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Mg metal anode‐based battery is a more sustainable, lower cost, and higher energy density alternative to Li‐ion. However, this battery chemistry also faces several challenges associated with the high charge density of Mg2+, including achieving high reversibility and low voltage hysteresis for Mg metal plating/stripping. While significant improvements are achieved in last decades, they involve rather complex electrolyte formulations and/or Mg salts difficult to produce, and the use of unpractical substrates such as platinum. Here, significant improvement in terms of Mg plating kinetics is achieved in electrolytes containing commercial magnesium bis(trifluoromethanesulfonyl)imide salt (Mg(TFSI)2) by using titanium substrate with similar crystal structure and lattice parameter as Mg leading to lower nucleation overpotential. Low salt concentration electrolyte and addition of dibutyl magnesium (Mg(butyl)2) also enable the formation of thinner interphase, richer in solvent based decomposition products, further improving Mg plating kinetics. This work highlights the complex role of Mg(butyl)2, often considered as a simple drying agent, and how it impacts ion solvation favoring the mobility of electroactive cationic species, paving the way toward better electrolyte design with improved cation transference number. [ABSTRACT FROM AUTHOR]

Sodium metal battery is considered as one of the most promising energy storage/conversion devices due to their high energy density, and abundant sodium reserves. However, its development is hampered by the limited metallic utilization and detrimental sodium dendrite growth ascribed to the unstable, and fragile solid electrolyte interphase (SEI). Here, the high stable and modulus SEI is constructed with a component of a thin and dense layer of high Na‐ion conductive Na2SiO3. It is in situ formed by the reaction between sodium anode and fish‐skin structure separator, which exhibits a 3D porous polyvinylidene fluoride‐based framework embedded with thin and robust vermiculite sheets. The robust interphase cannot only suppress sodium dendrite growth but also enable high energy density with small interphase‐consumed Na ions in anode‐less batteries. Accordingly, the as‐assembled NaNi1/3Fe1/3Mn1/3O2//Na cell shows 83% capacity retention after 5000 cycles at a rate of 5 °C. Moreover, the proof‐of‐concept pouch cells deliver an energy density of 205 Wh kg−1 (based on the total mass of the battery), and high safety (not catching fire after punctured) under anode‐less condition (with a low negative/positive capacity ratio of ≈2.1). [ABSTRACT FROM AUTHOR]

Anode‐free alkali metal batteries (AFAMBs) are regarded as the most promising candidates for next‐generation high‐energy systems owing to their high safety, high energy density, and low cost. However, the restricted alkali supply at the cathode, severe dendrite growth, and unstable electrode‐electrolyte interface result in low Coulombic efficiency and severely short cycle life. The optimization strategies are mainly based on laboratory‐level coin cells, but their effectiveness in practical‐level batteries is rarely discussed. This review presents a comprehensive overview of the recent developments and challenges of AFAMBs from the laboratory toward their practicability. First, the advances, major challenges, and optimization strategies are systematically summarized. More significantly, given the vast differences in battery structures and operating conditions, the gap between laboratory‐level and practical‐level batteries is particularly emphasized in this review. In addition, the failure mechanisms of practical‐level AFAMBs have been outlined and the key parameters affecting their performance are identified. Finally, insightful perspectives on practical AFAMBs are presented, aiming to provide helpful guidance for subsequent basic research to promote large‐scale commercial applications of AFAMBs. [ABSTRACT FROM AUTHOR]

Divalent metal batteries have attracted considerable attention in scientific exploration for sustainable energy storage solutions owing to the abundant reserves of magnesium (Mg) and calcium (Ca), the competitive low redox potentials of the Mg/Mg2+ (–2.37 V vs SHE) and Ca/Ca2+ (–2.87 V vs SHE) couples, as well as the high theoretical capacities of both metal anodes. However, the development of these batteries faces fundamental challenges stemming from the limited cycling stability and efficiency of Mg/Ca metal anodes. These issues primarily originate from the sluggish electrochemical redox kinetics of the divalent metals, particularly at the anode‐electrolyte interfaces. This comprehensive review provides an up‐to‐date overview of advancements in the field of the anode‐electrolyte interface for divalent metal batteries, covering aspects ranging from its formation, morphology, and composition to their influence on the reversible electrochemical deposition of divalent metals. Recent approaches aimed at enhancing the performance of metallic Mg and Ca anodes across various electrolytes are summarized and discussed, with the goal of providing insights for the development of new strategies in future research. [ABSTRACT FROM AUTHOR]

Alkali metals (e.g. Li, Na, and K) and multivalent metals (e.g. Zn, Mg, Ca, and Al) have become star anodes for developing high‐energy‐density rechargeable batteries due to their high theoretical capacity and excellent conductivity. However, the inevitable dendrites and unstable interfaces of metal anodes pose challenges to the safety and stability of batteries. To address these issues, covalent organic frameworks (COFs), as emerging materials, have been widely investigated due to their regular porous structure, flexible molecular design, and high specific surface area. In this minireview, we summarize the research progress of COFs in stabilizing metal anodes. First, we present the research origins of metal anodes and delve into their advantages and challenges as anodes based on the physical/chemical properties of alkali and multivalent metals. Then, special attention has been paid to the application of COFs in the host design of metal anodes, artificial solid electrolyte interfaces, electrolyte additives, solid‐state electrolytes, and separator modifications. Finally, a new perspective is provided for the research of metal anodes from the molecular design, pore modulation, and synthesis of COFs. [ABSTRACT FROM AUTHOR]

Perylene diimide radical anions (PDI–•) prepared by through photoelectric doping are capable of reducing aromatic halides and achieving aromatic hydrocarbon coupling. The active of electrically doped PDI–• is dependent on the conditions of electroreduction (e.g. electrode material), but little attention has been paid to the influence of electrode material, voltage, and electroreduction time on the activity of PDI–•. In this paper, we compared the active of PDI–• produced by different electrode materials, different reduction voltages and different reduction times based on the difference in UV-vis absorption spectra. In contrast to the characteristic absorption spectra of the anion of the PDI–•, the metal electrodes with certain reducing properties, such as zinc and magnesium, stabilize the radical anion and reduce the PDI–• activity due to the generation of positive zinc and magnesium ions during the electroreduction process. [ABSTRACT FROM AUTHOR]

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In times of an ever‐increasing demand for portable energy storage systems, post‐lithium‐based battery systems are increasingly coming into the focus of current research. In this realm, zinc–air batteries can be considered a very promising candidate to expand the existing portfolio of lithium‐based rechargeable battery systems due to their high theoretical energy density of 1086 Wh kg−1. Despite a steady increase in research over the past 5 years, a breakthrough in realizing fully electrically rechargeable zinc–air batteries has yet to come. This perspective article highlights pitfalls that have probably hampered the development of rechargeable zinc–air batteries over years. This involves a fundamental evaluation of the zinc–air battery system, whereby fallacies of an alleged rechargeability are uncovered. Especially, the electrode balancing of the zinc anode as well as the interface between anode and electrolyte is focused herein. Known phenomena such as morphological changes are re‐evaluated by taking the contrasting battery stresses from shallow discharge to a highly desirable deep discharge into account. Existing challenges are discussed and prospected based on current approaches aiming to shed new light on a fundamental understanding and an opening of new avenues for rechargeability in zinc–air batteries. [ABSTRACT FROM AUTHOR]

Metal–air batteries (MABs) have been paid much more attention owing to their greater energy density than the most advanced lithium-ion batteries (LIBs). Rechargeable MABs are considered as promising candidates for the next-generation of energy storage techniques for applications ranging from large-scale energy storage systems to electric vehicles and portable devices. However, there are still numerous scientific problems that must be overcome before their commercial application. With the aim of providing a comprehensive understanding of this new electrochemical system particularly Li–air batteries, this review paper provides an overview of the current status including corresponding strategies from the perspective of various battery components, including air cathode, metal anode and electrolyte. In addition, other promising MABs such as Zn–air, Mg–air and Al–air batteries are also introduced briefly for comparison. Finally, the applications and prospects of these four types of MABs are discussed and some perspectives for this research field are also provided. [ABSTRACT FROM AUTHOR]

Abstract Although three‐dimensional (3D) lithium metal electrode is effective in restricting the Li dendrite growth upon cycling, problems associated with the unstable electrode/electrolyte interphase become more severe due to increased interfacial area that is intrinsic of the 3D structures, being a major cause for the low Columbic efficiency. While building a desirable solid electrolyte interphase (SEI) serves as an effective solution to improve the electrode/electrolyte interfacial stability, the 3D nature of the electrode makes the task challenging. In the present work, we demonstrated the in‐situ formation of SEI on chemically/structurally modified carbon cloth that is used as the 3D host electrode for Li metal. Here we show that ZnS/ZnO nanotube arrays uniformly grown on the carbon cloth served as precursors for the in‐situ formation of Li2S/Li2O/LiZn containing artificial SEI in the first lithiation process. While Li2S and Li2O are preferred components in SEI, the in situ generated Zn functions as a lithiophilic site that guides the uniform lithium deposition upon repeated charging/discharging process. As a result, symmetric cells adopting the O‐, S‐, and Zn‐ modified 3D anode demonstrate significantly improved Coulombic efficiency (99.2% over 400 cycles at 1 mA cm−2/1 mA h cm−2). Furthermore, the Li/ZSONT/CC//LiFePO4 full cell shows a capacity retention of 71% after 4000 cycles at 2C. The present work sheds light on effective design strategies for SEI formation on a 3D electrode host with controllable SEI composition.

Alkali metal anodes are among the most promising candidates for next-generation high-capacity batteries like metal–air, metal–sulphur and all-solid-state metal batteries. The underlying interfacial mechanism of dendrite formation is not yet fully understood, preventing the practical implementation of metal batteries, particularly lithium, despite decades of research. Parallelly, there is an equal significance to the other alkali metal candidates viz sodium and potassium. The major challenges of alkali metal batteries, including dendrite formation, huge volume change, and unstable solid–electrolyte interface, are highlighted. Here, we also present an overview of the recent developments toward improving the anode interfaces. Given the enormous practical potential of alkali metal anodes as next-generation battery electrodes, we discuss some advanced probing techniques that enable a more complete understanding of the complex plating/stripping mechanism. Finally, perspectives and suggestions are provided on the remaining challenges and future directions in alkali metal battery research.

Abstract In times of an ever‐increasing demand for portable energy storage systems, post‐lithium‐based battery systems are increasingly coming into the focus of current research. In this realm, zinc–air batteries can be considered a very promising candidate to expand the existing portfolio of lithium‐based rechargeable battery systems due to their high theoretical energy density of 1086 Wh kg−1. Despite a steady increase in research over the past 5 years, a breakthrough in realizing fully electrically rechargeable zinc–air batteries has yet to come. This perspective article highlights pitfalls that have probably hampered the development of rechargeable zinc–air batteries over years. This involves a fundamental evaluation of the zinc–air battery system, whereby fallacies of an alleged rechargeability are uncovered. Especially, the electrode balancing of the zinc anode as well as the interface between anode and electrolyte is focused herein. Known phenomena such as morphological changes are re‐evaluated by taking the contrasting battery stresses from shallow discharge to a highly desirable deep discharge into account. Existing challenges are discussed and prospected based on current approaches aiming to shed new light on a fundamental understanding and an opening of new avenues for rechargeability in zinc–air batteries.

The improvement of our living standards puts forward higher requirements for energy storage systems, especially rechargeable batteries. Unfortunately, phenomena such as capacity failure, etc. have been major difficulties in the field of energy storage. Therefore, we need some advanced means to explore the reaction process and mechanisms of the cell. Electron paramagnetic resonance (EPR) has the advantages of a high sensitivity to electrons, lack of damage to samples, quantitative analysis, etc., which can make for a more in-depth exploration of most paramagnetic electrode materials and metal electrode materials. After a brief description of the principle of EPR, this review briefly summarizes the application of EPR to the characterization of transition metal oxide cathode and lithium metal anode electrode materials in recent years, such as showing how to study electrode materials by using EPR in situ and operando. [ABSTRACT FROM AUTHOR]

Solid‐state metal–air batteries have emerged as a research hotspot due to their high energy density and high safety. Moreover, side reactions caused by infiltrated gases (O2, H2O, or CO2) and safety issues caused by liquid electrolyte leakage will be eliminated radically. However, the solid‐state metal–air battery is still in its infancy, and many thorny problems still need to be solved, such as the large resistance of the metal/electrolyte interface and catalyst design. This review will summarize some important progress and key issues for solid‐state metal–air batteries, especially the lithium‐, sodium‐, and zinc‐based metal–air batteries, clarify some core issues, and forecast the future direction of the solid‐state metal–air batteries. [ABSTRACT FROM AUTHOR]

Abstract Solid‐state metal–air batteries have emerged as a research hotspot due to their high energy density and high safety. Moreover, side reactions caused by infiltrated gases (O2, H2O, or CO2) and safety issues caused by liquid electrolyte leakage will be eliminated radically. However, the solid‐state metal–air battery is still in its infancy, and many thorny problems still need to be solved, such as the large resistance of the metal/electrolyte interface and catalyst design. This review will summarize some important progress and key issues for solid‐state metal–air batteries, especially the lithium‐, sodium‐, and zinc‐based metal–air batteries, clarify some core issues, and forecast the future direction of the solid‐state metal–air batteries.

Rechargeable aqueous zinc-based hybrid supercapacitors (ZHSC) are widely used because of their safety, high capacity, cost-effectiveness, and environmental friendliness. However, the serious dendrite growth, low cycle life, and poor safety of zinc metal anodes greatly hinder their practical application. Additionally, the lack of excellent cathode materials also restricts further development of high-efficiency aqueous ZHSC. Herein, we report a novel persimmon-branch biomass carbon-based material with a naturally graded pore structure. Persimmon branch activated carbon (PBAC) was used as the cathode, and the anode was constructed using a zinc foil coated with one-step carbonized persimmon branch carbon (PBC). A new type of high-performance ZHSC was assembled using the porous structure of a carbon-based material and Cu2+-electrolyte additive. The hierarchical pore structure endowed the activated carbon with excellent electric double-layer capacitance characteristics as well as superb zinc ions storage ability. The artificial carbon-coated zinc metal anodes could homogenize the electric fields, and the Cu2+ from the electrolyte induced zinc metal deposition, which improved the cycle stability of the ZHSC. Therefore, the assembled ZHSC (PBAC 4 |ZnSO 4 +CuSO 4 |PBC@Zn) exhibited excellent electrochemical performance, high discharge capacity (182.8 mAh g−1), good rate performance (51.4 mAh g−1 at 10 A g−1), high energy density (27.1 W h kg−1 at 5 kW kg−1 based on the weight of the active material) and demonstrated a long cycle life with 73.8% capacitance retention after 3000 cycles at 5 A g−1 high current density. [Display omitted] [ABSTRACT FROM AUTHOR]

Lewis acid-base interactions are common in chemical processes presented in diverse applications, such as synthesis, catalysis, batteries, semiconductors, and solar cells. The Lewis acid-base interactions allow precise tuning of material properties from the molecular level to more aggregated and organized structures. This review will focus on the origin, development, and prospects of applying Lewis acid-base interactions for the materials design and mechanism understanding in the advancement of battery materials and chemistries. The covered topics relate to aqueous batteries, lithium-ion batteries, solid-state batteries, alkali metal-sulfur batteries, and alkali metal-oxygen batteries. In this review, the Lewis acid-base theories will be first introduced. Thereafter the application strategies for Lewis acid-base interactions in solid-state and liquid-based batteries will be introduced from the aspects of liquid electrolyte, solid polymer electrolyte, metal anodes, and high-capacity cathodes. The underlying mechanism is highlighted in regard to ion transport, electrochemical stability, mechanical property, reaction kinetics, dendrite growth, corrosion, and so on. Last but not least, perspectives on the future directions related to Lewis acid-base interactions for next-generation batteries are like to be shared., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Abstract With the rapid development of wearable and intelligent flexible electronic devices (FEDs), the demand for flexible energy storage/conversion devices (ESCDs) has also increased. Rechargeable flexible metal‐air batteries (MABs) are expected to be one of the most ideal ESCDs due to their high theoretical energy density, cost advantage, and strong deformation adaptability. With the improvement of the device design, material assemblies, and manufacturing technology, the research on the electrochemical performance of flexible MABs has made significant progress. However, achieving the high mechanical flexibility, high safety, and wearable comfortability required by FEDs while maintaining the high performance of flexible MABs are still a daunting challenge. In this review, flexible Zn‐air and Li‐air batteries are mainly exemplified to describe the most recent progress and challenges of flexible MABs. We start with an overview of the structure and configuration of the flexible MABs and discuss their impact on battery performance and function. Then it focuses on the research progress of flexible metal anodes, gel polymer electrolytes, and air cathodes. Finally, the main challenges and future research perspectives involving flexible MABs for FEDs are proposed.

Bi is a promising anode material for potassium-ion batteries (PIBs) due to its high theoretical capacity. However, severe pulverization upon cycling limits its practical applications. In this work, we propose a new approach of using metastable alloys with Bi elements. Metastable Bi:Co and Bi:Fe alloys nanodots@carbon anode materials (Bi:Co and Bi:Fe@C) are synthesized for the first time via simple annealing of their metal-organic frameworks (MOF) precursors. These prepared materials are demonstrated as ideal hosts for high-rate K-ion storage. Bi0.85Co0.15@C and Bi0.83Fe0.17@C electrodes respectively deliver superior 178 and 253 mAh·g−1 at 20 A·g−1, as well as stable cycling performance at 2 A·g−1. Ex situ scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) studies on Bi:Co@C indicate that the elemental Co separates out during the initial potassiation and stands during the following discharge/charge cycles. In situ formed Co precipitates can act as (1) "conductive binders" as well as (2) "separators" to prevent the severe aggregation of adjacent active elemental Bi nanoparticles and (3) accelerate the potassiation/de-potassiation kinetics in elemental Bi precipitates after initial discharge/charge cycles. This work could inspire the development of metal-type anodes. [ABSTRACT FROM AUTHOR]

Abstract Magnesium metal anode holds great potentials toward future high energy and safe rechargeable magnesium battery technology due to its divalent redox and dendrite-free nature. Electrolytes based on Lewis acid chemistry enable the reversible Mg plating/stripping, while they fail to match most cathode materials toward high-voltage magnesium batteries. Herein, reversible Mg plating/stripping is achieved in conventional carbonate electrolytes enabled by the cooperative solvation/surface engineering. Strongly electronegative Cl from the MgCl2 additive of electrolyte impairs the Mg…O = C interaction to reduce the Mg2+ desolvation barrier for accelerated redox kinetics, while the Mg2+-conducting polymer coating on the Mg surface ensures the facile Mg2+ migration and the effective isolation of electrolytes. As a result, reversible plating and stripping of Mg is demonstrated with a low overpotential of 0.7 V up to 2000 cycles. Moreover, benefitting from the wide electrochemical window of carbonate electrolytes, high-voltage (> 2.0 V) rechargeable magnesium batteries are achieved through assembling the electrode couple of Mg metal anode and Prussian blue-based cathodes. The present work provides a cooperative engineering strategy to promote the application of magnesium anode in carbonate electrolytes toward high energy rechargeable batteries.

Summary: Rechargeable zinc metal batteries (RZMBs) are emerging as promising candidates to replace lithium‐ion batteries due to their low cost, safety, and stability under ambient atmosphere. As the conductive substrates lower the actual current density, it is considered a chemical strategy to resolve the dendrite issue of RZMB. Herein, we propose to use the carbon nanofiber as a conductive substrate for the anode of RZMBs, which was prepared via heat treatment of electrospun PAN‐derived nanofiber. Through CV and SEM results performed at a constant current rate of 20 mA cm−2, the optimum amount of zinc deposited on the CNF was determined to be 10 mAh cm−2. Symmetric cell test for 400 hours showed 60.1% reduction in plating/stripping overpotential when zinc deposited carbon nanofiber was used. This overpotential reduction was attributed to the macroporous structure of ZnCNF and the preferred orientation of zinc to the (002) plane as confirmed by post mortem analyses. RZMB full cells pairing ZnCNF with β‐MnO2 were configured to deliver the 5C‐rate capacity of 106.54 mAh g−1, which was higher 34.13 mAh g−1 with bare zinc. Finally, the long‐term cyclability of ZnCNF|| MnO2 with much lower N/P ratio of 18.0 was confirmed, demonstrating the capacity retention of 89.4%, greater than 73% of bare zinc||MnO2 cell with the N/P ratio of 234.6 over 300 cycles. [ABSTRACT FROM AUTHOR]

Abstract Lithium‐ion batteries have exerted great influence on our daily life as important power supply. However, lithium‐ion batteries suffer from critical challenges, including dendrite effect and insufficient ion kinetics, which lead to low efficiency and poor cycling. Bio‐inspired structures, directly learned from nature, have some special characteristics with good mechanical properties, including large surface area, numerous active sites, and ion channels. The large surface area can accommodate more ions, and active sites facilitate intermediate conversion. The well‐designed ion channels are beneficial to ion migration, and then greatly promote charge–discharge processes. Here, we summarize typical bio‐inspired structures for lithium‐ion batteries, discuss influence of these structures on battery performance. Based on the theoretical analysis and our experimental experience, we highlight the design requirement of bio‐inspired structures to enable battery devices with high power density and stable cycling life. Finally, perspectives on existing issues in the filed have been made for future directions.

The improvement of our living standards puts forward higher requirements for energy storage systems, especially rechargeable batteries. Unfortunately, phenomena such as capacity failure, etc. have been major difficulties in the field of energy storage. Therefore, we need some advanced means to explore the reaction process and mechanisms of the cell. Electron paramagnetic resonance (EPR) has the advantages of a high sensitivity to electrons, lack of damage to samples, quantitative analysis, etc., which can make for a more in-depth exploration of most paramagnetic electrode materials and metal electrode materials. After a brief description of the principle of EPR, this review briefly summarizes the application of EPR to the characterization of transition metal oxide cathode and lithium metal anode electrode materials in recent years, such as showing how to study electrode materials by using EPR in situ and operando.

With the rapid development of wearable and intelligent flexible electronic devices (FEDs), the demand for flexible energy storage/conversion devices (ESCDs) has also increased. Rechargeable flexible metal‐air batteries (MABs) are expected to be one of the most ideal ESCDs due to their high theoretical energy density, cost advantage, and strong deformation adaptability. With the improvement of the device design, material assemblies, and manufacturing technology, the research on the electrochemical performance of flexible MABs has made significant progress. However, achieving the high mechanical flexibility, high safety, and wearable comfortability required by FEDs while maintaining the high performance of flexible MABs are still a daunting challenge. In this review, flexible Zn‐air and Li‐air batteries are mainly exemplified to describe the most recent progress and challenges of flexible MABs. We start with an overview of the structure and configuration of the flexible MABs and discuss their impact on battery performance and function. Then it focuses on the research progress of flexible metal anodes, gel polymer electrolytes, and air cathodes. Finally, the main challenges and future research perspectives involving flexible MABs for FEDs are proposed. [ABSTRACT FROM AUTHOR]

In recent years, several organic electrolytes have been reported allowing calcium metal electrodeposition. In all cases, some degree of passivation on the surface of the calcium electrode was reported. Following a recent report on borate-based passivation layer playing a crucial role for Ca plating in electrolyte solutions containing Ca(BF4)2, here we report the use of a boron-containing additive. The presence of this additive allows Ca plating and stripping using a Ca(TFSI)2 containing electrolyte, which otherwise lead to the formation of a fully Ca2+ blocking passivation layer.

Highlights: A cooperative solvation/surface engineering approach is reported to achieve the reversible Mg plating/stripping in conventional carbonate electrolytes. Benefitting from the strategy, Mg2+ can easily overcome the reduced desolvation barrier and penetrate the Mg2+-conducting polymer coating, deposited on the Mg metal anode successfully, promoting the application of magnesium anode in carbonate electrolytes toward high-energy rechargeable batteries.Magnesium metal anode holds great potentials toward future high energy and safe rechargeable magnesium battery technology due to its divalent redox and dendrite-free nature. Electrolytes based on Lewis acid chemistry enable the reversible Mg plating/stripping, while they fail to match most cathode materials toward high-voltage magnesium batteries. Herein, reversible Mg plating/stripping is achieved in conventional carbonate electrolytes enabled by the cooperative solvation/surface engineering. Strongly electronegative Cl from the MgCl2 additive of electrolyte impairs the Mg…O = C interaction to reduce the Mg2+ desolvation barrier for accelerated redox kinetics, while the Mg2+-conducting polymer coating on the Mg surface ensures the facile Mg2+ migration and the effective isolation of electrolytes. As a result, reversible plating and stripping of Mg is demonstrated with a low overpotential of 0.7 V up to 2000 cycles. Moreover, benefitting from the wide electrochemical window of carbonate electrolytes, high-voltage (> 2.0 V) rechargeable magnesium batteries are achieved through assembling the electrode couple of Mg metal anode and Prussian blue-based cathodes. The present work provides a cooperative engineering strategy to promote the application of magnesium anode in carbonate electrolytes toward high energy rechargeable batteries. [ABSTRACT FROM AUTHOR]

The reactivity of Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) solid electrolytes to form lithio-phobic species such as Li 2 CO 3 on their surface when exposed to trace amounts of H 2 O and CO 2 limits the progress of LLZTO-based solid-state batteries. Various treatments, such as annealing LLZTO within a glovebox or acid etching, aim at removing the surface contaminants, but a comprehensive understanding of the evolving LLZTO surface chemistry during and after these treatments is lacking. Here, glovebox-like H 2 O and CO 2 conditions were recreated in a near ambient pressure X-ray photoelectron spectroscopy chamber to analyze the LLZTO surface under realistic conditions. We find that annealing LLZTO at 600 °C in this atmosphere effectively removes the surface contaminants, but a significant level of contamination reappears upon cooling down. In contrast, HCl (aq) acid etching demonstrates superior Li 2 CO 3 removal and stable surface chemistry post treatment. To avoid air exposure during the acid treatment, an anhydrous HCl solution in diethyl ether was used directly within the glovebox. This novel acid etching strategy delivers the lowest lithium/LLZTO interfacial resistance and the highest critical current density.

Summary: Room temperature sodium-sulfur batteries possess higher specific energy and improved inherent safety compared to their high-temperature analogs used in stationary grid storage. The viability of room temperature sodium batteries depends critically on the mechanical and ionic transport properties of the solid electrolyte interphase. However, little emphasis has been placed on developing sodium anode interphases that combine high Young’s modulus (stiffness), high critical strain (ductility), and low ionic diffusion barrier for cycling at high rates. Here, we report an artificial biphasic interphase comprising two chemically distinct phases, NaOH and NaNH2, which combines high stiffness and high ductility. In addition, the biphasic interphase exhibits a low diffusion barrier for sodium ions, enabling reversible sodium plating and stripping behavior even at extremely high current densities (up to 50 mA cm−2) in symmetric cell configuration. Stable and reversible cycling of a room temperature sodium-sulfur battery is also demonstrated over 500 cycles.

Abstract Background Metals are considered a suitable anode material for microbial fuel cells (MFCs) because of their high electrical conductivity. However, only a few types of metals have been used as anodes, and an extensive screening of metals has not yet been conducted. In this study, to develop a new metal anode for increased electricity generation in MFCs, 14 different metals (Al, Ti, Fe, Ni, Cu, Zn, Zr, Nb, Mo, Ag, In, Sn, Ta, and W) and 31 of their oxidized forms were comprehensively tested. Oxidized-metal anodes were prepared using flame oxidation, heat treatment, and electrochemical oxidation. The selected anodes were further evaluated in detail using air–cathode single-chambered MFCs. Results The untreated Mo and electrochemically oxidized Mo anodes showed high averages of maximum power densities in the screening test, followed by flame-oxidized (FO) W, FO-Fe, FO-Mo, and Sn-based anodes. The untreated Mo and FO-W anodes were selected for further evaluation. X-ray analyses revealed that the surface of the Mo anode was naturally oxidized in the presence of air, forming a layer of MoO3, a known oxidation catalyst. A high maximum power density (1296 mW/m2) was achieved using the Mo anode in the MFCs, which was superior to that obtained using the FO-W anode (1036 mW/m2). The Mo anode, but not the FO-W anode, continued to produce current without detectable corrosion until the end of operation (350 days). Geobacter was abundant in both biofilms on the Mo and FO-W anodes, as analyzed by high-throughput sequencing of the 16S rRNA gene. Conclusions The screening test revealed that Mo, W, Fe, and Sn are useful MFC anode materials. The detailed analyses demonstrated that the Mo anode is a high-performance electrode with structural simplicity and long-term stability in MFCs. The anode can be easily prepared by merely shaping Mo materials to the desired forms. These properties would enable the large-scale preparation of the anode, required for practical MFC applications. This study also implies the potential involvement of Geobacter in the Mo and W cycles on Earth.

The practical applications of high capacity metallic Li electrodes is severely hindered by the uncontrollable Li nucleation and growth that lead to poor cycle life and growth of unsafe dendrites. Here we demonstrate the design of porous but robust sponges with Cu nanoparticles and graphene and their applications for enabling Li electrodes with stable cycling under high capacity and high current conditions. We discovered that the Cu nanoparticles decorated on graphene effectively direct the heterogeneous nucleation of Li whereas the graphene frameworks provide ample spaces for confining Li growth. These sponges are able to host at least 60 mAh cm−2 Li without forming dendrites and allow stable Li plating/stripping with low overpotentials for hundreds of cycles even at a high current of 7 mA cm−2. The sponges have remarkable mechanical strengths and exhibited minimal structural deformation after aggressive plating/stripping cycles. These superior properties enable Li metal batteries with substantially improved high current cyclic stability and rate performance, as demonstrated with both LiNi 0.4 Co 0.2 Mn 0.4 O 2 and LiFePO 4 cathodes. • Light weight but strong sponges were synthesized with simple and scalable methods. • The sponges directly controlled heterogeneous nucleation and confined growth of Li. • Cu NPs reduced the overpotential required to initiate heterogeneous nucleation of Li. • The sponges inhibited formation of dendrites after depositing of 60 mAh cm-2 Li. [ABSTRACT FROM AUTHOR]

Abstract In this study, sodium metal hybrid capacitors (SMHCs) composed of a metal anode and capacitive cathode are reported for the first time. The sodium metal anode was designed using catalytic carbon nanotemplates (C-CNTPs) and exhibited highly reversible sodium metal plating/stripping behaviors with an average Coulombic efficiency of ∼100% over 1000 galvanostatic cycles and significantly low cell-to-cell variations. Further, nanoporous pyroproteins (N-PPts) with a specific surface area of ∼4216 m2 g−1 and pore volume of 1.937 cm3 g−1 were fabricated as the capacitive cathode, exhibiting a high specific capacity of 168 mA h g−1, high rate capability of 0.5–10 A g−1, and stable cycling performance over 1000 cycles. The SMHCs based on C-CNTPs/N-PPts were operated in a voltage window of 1.0–4.0 V, delivering a high specific energy of ∼237.7 Wh kg−1 at ∼462 W kg−1 and a maximum power of ∼4800 W kg−1 at ∼66.7 Wh kg−1. In addition, stable cycling performance was maintained during 500 cycles, with a capacity retention of ∼82%. Graphical abstract Image 1 Highlights • Sodium metal anode was designed using catalytic carbon nanotemplates (C-CNTPs). • Nanoporous pyroproteins (N-PPts) were prepared as a cathode for sodium ion storage. • Sodium metal hybrid capacitors (SMHCs) based on the two electrodes were designed. • The SMHCs can deliver a high specific energy of ∼237.7 Wh kg−1 at ∼462 W kg−1. [ABSTRACT FROM AUTHOR]

The paper presents the results of a study of a pulsed proton beam generated of in a diode with a metal anode (stainless steel, titanium, and copper) operating in bipolar-pulse mode. The experiments were carried out on the TEMP-6 accelerator (250–300 kV, 120 ns) with a focusing diode geometry in a mode of self-magnetic insulation of electrons. For analysis of the ion beam parameters, we used the infrared imaging diagnostics of the beam energy density (spatial resolution of 2 mm) and the time-of-flight diagnostics of the beam compositions (time resolution 1 ns). It was found that with continuous supply of hydrogen into a hollow anode (with holes on the working surface) and a hydrogen pressure in the diode chamber of 30–80 mPa, the proton content in the beam exceeds 80%. An increase in the first pulse duration leads to an increase in the ion current density up to 100 A/cm2 and the energy density at the focus up to 3 J/cm2. We analyzed various mechanisms of proton beam generation: ions acceleration from the gas plasma in the plasma erosion mode; ions acceleration from the explosive emission plasma of a metal anode the near-surface layer of which is saturated with metal hydrides (anode material). It was found that hydrogen embrittlement of the near-surface layer of the anode occurs during the injection of hydrogen, and during the explosive emission of electrons, part of the material is sprayed in the form of finely dispersed clusters. • A proton beam was generated in a diode operating in bipolar-pulse mode. • A 2.5–3.5 J/cm2 proton beam was generated in an explosive electron emission diode. • Proton content in the beam exceeds 80% with hydrogen supply in the diode chamber. • Several mechanisms of proton beam generation were analyzed. • Hydrogen embrittlement of the anode surface occurs during injection of hydrogen. [ABSTRACT FROM AUTHOR]

Rechargeable magnesium (Mg)-based energy storage has attracted extensive attention in electrochemical storage systems with high theoretical energy densities. The Mg metal is earth-abundant and dendrite-free for the anode. However, there is a strong Coulombic interaction between Mg2+ and host materials that often inhibits solid-state diffusion, resulting in a large polarization and poor electrochemical performances. Herein, we develop a Mg–Li hybrid battery using a Mg-metal anode, an FeSe2 powder with uniform size and a morphology utilizing a simple solution-phase method as the counter electrode and all-phenyl-complex/tetrahydrofuran (APC)-LiCl dual-ion electrolyte. In the Li+-containing electrolyte, at a current density of 15 mA g−1, the Mg–Li hybrid battery (MLIB) delivered a satisfying initial discharge capacity of 525 mAh g−1. Moreover, the capacity was absent in the FeSe2|APC|Mg cell. The working mechanism proposed is the “Li+-only intercalation” at the FeSe2 and the “Mg2+ dissolved or deposited” at the Mg foil in the FeSe2|Mg2+/Li+|Mg cell. Furthermore, ex situ XRD was used to investigate the structural evolution in different charging and discharging states.

Abstract: Because of its remarkably high theoretical capacity and favorable redox voltage (−2.71 V vs the standard hydrogen electrode), Na is a promising anode material for Na ion batteries. In this study, macroporous catalytic carbon nanotemplates (MC‐CNTs) based on nanoweb‐structured carbon nanofibers with various carbon microstructures are prepared from microbe‐derived cellulose via simple heating at 800 or 2400 °C. MC‐CNTs prepared at 800 °C have amorphous carbon structures with numerous topological defects, and exhibit a lower voltage overpotential of ≈8 mV in galvanostatic charge/discharge testing. In addition, MC‐CNT‐800s exhibit high Coulombic efficiencies of 99.4–99.9% during consecutive cycling at current densities ranging from 0.2 to 4 mA cm−2. However, the carbon structures of MC‐CNTs prepared at 800 °C are gradually damaged by cycling. This results in significant capacity losses after about 200 cycles. In contrast, MC‐CNTs prepared at 2400 °C exhibit well‐developed graphitic structures, and maintain predominantly stable cycling behaviors over 1000 cycles with Coulombic efficiencies of ≈99.9%. This study demonstrates the superiority of catalytic carbon nanotemplates with well‐defined pore structures and graphitic microstructures for use in Na metal anodes. [ABSTRACT FROM AUTHOR]

Biochemical oxygen demand (BOD) is a widely used index of water quality in wastewater treatment; however, conventional measurement methods are time-consuming. In this study, we analyzed a novel flame-oxidized stainless steel anode (FO-SSA) for use as the probe of bioelectrochemical system (BES)-based biosensors to monitor the BOD of treated swine wastewater. A thinner biofilm formed on the FO-SSA compared with that on a common carbon-cloth anode (CCA). The FO-SSA was superior to the CCA in terms of rapid sensing; the response time of the FO-SSA to obtain the value of R2 > 0.8 was 1 h, whereas the CCA required 4 h. These results indicate that the FO-SSA offers better performance than traditional CCAs in BES biosensors and can be used to improve biomonitoring of wastewater. [ABSTRACT FROM AUTHOR]