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The potential of organic electrodes in lithium‐ion batteries (LIBs) is highlighted by their cost‐effectiveness and natural abundance. However, the dissolution of the active material in the electrolyte is a major obstacle to their use in LIBs. Although high‐concentration electrolytes (HCEs) have been proposed to address this issue, they face challenges such as high viscosity, poor wettability, and suboptimal ion conductivity. Hence, this study introduces diluted electrolytes as non‐solvating electrolytes to offset the physical limitations of HCEs and suppress the dissolution of organic electrodes. When a diluted electrolyte is used, perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA)—a notable organic electrode material—demonstrates superior capacity retention and rate performance, achieving 91% of capacity retained at 1000 mA g−1 over 1000 cycles. Through electrochemical and spectroscopic measurements and molecular dynamics simulations, the diluted electrolyte successfully inhibits and demonstrates the dissolution of the active material, preventing capacity loss and the detrimental shuttle effect. This study presents a promising strategy for achieving highly reversible organic electrode‐based LIBs through the development of nonsolvating electrolytes. [ABSTRACT FROM AUTHOR]

All-solid-state batteries (ASSBs) are promising alternatives to lithium-ion batteries owing to their high energy density and safety. Recent studies on "anodeless" electrodes with Li-soluble metallic materials (e.g., silver nanoparticles) and carbon materials in ASSBs have shown improvements in the energy density of these cells. However, poor dispersion between metal nanoparticles and carbon materials in anodeless electrodes leads to disproportionate electrochemical phenomena. Moreover, the dendritic growth and uneven reactions caused by these imbalances impair the life cycle of ASSB cells. To address this issue, we introduce carbon-supported silver nanoparticle-based anodeless electrodes. Ag ion complexes were thermally reduced, and the reduced silver nanoparticles were well dispersed on the carbon surface. This electrode reduces overpotential during the lithiation process with less silver and provides high-rate performance. An ASSB cell using the anodeless electrode with carbon-supported silver nanoparticles exhibits 91% capacity retention after 500 cycles. [ABSTRACT FROM AUTHOR]

The use of a redox mediator (RM) to chemically decompose Li2O2 is an efficient approach to improve the efficiency and cyclability of lithium–oxygen batteries. It has been suggested that RMs can react with the singlet oxygen (1O2) but no attempt has been made to categorize the reactivity of different RMs with 1O2, or investigate the impact of this reaction on the electrochemical behavior of RMs. Here we show that the reactivity of RMs with 1O2 depends on the unique chemistry of the RM, and that the Li2O2 decomposition kinetics of RMs are considerably affected by their reactivity towards 1O2. We examine changes to the chemical and electrochemical properties of RMs after exposure to 1O2. These results suggest that the activity and lifetime of RMs in Li–O2 cells are affected by their reactivity towards 1O2, and that RMs can be classified depending on how easily they react with, or physically quench 1O2. [ABSTRACT FROM AUTHOR]

Li–O2 batteries attract extensive attention because they exhibit the highest theoretical energy density among the rechargeable batteries reported so far. However, most studies have focused on improving the cyclability and efficiency of Li–O2 batteries under low-capacity conditions instead of under practical conditions. Here, we increase the capacity range of Li–O2 batteries to a practical condition of 5 mA h cm−2 by introducing CF3(CF2)2I as a dual-functional additive. An electrolyte comprising 1 M LiNO3 in N,N-dimethylacetamide and CF3(CF2)2I provides stable cycle retention and high reversibility even at high areal capacity. Ab initio molecular dynamics simulations demonstrate that the reaction between CF3(CF2)2I and Li metal is spontaneous and leads to the simultaneous formation of LiF as a protective layer on Li metal and LiI as a redox mediator for the oxygen evolution reaction. This study provides new insights for the development of electrolyte additives toward practical Li–O2 batteries. [ABSTRACT FROM AUTHOR]

Metal–oxygen batteries (MOBs) are great candidates for next-generation energy storage systems due to their high safety, low cost, environmental friendliness, and especially high volumetric energy density. However, during the oxygen reduction process in MOBs, the solid discharge products can deposit/accumulate, clog the small pores of the air electrode, and block the transport of oxygen and various ion species in aqueous or non-aqueous electrolytes, therefore leading to increased impedance and shortened cycle life of MOBs. Herein, we demonstrate that a three-dimensionally semi-ordered macroporous (3D-SOM) structure of ruthenium/single-walled carbon nanotubes air electrode can largely alleviate detrimental effects due to the accumulation of reaction products during the discharge process, facilitating the smooth flow of active species, including oxygen and ions in an air electrode during the charge/discharge processes of MOBs such as non-aqueous lithium–oxygen and aqueous zinc–oxygen batteries. As a result, the 3D-SOM structured air electrode can be used as an effective approach to reduce the overpotential and impedance of MOBs, therefore enhancing their capacity and cycle life. [ABSTRACT FROM AUTHOR]

Side reactions caused by reactive oxygen species (e.g., superoxide and singlet oxygen) are limiting factors in the lithium–oxygen batteries (LOBs). Superoxide dismutase mimetics (SODms), which suppress superoxide‐triggered side reactions by accelerating the disproportionation reaction during discharge, are introduced as soluble additives in the LOBs. However, although SODms promote the disproportionation reaction, which is the main pathway for singlet oxygen evolution, the correlation between SODms and singlet oxygen has not been verified. Here, 4‐carboxy‐TEMPO is selected as a representative SODm that effectively promotes the disproportionation reaction and chemically verifies acceleration of singlet oxygen evolution. Furthermore, by using quencher, it is reported that the release of singlet oxygen evolved by the SODm is decreased. Because this study closely examines the relationship between the additives and singlet oxygen, it is believed that this study provides an important reference for the development of additives for the practical application of LOBs. [ABSTRACT FROM AUTHOR]

Lithium oxygen batteries (LOBs) are considered promising next‐generation lithium batteries owing to their high theoretical specific energy density. However, several issues must be addressed for realizing the practical applications of LOBs. Among them, the evolution of singlet oxygen (1O2)—which undergoes vigorous reactions that compromise the stability of the system—is a key challenge. The high overpotential induced by low‐conductivity lithium peroxide necessitates the use of a redox mediator (RM) to facilitate the charging process; however, RMs can also be degraded by 1O2, which limits their efficacy in the long term. Recently, it was revealed that certain RMs play a role in suppressing the generation of 1O2. In this review, the relationship between the RM and 1O2 is described. Based on recent understandings, clear insight into RM reactions toward 1O2 and possible future research directions will be provided. [ABSTRACT FROM AUTHOR]

A stable electrolyte is critical for practical application of lithium–oxygen batteries (LOBs). Although the ionic conductivity and electrochemical stability of the electrolytes have been extensively investigated before, their oxygen solubility, viscosity, volatility, and the stability against singlet oxygen (1O2) still need to be comprehensively investigated to provide a full picture of the electrolytes, especially for an open system such as LOBs. Herein, a systematic investigation is reported on the localized high‐concentration electrolytes (LHCEs) using different fluorinated diluents in comparison with those of conventional electrolytes. The physical properties and activation energies for reactions with singlet oxygen (1O2) of these electrolytes are calculated by density functional theory. The electrochemical performances of LOBs using these electrolytes are compared. This study reveals that the correlation between the stability of the electrolytes and their physical and electrochemical properties depends strongly on the diluents in LHCEs. Therefore, it shines light on the rational design of new electrolytes for LOBs. [ABSTRACT FROM AUTHOR]

Potassium, the third alkali element after sodium on the periodic table, provides several advantages over lithium and sodium as a charge carrier in rechargeable batteries. Pertaining to its natural features, potassium has a lower standard redox potential than other metallic elements (−2.93 V vs. the standard hydrogen electrode (SHE)) and is highly abundant in the Earth's crust. For these reasons, to date, the development of rechargeable potassium batteries has attracted considerable attention in the search for high-energy and cost-effective energy storage systems. In the development of rechargeable potassium batteries, K metal anodes are the key material and act as the counter electrode to evaluate electrochemical electrode materials in the half-cell configuration. Moreover, they are also an essential component of full-cell potassium–sulfur and potassium–oxygen systems. However, the main hurdle in the widespread acceptance of K metal as an anode in rechargeable potassium batteries lies in identifying fundamental problems and developing suitable solutions. Here, we initially investigate and evaluate potassium metal as an anode for rechargeable potassium batteries and detail the major challenges for K metal systems, that at this time, limit the feasibility of rechargeable potassium batteries, particularly, dendritic growth for liquid systems, poor coulombic efficiency, and the unstable interface between the K metal and electrolyte. In addition, we also highlight the key developments and recent achievements in the stabilization of K metal anodes and their application. This will be helpful in reducing trial and error in studies pertaining to the development of rechargeable potassium batteries and provide crucial insights for potential scientific and industrial applications. [ABSTRACT FROM AUTHOR]

The goal of limiting global warming to 1.5 °C requires a drastic reduction in CO2 emissions across many sectors of the world economy. Batteries are vital to this endeavor, whether used in electric vehicles, to store renewable electricity, or in aviation. Present lithium-ion technologies are preparing the public for this inevitable change, but their maximum theoretical specific capacity presents a limitation. Their high cost is another concern for commercial viability. Metal-air batteries have the highest theoretical energy density of all possible secondary battery technologies and could yield step changes in energy storage, if their practical difficulties could be overcome. The scope of this review is to provide an objective, comprehensive, and authoritative assessment of the intensive work invested in nonaqueous rechargeable metal-air batteries over the past few years, which identified the key problems and guides directions to solve them. We focus primarily on the challenges and outlook for Li-O2 cells but include Na-O2, K-O2, and Mg-O2 cells for comparison. Our review highlights the interdisciplinary nature of this field that involves a combination of materials chemistry, electrochemistry, computation, microscopy, spectroscopy, and surface science. The mechanisms of O2 reduction and evolution are considered in the light of recent findings, along with developments in positive and negative electrodes, electrolytes, electrocatalysis on surfaces and in solution, and the degradative effect of singlet oxygen, which is typically formed in Li-O2 cells. [ABSTRACT FROM AUTHOR]

Redox mediators have been studied intensively to improve the energy efficiency and cycle life of lithium–oxygen batteries by facilitating the decomposition of the discharge product (lithium peroxide), thus reducing the side reactions at a high potential during charging. Nevertheless, the cycling performance of lithium–oxygen batteries with redox mediators is unsatisfactory; this problem must be resolved for the successful application of redox mediators. In this study, we confirmed that a redox mediator cannot decompose the by-products on the cathode, leading to the passivation of the cathode surface despite the successful decomposition of lithium peroxide by the redox mediator. By schematizing the routes for by-product formation, we described the processes by which the by-products are accumulated on the cathode in the absence and presence of a redox mediator. Based on the intuitive verification of the unproven relationship between a redox mediator and the by-products, we proposed a complementary strategy to overcome the limitations of the redox mediator and prevent the accumulation of the by-products, which is essential for the improvement of lithium–oxygen batteries. [ABSTRACT FROM AUTHOR]

The problem of Li metal degradation, which leads to drastic side reactions, must be solved for improving the long-term cycle performance of lithium–oxygen (Li–O2) batteries. Recently, a number of methodologies have been proposed for Li metal surface protection, but evaluation of the stability of the protective materials is insufficient. Therefore, in this study, we fabricated an NCL (Nafion-based composite layer) as a mechanically and chemically stable protective layer for Li metal in Li–O2 batteries. In addition, comparative experiments were conducted to investigate the mechanical and chemical stability of protective layers. Li–O2 batteries using NCL-coated Li metal exhibited reversible oxygen reduction and evolution without any side reactions caused by reactive oxygen species that decompose chemically unstable protective materials. The NCL also exhibited effective mechanical strength which was verified with not only a Li stripping and plating test but also using a large scale Li–O2 pouch cell which had has severe operating conditions with high current and capacity values. [ABSTRACT FROM AUTHOR]

Abstract: Recently, various approaches for adding redox mediators to electrolytes and introducing protective layers onto Li metal have been suggested to overcome the low energy efficiency and poor cycle life of Li–O2 batteries. However, the catalytic effect of the redox mediator for oxygen evolution gradually deteriorates during repeated cycling owing to its decomposition at the surfaces of both the oxygen electrode (cathode) and the Li metal electrode (anode). Here, optimized Li–O2 batteries are designed with a continuously effective redox mediator and a stable protective layer for the Li metal electrode by optimizing the LiBr concentration and introducing a graphene–polydopamine composite layer, respectively. These synergistic modifications lead to a reduction of the charge potential to below 3.4 V and significantly improve the stability and cycle life of Li–O2 batteries. Consequently, a high energy efficiency of above 80% is maintained over 150 cycles. Herein, it is confirmed that the relationships between all the battery materials should be understood in order to improve the performance of Li–O2 batteries. [ABSTRACT FROM AUTHOR]

Lithium-oxygen batteries are in fact the only rechargeable batteries that can rival internal combustion engines, in terms of high energy density. However, they are still under development due to low-efficiency and short lifetime issues. There are problems of side reactions on the cathode side, high reactivity of the Li anode with solution species, and consumption of redox mediators via reactions with metallic lithium. Therefore, efforts are made to protect/block the lithium metal anode in these cells, in order to mitigate side reactions. However, new approach is required in order to solve the problems mentioned above, especially the irreversible reactions of the redox mediators which are mandatory to these systems with the Li anode. Here, optimized bicompartment two solution cells are proposed, in which detrimental crossover between the cathode and anode is completely avoided. The Li metal anode is cycled in electrolyte solution containing fluorinated ethylene carbonate, in which its cycling efficiency is excellent. The cathode compartment contains ethereal solution with redox mediator that enables oxidation of Li2O2 at low potentials. The electrodes are separated by a solid electrolyte membrane, allowing free transport of Li ions. This approach increases cycle life of lithium oxygen cells and their energy efficiency. [ABSTRACT FROM AUTHOR]

Sodium–oxygen batteries have received much attention recently due to their possible higher energy efficiency and lower cost than lithium–oxygen batteries. Na+ ions are less electrophilic than Li+ ions (softer Lewis bases). Thereby, oxygen reduction in the presence of Na+ ions may undergo a highly reversible one electron process to form sodium superoxide as a main product. However, sodium superoxide may have adverse effects on the stability and cycle life of sodium–oxygen batteries because of its high reactivity towards all kinds of relevant solvents. Therefore, sodium–oxygen batteries, in which the major oxygen reduction products are sodium peroxide moieties, may have an advantage in terms of better stability. This paper reports for the first time on sodium–oxygen batteries in which the cathodes comprise carbon nanotubes (CNTs) decorated with nanoparticles of ruthenium serving as a stationary catalyst. With these cathodes both oxygen reduction and evolution reactions are effectively catalyzed. The main oxygen reduction product on these CNT/Ru containing cathodes was deficient sodium peroxide, analyzed by XRD, XPS and SEM. Sodium–oxygen cells with Ru decorated CNT cathodes exhibited stable cycling performance over 100 cycles, while similar cells having CNT based cathodes showed much lower stability. It was clear that the limiting factor in the sodium–oxygen batteries containing CNT/Ru cathodes was the sodium anodes. Thereby it is believed that the present study is a step forward in the efforts to develop sodium–oxygen batteries. [ABSTRACT FROM AUTHOR]

The slow kinetics of Li–O2 batteries cause a large overpotential, which leads to low round-trip efficiency and poor cyclability. Applying a suitable bifunctional catalyst can be an effective way to solve this problem. We anticipated that the ruthenium ion dissolved in the electrolyte will not only overcome the disadvantages of solid phase catalysts, but also reduce the overpotential for both charge and discharge. This is possible due to the suitable redox potential of the ruthenium ion, which effectively reduced the oxygen evolution reaction (OER) overpotential, and the affinity between the ruthenium ion and oxygen, which facilitated the oxygen reduction reaction (ORR) and suppressed the degradation of the cathode. Here, we propose a new soluble catalyst, ruthenium bromide, for Li–O2 batteries. The battery using ruthenium bromide clearly exhibited enhanced cycling performance, increasing round-trip efficiency (from 68.2% to 80.5%) and rate capability. A new understanding and application of the soluble ruthenium catalyst, which is commonly used as a solid catalyst, will not only overcome the existing problems but also provide a promising platform for Li–O2 batteries. [ABSTRACT FROM AUTHOR]

Due to their high theoretical specific capacity and energy density, LiO2 batteries are considered as candidates for next-generation battery systems in place of conventional Li-ion batteries for advanced applications such as electric vehicles. However, low energy efficiency, poor cycle life, and Li-metal safety issues make the use of LiO2 batteries yet impractical. In addition, actual cell capacities are very low, and since only small-scale electrodes are currently tested, it is hard to predict the properties of large-size electrodes and cells, thus evaluating and judging real practical challenges related to this battery technology. In this work, the behavior of pouch-type LiO2 cells using 3 × 5 cm2 sized electrodes is investigated and it is confirmed that Li-metal is a key issue for the upscale of LiO2 cells. This study can help to determine which parameters are the most important for developing practical LiO2 batteries. [ABSTRACT FROM AUTHOR]

Despite the extremely high theoretical specific capacity of lithium oxygen (Li–O2) electrochemistry, low energy efficiency resulting from the large potential gap between the discharge and charge makes this system impractical. In this report, an iron cobalt bimetal decorated carbon nanotube (FeCo–CNT) composite was synthesized as a catalytic air cathode material for Li–O2 batteries. An Li–O2 battery using FeCo–CNT air electrodes exhibited higher efficiency (72.15%) than that of pristine CNTs (62.57%) as well as higher capacity (3600 mA h g−1vs. 1276 mA h g−1). Spectroscopic and electron microscopy analyses showed that the improved cell performances can be attributed to the catalytic effect of FeCo. As cost-effective non-noble metal catalysts, FeCo–CNTs demonstrated performance comparable to noble metal catalysts in Li–O2 systems. [ABSTRACT FROM AUTHOR]

Silver nanowires have been investigated as a catalytic cathode material for lithium-oxygen batteries. Their high aspect ratio contributes to the formation of a corn-shaped layer structure of the poorly crystalline lithium peroxide (Li 2 O 2 ) nanoparticles produced by oxygen reduction in poly-ether based electrolyte solutions. The nanowire morphology seems to provide the necessary large contact area and facile electron supply for a very effective oxygen reduction reaction. The unique morphology and structure of the Li 2 O 2 deposits and the catalytic nature of the silver nano-wires promote decomposition of Li 2 O 2 at low potentials (below 3.4 V) upon the oxygen evolution. This situation avoids decomposition of the solution species and oxidation of the electrodes during the anodic (charge) reactions, leading to high electrical efficiently of lithium-oxygen batteries. [ABSTRACT FROM AUTHOR]

Mankind has been in an unending search for efficient sources of energy. The coupling of lithium and oxygen in aprotic solvents would seem to be a most promising direction for electrochemistry. Indeed, if successful, this system could compete with technologies such as the internal combustion engine and provide an energy density that would accommodate the demands of electric vehicles. All this promise has not yet reached fruition because of a plethora of practical barriers and challenges. These include solvent and electrode stability, pronounced overvoltage for oxygen evolution reactions, limited cycle life and rate capability. One of the approaches suggested to facilitate the oxygen evolution reactions and improve rate capability is the use of redox mediators such as iodine for the fast oxidation of lithium peroxide. In this paper we have examined LiI as an electrolyte and additive in Li oxygen cells with ethereal electrolyte solutions. At high concentrations of LiI, the presence of the salt promotes a side reaction that forms LiOH as a major product. In turn, the presence of oxygen facilitates the reduction of I3− to 3I− in these systems. At very low concentrations of LiI, oxygen is reduced to Li2O2. The iodine formed in the anodic reaction serves as a redox mediator for Li2O2 oxidation. [ABSTRACT FROM AUTHOR]

The lithium storage capacity of an iron oxide-based anode of porous carbon-Fe3O4 (i.e., PC-Fe3O4) was investigated by varying the initial current and mass density of the electrode to achieve a good utilization coefficient of the oxide. It was confirmed that these factors largely affected the capacity of PC-Fe3O4 and a certain mass density of the electrode was key to achieve a high area capacity (μAh cm−2). Moreover, the chemical and electrochemical lithiation of PC-Fe3O4 were related to the lithiation time and pressure and both were both systemically studied. After optimization, a new battery of PC-Fe3O4/Li[Ni0.59Co0.16Mn0.25]O2 with a high area capacity of 748 μAh cm−2 (≈150 mAh g−1) and superior energy density of 483 Wh kg−1 (work voltage≈3.2 V) was developed. The battery showed reversible work ability in the rate window of 50-800 mA g−1, and also it could be charged/discharged for well over 1000 cycles with a capacity retention of 63.8 % under the high current value of 0.505 mA (current density, 50 mA g−1). [ABSTRACT FROM AUTHOR]

With the separation of cathode and anode sides of Li‐O2 cells, and matching a suitable solution, the efficiency and cyclability can be remarkably improved. Redox mediator that facilitates Li2O2 decomposition at the cathode cannot crossover to the Li metal anode. The additive that stabilizes the Li metal anode cannot be attacked by the oxygen species at the cathode. This is reported by Doron Aurbach, Yang‐Kook Sun, and co‐workers in article number 1701232. [ABSTRACT FROM AUTHOR]

Despite numerous studies aimed at solving the detrimental dissolution issue of organic electrode materials (OEMs), a fundamental understanding of their dissolution mechanism has not yet been established. Herein, we systematically investigate how changes in electrolyte composition affect the ion-solvent interactions propagating to OEM dissolution by changing the cation. The cyclability of OEM is significantly different by alkali cations, where the OEM with K is stable even after 300 cycles and that with Li is drastically decayed within 100 cycles. This different behavior is owing to the dissolution of OEM into electrolytes, and the dissolution of OEMs was found to be highly dependent on the cation-solvent interaction. Strong cation-solvent interactions induce cointercalation into the layered structure of the electrode and cause electrode deformation. This behavior allows OEMs to easily detach from their original location, consequently leading to dissolution and severe capacity decay. The cation-solvent interaction-dependent phenomenon is similar to that of OEMs with high-concentration electrolytes, in which fewer cation-solvent pairs exist. The result provides insight into proper electrolyte selection and is expected to set a constructive milestone in the utilization of organic electrodes.

The utilization of redox mediators (RMs) in lithium-oxygen batteries (LOBs) has underscored their utility in high overpotential during the charging process. Among the currently known RMs, it is exceptionally challenging to identify those with a redox potential capable of attenuating singlet oxygen ( 1 O 2 ) generation while resisting degradation by reactive oxygen species (ROS), such as 1 O 2 and superoxide (O 2 •- ). In this context, computational and experimental approaches for rational molecular design have led to the development of 7,7'-bi-7-azabicyclo[2.2.1]heptane (BAC), a newly suggested RM incorporating N-N interconnected aza-bicycles. BAC harnesses the advantages of falling within the potential range that suppresses 1 O 2 generation, as previously reported N-N embedded non-bicyclic RMs, and effectively defends against ROS-induced degradation due to the incorporation of a novel bicyclic moiety. Unlike the non-bicyclic RMs, which exhibit reduced O 2 evolution after exposure to 1 O 2 , BAC maintains consistent O 2 profiles during charging, indicating its superior 1 O 2 resistance and steady redox-catalyst performance in LOBs. This study introduces a precise and rational design strategy for low-molecular-weight RMs, marking a significant step forward in advancing LOB development by improving efficiency, stability, and practical applicability., (© 2025 Wiley‐VCH GmbH.)

Using UV-vis spectroscopy in conjunction with various electrochemical techniques, we have developed a new effective operando methodology for investigating the oxygen reduction reactions (ORRs) and their mechanisms in nonaqueous solutions. We can follow the in situ formation and presence of superoxide moieties during ORR as a function of solvent, cations, anions, and additives in the solution. Thus, using operando UV-vis spectroscopy, we found evidence for the formation of superoxide radical anions during oxygen reduction in LiTFSI/diglyme electrolyte solutions. Nitro blue tetrazolium (NBT) was used to indicate the presence of superoxide moieties based on its unique spectral response. Indeed, the spectral response of NBT containing solutions undergoing ORR could provide a direct indication for the level of association of the Li cations with the electrolyte anions.

As a substitute for the current lithium-ion batteries, rechargeable lithium oxygen batteries have attracted much attention because of their theoretically high energy density, but many challenges continue to exist. For the development of these batteries, understanding and controlling the main discharge product Li 2 O 2 (lithium peroxide) are of paramount importance. Here, we comparatively analyzed the amount of Li 2 O 2 in the cathodes discharged at various discharge capacities and current densities in dimethyl sulfoxide (DMSO) and tetraethylene glycol dimethyl ether (TEGDME) solvents. The precise assessment entailed revisiting and revising the UV-vis titration analysis. The amount of Li 2 O 2 electrochemically formed in DMSO was less than that formed in TEGDME at the same capacity and even at a much higher full discharge capacity in DMSO than in TEGDME. On the basis of our analytical experimental results, this unexpected result was ascribed to the presence of soluble LiO 2 -like intermediates that remained in the DMSO solvent and the chemical transformation of Li 2 O 2 to LiOH, both of which originated from the inherent properties of the DMSO solvent.

In this study, we present a new aprotic solvent, 2,4-dimethoxy-2,4-dimethylpentan-3-one (DMDMP), which is designed to resist nucleophilic attack and hydrogen abstraction by reduced oxygen species. Li-O 2 cells using DMDMP solutions were successfully cycled. By various analytical measurements, we showed that even after prolonged cycling only a negligible amount of DMDMP was degraded. We suggest that the observed capacity fading of the Li-O 2 DMDMP-based cells was due to instability of the lithium anode during cycling. The stability toward oxygen species makes DMDMP an excellent solvent candidate for many kinds of electrochemical systems which involve oxygen reduction and assorted evaluation reactions.

Aprotic Li-O 2 battery is an exciting concept. The enormous theoretical energy density and cell assembly simplicity make this technology very appealing. Nevertheless, the instability of the cell components, such as cathode, anode, and electrolyte solution during cycling, does not allow this technology to be fully commercialized. One of the intrinsic challenges facing researchers is the use of lithium metal as an anode in Li-O 2 cells. The high activity toward chemical moieties and lack of control of the dissolution/deposition processes of lithium metal makes this anode material unreliable. The safety issues accompanied by these processes intimidate battery manufacturers. The need for a reliable anode is crucial. In this work we have examined the replacement of metallic lithium anode in Li-O 2 cells with lithiated hard carbon (HC) electrodes. HC anodes have many benefits that are suitable for oxygen reduction in the presence of solvated lithium cations. In contrast to lithium metal, the insertion of lithium cations into the carbon host is much more systematic and safe. In addition, with HC anodes we can use aprotic solvents such as glymes that are suitable for oxygen reduction applications. By contrast, lithium cations fail to intercalate reversibly into ordered carbon such as graphite and soft carbons using ethereal electrolyte solutions, due to detrimental co-intercalation of solvent molecules with Li ions into ordered carbon structures. The hard carbon electrodes were prelithiated prior to being used as anodes in the Li-O 2 rechargeable battery systems. Full cells containing diglyme based solutions and a monolithic carbon cathode were measured by various electrochemical methods. To identify the products and surface films that were formed during cells operation, both the cathodes and anodes were examined ex situ by XRD, FTIR, and electron microscopy. The HC anodes were found to be a suitable material for (Li-ion)-O 2 cell. Although there are still many challenges to tackle, this study offers a more practical direction for this promising battery technology and sets up a platform for further systematic optimization of its various components.

Although lithium-oxygen batteries are attracting considerable attention because of the potential for an extremely high energy density, their practical use has been restricted owing to a low energy efficiency and poor cycle life compared to lithium-ion batteries. Here we present a nanostructured cathode based on molybdenum carbide nanoparticles (Mo2C) dispersed on carbon nanotubes, which dramatically increase the electrical efficiency up to 88% with a cycle life of more than 100 cycles. We found that the Mo2C nanoparticle catalysts contribute to the formation of well-dispersed lithium peroxide nanolayers (Li2O2) on the Mo2C/carbon nanotubes with a large contact area during the oxygen reduction reaction (ORR). This Li2O2 structure can be decomposed at low potential upon the oxygen evolution reaction (OER) by avoiding the energy loss associated with the decomposition of the typical Li2O2 discharge products.

A positive effect of the polyacrylic acid (PAA)-carboxymethyl cellulose (CMC) binder to enhance the performance of an oxide-based anode was reported in batteries. A series of super high capacity and cycling ability oxide powders rarely achieved before was obtained, particularly most of them without any specific carbon modification and/or morphology control.

A new physical pulverization strategy has been developed to prepare a highly active composite of CoOx and crushed graphite (CG) for the cathode in lithium-oxygen batteries. The effect of CoOx loading on the charge potential in the oxygen evolution reaction (Li(2)O(2) →2 Li(+) +O(2) +2e(-)) was investigated in coin-cell tests. The CoOx (38.9 wt %)/CG composite showed a low charge potential of 3.92 V with a delivered capacity of 2 mAh cm(-2) under a current density of 0.2 mA cm(-2). The charge potential was 4.10 and 4.15 V at a capacity of 5 and 10 mAh cm(-2), respectively, with a current density of 0.5 mA cm(-2). The stability of the electrolyte and discharge product on the gas-diffusion layer after the cycling were preliminarily characterized by (1)H nuclear magnetic resonance spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The high activity of the composite was further analyzed by electrochemical impedance spectroscopy, cyclic voltammetry, and potential-step chronoamperometry. The results indicate that our near-dry milling method is an effective and green approach to preparing a nanocomposite cathode with high surface area and porosity, while using less solvent. Its relative simplicity compared with the traditional solution method could facilitate its widespread application in catalysis, energy storage, and materials science., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)