γ-Ray Irradiation-Derived MnO/rGO Composites for High Performance Lithium Ion Batteries

We report a γ-ray irradiation reduction method to prepare MnO/reduced graphene oxide (rGO) nanocomposite for the anode of lithium ion batteries. γ-Ray irradiation provides a clean way to generate homogeneously dispersed MnO nanoparticles with finely tuned size on rGO surface without the use of surfactant. The MnO/rGO composite enables a fully charge/discharge in 2 min to gain a reversible specific capacity of 546 (mA·h)/g which is 45% higher than the theoretical value of commercial graphite anode.     

Studies on Electrochemical Property of LiFePO4/C as Cathode Material for Lithium Ion Batteries

IntroductionLithium ion batteries are key components of mobiletelephones and portable computers.Among the knownLi-intercalation materials for lithium ion battery cath-odes,LiCoO2,LiNiO2,and LiMn2O4have been stud-ied extensively[1—3].LiCoO2is nowused in c…     

A Two-Dimensional Mesoporous Polypyrrole–Graphene Oxide Heterostructure as a Dual-Functional Ion Redistributor for Dendrite-Free Lithium Metal Anodes

Guiding the lithium ion (Li-ion) transport for homogeneous, dispersive distribution is crucial for dendrite-free Li anodes with high current density and long-term cyclability, but remains challenging for the unavailable well-designed nanostructures. Herein, we propose a two-dimensional (2D) heterostructure composed of defective graphene oxide (GO) clipped on mesoporous polypyrrole (mPPy) as a dual-functional Li-ion redistributor to regulate the stepwise Li-ion distribution and Li deposition for extremely stable, dendrite-free Li anodes. Owing to the synergy between the Li-ion transport nanochannels of mPPy and the Li-ion nanosieves of defective GO, the 2D mPPy-GO heterostructure achieves ultralong cycling stability (1000 cycles), even tests at 0 and 50 °C, and an ultralow overpotential of 70 mV at a high current density of 10.0 mA cm⁻², outperforming most reported Li anodes. Furthermore, mPPy-GO-Li/LiCoO₂ full batteries demonstrate remarkably enhanced performance with a capacity retention of >90 % after 450 cycles. Therefore, this work opens many opportunities for creating 2D heterostructures for high-energy-density Li metal batteries.     

Double Hydrothermal Synthesis of Graphene Supported TiO2（b） Nanosheets as Anode Materials for Lithium Ion Batteries

The synthesis of graphene supported TiO2（b） nanosheets by a double hydrother- mal method for lithium storage was reported. The titanate nanosheets synthesized by the first hydrothermal progress and the graphene oxide obtained by the oxidation of graphite were hydrothermally treated together to fabricate the TiO2（b）/graphene composite. The electrochemical measurements illustrate that the graphene supporter obviously improves the cyclic performance of TiO2（b）, which can be attributed to the better dispersion and the decrease of resistance for the TiO2（b） nanosheets in the composite.     

Electrochemical Sensor for Detection of p-Nitrophenol Based on Nickel Oxide Nanoparticles/α-Cyclodextrin Functionalized Reduced Graphene Oxide

p-Nitrophenol (p−NP) is a high priority toxic pollutant and that has harmful effects on human, animals and plants. Thus, the detection and determination of p−NP present in the environment is an urgent as well as highly important requisite. The present article, therefore focused on the construction of a novel electrochemical sensor based on NiO nanoparticles/α-cyclodextrin functionalized reduced graphene oxide modified glassy carbon electrode (NiO−NPs-α-CD-rGO-GCE) for the selective and sensitive detection of p−NP. UV-vis, high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction pattern (SAED) and X-ray diffraction (XRD) analysis confirms the formation of highly pure NiO nanoparticles. Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and cyclic voltammetry (CV) were used to characterize the step-wise electrode modification process. DPV was carried out to quantify p−NP within the concentration range of 1−10 μM and found the detection limit of 0.12 nM on the basis of the signal-to-noise ratio S/N=3. The electrode can able to detect different isomers of nitrophenols. Interferences of other pollutants such as phenol, p-aminophenol, o- and m- nitrophenol, 4-chlorophenol, 2,6-dichlorophenol and ions like K⁺, Cd²⁺, Cl⁻, SO₄²⁻ did not affect the sensing of p−NP. The newly developed sensor exhibited diffusion controlled kinetics and had excellent sensitivity, selectivity and reproducibility for the detection of p−NP. The electrode showed good recoveries in real sample analysis.     

Engineering Functional Interface with Built-in Catalytic and Self-Oxidation Sites for Highly Stable Lithium–Sulfur Batteries

Lithium−sulfur (Li−S) batteries have attracted great attention due to their high theoretical energy density. The rapid redox conversion of lithium polysulfides (LiPS) is effective for solving the serious shuttle effect and improving the utilization of active materials. The functional design of the separator interface with fast charge transfer and active catalytic sites is desirable for accelerating the conversion of intermediates. Herein, a graphene-wrapped MnCO₃ nanowire (G@MC) was prepared and utilized to engineer the separator interface. G@MC with active Mn²⁺ sites can effectively anchor the LiPS by forming the Mn−S chemical bond according to our theoretical calculation results. In addition, the catalytic Mn²⁺ sites and conductive graphene layer of G@MC could accelerate the reversible conversion of LiPS via the spontaneous “self-redox” reaction and the rapid electron transfer in electrochemical process. As a result, the G@MC-based battery exhibits only 0.038 % capacity decay (per cycle) after 1000 cycles at 2.0 C. This work affords new insights for designing the integrated functional interface for stable Li−S batteries.     

Band Structure Engineering of Single Pt Atoms on Fe−TiO2 for Enhanced Photocatalytic Performance

Single atomic site catalysts display the maximal atom-utilization efficiency, unique structural properties, and remarkable enhancements on catalytic activity. Herein, single Pt atoms loaded Fe−TiO₂ catalysts were prepared. Fe³⁺ doping leads to the formation of oxygen vacancies and improve the interaction between TiO₂ and Pt. Single Pt atoms are thus anchored and effectively modify the local energy band structure of TiO₂. The optimized local band structures improve the intrinsic photoexcitation of Pt/Fe−TiO₂, promote the separation of photogenerated carriers, and extend the lifetime of photogenerated carriers. Meanwhile, the electrons transfer from the excited dyes to the conduction band edge of Pt/Fe−TiO₂ is also facilitated due to the shift-down of the conduction band edge. Therefore, with the increase of the Pt content (till up to 0.6 wt%), the photocatalytic performance of Pt/ Fe−TiO₂ with the confined single Pt atoms is significantly boosted in either the intrinsic or the sensitized photocatalytic process.     

Graphene Oxide Doped Poly（hydroxymethylated-3,4- ethylenedioxythiophene）： Enhanced Sensitivity for Electrochemical Determination of Rutin and Ascorbic Acid

A novel graphene oxide doped poly(hydroxymethylated-3,4-ethylenedioxythiophene)(PEDOT-MeOH/GO) composite film was synthesized and utilized as an efficient electrode material for simultaneous detection of rutin and ascorbic acid(AA). PEDOT-MeOH/GO films were synthesized on glassy carbon electrode(GCE) by a facile one-step electrochemical approach and were characterized by scanning electron microscopy, UV-Vis spectroscopy, FTIR spectra and electrochemical methods. Then the PEDOT-MeOH/GO/GCE was applied successfully in the simultaneous detection of rutin and AA. The results showed that the oxidation peak currents of rutin and AA obtained at the PEDOT-MeOH/GO/GCE were much higher than those at the traditional conducting polymer PEDOT/GO/GCE, PEDOT-MeOH/GCE, PEDOT/GCE and bare GCE. Under optimized conditions, the linear ranges for rutin and AA are 20 nmol/L-10 μmol/L and 8 μmol/L-1 mmol/L, respectively. The detection limit is 6 nmol/L for rutin and 2 μmol/L for AA(S/N = 3), which are lower than those of the reported electrochemical sensors.     

Electrochemical Sensor Based on Magnetic Fe3O4–Reduced Graphene Oxide Hybrid for Sensitive Detection of Binaphthol

Russian Journal of Electrochemistry - Naphthol is an environmental pollutant with highly toxic and corrosive. Naphthol can be absorbed by the body easily through the skin, and can cause serious...     

New Oxyhalide Solid Electrolytes with High Lithium Ionic Conductivity >10 mS cm−1 for All-Solid-State Batteries

All-solid-state batteries (ASSBs) with inorganic solid electrolytes (SEs) have attracted significant interest as next-generation energy storage. Halides such as Li₃YCl₆ are promising candidates for SE because they combine high oxidation stability and deformability. However, the ionic conductivities of halide SEs are not as high as those of other SEs, especially sulfides. Here, we discover new lithium-metal-oxy-halide materials, LiMOCl₄ (M=Nb, Ta). They exhibit extremely high ionic conductivities of 10.4 mS cm⁻¹ for M=Nb and 12.4 mS cm⁻¹ for M=Ta, respectively, even in cold-pressed powder forms at room temperature, which are comparable to or surpass those of organic liquid electrolytes used in lithium-ion batteries. Bulk-type ASSB cells using the oxyhalides as the cathode SE demonstrate an outstanding rate capability with a capacity retention of 80 % at 5 C/0.1 C. We believe that the proposed oxyhalides are promising SE candidates for the practical applications of ASSBs.     

Novel Gel—like Process for Synthesizing Submicron LiaNi0.8Co0.2O2 Powders Used in Lithium Ion Batteries

A novel gel-like process has been developed for synthesizing LiaNi0.8Co0.2O2 powders,using citric acid as a chelating agent. This process improves the homogeneity of constituent cation and enhances their reactivity in the obtained precursor. The results of electrochemical test demonstrated that these materials exhibited excellent electrochemical properties. Its initial capacity reached 181.6 mAh/g and reversible efficiency at the first cycle is about 88.6%.     

General Synthesis of Sulfonate-Based Metal–Organic Framework Derived Composite of MxSy@N/S-Doped Carbon for High-Performance Lithium/Sodium Ion Batteries

A general and simple strategy is realized for the first time for the preparation of metal sulfide (M_xS_y) nanoparticles immobilized into N/S co-doped carbon (NSC) through a one-step pyrolysis method. The organic ligand 1,5-naphthalenedisulfonic acid in the metal–organic framework (MOF) precursor is used as a sulfur source, and metal ions are sulfurized in situ to form M_xS_y nanoparticles, resulting in the formation of M_xS_y/NSC (M=Fe, Co, Cu, Ni, Mn, Zn) composites. Benefiting from the M_xS_y nanoparticles and conductive carbon, a synergistic effect of the composite is achieved. For instance, the composite of Fe₇S₈/NSC as an anode displays excellent long-term cycling stability in lithium/sodium ion batteries. At 5 A g⁻¹, large capacities of 645 mA h g⁻¹ and 426.6 mA h g⁻¹ can be retained after 1500 cycles for the lithium-ion battery and after 1000 cycles for the sodium-ion battery, respectively.     

A Novel Electrochemical Sensor Based on Reduced Graphene Oxide–TiO2 Nanocomposites with High Selectivity for the Determination of Hydroxychloroquine

Russian Journal of Electrochemistry - A simply sensitive sensor based on a reduced graphene oxide–TiO2 nanocomposite modified glassy carbon electrode (RGO–TiO2/GCE) was developed for...     

Starch-Based Superabsorbent Hydrogel with High Electrolyte Retention Capability and Synergistic Interface Engineering for Long-Lifespan Flexible Zinc−Air Batteries

The advent of wearable electronics has strongly stimulated advanced research into the exploration of flexible zinc−air batteries (ZABs) with high theoretical energy density, high inherent safety, and low cost. However, the half-open battery structure and the high concentration of alkaline aqueous environment pose great challenges on the electrolyte retention capability and the zinc anode stability. Herein, a starch-based superabsorbent hydrogel polymer electrolyte (SSHPE) with high ionic conductivity, electrolyte absorption and retention capabilities, strong alkaline resistance and high zinc anode stability has been designed and applied in ZABs. Experimental and calculational analyses probe into the root of the superiority of SSHPEs, confirming the significance of the carboxyl functional groups along their polymer chains. These features endow the as-fabricated ZAB a long cycle life of 300 h, much longer than that with commonly used poly(vinyl alcohol)-based electrolyte.     

Understanding the High-Performance Anode Material of CoC2O4⋅2 H2O Microrods Wrapped by Reduced Graphene Oxide for Lithium-Ion and Sodium-Ion Batteries

Metal oxalate has become a most promising candidate as an anode material for lithium-ion and sodium-ion batteries. However, capacity decrease owing to the volume expansion of the active material during cycling is a problem. Herein, a rod-like CoC₂O₄⋅2 H₂O/rGO hybrid is fabricated through a novel multistep solvo/hydrothermal strategy. The structural characteristics of the CoC₂O₄⋅2 H₂O microrod wrapped using rGO sheets not only inhibit the volume variation of the hybrid electrode during cycling, but also accelerate the transfer of electrons and ions in the 3 D graphene network, thereby improving the electrochemical properties of CoC₂O₄⋅2 H₂O. The CoC₂O₄⋅2 H₂O/rGO electrode delivers a specific capacity of 1011.5 mA h g⁻¹ at 0.2 A g⁻¹ after 200 cycles for lithium storage, and a high capacity of 221.1 mA h g⁻¹ at 0.2 A g⁻¹ after 100 cycles for sodium storage. Moreover, the full cell CoC₂O₄⋅2 H₂O/rGO//LiCoO₂ consisting of the CoC₂O₄⋅2 H₂O/rGO anode and LiCoO₂ cathode maintains 138.1 mA h g⁻¹ after 200 cycles at 0.2 A g⁻¹ and has superior long-cycle stability. In addition, in situ Raman spectroscopy and in situ and ex situ X-ray diffraction techniques provide a unique opportunity to understand fully the reaction mechanism of CoC₂O₄⋅2 H₂O/rGO. This work also gives a new perspective and solid research basis for the application of metal oxalate materials in high-performance lithium-ion and sodium-ion batteries.     

Evolution of Stabilized 1T-MoS2 by Atomic-Interface Engineering of 2H-MoS2/Fe−Nx towards Enhanced Sodium Ion Storage

Metallic conductive 1T phase molybdenum sulfide (MoS₂) has been identified as promising anode for sodium ion (Na⁺) batteries, but its metastable feature makes it difficult to obtain and its restacking during the charge/discharge processing result in part capacity reversibility. Herein, a synergetic effect of atomic-interface engineering is employed for constructing 2H-MoS₂ layers assembled on single atomically dispersed Fe−N−C (SA Fe−N−C) anode material that boosts its reversible capacity. The work-function-driven-electron transfer occurs from SA Fe−N−C to 2H-MoS₂ via the Fe−S bonds, which enhances the adsorption of Na⁺ by 2H-MoS₂, and lays the foundation for the sodiation process. A phase transfer from 2H to 1T/2H MoS₂ with the ferromagnetic spin-polarization of SA Fe−N−C occurs during the sodiation/desodiation process, which significantly enhances the Na⁺ storage kinetics, and thus the 1T/2H MoS₂/SA Fe−N−C display a high electronic conductivity and a fast Na⁺ diffusion rate.     

Ionic Liquid Electrolyte with Weak Solvating Molecule Regulation for Stable Li Deposition in High-Performance Li−O2 Batteries

Li−O₂ batteries with bis(trifluoromethanesulfonyl)imide-based ionic liquid (TFSI-IL) electrolyte are promising because TFSI-IL can stabilize O₂⁻ to lower charge overpotential. However, slow Li⁺ transport in TFSI-IL electrolyte causes inferior Li deposition. Here we optimize weak solvating molecule (anisole) to generate anisole-doped ionic aggregate in TFSI-IL electrolyte. Such unique solvation environment can realize not only high Li⁺ transport parameters but also anion-derived solid electrolyte interface (SEI). Thus, fast Li⁺ transport is achieved in electrolyte bulk and SEI simultaneously, leading to robust Li deposition with high rate capability (3 mA cm⁻²) and long cycle life (2000 h at 0.2 mA cm⁻²). Moreover, Li−O₂ batteries show good cycling stability (a small overpotential increase of 0.16 V after 120 cycles) and high rate capability (1 A g⁻¹). This work provides an effective electrolyte design principle to realize stable Li deposition and high-performance Li−O₂ batteries.     

Electrochemical Enabled Cascade Phosphorylation of N−H/O−H/S−H Bonds with P−H Compounds: An Efficient Access to P(O)-X Bonds

An electrochemical three component cascade phosphorylation reaction of various heteroatoms-containing nucleophiles including carbazoles, indoles, phenols, alcohols, and thiols with Ph₂PH has been established. Electricity is used as the “traceless” oxidant and water and air are utilized as the “green” oxygen source. All kinds of structurally diverse organophosphorus compounds with P(O)-N/P(O)-O/P(O)-S bonds are assembled in moderate to excellent yields (three categories of phosphorylation products, 50 examples, up to 97 % yield). A tentative free radical course is put forward to rationalize the reaction procedure.     

Synthesis and Examination of Electrolytic Sodium–Vanadium Oxide Compounds Intended for Cathodes of Lithium Batteries: The Mechanism of Formation of Electrolytic Bronze β-NaxV2O5

To determine the mechanism responsible for the formation of electrolytic sodium–vanadium oxide bronze e-Na _x V₂O₅, synthesized earlier from acid vanadyl sulfate electrolyte, -bronze i-Na _x V₂O₅is synthesized by exposing electrolytic oxide e-V₂O₅in the same sodium-containing electrolyte under open-circuit conditions, with a subsequent annealing of the sample. It is established that the two modifications of -bronze (e-Na _x V₂O₅and i-Na _x V₂O₅) are identical and that electrolytic precursors of -bronze Na _x V₂O₅form via an ion-exchange mechanism.     

Preparation and Electrochemical Performance of Cobalt-free Cathode Material Ba0.5Sr0.5Fe0.9Nb0.1O3-δ for Intermediate-temperature Solid Oxide Fuel Cells

Perovskite oxide Ba0.5Sr0.5Fe0.9Nb0.1O3-δ（BSFN） as a cobalt-free cathode for intermediate-temperature solid oxide fuel cells（IT-SOFCs） on the Ce0.5Sm0.2O1.9（SDC） and La0.9Sr0.1Ga0.8Mg0.23O3-δ（LSGM） electrolytes was prepared and investigated. The single phase BSFN oxide with a cubic perovskite structure and relatively high elec- trical conductivities was obtained after sintering at 1250℃ for 10 h in air. The BSFN cathode exhibited excellent chemical stability on the SDC and LSGM electrolytes at temperatures below 950 ℃. The area specific resistance of the BSFN cathode on the SDC and LSGM electrolytes were 0.024 and 0.021 Ω·cm2 at 800℃, respectively. The maximum power densities of the single cell with BSFN cathode in 300 μm-thick SDC and LSGM electrolytes achieved 414 and 516 mW/cm2 at 800℃, respectively. These results show that the BSFN material is a promising co- bait-free cathode candidate to be used in IT-SOFCs. A combination of the BSFN cathode and LSGM electrolyte is preferred owing to its excellent electrochemical performance.