Electrode Preparation Procedure Research Articles

Incorporation of Bismuth(III) Oxide Nanoparticles into Carbon Ceramic Composite: Electrode Material with Improved Electroanalytical Performance in 4-Chloro-3-Methylphenol Determination.

In this study, a carbon ceramic electrode (CCE) with improved electroanalytical performance was developed by bulk-modifying it with bismuth(III) oxide nanoparticles (Bi-CCE). Characterization of the Bi-CCE was conducted employing atomic force microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy. Comparative analysis was conducted using an unmodified CCE. The findings proved that the incorporation of Bi2O3 nanoparticles into the CCE significantly altered the morphology and topography of the ceramic composite, and it improved the electrochemical properties of CCE. Notably, the Bi-CCE demonstrated a prolonged operational lifespan of at least three months, and there was a high reproducibility of the electrode preparation procedure. The developed Bi-CCE was effectively employed to explore the electrochemical behavior and quantify the priority environmental pollutant 4-chloro-3-methylphenol (PCMC) using CV and square-wave voltammetry (SWV), respectively. Notably, the developed SWV procedure utilizing Bi-CCE exhibited significantly enhanced sensitivity (0.115 µA L mol-1), an extended linearity (0.5-58.0 µmol L-1), and a lower limit of detection (0.17 µmol L-1) in comparison with the unmodified electrode. Furthermore, the Bi-CCE was utilized effectively for the detection of PCMC in a river water sample intentionally spiked with the compound. The selectivity toward PCMC determination was also successfully assessed.

Influence of Primary Particle Morphology and Hydrophilicity of Carbon Matrix on Electrode Coating Quality and Performance of Practical High‐Energy‐Density Li–S Batteries

AbstractLi–S batteries have attracted attention as the next‐generation secondary batteries. While substantial progress is made in understanding Li–S chemistry at a fundamental level, only a limited number of studies are dedicated to achieving high energy density at the practical pouch cell level. The challenge lies in attaining high‐energy‐density Li–S batteries under harsh conditions, which involve a minimal amount of electrolyte and a relatively high areal S‐loading cathode. This discrepancy creates a substantial gap between fundamental material research and comprehensive cell‐level investigations. In this study, it is investigated how the morphology and properties of two carbon materials, namely Ketjen black (KB) and mesoporous carbon nano‐dendrites (MCND), influence the composite cathode architecture and determine the performance of Li–S batteries. Unlike KB, MCND allows for a higher sulfur‐loading cathode without evident cracks in the composite cathode. This achievement can be attributed to the high porosity, excellent wettability, and high conductivity exhibited during an identical electrode preparation procedure. Furthermore, large‐format Li–S pouch cells incorporating MCND/S cathodes are successfully fabricated. These cells demonstrate an energy density surpassing 250 Wh kg−1 and an initial discharge capacity of 3.7 Ah under challenging conditions (S‐loading > 5 mg cm−2 and E/S < 3.5 µL mg−1).

Wrinkled MXene-modified screen-printed electrodes for highly efficient sarcosine detection

MXenes are gaining immense attention owing to their robust conductivity, presence of favorable surface-functional groups and excellent hydrophilicity. Herein, a simple solution-based approach was adopted to functionalize few-layer thick MXene-Ti3C2Tx with chitosan (Chi) molecules, creating a stable electro-active screen-printed electrode (SPE) platform for the detection of sarcosine (SAR), a new biomarker for prostate cancer. In comparison to pristine MXene, the chitosan-functionalized Ti3C2Tx (MX-Chi/SPE) offered favorable surface functionalization for easy immobilization of sarcosine oxidase (SOx) enzymes, which led to the improved enzymatic oxidation of SAR. The detection mechanism relied upon the efficient reduction of enzymatically produced H2O2 over MX-Chi/SPE, enabling selective detection of SAR both in low (0.1–0.3 µM) and high (1.5–3.5 µM) concentration ranges, with an estimated limit of detection (LOD) values of 0.012 µM and 0.14 µM (S/N = 3), respectively. Due to its robust enzymatic configuration, the biosensor enabled selective detection of SAR even in the presence of interfering species like ascorbic acid, uric acid, and glucose. Furthermore, the biosensor demonstrated excellent signal repeatability and stability and effectively recovered spiked SAR levels (98–106%) from artificial urine samples. This approach demonstrated the successful integration of MXenes as redox-active materials in clinical biosensors with a simple electrode preparation procedure, which has the potential to be extended to other MXene compositions.

Facile Functionalization of Carbon Electrodes for Efficient Electroenzymatic Hydrogen Production.

Enzymatic electrocatalysis holds promise for new biotechnological approaches to produce chemical commodities such as molecular hydrogen (H2). However, typical inhibitory limitations include low stability and/or low electrocatalytic currents (low product yields). Here we report a facile single-step electrode preparation procedure using indium-tin oxide nanoparticles on carbon electrodes. The subsequent immobilization of a model [FeFe]-hydrogenase from Clostridium pasteurianum ("CpI") on the functionalized carbon electrode permits comparatively large quantities of H2 to be produced in a stable manner. Specifically, we observe current densities of >8 mA/cm2 at -0.8 V vs the standard hydrogen electrode (SHE) by direct electron transfer (DET) from cyclic voltammetry, with an onset potential for H2 production close to its standard potential at pH 7 (approximately -0.4 V vs. SHE). Importantly, hydrogenase-modified electrodes show high stability retaining ∼92% of their electrocatalytic current after 120 h of continuous potentiostatic H2 production at -0.6 V vs. SHE; gas chromatography confirmed ∼100% Faradaic efficiency. As the bioelectrode preparation method balances simplicity, performance, and stability, it paves the way for DET on other electroenzymatic reactions as well as semiartificial photosynthesis.

High-temperature PEM fuel cell electrode catalyst layers Part 2: Experimental validation of its effective transport properties

In this study, the experimental approach for determination of high-temperature PEM fuel cell, PBI-bonded catalyst layer conductivity and transfer properties was developed and optimised. Electrical conductivity was determined by chronopotentiometry combined with mathematical model, using uncompressed catalyst layer on a conductive glass support. Effective transport properties were determined using gas-diffusion electrode samples fixed in the Wicke-Kallenbach cell. Experimental results were compared with quantities calculated from FIB-SEM tomography. Very good agreement between the results was reached. Theoretical data evaluated on the base of tomography may thus be considered as validated. The results confirm the heat treatment of the catalyst layer to lead to its reorganisation to less porous and better-defined structure with improved electrical conductivity. Changes in effective transport properties, however, were not pronounced. This is due to the nature of gas-diffusion electrode samples. Determined electrical conductivities and transfer properties of catalyst layer underlined the importance of gas-diffusion electrode preparation procedure. This represents an important input for further studies, focused on optimisation of membrane-electrode assemblies for HT PEM FC.

Simultaneous heteroatom doping and microstructure construction by solid thermal melting method for enhancing photoelectrochemical property of g-C3N4 electrodes

A phosphorus (P) doped g-C3N4 needle (PCNN) electrode with great photoelectrochemical (PEC) property is fabricated by a facile solid thermal melting approach. The proposed thermal melting method owns the advantages of low-cost, simple and easy operation, as only the solid mixing of melamine (C and N precursor) and triphenylphosphine oxide (P precursor) is needed in electrode preparation procedure. This method is further conducive to the formation of uniform film with doped heteroatom and unique microstructure on fluorine-doped tin oxide- coated glass (FTO). The PCNN photoelectrode holds a tip structure, which highly inhibits the recombination of photo-generated electron and hole. Particularly, the doped P in PCNN can further accelerate the photo-generated carrier separation and enhance the optical absorption property. As a result, the PCNN photoelectrode displays a five-fold enhancement of photocurrent density over pristine g-C3N4, reaching up to 127.4 µA cm-2 at 1.23 V versus reversible hydrogen electrode (RHE), as well as good optical, chemical and physical stability. The PCNN photoelectrode further exhibits great property in PEC removal of pollutant in water. This study provides an effective fabrication method and opens new avenues for the significant improvement of g-C3N4 based electrode in their various energy conversion and environmental application.

Near-Atomic-Thick Bismuthene Oxide Microsheets for Flexible Aqueous Anodes: Boosted Performance upon 3D → 2D Transition

Aqueous batteries provide safety, but they usually suffer from low energy and short lifetimes, limiting their use for large-scale energy storage. Two-dimensional materials with infinite lateral dimensions have inherent properties such as high surface area and remarkable power density and cycling stability that are shown to be critical for the next generation of energy storage systems. Here, ultrathin bismuthene oxide with a large aspect ratio is studied as an anode material for rechargeable aqueous metal-ion batteries. The metal oxides are prepared via a novel electrochemical system allowing for a smooth, high-quality transition of bismuthene to bismuthene oxide in a short time. This anodic system is shown to overcome major limiting factors of such batteries, including low capacity and irreversible and unstable redox reactions in aqueous electrolytes. The essential energy storage properties of two-dimensional (2D) microsheets, without the addition of conductive additives and binders, are compared with those of the corresponding three-dimensional (3D) structures. Notably, the battery performance of 2D microsheets is significantly better than that of nanoparticles from all examined aspects, including power density and potential and cycling stability, while exhibiting a capacity density close to their theoretical value. Moreover, 2D microsheets have shown impressive mechanical flexibility related to the ultrathin thickness of individual microsheets and strong interaction between them after film deposition. Combining the excellent energy storage properties of bismuthene oxide, the simple electrode preparation procedure, the inherent flexing characteristic, and the nontoxicity of both the battery material and the electrolyte makes this 2D material an exceptional candidate for large-scale wearable green electronics.

Electrochemical oxidation of Rhodamine B with cerium and sodium dodecyl benzene sulfonate co-modified Ti/PbO2 electrodes: Preparation, characterization, optimization, application

Schematic diagram of electrode preparation procedure and application. Regulation of the electronic structure and interface property becomes a major strategy in the preparation of electro-catalyst. This paper reports the synthesis of cerium (Ce) and sodium dodecyl benzene sulfonate (SDBS) co-modified Ti/PbO 2 electrodes (Ti/PbO 2 -Ce-SDBS). Ce and SDBS could greatly change the electronic structure and interface property of PbO 2 . Ti/PbO 2 -Ce-SDBS exhibited excellent electrocatalytic activity and stability in Rhodamine B (RhB) electrocatalytic oxidation reaction. The improved electrocatalytic activity associates with the synergistic effect of electronic and interface factors. In the electrochemical degradation of RhB, the removal efficiencies of RhB and COD are about 0.880 and 0.694 respectively after the electrolysis of 220 min with Ti/PbO 2 -Ce-4-SDBS-40, which are higher than the contrast Ti/PbO 2 electrodes. In the meantime, the accelerated lifetime of Ti/PbO 2 -Ce-4-SDBS-40 is more than 6.2 times than that of Ti/PbO 2 .

Quantifying Electrocatalytic Reduction of CO2 on Twin Boundaries

Summary A protocol relying on the use of silver nanostructures with well-defined dimensions and morphologies (e.g., nanocubes and nanowires) has been developed to differentiate and quantitatively determine the atom-specific activities of different surface atoms toward catalyzing electrochemical CO2 reduction reaction (CO2RR). The atom-specific activity of the twin-boundary edges (TBEs) is comparable to (or slightly higher than) that of the single-crystal edges (SCEs) formed from the crossing of two {100} surfaces, and it is on the order of ∼16 attoampere/atom (aA/atom) toward electrochemical CO2RR. This value is more than two orders higher than the atom-specific activity of the {100} surface atoms, i.e., ∼0.1 aA/atom. The high catalytic activity of the TBEs, which represent a class of commonly existing surface defects in stable metal nanostructures with face-centered cubic lattices, is consistent with the DFT calculations, in which the bridge-type binding configuration of COOH∗ at the TBEs stabilizes this intermediate to promote overall CO2RR.

Clarifying the Controversial Catalytic Performance of Co(OH)2 and Co3O4 for Oxygen Reduction/Evolution Reactions toward Efficient Zn-Air Batteries.

Cobalt-based nanomaterials have been widely studied as catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) due to their remarkable bifunctional catalytic activity, low cost, and easy availability. However, controversial results concerning OER/ORR performance exist between different types of cobalt-based catalysts, especially for Co(OH)2 and Co3O4. To address this issue, we develop a facile electrochemical deposition method to grow Co(OH)2 directly on the skeleton of carbon cloth, and further Co3O4 was obtained by post thermal treatment. The entire synthesis strategy removes the use of any binders and also avoids the additional preparation process (e.g., transfer and slurry coating) of final electrodes. This leads to a true comparison of the ORR/OER catalytic performance between Co(OH)2 and Co3O4, eliminating uncertainties arising from the electrode preparation procedures. The surface morphologies, microstructures, and electrochemical behaviors of prepared Co(OH)2 and Co3O4 catalysts were systemically investigated by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and electrochemical characterization methods. The results revealed that the electrochemically deposited Co(OH)2 was in the form of vertically aligned nanosheets with average thickness of about 4.5 nm. After the thermal treatment in an air atmosphere, Co(OH)2 nanosheets were converted into mesoporous Co3O4 nanosheets with remarkably increased electrochemical active surface area (ECSA). Although the ORR/OER activity normalized by the geometric surface area of mesoporous Co3O4 nanosheets is higher than that of Co(OH)2 nanosheets, the performance normalized by the ECSA of the former is lower than that of the latter. Considering the superior apparent overall activity and durability, the Co3O4 catalyst has been further evaluated by integrating it into a Zn-air battery prototype. The Co3O4 nanosheets in situ supported on carbon cloth cathode enable the assembled Zn-air cells with large peak power density of 106.6 mW cm-2, low charge and discharge overpotentials (0.67 V), high discharge rate capability (1.18 V at 20 mA cm-2), and long cycling stability (400 cycles), which are comparable or even superior to the mixture of state-of-the-art Pt/C and RuO2 cathode.

Improving the Electrolytic Hydrogen Production Using Co-Cu-Mo Based Ionic Activator

Alkaline water electrolysis is used when there is a need for the efficient, on-site production of the high purity hydrogen and oxygen, especially when coupled to the renewable energy sources, such as wind and solar energy. Hydrogen produced in this way can be stored and transported for remote power generation in fuel cells. In order to expand commercialization of the alkaline electrolyzers, operating and capital costs should be reduced. High power consumption of the electrolytic process could be decreased by using more efficient electrode materials, keeping in mind its costs. This manuscript presents a contribution on the improved efficiency of the alkaline electrolytic production of hydrogen by in situ adding activating compounds directly into the electrolyte during the electrolytic process. New elec­trode material was formed, based on the mixture of co-deposition of Co and Cu complexes and Mo oxide, applied as activating compound i.e. ionic activator. Electrocatalytic efficiency of ternary system CoCuMo was studied using quasi-potentiostatic, galvanostatic and impedance spectroscopy techniques. The electrodeposited ionic activator on the plain nickel electrode, is shown to have a great influence on the kinetics of the hydrogen evolution reaction, lowering the overvoltage for about 300 mV at current density of 100 mA cm-2. Morphological investigations using SEM shows formation of the porous structure on the cathode resulting in significant increase of the surface area, and UV/VIS spectra of the electrolyte, recorded during the electrolytic process shows decreased concentrations of the ionic activators making a deposit on the surface of the Ni cathode. This ionic activator was applied in the laboratory alkaline electrolytic cell and we found that the energy requirements per mass unit of hydrogen produced is reduced for more than 20%, compared to non-activated system, when operated at elevated temperatures. The use of the in-situ activation with CoCuMo based activators added directly into alkaline electrolyte could be of great interest, since it offers simplified electrode preparation procedure and provides reduction in the alkaline electrolyzer operating cost. Figure 1

Performance Optimization of Cermet SOFC Anodes: An Evaluation of Nanostructured NiO

Anode cermets of metallic Ni and stabilized zirconia are among the most common SOFC materials. The electrochemical performance of the composite anodes is essentially governed by the triple phase boundary formed by electronic conductor, solid electrolyte and gaseous phase. One important approach to optimize the anode morphology relates to decreasing particle size of the initial powders. On the other hand, a drastic reduction of the component particle size may lead to dramatic changes in the material properties. The tendencies to agglomeration, a presence of modified surface layers and fast rates of microstructural alterations under SOFC operating conditions are all expected to considerably affect the electrode preparation procedure and anode behavior. The present work is centered on the analysis of key relationships between the morphology of initial NiO powders used to form Ni-containing cermets and overall quality of the composite SOFC anodes. The commercial Nickel (II) oxide nanopowder (99.8% purity, Sigma-Aldrich) was employed as a model starting material for these studies. A large series of NiO powders were prepared by annealing of initial NiO at different temperatures (RT-1100 oC). Scanning and transmission microscopy, X-ray diffraction, thermogravimetry, X-ray photoelectron and Raman spectroscopic analyses were employed for morphological, chemical and structural characterization. Then the powders were mixed with highly dispersed solid electrolyte of 10 mol.% Sc2O3 and 1% mol.% CeO2 stabilized zirconia (10Sc1CeSZ) and an organic solvent to obtain screen-printable pastes, used to deposit anode layers onto 10 mol.% Sc2O3 and 1% mol.% Y2O3 stabilized ZrO2 membranes for further microstructural and electrochemical studies. The results showed, in particular, that starting NiO nanopowder (Fig. 1) possesses a core-shell structure, with the crystalline core covered by amorphous shell rich of excessive oxygen and adsorbed water. These surface layers, having critical impact on the integrity and performance of resultant anodes, can be eliminated by thermal pre-treatment. Fig. 1. TEM image of starting NiO powder. Figure 1

Graphene oxide-mediated electrochemistry of glucose oxidase on glassy carbon electrodes.

Glucose oxidase (GOD) was immobilized on glassy carbon electrodes in the presence of graphene oxide (GO) as a model system for the interaction between GO and biological molecules. Lyotropic properties of didodecyldimethylammonium bromide (DDAB) were used to stabilize the enzymatic layer on the electrode surface resulting in a markedly improved electrochemical response of the immobilized GOD. Transmission electron microscopy images of the GO with DDAB confirmed the distribution of the GO in a two-dimensional manner as a foil-like material. Although it is known that glassy carbon surfaces are not ideal for hydrogen peroxide detection, successful chronoamperometric titrations of the GOD in the presence of GO with β-d-glucose were performed on glassy carbon electrodes, whereas no current response was detected upon β-d-glucose addition in the absence of GO. The GOD-DDAB-GO system displayed a high turnover efficiency and substrate affinity as a glucose biosensor. The simplicity and ease of the electrode preparation procedure of this GO/DDAB system make it a good candidate for immobilizing other biomolecules for fabrication of amperometric biosensors.

Gluconic Acid Synthesis in an Electroenzymatic Reactor

Glucose was selectively oxidized to gluconic acid in a membraneless, flow-through electroenzymatic reactor operated in the mode of co-generating chemicals and electrical energy. At the anode the enzyme glucose oxidase (GOx) in combination with the redox mediator tetrathiafulvalene (TTF) was used as catalyst, while the cathode was equipped with an enzyme cascade consisting of GOx and horseradish peroxidase (HRP). The influence of the electrode preparation procedure, the structural and the operating parameters on the reactor performance was investigated in detail. Under optimized conditions, an open circuit potential of 0.75V, a current density of 0.6mAcm−2 and a power density of 100μAcm−2 were measured. The space time yield of gluconic acid achieved at a glucose conversion of 47% was 18.2gh−1cm−2.

The electrochemical performance of commercial ferric oxide anode with natural graphite adding and sodium alginate binder

A low cost and facile way was developed to prepare high performance Fe2O3/natural graphite electrode for lithium ion batteries. For the purpose of reducing the cost and improving the feasibility of large-scale fabrication, commercial ferric oxide and natural graphite were adopted as raw materials and mechanical milling was adopted as preparation method in material fabrication process, and water soluble sodium alginate was adopted as binder in electrode preparation procedure. The Fe2O3/natural graphite electrode delivers initial discharge and charge capacity of 943.8 and 691.4mAhg-1 at a specific current of 72mAg-1, maintaining of 687.6 and 679.3mAhg-1 after 100 cycles. After 60 cycles at various specific currents from 104 to 3470mAg-1, the discharge and charge capacity of the Fe2O3/natural graphite electrode can restore well when lowering the specific current to 104mAg-1. A novel electrochemical reconstruction between Fe2O3 and natural graphite was observed for the electrode after cycling, which results in the formation of an integrated architecture with good combination between Fe2O3 and natural graphite, being responsible for the good electrochemical performance.

Influence of the surface morphology of smooth platinum electrodes for the sodium borohydride oxidation reaction

In this study, we show that the platinum electrode preparation procedure influences its behavior towards the borohydride electrooxidation reaction (BOR) mechanism. Cycling a smooth polycrystalline Pt electrode in alkaline electrolyte within the water stability domain prior to the BOR characterization radically changes the shape of the BOR voltammogram obtained in hydrodynamic conditions using the rotating disk electrode (RDE) setup, compared to the “classical” one measured on a smooth polycrystalline Pt electrode just polished before the BOR RDE study. This particular BOR voltammogram is reversibly brought back to the “classical” one after voltammetric cycling in borohydride alkaline media. These changes in the BOR voltammogram highlight the sensitivity of the BOR mechanism towards the Pt surface morphology. A first comparison of the Pt electrode surface before and after the voltammetric cycling in alkaline media using tapping mode atomic force microscopy (AFM) shows no morphological differences between the two surfaces within the AFM observation range, suggesting a very fine atomic structure disordering of the Pt surface. Such strong dependence of the BOR mechanism on Pt regarding the electrode atomic structuring opens the way to future studies focusing on the BOR on well-defined Pt single crystals.

Degradation of Rhodamine B with Visible Light Response of Fe2O3/TiO2 Film Electrode

Fe2O3/TiO2 film electrodes were prepared by a new process with the sol-gel and hydrothermal methods, and various factors were studied to optimize the electrode preparation procedures, such as the precursor solution concentration, reaction time and annealing temperature. The Fe2O3/TiO2 film electrodes prepared by successively adding 0.4 M Fe(NO3)3 precursor solution, reacting for 24 h and annealing at 450°C for 2 h were found to have the highest photocatalytic efficiency, with the average photocurrent in response to visible light up to 105 μA, which was superior to other modified film electrodes and far better than pure TiO2 film electrodes. Using the optimal Fe2O3/TiO2 film electrodes, the decolorization rate of Rhodamine B by photoelectrocatalytic degradation could reach 100%, and the decolorization ratio gradually increased after three repetitions.

Puzzling out the origin of the electrochemical activity of black P as a negative electrode material for lithium-ion batteries

Black phosphorus prepared via the mineralization concept displays promising characteristics with respect to Li-ion battery applications. Although the theoretical specific capacity of black phosphorus as a negative electrode material is 2596 mA h g−1, a good cycling stability at high capacities, however, is still missing. Even worse, a large capacity drop after the first cycle is present and, depending on the electrode preparation, a poor first cycle coulombic efficiency (only 8%) represents a huge challenge to overcome. Herein we report on the performances of black phosphorus as a negative electrode material and display the roles of Cu3P and the copper current collector in this context. Furthermore, a composite material prepared by reacting pristine black phosphorus particles with a copper solution under solvothermal conditions shows a first cycle coulombic efficiency of 43%. We show that the presence of copper is crucial for the electrochemical performance of black phosphorus and that also the particle size and the electrode preparation procedure play a crucial role.

Analysis of Pt/C electrode performance in a flowing-electrolyte alkaline fuel cell

We characterize the performance of Pt/C-based electrodes under alkaline conditions using a microfluidic H 2/O 2 fuel cell as an analytical platform. Both anodes and cathodes were investigated as a function of electrode preparation procedures ( i.e., hot pressing, acclimatization) and fuel cell operating parameters (i.e., electrolyte composition) via chronoamperometric and electrochemical impedance analyses. X-ray micro-computed tomography was employed to link electrode structure to performance. In addition, the flowing electrolyte stream is used to study the effects of carbonates on individual electrode and overall fuel cell performance. Our studies provide direct evidence that the performance of hydrogen-fueled room-temperature alkaline fuel cells (AFCs) is limited by transport processes to and from the anode primarily due to water formation. Furthermore, the presence of carbonate species in the electrolyte appears to impact only anode performance whereas cathode performance remains unchanged.

Investigation on the charging process of Li 2O 2-based air electrodes in Li–O 2 batteries with organic carbonate electrolytes

The charging process of Li 2O 2-based air electrodes in Li–O 2 batteries with organic carbonate electrolytes was investigated using in situ gas chromatography/mass spectroscopy (GC/MS) to analyze gas evolution. A mixture of Li 2O 2/Fe 3O 4/Super P carbon/polyvinylidene fluoride (PVDF) was used as the starting air electrode material, and 1-M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in carbonate-based solvents was used as the electrolyte. We found that Li 2O 2 was actively reactive to 1-methyl-2-pyrrolidinone and PVDF that were used to prepare the electrode. During the first charging (up to 4.6 V), O 2 was the main component in the gases released. The amount of O 2 measured by GC/MS was consistent with the amount of Li 2O 2 that decomposed during the electrochemical process as measured by the charge capacity, which is indicative of the good chargeability of Li 2O 2. However, after the cell was discharged to 2.0 V in an O 2 atmosphere and then recharged to ∼4.6 V, CO 2 was dominant in the released gases. Further analysis of the discharged air electrodes by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy indicated that lithium-containing carbonate species (lithium alkyl carbonates and/or Li 2CO 3) were the main discharge products. Therefore, compatible electrolytes and electrodes, as well as the electrode-preparation procedures, need to be developed for rechargeable Li-air batteries for long term operation.