다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

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A review of electrode materials for electrochemical supercapacitors

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

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Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Rechargeable lithium-sulfur batteries.

Silicon (Si) anode materials have received much attention on account of their unparalleled theoretical specific capacity, but they suffer from huge volumetric expansion and particle pulverization, which leads to rapid capacity fading and poor electrical conductivity as well. In this work, a quaternary silicon/carbon (Si/C) composite anode material is proposed which combines the advantages of both graphene and the three-dimensional carbon framework through rational structural design and simple synthesis methods. Nanosilicon/carbon nanofibers/pyrolytic carbon (SCC) composite particles are first synthesized by spray drying and pyrolysis, which are then wrapped by graphene nanosheets through a second spray drying and pyrolysis process to obtain the final product (SGCC). In this composite, a 3D carbon skeleton composed of carbon nanofibers and pyrolytic carbon serves as an electric conductive matrix that supports and stabilizes Si nanoparticles, while graphene nanosheets wrapped on the surface further improve the conductivity and structure stability of the composite particles, and isolate the particles from direct contact with electrolytes. Meanwhile, the rich pores of the composite particles can effectively provide space for the volume expansion of Si during lithiation. As a consequence, the as-prepared SGCC composite shows a high initial Coulomb efficiency of 84.7%, a high reversible capacity of 2150.8 mA h g–1, and a good capacity retention rate of 83.75% after 100 cycles. 

Graphene-Wrapped Composites of Si Nanoparticles, Carbon Nanofibers, and Pyrolytic Carbon as Anode Materials for Lithium-Ion Batteries

Li-rich layered oxides (LLOs) are regarded as one of the most desirable cathode materials due to their high specific capacity. Nevertheless, the irreversible oxygen release associated with low oxygen stability prevents their widespread application. Herein, an improved oxygen redox reversibility was achieved by constructing Ni2+-O2--Ni2+ configurations. Superconducting Quantum Interference Device (SQUID) magnetometry measurements are used to track the evolution of the Ni2+-O2--Ni2+ configuration during the electrochemical process. The strongest 180° superexchange interaction in the Ni2+-O2--Ni2+ configuration, derived from the inevitable Li/Ni mixing in LLOs, regulates the local structure to form the ferrimagnetic (FiM) structural units. Consequently, the FiM structural units prevent the irreversible oxygen release and endow LLOs with high initial Coulombic efficiency (ICE). This work emphasizes the importance of the Ni2+-O2--Ni2+ configuration for LLOs with high reversible capacity and proposes a synthesis approach to modulate the amount of FiM structural units.

Tuning Local Structural Configurations to Improve Oxygen-Redox Reversibility of Li-Rich Layered Oxides.


 As an indispensable part of the electrodes in lithium-ion batteries, conductive additives play an important role not only in electron transport, but in the electrode structure as they form carbon-binder domains (CBD) that are located in the voids among active materials. The latter is expected to have a significant effect on Li-ion diffusion in the electrode, but has been paid little attention in previous research reports. Accordingly, two typical types of conductive additives with distinct structures, including carbon black and graphene, are employed in LiNi0.8Co0.1Mn0.1O2 (NCM 811) electrodes to investigate this important issue in this work by quantitative analysis of Li-ion diffusion resistance (Rion) and charge transfer resistance (Rct) by electrochemical impedance spectroscopy (EIS) using a symmetric cell configuration combined with the transmission line model. The EIS results confirm that addition of graphene is more effective to enhance Li-ion diffusion comparing with carbon black. Meanwhile, for constructing better CBD, graphene and carbon black are equally crucial, and the combination of both is necessary to achieve the best rate performance, as Li-ion diffusion, electronic conductivity, and charge transfer process which is affected by the electroactive surface area in the electrode should be taken into consideration at the same time.

Unraveling the Effect of Conductive Additives on Li-Ion Diffusion Using Electrochemical Impedance Spectroscopy: A Case Study of Graphene vs. Carbon Black

A Flexible Composite Film Electrode and Supercapacitor Based on Combined Effect between Graphene Oxide and Graphene

Open AccessRenewablesRESEARCH ARTICLES14 Jan 2023Hierarchically Structured 3D Carbon Based Integrated Electrodes with Enhanced Pseudocapacitance and Deformability Bo-Hao Xiao, Wei-Jie Cai, Pei-Yuan Wu, Kang Xiao and Zhao-Qing Liu Bo-Hao Xiao Google Scholar More articles by this author , Wei-Jie Cai Google Scholar More articles by this author , Pei-Yuan Wu Google Scholar More articles by this author , Kang Xiao Google Scholar More articles by this author and Zhao-Qing Liu Google Scholar More articles by this author https://doi.org/10.31635/renewables.023.202200009 SectionsSupplemental MaterialAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Compressible supercapacitors are playing an increasingly significant role in flexible sensors and wearable electronic devices. However, the integration of mechanical compressibility and excellent electrochemical performance into a single device remains a challenge. Herein, we demonstrate a compressible and high-performance supercapacitor based on an elastomer N-doped carbon foam with hierarchical carbon nanotubes. Hierarchically structured Fe3[email protected] carbon nanotubes/N-doped carbon foam and [email protected] carbon nanotubes/N-doped carbon foam have been synthesized via a simple and universal self-catalytic strategy. The hierarchical structural features of self-catalytic N-doped carbon nanotubes can serve as a cushion when the composite is subjected to an external force, exhibiting excellent mechanical properties with a maximum compressive strain of 80% and fatigue resistance of 1000 cycles. Moreover, the different electroactive potentials of the transition metal species in the composites afford the assembled device to possess a maximum operating voltage of 1.4 V, which shows a maximum energy density of ∼10.74 Wh kg−1 (0.084 mWh cm−3) at the power density of ∼179.2 W kg−1 (1.4 mWh cm−3), and retains 88.4% of the original capacitance after 20 000 charge-discharge cycles, even at a strain of 80%. This work paves the way for controllable fabrication of compressible electrodes and supercapacitors. Download figure Download PowerPoint Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentVolume 0Issue jaPage: 1-27Supporting Information Copyright & Permissions© 2023 Chinese Chemical Society Downloaded 1 times PDF downloadLoading ... 

Zhaoping Liu

Papers

Graphene-Wrapped Composites of Si Nanoparticles, Carbon Nanofibers, and Pyrolytic Carbon as Anode Materials for Lithium-Ion Batteries

Tuning Local Structural Configurations to Improve Oxygen-Redox Reversibility of Li-Rich Layered Oxides.

Unraveling the Effect of Conductive Additives on Li-Ion Diffusion Using Electrochemical Impedance Spectroscopy: A Case Study of Graphene vs. Carbon Black

A Flexible Composite Film Electrode and Supercapacitor Based on Combined Effect between Graphene Oxide and Graphene

Hierarchically Structured 3D Carbon Based Integrated Electrodes with Enhanced Pseudocapacitance and Deformability