating oxygen release, electrolyte degradation and preventing fractures. Using solid-state NMR coupled with dynamic nuclear polarization, detailed molecular-level characterization of the ACEI is presented. The proposed CEI enabled improved energy-density at high rates (644 Wh.kg-1, compared to uncoated material with 457 Wh.kg-1 at 4C) with suppressed parasitic reactions and O2 evolution. The efficacy of the CEI is demonstrated in full graphite/LMR-NCM pouch cells with ~ 35% enhanced capacity and >80% capacity retention over 200 cycles. Altogether, these results present the importance of careful selection and design of surface chemistry for stabilizing the electrode/electrolyte interphase in challenging battery chemistries.

Exploring and identifying efficient materials with operative active sites for electrochemical oxygen evolution reaction (OER) is of paramount importance for the future of energy conversion technolo...

We demonstrate a novel surface modification of Li- and Mn-rich cathode materials 0.33Li2MnO3·0.67LiNi0.4Co0.2Mn0.4O2 for lithium-ion batteries (high-energy Ni-Co-Mn oxides, HE-NCM) via their heat treatment with trimesic acid (TA) or terephthalic acid at 600 °C under argon. We established the optimal regimes of the treatment-the amounts of HE-NCM, acid, temperature, and time-resulting in a significant improvement of the electrochemical behavior of cathodes in Li cells. It was shown that upon treatment, some lithium is leached out from the surface, leading to the formation of a surface layer comprising rock-salt-like phase Li0.4Ni1.6O2. The analysis of the structural and surface studies by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy confirmed the formation of the above surface layer. We discuss the possible reactions of HE-NCM with the acids and the mechanism of the formation of the new phases, Li0.4Ni1.6O2 and spinel. The electrochemical characterizations were performed by testing the materials versus Li anodes at 30 °C. Importantly, the electrochemical results disclose significantly improved cycling stability (much lower capacity fading) and high-rate performance for the treated materials compared to the untreated ones. We established a lower evolution of the voltage hysteresis with cycling for the treated cathodes compared to that for the untreated ones. Thermal studies by differential scanning calorimetry also demonstrated lower (by ∼32%) total heat released in the reactions of the materials treated with fluoroethylene carbonate (FEC)-dimethyl carbonate (DEC)/LiPF6 electrolyte solutions, thus implying their significant surface stabilization because of the surface treatment. It was established by a postmortem analysis after 400 cycles that a lower amount of transition-metal cations dissolved (especially Ni) and a reduced number of surface cracks were formed for the 2 wt % TA-treated HE-NCMs compared to the untreated ones. We consider the proposed method of surface modification as a simple, cheap, and scalable approach to achieve a steady and superior electrochemical performance of HE-NCM cathodes.

Na3V2(PO4)2F3 (NVPF) has been extensively studied, and has demonstrated excellent electrochemical activity in Na-ion batteries owing to its high reversible specific capacity and stability. The direct chemical synthesis of a Li analogue of NVPF (LVPF) is aided by the high thermodynamic stability of intermediate products. Even more challenging is the synthesis of LVPF with a well-controlled uniform morphology and a stable crystal structure. Herein, an electrochemical ion exchange approach was used to synthesize Na0.7Li2.3V2(PO4)F3 (N0.7L2.3VPF), an isostructural composition of Li3V2(PO4)F3. This compound was prepared via lithiation of Na0.7V2(PO4)F3 with a hierarchical morphology prepared by desodiation of NVPF. We track the phase formation, reversible structural transformation from Pnnm to Cmc21 and back to Pnnm. An initial specific discharge capacity of 185 mA h g−1 and two distinct voltage plateaus visualize the prominence of N0.7L2.3VPF as a cathode material for LIBs. It exhibits a specific discharge capacity of 173, 159, 154, 134 and 114 mA h g−1 at 45, 105, 135, 265, and 535 mA g−1 respectively along with >98% coulombic efficiency, which indicates pronounced electrochemical activity at high current rates due to better diffusivity of smaller Li+ ions than Na+ ions through the partially occupied alkali metal sites in the lattice. Long-term cycling at 45 mA g−1 exhibits 173 mA h g−1 with 96% of capacity retention for 200 cycles. This stable performance further indicates the prominence of N0.7L2.3VPF HMS as a cathode for LIBs. Our findings provide a strategic pathway towards controlling the morphology and crystal structure and shed light on its importance in realization as a cathode material for LIBs.

Catalyst poisoning is a prominent issue, reducing the lifetime of catalysts and increasing the costs of the processes that rely on them. The electrocatalysts that enable green energy conversion and storage, such as proton exchange membrane fuel cells and hydrogen bromine redox flow batteries, also suffer from this issue, hindering their utilization. Current solutions to protect electrocatalysts from harmful species fall short of effective selectivity without inhibiting the required reactions. This article describes the protection of a standard 50% Pt/C catalyst with a V2O5 coating through atomic layer deposition (ALD). The ALD selectively deposited V2O5 on the Pt, which enhanced hydrogen transport to the Pt surface and resulted in a higher mass activity in alkaline electrolytes. Cyclic voltammetry and X-ray photoelectron spectroscopy showed that the Pt was protected by the coating in the HBr/Br2 electrolyte which dissolved the uncoated 50% Pt/C in under 3 min.

Disordered carbons are promising anode materials for sodium ion batteries. However, a major drawback of these materials is their low coulombic efficiency in the first cycles, which indicates parasitic reactions. Such reactions can be suppressed by alumina coating on the surface of the anodic materials; more ions are then available for electrochemical activity, and less electrolyte solution is lost. On the other hand, some pores and surface edge sites are passivated by the coating and are no longer available for reversible reaction with sodium ions; hence, their contribution is eliminated, leading to reduction in specific capacity. We show herein that electrochemical insertion of sodium ions into carbon anodes prior to alumina coating has a double positive effect on anode perfomances, meaning preventing passivation and maintaining high specific capacity. We show that the artificial layer still prevented parasitic reactions, while the pores and surface edge sites retained electrochemical activity. The capacity values were thus restored and even became higher as a result of preventing the development of a surface layer. Ultraviolet photoelectron spectroscopy measurements assessed the energetic states of the electrodes and confirmed that the alumina coating forms a barrier for interfacial electron transfer from the electrode to the solution at any polarization stage.

In the present work, a simple and agile methodology for atomic surface reduction of interfaces is introduced. Using a surface directed vapor phase reaction, at relatively low temperature, we show that a highly reactive and volatile molecule can be used to selectively reduce the interface, without changing the bulk of the treated material, and without the need of alternating sequence of multiple precursors, normally involved in ALD. The model system we use to demonstrate the efficacy, and potential of our approach is trimethyl aluminum, and high energy Li and Mn rich cathode (HE-NCM) as the functional material of interest. We demonstrate that with the proposed method, the particles of HE-NMC were conformally coated with ~ 3 nm amorphous layer of the reduced surface in less than 1 h (including the cooling time),as witnessed using HR-TEM. XPS and solid-state NMR, further confirmed that surface treatment was successfully achieved using the proposed method and is well explained by DFT calculations. Utilizing online electrochemical mass spectrometry (OEMS), we show in-operando that this amorphous layer helps to suppress parasitic reactions under extreme electrochemical conditions as indicated by the significant reduction in oxygen and CO2 evolution. The surface treatment further resulted in enhancement in specific capacity during the first cycle. This methodology provides a non-conventional path to achieve thin layer surface modification under facile conditions, and opens a new way to meet the requirements of surface modification strategies for improving the performance of electrode materials without utilizing expensive instrumentation and high temperature processes.

In recent decades, rechargeable Mg batteries (RMBs) technologies have attracted much attention because the use of thin Mg foil anodes may enable development of high‐energy‐density batteries. One of the most critical challenges for RMBs is finding suitable electrolyte solutions that enable efficient and reversible Mg cells operation. Most RMB studies concentrate on the development of novel electrolyte systems, while only few studies have focused on the practical feasibility of using pure metallic Mg as the anode material. Pure Mg metal anodes have been demonstrated to be useful in studying the fundamentals of nonaqueous Mg electrochemistry. However, pure Mg metal may not be suitable for mass production of ultrathin foils (, Ultra‐thin Mg alloy: Rechargeable magnesium batteries are considered as the most promising alternative to lithium battery technologies Similar electrochemical performance of 100 μm thick pure Mg foils and 25 μm thin and ductile AZ31 Mg alloy foils as anodes in rechargeable Mg batteries is demonstrated. Comprising Chevrel‐phase (Mo6S8) cathodes, thin foils of AZ31 Mg alloy can serve as very suitable anodes in rechargeable Mg batteries.

Out of the many challenges in the realization of lithium–O2 batteries (LOB), the major is to deal with the instability of the electrolyte and the cathode interface under the stringent environment of both oxygen reduction and evolution reactions. Lithium nitrate was recently proposed as a promising salt for LOB because of its capability to stabilize the lithium anode by the formation of a solid electrolyte interphase, its low level of dissociation in aprotic solvents, and its catalytic effect toward oxygen evolution reaction (OER) in rechargeable LOB. Nevertheless, a deeper understanding of the influence of nitrate on the stability and electrochemical response of the cathode in LOB is yet to be realized. Additionally, it is well accepted that carbon instability toward oxidation is a major reason for early failure of LOB cells; therefore, it is essential to investigate the effect of electrolyte components on this side of the battery. In the present work, we show that nitrate leads to interfacial changes, wh...

To mitigate the associated challenges of instability and capacity improvement in Na3 V2 (PO4 )2 F3 (NVPF), rationally designed uniformly distributed hollow spherical NVPF and coating the surface of NVPF with ultrathin (≈2 nm) amorphous TiO2 by atomic layer deposition is demonstrated. The coating facilitates higher mobility of the ion through the cathode electrolyte interphase (CEI) and enables higher capacity during cycling. The TiO2 @NVPF exhibit discharge capacity of >120 mAhg-1 , even at 1C rates, and show lower irreversible capacity in the first cycle. Further, nearly 100% capacity retention after rate performance in high current densities and 99.9% coulombic efficiency after prolonged cycling in high current density is reported. The improved performance in TiO2 @NVPF is ascribed to the passivation behavior of TiO2 coating which protects the surface of NVPF from volume expansion, significantly less formation of carbonates, and decomposition of electrolyte, which is also validated through post cycling analysis. The study shows the importance of ultrathin surface protection artificial CEI for advanced sodium-ion battery cathodes. The protection layer is diminishing parasitic reaction, which eventually enhances the Na ion participation in reaction and stabilizes the cathode structure.

During the last two decades, we have observed a dramatic increase in the electrification of many technologies. What has enabled this transition to take place was the commercialization of Li-ion batteries in the early nineties. Mobile technologies such as cellular phones, laptops, and medical devices make these batteries crucial for our contemporary lifestyle. Like any other electrochemical cell, the Li-ion batteries are restricted to the thermodynamic limitations of the materials. It might be that the energy density of the most advance Li-ion battery is still too low for demanding technologies such as a full electric vehicle. To really convince future customers to switch from the internal combustion engine, new batteries and chemistry need to be developed. Non-aqueous metal-oxygen batteries—such as lithium–oxygen, sodium–oxygen, magnesium–oxygen, and potassium–oxygen—offer high capacity and high operation voltages. Also, by using suitable polar aprotic solvents, the oxygen reduction process that occurs during discharge can be reversed by applying an external potential during the charge process. Thus, in theory, these batteries could be electrically recharged a number of times. However, there are many scientific and technical challenges that need to be addressed. The current review highlights recent scientific insights related to these promising batteries. Nevertheless, the reader will note that many conclusions are applicable in other kinds of batteries as well.

One of the many challenges in the study of chiral nanosurfaces and nanofilms is the design of accurate and controlled nanoscale films with enantioselective activity. Controlled design of chiral nanofilms creates the opportunity to develop chiral materials with nanostructured architecture. Molecular layer deposition (MLD) is an advanced surface-engineering strategy for the preparation of hybrid inorganic-organic thin films, with a desired embedded property; in our study this is chirality. Previous attempts to grow enantioselective thin films were mostly focused on self-assembled monolayers or template-assisted synthesis, followed by removal of the chiral template. Here, we report a method to prepare chiral hybrid inorganic-organic nanoscale thin films with controlled thickness and impressive enantioselective properties. We present the use of an MLD reactor for sequenced vapor deposition to produce enantioselective thin films, by embedding the chirality of chiral building blocks into thin films. The prepared thin films demonstrate enantioselectivity of ∼20% and enantiomeric excess of up to 50%. We show that our controlled synthesis of chiral thin films generates opportunities for enantioselective coatings over various templates and 3D membranes.

Rechargeable Mg battery has been considered a major candidate as a beyond lithium ion battery technology, which is apparent through the tremendous works done in the field over the past decades. The challenges for realization of Mg battery are complicated, multidisciplinary, and the tremendous work done to overcome these challenges is very hard to organize in a regular review paper. Additionally, we claim that organization of the huge amount of information accumulated by the great scientific progress achieved by various groups in the field will shed the light on the unexplored research domains and give clear perspectives and guidelines for next breakthrough to take place. In this Perspective, we provide a convenient map of Mg battery research in a form of radar chart of Mg electrolytes, which evaluates the electrolyte under the important components of Mg batteries. The presented radar charts visualize the accumulated knowledge on Mg battery and allow for navigation of not only the current research state but also future perspective of Mg battery at a glance.

Materials that undergo conversion reactions to form different materials upon lithiation typically offer high specific capacity for energy storage applications such as Li ion batteries. However, since the reaction products often involve complex mixtures of electrically insulating and conducting particles and significant changes in volume and phase, the reversibility of conversion reactions is poor, preventing their use in rechargeable (secondary) batteries. In this paper, we fabricate and protect 3D conversion electrodes by first coating multiwalled carbon nanotubes (MWCNT) with a model conversion material, RuO2, and subsequently protecting them with conformal thin-film lithium phosphous oxynitride (LiPON), a well-known solid-state electrolyte. Atomic layer deposition is used to deposit the RuO2 and the LiPON, thus forming core double-shell MWCNT@RuO2@LiPON electrodes as a model system. We find that the LiPON protection layer enhances cyclability of the conversion electrode, which we attribute to two factors. (1) The LiPON layer provides high Li ion conductivity at the interface between the electrolyte and the electrode. (2) By constraining the electrode materials mechanically, the LiPON protection layer ensures electronic connectivity and thus conductivity during lithiation/delithiation cycles. These two mechanisms are striking in their ability to preserve capacity despite the profound changes in structure and composition intrinsic to conversion electrode materials. This LiPON-protected structure exhibits superior cycling stability and reversibility as well as decreased overpotentials compared to the unprotected core-shell structure. Furthermore, even at very low lithiation potential (0.05 V), the LiPON-protected electrode largely reduces the formation of a solid electrolyte interphase.

This work continues our systematic study of Li- and Mn- rich cathodes for lithium-ion batteries. We chose Li2MnO3 as a model electrode material with the aim of correlating the improved electrochemical characteristics of these cathodes initially activated at 0 &deg, C with the sstructural evolution of Li2MnO3, oxygen loss, formation of per-oxo like species (O22&minus, ) and the surface chemistry. It was established that performing a few initial charge/discharge (activation) cycles of Li2MnO3 at 0 &deg, C resulted in increased discharge capacity and higher capacity retention, and decreased and substantially stabilized the voltage hysteresis upon subsequent cycling at 30 &deg, C or at 45 &deg, C. In contrast to the activation of Li2MnO3 at these higher temperatures, Li2MnO3 underwent step-by-step activation at 0 &deg, C, providing a stepwise traversing of the voltage plateau at &gt, 4.5 V during initial cycling. Importantly, these findings agree well with our previous studies on the activation at 0 &deg, C of 0.35Li2MnO3&middot, 0.65Li[Mn0.45Ni0.35Co0.20]O2 materials. The stability of the interface developed at 0 &deg, C can be ascribed to the reduced interactions of the per-oxo-like species formed and the oxygen released from Li2MnO3 with solvents in ethylene carbonate&ndash, methyl-ethyl carbonate/LiPF6 solutions. Our TEM studies revealed that typically, upon initial cycling both at 0 &deg, C and 30 &deg, C, Li2MnO3 underwent partial structural layered-to-spinel (Li2Mn2O4) transition.

Rechargeable magnesium batteries (RMBs) have attracted a lot of attention in recent decades due to the theoretical properties of these systems in terms of energy density, safety, and price. Nevertheless, to date, fully rechargeable magnesium battery prototypes with sufficient longevity and reversibility were realized only with low voltage and low capacity intercalation cathode materials based on Cheverel phases. The community is therefore actively looking for high-capacity cathodes that can work with metallic magnesium anodes in viable RMB systems. One of the most promising cathode materials, in terms of very high theoretical specific capacity, is, naturally, sulfur. A number of recent works studied the electrochemical performances of rechargeable sulfur cathodes in RMB, with success to some extent on the cathode side. Nevertheless, as known from the lithium-sulfur rechargeable battery systems, the formation of soluble polysulfides during discharge affects strongly the behavior of the anode side. In this article and the work it describes, we focus on soluble polysulfides impact on Mg-S electrochemichal systems. We carefully designed herein conditions that mimic the Mg-S battery prototypes containing balanced Mg and elemental sulfur electrodes. Under these conditions, we extensively studied the Mg anode behavior. The study shows that when elemental sulfur cathodes are discharged in the Mg-S cells containing electrolyte solutions in which Mg anodes behave reversibly, the polysulfide species thus formed migrate to the anode and eventually fully passivate it by the formation of very stable surface layers. The work involved electrochemical, spectroscopic, and microscopic studies. The present study clearly shows that to realize practical rechargeable Mg-S batteries, the transport of any sulfide moieties from the sulfur cathode to the magnesium anode has to be completely avoided. Such a condition is mandatory for the operation of secondary Mg-S batteries.

The combination of high electronic conductivity, enhanced ionic mobility, and high pore volume make ordered mesoporous carbons promising scaffolds for active energy storage materials. However, mesoporous morphology and structural stability needs to be more thoroughly addressed. In this paper, we demonstrate Fe2O3 impregnation into 1D cylindrical (FDU-15), 2D hexagonal (CMK-3), and 3D bicontinuous (CMK-8) symmetries of mesoporous carbons. We use these materials for a systematic study of the effect of mesoporous architecture on the structure stability, ion mobility, and performance of mesoporous composite electrodes. By optimization of the porous structure, the oxide impregnation enabled relatively high performance: >650 F g−1 of Fe2O3 and >200 F g−1 total capacitance. This work highlights the new considerations of structure degradation in different pore symmetries with active material impregnation and its effect on ion mobility and electrochemical performance in porous scaffold electrodes. The results show that the most commonly used 2D CMK-3 is not suitable as a host material due to its poor structure stability and ion mobility, while the 1D FDU-15 and 3D CMK-8 have their own merits related to framework stability and porous structures.

Lithium metal is considered to be the most promising anode for next-generation batteries due to its high energy density of 3840 mAh g(-1). However, the extreme reactivity of the Li surface can induce parasitic reactions with solvents, contamination, and shuttled active species in the electrolyte, reducing the performance of batteries employing Li metal anodes. One promising solution to this issue is application of thin chemical protection layers to the Li metal surface. Using a custom-made ultrahigh vacuum integrated deposition and characterization system, we demonstrate atomic layer deposition (ALD) of protection layers directly on Li metal with exquisite thickness control. We demonstrate as a proof-of-concept that a 14 nm thick ALD Al2O3 layer can protect the Li surface from corrosion due to atmosphere, sulfur, and electrolyte exposure. Using Li-S battery cells as a test system, we demonstrate an improved capacity retention using ALD-protected anodes over cells assembled with bare Li metal anodes for up to 100 cycles.

Carbon/metal oxide composites are considered promising materials for high energy density supercapacitors. So far, impregnation of the oxide into ordered mesoporous carbon materials has been demonstrated either in hard-templated carbon synthesized by using ordered mesoporous silica or alumina scaffolds, or soft-templated carbon derived from surfactant micelles. The hard-template method can provide a high pore volume but the instability of these mesostructures hinders total electrode performances upon oxide impregnation. While the soft-template methods can provide a stable mesostructure, these methods produce scaffolds with a much smaller pore volume and surface area, leading to limited metal oxide loading and electrode capacitance. Herein, anodized aluminum oxide (AAO) and triblock copolymer F127 are used together as hard and soft-templates to fabricate ordered mesoporous carbon nanowires (OMCNWs) as a host material for Fe2O3 nanoparticles. This dual-template strategy provides a high pore volume and surface area OMCNW that retains its stable structure even for high metal oxide loading amounts. Additionally, the unique nanowire morphology and mesoporous structure of the OMCNW/Fe2O3 facilitate high ionic mobility in the composite, leading to >260 F g−1 specific capacitance with good rate capability and cycling stability. This work highlights the dual-template approach as a promising strategy for the fabrication of next generation heterogeneous composites for electrochemical energy storage and conversion.

Oxygen reduction in nonaqueous electrolyte solutions containing Li salts is a complex field of research involving solution reactions with oxygen radicals and lithium oxides. The aprotic polar solve...

We present a new method for synthesis of thick, self-standing porous carbon electrodes with improved physicochemical properties and unique porous structure. The synthesis is based on the use of vertically aligned carbon nanotubes (VACNT) as templates for polymer-based activated carbon materials. The VACNT template enables the production of 1 mm thick, binder-free electrodes with high capacity values even at high rates (>160 Fg−1 at more than 1 Ag−1 for 1 mm thick electrode), and very good stability upon cycling. The electrochemical performance after more than 50,000 cycles, the pore characterization by adsorption isotherms, and the structural analysis of the composite electrode are also reported.

Carbonaceous materials are widely used in electrochemistry. All allotropic forms of carbons—graphite, glassy carbon, amorphous carbon, fullerenes, nanotubes, and doped diamond—are used as important electrode materials in all fields of modern electrochemistry. Examples include graphite and amorphous carbons as anode materials in high-energy density rechargeable Li batteries, porous carbon electrodes in sensors and fuel cells, nano-amorphous carbon as a conducting agent in many kinds of composite electrodes (e.g., cathodes based on intercalation inorganic host materials for batteries), glassy carbon and doped diamond as stable robust and high stability electrode materials for all aspects of basic electrochemical studies, and more. Amorphous carbons can be activated to form very high specific surface area (yet stable) electrode materials which can be used for electrostatic energy storage and conversion [electrical double-layer capacitors (EDLC)] and separation techniques based on electro-adsorption, such as water desalination by capacitive de-ionization (CDI). Apart from the many practical aspects of activated carbon electrodes, there are many highly interesting and important basic aspects related to their study, including transport phenomena, molecular sieving behavior, correlation between electrochemical behavior and surface chemistry, and more. In this article, we review several important aspects related to these electrode materials, in a time perspective (past, present, and future), with the emphasis on their importance to EDLC devices and CDI processes.

A straightforward method is presented for characterizing the quality of carbon nanotube (CNT) dispersions using scanning electron microscopy (SEM) imaging of samples prepared using a unique procedure, which successfully prevents re-coagulation of the CNTs during the evaporation of the dispersant. The images obtained more accurately reflect the status of the bulk dispersion in the liquid state. This method can be used to comparatively analyze the degree of disaggregation and the extent of tube breakage following a dispersion protocol in either aqueous or non-aqueous solutions, with or without surfactants, and regardless of the original condition of the CNTs.

One of the greatest obstacles for the realization of the nonaqueous Li-O2 battery is finding a solvent that is chemically and electrochemically stable under cell operating conditions. Dimethyl sulfoxide (DMSO) is an attractive candidate for rechargeable Li-O2 battery studies; however, there is still significant controversy regarding its stability on the Li-O2 cathode surface. We performed multiple experiments (in situ XPS, FTIR, Raman, and XRD) which assess the stability of the DMSO-Li2O2 interface and report perspectives on previously published studies. Our electrochemical experiments show long-term stable cycling of a DMSO-based operating Li-O2 cell with a platinum@carbon nanotube core-shell cathode fabricated via atomic layer deposition, specifically with45 cycles of 40 h of discharge per cycle. This work is complemented by density functional theory calculations of DMSO degradation pathways on Li2O2. Both experimental and theoretical evidence strongly suggests that DMSO is chemically and electrochemically stable on the surface of Li2O2 under the reported operating conditions.

Pushing lithium-ion battery (LIB) technology forward to its fundamental scaling limits requires the ability to create designer heterostructured materials and architectures. Atomic layer deposition (ALD) has recently been applied to advanced nanostructured energy storage devices due to the wide range of available materials, angstrom thickness control, and extreme conformality over high aspect ratio nanostructures. A class of materials referred to as conversion electrodes has recently been proposed as high capacity electrodes. RuO2 is considered an ideal conversion material due to its high combined electronic and ionic conductivity and high gravimetric capacity, and as such is an excellent material to explore the behavior of conversion electrodes at nanoscale thicknesses. We report here a fully characterized atomic layer deposition process for RuO2, electrochemical cycling data for ALD RuO2, and the application of the RuO2 to a composite carbon nanotube electrode scaffold with nucleation-controlled RuO2 growth. A growth rate of 0.4 A/cycle is found between ∼ 210-240 °C. In a planar configuration, the resulting RuO2 films show high first cycle electrochemical capacities of ∼ 1400 mAh/g, but the capacity rapidly degrades with charge/discharge cycling. We also fabricated core/shell MWCNT/RuO2 heterostructured 3D electrodes, which show a 50× increase in the areal capacity over their planar counterparts, with an areal lithium capacity of 1.6 mAh/cm(2).