High-Performance Lithium Storage Achieved by Chemically Binding Germanium Nanoparticles with N‑Doped Carbon

Germanium (Ge) is a promising anode material for lithium ion batteries due to its high theoretical capacity. However, its poor cycling stability associated with its large volume changes during discharging and charging processes are urgent problems to solve. This provides opportunities to engineer materials to overcome these issues. Here, we demonstrated a facile and scalable method to synthesize Ge nanoparticles/N-doped carbon monolith with a hierarchically porous structure. The combination of a solvothermal method and annealing treatment results in a well-connected three-dimensional N-doped carbon network structure consisting of Ge nanoparticles firmly coated by the conducting carbon. Such a hierarchical architecture features multiple advantages, including a continuous conductive carbon network, binding the Ge nanoparticles with carbon through a Ge–N chemical bond, and a porous structure for alleviating volume expansion of Ge particles. When serving as an anode for lithium ion batteries, the as-formed hybrid displays high capacities up to 1240.3 mAh g^–1 at 0.1 A g^–1 and 813.4 mAh g^–1 at 0.5 A g^–1 after 90 cycles, and at the same time, it also exhibits good cycling stability and excellent rate capability

Carbon-Anchored MnO Nanosheets as an Anode for High-Rate and Long-Life Lithium-Ion Batteries

Developing electrode materials with high rate as well as prolonged cycle is particularly necessary for the ever-growing market penetration of electric vehicles and hybrid electric vehicle. Herein, we demonstrate a facile and efficient strategy to synthesize MnO/C hybrid via freeze-drying followed by thermal treatment in N₂ atmosphere. The MnO nanosheets are firmly anchored onto carbon layers to form MnO/C hybrid. When used as an anode in lithium-ion batteries, the typical MnO/C hybrid displays a high initial Coulombic efficiency of 83.1% and delivers a high capacity of 1449.8 mAh g^–1 after 100 cycles at 0.3 A g^–1. Furthermore, the typical MnO/C hybrid can still maintain significantly high capacity of 1467.0 mAh g^–1 after 2000 cycles at 5 A g^–1, which may be the best performance reported so far for MnO-based materials. The superior electrochemical performance of the MnO/C hybrid may be attributed to its unique microstructure features such as effective conductive pathway of carbon sheets, firm connection between MnO and carbon sheets, and small-sized MnO

Core–Shell Bimetallic Carbide Nanoparticles Confined in a Three-Dimensional N‑Doped Carbon Conductive Network for Efficient Lithium Storage

Carbides represent a class of functional materials with unique properties and increasing importance. However, the harsh conditions in conventional synthetic strategies impede subtle control over size and morphology of carbides, which is highly imperative for their practical applications. Herein, we report a facile, simple approach to prepare porous Co₃ZnC/N-doped carbon hybrid nanospheres. In this structure, the Co₃ZnC nanoparticles exhibit a core–shell structure and they are uniformly confined in N-doped carbon conductive networks forming rather uniform nanospheres. The hybrid nanospheres have a specific surface area as high as 170.5 m² g^–1. When evaluated as an anode material for lithium ion batteries, they show an excellent lithium storage performance, which can be attributed to the combined effect of the core–shell Co₃ZnC nanoparticles, the pore structure and the highly conductive and elastic N-doped carbon networks. This work provides an efficient route for the facile production of nanoscale carbides with desirable manipulation over size and morphology for many of important applications

Micro-Intertexture Carbon-Free Iron Sulfides as Advanced High Tap Density Anodes for Rechargeable Batteries

Numerous materials have been considered as promising electrode materials for rechargeable batteries; however, developing efficient materials to achieving good cycling performance and high volumetric energy capacity simultaneously remains a great challenge. Considering the appealing properties of iron sulfides, which include low cost, high theoretical capacity, and favorable electrochemical conversion mechanism, in this work, we demonstrate the feasibility of carbon-free microscale Fe_1–<i>x</i>S as high-efficiency anode materials for rechargeable batteries by designing hierarchical intertexture architecture. The as-prepared intertexture Fe_1–<i>x</i>S microspheres constructed from nanoscale units take advantage of both the long cycle life of nanoscale units and the high tap density (1.13 g cm^–3) of the micro-intertexture Fe_1–<i>x</i>S. As a result, high capacities of 1089.2 mA h g^–1 (1230.8 mA h cm^–3) and 624.7 mA h g^–1 (705.9 mA h cm^–3) were obtained after 100 cycles at 1 A g^–1 in Li-ion and Na-ion batteries, respectively, demonstrating one of the best performances for iron sulfide-based electrodes. Even after deep cycling at 20 A g^–1, satisfactory capacities could be retained. Related results promote the practical application of metal sulfides as high-capacity electrodes with high rate capability for next-generation rechargeable batteries

Na Storage Capability Investigation of a Carbon Nanotube-Encapsulated Fe_1–<i>x</i>S Composite

A promising anode material consisting of Fe_1–<i>x</i>S nanoparticles and bamboo-like carbon nanotubes (CNTs) has been designed and prepared by an effective in situ chemical transformation. The resultant Fe_1–<i>x</i>S@CNTs with a three-dimensional network not only provide high conductivity paths and channels for electrons and ions but also offer the combined merits of iron sulfide and CNTs in electrochemical energy storage applications, leading to outstanding performance as an anode material for sodium-ion batteries. When tested in a half-cell, a high capacity of 449.2 mAh g^–1 can be retained after 200 cycles at 500 mA g^–1, corresponding to a high retention of 97.4%. Even at 8000 mA g^–1, a satisfactory capacity of 326.3 mAh g^–1 can be delivered. When tested in the full cell, a capacity of 438.5 mAh g^–1 with capacity retention of 85.0% is manifested after 80 cycles based on the mass of the anode. The appealing structure and electrochemical performance of this material demonstrate its great promise for applications in practical rechargeable batteries

Effects of isoflurane on MAP, CoBF, and DPOAE.

<p>1.15% (isoflurane dose 1), 2.30 vol% (isoflurane dose 2), and 3.45 vol% (isoflurane dose 3) were inhaled for 2 h. A, MAP values. * P<0.05 MAP 20 min after inhalation vs B. # P<0.01 MAP 20 min after inhalation vs B. § P<0.005 MAP 20 min after inhalation vs B. B, CoBF values. * P<0.01 CoBF 25 min after inhalation vs B. # P<0.005 CoBF 25 min after inhalation vs B. C, DPOAE amplitudes. * P<0.01 DPOAE amplitude 2 h after inhalation vs B. # P<0.01 DPOAE amplitude 1 h after the stop of isoflurane dose 2 vs B. § P<0.05 DPOAE amplitude 1 h after the stop of isoflurane dose 3 vs DPOAE amplitude 1 h after the stop of isoflurane dose 2.</p

Economical Synthesis and Promotion of the Electrochemical Performance of Silicon Nanowires as Anode Material in Li-Ion Batteries

Silicon is considered as one of the most promising anodes alternative, with a low voltage and a high theoretical specific capacity of ∼4200 mAh/g, for graphite in lithium-ion batteries. However, the large volume change and resulting interfacial changes of the silicon during cycling cause unsatisfactory cycle performance and hinder its commercialization. In this study, electrochemical performance and interfacial properties of silicon nanowires (SiNWs) which are prepared by the Cu-catalyzed chemical vapor deposition method, with 1 M LiPF₆/EC + DMC (1:1 v/v) containing 2 wt % or no vinylene carbonate (VC) electrolyte, are investigated by using different electrochemical and spectroscopic techniques, i.e., cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques. It is shown that the addition of VC has greatly enhanced the cycling performance and rate capability of SiNWs and should have an impact on the wide utilization of silicon anode materials in Li-ion batteries

DNA Catalysis of a Normally Disfavored RNA Hydrolysis Reaction

We recently used in vitro selection to identify many deoxyribozymes that catalyze DNA phosphodiester bond hydrolysis and create 5′-phosphate and 3′-hydroxyl termini. Alternatively, numerous deoxyribozymes have been identified for catalysis of RNA cleavage by 2′-hydroxyl transesterification, forming 2′,3′-cyclic phosphate and 5′-hydroxyl termini. In this study, we investigated the ability of DNA to catalyze RNA cleavage by hydrolysis rather than transesterification, although normally the hydrolysis reaction is substantially disfavored relative to transesterification. Via a series of in vitro selection experiments, we found that reselection of a DNA-hydrolyzing deoxyribozyme leads either to transesterification or hydrolysis, depending on exclusion or inclusion of a stringent selection pressure for hydrolysis. An entirely new selection starting from a random DNA pool, using an all-RNA substrate and imposing the same selection pressure, also leads to RNA hydrolysis. Collectively, these results establish experimentally that small DNA sequences have the catalytic ability to direct a chemical reaction down a disfavored pathway, even when a more favorable mechanism is readily available. Our view of DNA catalysis is therefore expanded beyond merely increasing the rates of reactions that would have occurred more slowly without the catalyst

Scanning electron microscopy observations of OHCs.

<p>OHCs were well-arranged with normal ciliary structure at three doses of propofol (3a, b, c) and 1.15 vol% isoflurane (3d). Following inhalation of 2.30 vol% isoflurane, certain areas of OHCs were disordered and showed swelling and lodging cilia (3e)(marked by arrows). Following inhalation of 3.45 vol% isoflurane, numerous OHCs had disparate cilia and OHCs were absent in some regions (3f) (marked by asterisk).</p

The correlations between age, education and MoCA-BJ cognitive domains and the correlation between cognitive domains and MoCA-BJ total score.

<p>MoCA-BJ, Beijing version of the Montreal Cognitive Assessment</p><p>The correlations between age, education and MoCA-BJ cognitive domains and the correlation between cognitive domains and MoCA-BJ total score.</p