Interstitial Cavities Research Articles

Honeycomb Electron Lattice Induced Dirac Fermion with Trigonal Warping in Bilayer Electrides.

Emergent fermions arising from the excess electrons of electrides provide a new perspective for exploring semimetal states with unique Fermi surface geometries. In this study, a class of unique two-dimensional (2D) highly anisotropic Dirac fermions is designed using a sandwich structure. Based on the structural design and first-principles calculations, 2D electride MB (M = Ca/Sr, B = Cl/Br/I) is an ideal candidate material. The excess electrons of the bilayer MB could be stably localized in the interstitial cavities, constructing a natural zigzag honeycomb electron sublattice that further forms a Dirac fermion. Compared with traditional Dirac semimetals, 2D Dirac electrides exhibited rich physical properties: i) The Fermi surface shows trigonal warping in low-energy regions. In particular, the geometry of the Fermi surface determines the high anisotropy of the Fermi velocity. ii) A pair of Dirac fermions are protected by three-fold rotational symmetry and exhibit strong robustness. iii) Electride MB possesses a lower work function that strongly correlates with the surface area of the emission channel. Based on these properties, an electron-emitting device with multifunctional applications is fabricated. Therefore, this study provides an ideal platform for studying potential entanglement between structures, electrides, and topological states.

Hydrogen sorption by nanostructures at low temperatures (Review article)

The features of hydrogen sorption by a wide range of nanostructures — fullerite C60, carbon nanotubes, graphene structures, nanodispersed carbon, including Pd-containing nanoclusters, ordered silicon-oxide-based nanostructures (the MCM-41 family) and silicon-oxide aerogel — have been reviewed. Special attention is given to the sorption characteristics of carbon nanostructures that have been exposed to various modifying treatments (oxidation, gamma-ray irradiation in gas atmosphere, action of pulsed high frequency gas discharge). Two mechanisms of physical low-temperature sorption of hydrogen have been revealed to predominate in such nanostructures in different temperature intervals. At the lowest temperatures (8–12 K), the sorption can actually proceed without thermal activation: it is realized through the tunnel motion of hydrogen molecules along the nanostructure surfaces. The periodic structure of the potential relief, allowed by the surface frame of carbon and silicon-oxide nanostructures, along the rather low interpit barriers are beneficial for the formation of low-dimensional (including quantum) hydrogen-molecule systems practically without thermally activated diffusion. In such nanostructures, the hydrogen diffusion coefficients are actually independent of temperature at 8–12 K. At higher temperatures (12–295 K), a thermally activated mechanism of hydrogen diffusion prevails. The periodic structure of fullerite C60 contains periodic interstitial cavities, separated by rather low potential barriers. Their sizes are sufficient to accommodate impurity hydrogen molecules and, thus, allow diffusion processes, which can also have a tunnel nature. It is shown that gamma-irradiation and high-frequency gas discharge processing increase markedly the quantity of hydrogen strongly bonded to carbon nanostructures.

First-principles calculations to investigate electronic, elastic, and optical properties of one dimensional electride Y5Si3

Y5Si3 is an air- and water- stable electride in which part of electrons are confined in one-dimensional channels composed of Y atoms. Y5Si3 has a promoting effect on ammonia synthesis at ambient pressure due to the unique properties of these electrons at interstitial cavities (anionic electrons). Here we carry out a detailed study of electronic structure, optical and elastic properties of Y5Si3. It is found that the anionic electrons form a valence band near the Fermi energy level and it is mainly contributed by the Y-4d orbital. The calculated results of optical and mechanical properties indicated that Y5Si3 is a brittle metal and exhibits weak anisotropy. Our present work provides a comprehensive understanding on physical properties of Y5Si3.

Hydrogen-bond network distortion of water in the soft confinement of Nafion membrane.

A Compton spectroscopy investigation is carried out in hydrated Nafion membranes, enabling identification of distortions in the hydrogen-bond distribution of the polymer hydrating water by means of the subtle changes reflected by the Compton profiles. Indeed, deformations of the Compton profiles are observed when varying hydration, and two different bonding kinds are associated with the water molecules: at low hydration, water surrounds the sulfonic groups, while on increasing hydration, water molecules occupy the interstitial cavities formed upon swelling of the membrane. The analysis is proposed in terms of averaged OH bond length variation. A sizable contraction of the OH distance is observed at low hydration (∼0.09 Å), while at higher hydration levels, the contraction is smaller (∼0.02 Å) and the OH bond length is closer to bulk water. An evaluation of the electron kinetic energy indicates that the spatial changes associated with the water distribution correspond to a consistent binding energy increase. Distinct temperature dependences of each water population are observed, which can be straightly related to water desorption into ice on cooling below the freezing point.

First-principles design of halide-reduced electrides: Magnetism and topological phases

We propose a design scheme for potential electrides derived from conventional materials. Starting with rare-earth-based ternary halides, we exclude halogens and perform global structure optimization to obtain thermodynamically stable or metastable phases but having an excess of electrons confined inside interstitial cavities. Then, spin-polarized interstitial states are induced by chemical substitution with magnetic lanthanides. To demonstrate the capability of our approach, we test with 11 ternary halides and successfully predict 30 stable and metastable phases of nonmagnetic electrides subject to 3 different stoichiometric categories, and successively 28 magnetic electrides via chemical substitution with Gd. 56 out of these 58 designed electrides are discovered for the first time. Two electride systems, the monoclinic $A$C ($A=$ La, Gd) and the orthorhombic $A_2$Ge ($A=$ Y, Gd), are thoroughly studied to exemplify the set of predicted crystals. Interestingly, both systems turn out to be topological nodal line electrides (TNLE) in the absence of spin-orbit coupling and manifest spin-polarized interstitial states in the case of $A=$ Gd. Our work establishes a novel computational approach of functional electrides design and highlights the magnetism and topological phases embedded in electrides.

Effectiveness of Faradism Under Pressure Versus Complex Decongestive Therapy in Subjects with Peripheral Oedema

Background: Oedema is defined as excessive accumulation of free fluid in interstitial tissue spaces andserous cavities. The oedema may be of 2 main types: Localized when a particular organ or limb is involvede.g. lymphatic oedema, inflammatory oedema, allergic oedema and generalized when it is systemic indistribution, particularly seen in the subcutaneous tissues. The gold standard therapy for lymphedema iscomplex decongestive therapy (CDT). The first stage of CDT includes manual lymphatic drainage (MLD),compression therapy, exercise, and good skin care. The second phase, consisting of self-managing lymphaticmassage, daily use of compression garments, and self-directed continuation of the exercises, should beimplemented only after the completion of the first phase. Also, Faradism under pressure (FUP) is beneficialin oedematous conditions. In FUP, the pumping action of the alternate muscle contraction and relaxation,brings about increased venous and lymphatic return. The fluid is propelled towards the heart by an inwardpressure on the tissue spaces and veins caused by the contraction of the muscle.Objectives: The objectives of the study were as follows: To determine effect of faradism under pressure inperipheral oedema. To determine effect of complex decongestive therapy. To compare the effect of faradismunder pressure and complex decongestive therapy in peripheral oedematous conditions.Methods: Ethical clearance was obtained from the institutional ethical committee. A total of 20 subjectswere assessed and all were included in the study based on inclusion criteria. Oedema was diagnosed usingvolumetric and girth assessment. Results: Intra-group statistical analysis of intervention group, pre-postvolumetric measurement score was 33.6 ±9.192 and was found to be extremely significant and pre-post girthassessment score was 2.540 ± 0.9513 which was extremely significant. Conclusion: We found that both FUPand CDT were significantly effective in reducing peripheral oedema but CDT was more effective comparedto FUP. This treatment was effective by reducing the volumetric and girth measurements which improvedquality of life of patients.

Surgical Treatment of Lung Cancer Combined with Interstitial Lung Disease

背景与目的间质性肺病(interstitial lung disease, ILD)是一组主要累及肺间质和肺泡腔导致肺泡-毛细血管功能单位丧失的弥漫性肺疾病, 常导致限制性通气功能障碍和弥散功能障碍。ILD基础上肺癌发病率增高, 肺癌合并间质性肺病(lung cancer combined with ILD, LC-ILD)的手术风险明显增加。本研究旨在探讨LC-ILD外科治疗的安全性, 总结围术期诊治经验。方法回顾性分析2012年1月-2019年12月北京医院胸外科收治的LC-ILD行肺切除术的患者资料, 总结其临床表现、影像、病理、手术安全性、围术期并发症和诊治经验。结果本研究共纳入23例患者, 男性20例(87.0%), 平均年龄(69.1±7.8)岁, 吸烟者19例(82.6%)。ILD类型包括特发性肺纤维化14例(60.9%)、特发性非特异性间质性肺炎7例(30.4%)、结缔组织病相关ILD 2例(8.7%)。肺癌病理包括腺癌7例(30.4%)、小细胞癌7例(30.4%)、鳞癌6例(26.1%)、小细胞癌混合鳞癌1例(4.3%)、大细胞癌2例(8.7%)。手术入路包括经电视胸腔镜16例(69.6%)和前外侧开胸7例(30.4%), 切除方式包括肺叶切除13例(56.5%)、双肺叶切除1例(4.3%)和亚肺叶切除9例(39.1%)。术后90 d并发症11例(47.8%), 其中肺部并发症8例(34.8%), ILD急性加重(acute exacerbation of ILD, AE-ILD)4例(17.4%), 心房纤颤6例(26.1%), 急性左心功能不全1例(4.3%)。术后90 d死亡2例(8.7%), 死因均为AE-ILD。结论LC-ILD以合并症多、肺功能差的高龄患者居多, 手术风险明显增高。术前应充分控制ILD病情, 术中尽量降低手术创伤, 术后应特别关注肺部并发症和AE-ILD。AE-ILD预后差, 治疗难度大, 糖皮质激素有助于改善病情, 早诊早治是治疗关键。

Exotic Cu-mineralization in Triassic red beds from Navas de San Juan (Jaén, Spain)

The Navas de San Juan copper deposit is located at the southeast edge of the Iberian massif (Spain). It occurs within Triassic continental red beds that represent an undeformed, horizontal to sub-horizontal sequence, overlying unconformably folded Paleozoic metasedimentary rocks and, locally, granitic rocks. The red beds consist essentially of siliciclastic detrital materials including sandstone, silt, and clay, with some thin layers of micritic limestones and edaphic carbonates. This sequence was formed in a sedimentary framework typical of a low sinuosity fluvial system of braided type. The copper mineralization is hosted by a fine-grained sandstone (arkose) with abundant plant debris and detrital grains cemented by dolomite, which was deposited in a secondary fluvial channel.The copper mineralization includes chrysocolla, azurite and malachite with a stratabound morphology. Chrysocolla occurs unevenly in the sandy levels of the mineralized horizon replacing feldspar grains, coating detrital grains and dolomitic cement, and filling pores and cavities. Copper carbonates appear essentially inside or near the organic matter-rich zones filling cavities and veinlets. They also replace more or less limonitized plant debris preserving the original cellular structure of organic material. Azurite and malachite occur in different layers or zones without any evidence of reaction between them.The δ13C-values of azurite and malachite are indicative of a carbon source derived from the decomposition of C3 plant debris. The δ 18O values of the solutions in equilibrium with copper carbonates are consistent with solutions of meteoric origin. The differences between the values for azurite and malachite would reflect variations of the climatic conditions, probably related to seasonal changes in the hydrological parameters and arid degree of the system.Chrysocolla formation was due to the neutralization of copper solutions during the hydrolysis and replacement of the feldspars, with additional precipitation of chrysocolla in interstitial spaces, cavities and microfractures. Copper carbonates derived from the interaction between the neutralized copper solutions and the CO2 released by the decomposition of organic matter under oxidizing conditions. Based on geological, mineralogical and petrographic criteria, in conjunction with isotopic data, the Navas de San Juan deposit is interpreted to represent an exotic copper mineralization. The Cu-bearing vein mineralizations located in the Variscan basement are inferred as the possible copper source.

Clinical Relevance of Cerebral Small Vessel Diseases.

Clinical Relevance of Cerebral Small Vessel Diseases.

Enhanced wettability and electrolyte uptake of coated commercial polypropylene separators with inorganic nanopowders for application in lithium-ion battery

In this research, inorganic material type and content influence on coating of commercially available polypropylene (PP) separator were studied for improving its performance and safety as lithium ion battery separator. Heat-resistant nanopowders of Al2O3, SiO2 and ZrO2 were coated using polyvinylidene fluoride (PVDF) binder. Coating effects on the separators morphology, wettability, high temperatures dimensional stability and electrochemical properties were investigated via their scanning electron microscopy images, electrolyte contact angles, electrolyte uptakes, thermal shrinkages analysis and ion conductivities. Furthermore, their performances were studied as the lithium ion batteries separator. All the coated separators have lower thermal shrinkages compared to the commercial neat PP separator. In addition, almost all of the coated separators have shown higher porosities and electrolyte uptakes than those of the commercial neat PP separators. The coated separator with Al2O3 / binder ratio of 8 (MOA8) revealed highest improvement in electrolyte contact angle of 0 °, electrolyte uptake of 218 % (2.04 times increment), ion conductivity of 1.685 mS/cm (1.89 times increment), 52 % porosity compared with the neat PP separator due to proper coating surface morphology, interstitial cavities and a higher Al2O3 dielectric constant than SiO2. In terms of assembled battery discharge capacity reduction after 100 cycles, MOA8 separator showed better cyclic performance as 8.89 % compared with that of the neat PP separator as 16.6 %.

Preparation of 4A zeolite coated polypropylene membrane for lithium‐ion batteries separator

ABSTRACTThis study aims to improve wettability and thermal resistance of lithium‐ion batteries separators. For this purpose, a commercial polypropylene (PP) separator was coated by 4A zeolite using poly(vinylidene fluoride) as binder and effects of the separators' zeolite content was investigated. All the coated separators showed lower contact angles, higher electrolyte uptakes, and less thermal shrinkages compared to the neat commercial separator. The coated PPA8 separator (zeolite to binder ratio of 8) showed the lowest wettability (contact angle of 0°) and electrolyte uptake (270%) due to its surface porosity resulting from the zeolite particles interstitial cavities as well as their internal cavities. Also, the PPA8 separator ion conductivity was found as 2.25 mS cm−1 and C‐rate and cycling performance of its assembled battery were higher compared to those of the commercial PP separator assembled battery. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47841.

Self-Assembly of Goldberg Polyhedra from a Concave [WV5O11(RCO2)5(SO4)]3- Building Block with 5-Fold Symmetry.

Nanoscale regular polyhedra with icosahedral symmetry exist naturally as exemplified by virus capsids and fullerenes. Nevertheless, their generation by supramolecular chemistry through the linking of 5-fold symmetry vertices remains unmet because of the absence of 5-fold symmetry building blocks with the requisite geometric features. This situation contrasts with that of tetrahedral and octahedral symmetry metal-organic polyhedra (MOPs), for which appropriate triangular and square molecular building blocks (MBBs) that can serve as vertices or faces are readily available. Herein, we report isolation of a pentagonal [WV5O11(SO4)6]8- cluster and reveal its utility to afford the first four examples of nanoscale Goldberg MOPs, based upon 5-fold MBBs. Two 32-faced G v(1,1) MOPs and two 42-faced G v(2,0) MOPs were formed using linear or triangular organic ligands, respectively. The largest Goldberg MOP-4, exhibits a diameter of 4.3 nm, can trap fullerene C60 molecules in its interstitial cavities.

Magnetic Nanocomposites Based on Opal Matrices

Features of obtaining magnetic nanocomposites based on the lattice packing of SiO2 nanoscale (opal matrices) with clusters of multiferroic materials (Li-Zn, Bi, Fe, Dy, Gd and Yb titanates) in their interstitial cavities have been considered. For magnetic nanocomposites creation opal matrices with SiO2 nanoscale of ~ 260 nm in diameter have been used. The composition of nanocomposites has been also studied using X-ray diffractometry and Raman spectroscopy. The results of the frequency dependences measurement for the dielectric constant of the nanostructures obtained have been presented. Hysteresis loops have been examined for the samples obtained in the temperature range from 2 to 400 K.

Neutron Irradiated Reactor Internals: An Applied Methodology for Specimen Preparation and Post Irradiation Examination by Electron Microscopy Methods

Radiation-induced microstructural defects cause degradation of mechanical properties and a life time reduction of reactor structural components during nuclear power plant operation. The effect of neutron irradiation fluence and flux, neutron spectrum, corrosion environment, etc. on mechanical properties is investigated under the NPP's surveillance programs and additional nuclear material research. The material strength typically increases while ductility and fracture toughness decrease after neutron irradiation. Transmission Electron Microscopy is one of the methods for Post Irradiation Examination (PIE) which helps to understand the material behaviour exposed to different reactor operating conditions. Therefore, such PIE methods are important to develope and optimize. In this study, we introduce the specimen preparation methodology and radiation-induced damage (RID) evaluation of stainless steel SSRT test specimens by the means of Scanning and Transmission Electron Microscopy (SEM, TEM). In austenitic microstructure, Frank interstitial dislocation loops, cavities or voids and radiation-induced precipitates are the dominant RID evolved under neutron irradiation. Futhermore, the material susceptibility to segregation related to the IASCC mechanism is widely studied within 300-series stainless steels. The proper determination of RID size distribution refers to degradation mechanisms in reactor materials. In our research, the RID characterization is demonstrated on the specimens irradiated to ~ 15 dpa in PWR conditions. Distribution of cavities, Frank loops and radiation-induced precipitates were evaluated in bright/dark field kinematical conditions and through-focal series. The nature of cavities, i. e. voids/He or H stabilized bubbles with the size less than 3 nm, was not recognized in the specimens prepared by standard electrolytic polishing method. Radiation-induced segregation in a narrow area up to 10 nm was detected by point STEM-EDS analysis. To evaluate RID size distribution, the automatic image-processing program was developed and compared to the visual analysis. So far, the results were optimized on Frank loops and precipitates and are in a good agreement with the manual processing.

Intercalation of barium into monoclinic tungsten oxide nanoplates for enhanced photoelectrochemical water splitting

Intercalating alkali earth metals into WO3 lattice is a promising strategy to tune its optical and electrical properties. However, hollow cubic tunnels present in monoclinic WO3 do not provide sufficient space for the diffusion and intercalation of large ions into its interstitial cavities. Therefore, a unique synthesis strategy is required to intercalate large ions into the monoclinic WO3 lattice without causing structural distortion or damage. In this study, a single-step hydrothermal method is proposed for the fabrication of barium-intercalated monoclinic WO3 thin films for efficient photoelectrochemical water splitting applications. The intercalation of barium into WO3 is achieved by the hydrothermal condensation of peroxopolytungstic acid solution. The proposed method yields hydrated orthorhombic WO3, which provides enough space in the hexagonal interstitial cavities between its [001] planes for the stable intercalation of barium. Subsequently, stable barium-intercalated monoclinic WO3 is obtained via reconstructive transformation without causing any significant structural distortion or damage. The intercalation of barium affects the preferential direction of crystal growth and the morphology of WO3. Furthermore, barium intercalation reduces the bandgap of WO3 and slightly increases its carrier density. As a result, higher photocurrent and incident photon-to-current efficiency values are achieved. Based on spectroscopic and electrochemical results, a probable band diagram of barium-intercalated WO3 is proposed. Importantly, the proposed method can be efficiently extended to fabricate monoclinic WO3 thin films intercalated with large alkali metal and alkali earth metal ions for various applications.

Tungsten Oxide for Proton Batteries and Its Storage Mechanism

The proton insertion capability of a new composite, tungsten oxide hydrate, WO3•0.6H2O, synthesized in a simple hydrothermal method is demonstrated as an anode material for rechargeable proton batteries using sulfuric acid as the electrolyte. Using Ag/AgCl and active carbon as the reference electrode and counter electrode respectively, the electrochemical performance of WO3•0.6H2O was carried out by using a three electrode cell. The cell shows a reversible proton insertion/extraction reaction with a charge capacity of 90 mAh/g at a rate of 1C, with an average discharge voltage at -0.25 V (vs. Ag/AgCl). The cycling performance tested at 20C, the charge capacity is still stable at 80 mAh/g after 10,000 cycles. XRD rietveld refinement indicates that WO3•0.6H2O is a channel hexagonal structure and the zeolitic waters are located in the center of the interstitial cavities. Ex-situ XRD studies also confirms that the protons are inserted through the bridge oxygen which causes the expansion of the ab plane and shrinkage in the c direction. Pairing it with Prussian blue (Fe/Fe), a 1.5V full proton cell was made and showed a capacity around 50mAh/g (based on the anode) at current rate of 2Ag-1 . These results demonstrate that WO3•0.6H2O is a promising anode material to be utilized for proton batteries.

Potassium nickel hexacyanoferrate as a high-voltage cathode material for nonaqueous magnesium-ion batteries

The magnesium insertion capability of Prussian blue (PB) analogue, potassium nickel hexacyanoferrate K0.86Ni[Fe(CN)6]0.954(H2O)0.766 (KNF-086), is demonstrated as a cathode material for rechargeable magnesium-ion batteries using a conventional organic electrolyte. K1.51Ni[Fe(CN)6]0.954(H2O)0.766 is synthesized first, and potassium ions are electrochemically extracted to prepare the KNF-086 cathode. The electrochemical test cell is composed of KNF-086 as the working electrode, an activated carbon as the counter and reference electrode, and 0.5 M Mg(ClO4)2 in acetonitrile as the electrolyte. The cell shows a reversible magnesium insertion/extraction reaction with a discharge capacity of 48.3 mAh g−1 at a 0.2 C rate, and an average discharge voltage at 2.99 V (vs. Mg/Mg2+) that is the highest among the cathode materials ever reported for magnesium-ion batteries. Elemental analysis and Fourier electron-density map analysis from powder X-ray diffraction data confirm that the magnesium-inserted phase is Mg0.27K0.86Ni[Fe(CN)6]0.954(H2O)0.766 (MKNF-086), and the magnesium ions in MKNF-086 are positioned at the center of the large interstitial cavities of cubic PB. Compared to KNF-086, MKNF-086 exhibits a decreased unit cell parameter (0.8%) and volume (2.4%). These results demonstrate that a PB analogue, potassium nickel hexacyanoferrate, could be utilized as a potential cathode material for conventional organic electrolyte-based magnesium-ion batteries.

Synthesis and crystal structure of a new magnesium phosphate Na3RbMg7(PO4)6.

A new magnesium phosphate, Na3RbMg7(PO4)6 [tris-odium rubidium hepta-magnesium hexakis(ortho-phosphate)], has been synthesized as single crystals by the flux method and exhibits a new structure type. Its original structure is built up from MgO x (x = 5 and 6) polyhedra linked directly to each other through common corners or edges and reinforced by corner-sharing with PO4 tetra-hedra. The resulting anionic three-dimensional framework leads to the formation of channels along the [010] direction, in which the Na+ cations are located, while the Rb+ cations are located in large inter-stitial cavities.

Organic electrolyte-based rechargeable zinc-ion batteries using potassium nickel hexacyanoferrate as a cathode material

Abstract This study demonstrates an organic electrolyte-based rechargeable zinc-ion battery (ZIB) using Prussian blue (PB) analogue potassium nickel hexacyanoferrate K 0.86 Ni[Fe(CN) 6 ] 0.954 (H 2 O) 0.766 (KNF-086) as the cathode material. KNF-086 is prepared via electrochemical extraction of potassium ions from K 1.51 Ni[Fe(CN) 6 ] 0.954 (H 2 O) 0.766 (KNF-151). The cell is composed of a KNF-086 cathode, a zinc metal anode, and a 0.5 M Zn(ClO 4 ) 2 acetonitrile electrolyte. This cell shows a reversible discharge capacity of 55.6 mAh g −1 at 0.2 C rate with the discharge voltage at 1.19 V (vs. Zn 2+ /Zn). As evidenced by Fourier electron density analysis with powder XRD data, the zinc-inserted phase is confirmed as Zn 0.32 K 0.86 Ni[Fe(CN) 6 ] 0.954 (H 2 O) 0.766 (ZKNF-086), and the position of the zinc ion in ZKNF-086 is revealed as the center of the large interstitial cavities of the cubic PB. Compared to KNF-086, ZKNF-086 exhibits a decreased unit cell parameter (0.9%) and volume (2.8%) while the interatomic distance of d (Fe-C) increased (from 1.84 to 1.98 A), and the oxidation state of iron decreases from 3 to 2.23. The organic electrolyte system provides higher zinc cycling efficiency (>99.9%) than the aqueous system (ca. 80%). This result demonstrates an organic electrolyte-based ZIB, and offers a crucial basis for understanding the electrochemical intercalation chemistry of zinc ions in organic electrolytes.

Vertically Aligned Two-Dimensional Graphene-Metal Hydroxide Hybrid Arrays for Li-O2 Batteries.

Lithium oxygen batteries (LOBs) are a very promising upcoming technology which, however, still suffers from low lifespan and dramatic capacities fading. Solid discharge products increase the contact resistance and block the electrochemically active electrodes. The resulting high oxidative potentials and formation of Li2CO3 due to electrolyte and carbon electrode decomposition at the positive electrode lead to irreversible deactivation of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) sites. Here we demonstrate a facile strategy for the scalable production of a new electrode structure constituted of vertically aligned carbon nanosheets and metal hydroxide (M(OH)x@CNS) hybrid arrays, integrating both favorable ORR and OER active materials to construct bifunctional catalysts for LOBs. Excellent lithium-oxygen battery properties with high specific capacity of 5403 mAh g-1 and 12123 mAh g-1 referenced to the carbon and M(OH)x weight, respectively, long cyclability, and low charge potentials are achieved in the resulting M(OH)x@CNS cathode architecture. The properties are explained by improved O2/ion transport properties and spatially limited precipitation of Li2O2 nanoparticles inside interstitial cavities resulting in high reversibility. The strategy of creating ORR and OER bifunctional catalysts in a single conductive hybrid component may pave the way to new cathode architectures for metal air batteries.