Abstract
A novel coronavirus disease (COVID-19), caused by infection with SARS-CoV-2, has swept across 31 provinces in China and over 40 countries worldwide. The transition from first symptoms to ...acute respiratory distress syndrome (ARDS) is highly likely to be due to uncontrolled cytokine release. There is an urgent need to identify safe and effective drugs for treatment. Chloroquine (CQ) exhibits a promising inhibitory effect. However, the clinical use of CQ can cause severe side effects. We propose that hydroxychloroquine (HCQ), which exhibits an antiviral effect highly similar to that of CQ, could serve as a better therapeutic approach. HCQ is likely to attenuate the severe progression of COVID-19, inhibiting the cytokine storm by suppressing T cell activation. It has a safer clinical profile and is suitable for those who are pregnant. It is cheaper and more readily available in China. We herein strongly urge that clinical trials are performed to assess the preventive effects of HCQ in both disease infection and progression.
Engineering heterogeneous composite electrodes consisting of multiple active components for meeting various electrochemical and structural demands have proven indispensable for significantly boosting ...the performance of lithium‐ion batteries (LIBs). Here, a novel design of ZnS/Sn heterostructures with rich phase boundaries concurrently encapsulated into hierarchical interconnected porous nitrogen‐doped carbon frameworks (ZnS/Sn@NPC) working as superior anode for LIBs, is showcased. These ZnS/Sn@NPC heterostructures with abundant heterointerfaces, a unique interconnected porous architecture, as well as a highly conductive N‐doped C matrix can provide plentiful Li+‐storage active sites, facilitate charge transfer, and reinforce the structural stability. Accordingly, the as‐fabricated ZnS/Sn@NPC anode for LIBs has achieved a high reversible capacity (769 mAh g−1, 150 cycles at 0.1 A g−1), high‐rate capability and long cycling stability (600 cycles, 645.3 mAh g−1 at 1 A g−1, 92.3% capacity retention). By integrating in situ/ex situ microscopic and spectroscopic characterizations with theoretical simulations, a multiscale and in‐depth fundamental understanding of underlying reaction mechanisms and origins of enhanced performance of ZnS/Sn@NPC is explicitly elucidated. Furthermore, a full cell assembled with prelithiated ZnS/Sn@NPC anode and LiFePO4 cathode displays superior rate and cycling performance. This work highlights the significance of chemical heterointerface engineering in rationally designing high‐performance electrodes for LIBs.
A viable anode material composing of new‐type ZnS/Sn heterostructures with rich phase boundaries concurrently encapsulated into hierarchical interconnected porous nitrogen‐doped carbon frameworks (ZnS/Sn@NPC) is developed for high‐performance lithium ion batteries. Its Li+‐storage mechanism and origins of the superior performance are explicitly elucidated by combining in situ TEM/XRD/Raman studies, a suite of ex situ microscopic and spectroscopic characterizations with theoretical simulations.
Antimony trisulfide‐based materials have drawn growing attention as promising anode candidates for potassium‐ion batteries (PIBs) because of their high capacity and good working potential. Despite ...the extensive investigations on their electrochemical properties, the fundamental reaction mechanisms of Sb2S3 anodes, especially the reaction kinetics, structural changes, and phase evolutions, remain controversial or even largely unknown. Here, using in situ transmission electron microscopy, the entire potassiation–depotassiation cycles of carbon‐coated Sb2S3 single‐crystal nanowires are tracked in real time at the atomic scale. The potassiation of Sb2S3 involves multistep reactions including intercalation, conversion, and two‐step alloying, and the final products are identified as cubic K2S and hexagonal K3Sb. These findings are confirmed by density functional theory calculations. Interestingly, a rocket‐launching‐like nanoparticle growth behavior is observed during alloying reactions, which is driven by the K+ concentration gradient and release of stress. More impressively, the potassiated products (i.e., K3Sb and K2S) can transform into the original Sb2S3 phase during depotassiation, indicating a reversible phase transformation process, as distinct from other metal chalcogenide based electrodes. This work reveals the detailed potassiation/depotassiation mechanisms of Sb2S3‐based anodes and can facilitate the analysis of the mechanisms of other metal chalcogenide anodes in PIBs.
The atomic‐scale potassiation/depotassiation mechanisms of Sb2S3@carbon nanowires are investigated using an in situ transmission electron microscopy and density functional theory calculations. The potassiation involves multistep reactions including intercalation, conversion, and two‐step alloying featured by the growth of K‐Sb alloying nanoparticles that resembles the launching of a rocket. Impressively, the phase transformations are reversible during depotassiation, distinct from other metal chalcogenide‐based electrodes.
The nucleation and growth of Li metal during deposition and the associated dendrite penetration are the critical and fundamental issues influencing the safety and power density of solid‐state lithium ...metal batteries (SSLBs). However, investigations on Li metal deposition/dissolution especially the formation and growth of Li dendrites and their determining factors in the all‐solid‐state electrochemical systems are still lacking. In this work, in situ observations of the Li metal growth process, and defects induced heterogeneous deposition under cathodic load, are reported. By exploiting in situ scanning electron microscopy, along with electrochemical analytical approaches, the spatial distribution and morphological evolution of the deposited Li at the electrode|solid electrolyte interface are obtained and discussed. This investigation reveals that the formation of lithium whiskers is decided by the local Li ion flux and the deposition active sites, which are closely dependent on the content and types of defects in the polycrystalline electrolyte. Moreover, the defect regions exhibit faster Li deposition kinetics and higher nucleation tendency. These results can advance the fundamental understanding of the Li penetration mechanism in SSLBs.
The nucleation and growth of Li whiskers is closely related to the content and types of defects in the polycrystalline electrolyte. High‐quality solid electrolyte (SE) can effectively promote uniformity of Li ion flux and increase the numbers of deposition active sites at the Li|SE interface, thus reducing the inhomogeneity of interface current density distribution and increasing critical current density of the electrolytes.
The properties of high theoretical capacity, low cost, and large potential of metallic sodium (Na) has strongly promoted the development of rechargeable sodium‐based batteries. However, the issues of ...infinite volume variation, unstable solid electrolyte interphase (SEI), and dendritic sodium causes a rapid decline in performance and notorious safety hazards. Herein, a highly reversible encapsulation‐based sodium storage by designing a functional hollow carbon nanotube with Zn single atom sites embedded in the carbon shell (ZnSA‐HCNT) is achieved. The appropriate tube space can encapsulate bulk sodium inside; the inner enriched ZnSA sites provide abundant sodiophilic sites, which can evidently reduce the nucleation barrier of Na deposition. Moreover, the carbon shell derived from ZIF‐8 provides geometric constraints and excellent ion/electron transport channels for the rapid transfer of Na+ due to its pore‐rich shell, which can be revealed by in situ transmission electron microscopy (TEM). As expected, Na@ZnSA‐HCNT anodes present steady long‐term performance in symmetrical battery (>900 h at 10 mA cm−2). Moreover, superior electrochemical performance of Na@ZnSA‐HCNT||PB full cells can be delivered. This work develops a new strategy based on carbon nanotube encapsulation of metallic sodium, which improves the safety and cycling performance of sodium metal anode.
Designing a functional encapsulation‐based sodium storage void with abundant pore structure and enriched Zn single atom sites in the inner wall is presented here. Zn single atoms provide abundant selective sodiophilic nucleation sites. Due to the rich pore structure, ZIF‐derived carbon shells can provide geometric constraints and excellent ion/electron transport channels to maintain fast electron/ion contact, benefiting for encapsulating large amounts of metallic sodium.
Separations and analyses of chiral compounds are important in many fields, including pharmaceutical production, preparation of chemical intermediates, and biochemistry. High‐performance liquid ...chromatography using a chiral stationary phase is regarded as one of the most valuable methods for enantiomeric separation and analysis because it is highly efficient, is broadly applicable, and has powerful separation capability. The focus for development of this method is the identification of novel chiral stationary phases with superior recognition performance and good stability. The present article reviews recent progress in the development of new chiral stationary phases for high‐performance liquid chromatography between January 2018 and June 2021. These newly reported chiral stationary phases are divided into three categories: small organic molecule‐based (cyclodextrin and its derivatives, macrocyclic antibiotics, cinchona alkaloids, and other low molecular weight chiral molecules), macromolecule‐based (cellulose and amylose derivatives, chitin and chitosan derivatives, and synthetic helical polymers) and chiral porous material‐based (chiral metal‐organic frameworks, chiral covalent organic frameworks, and chiral inorganic mesoporous silicas). Each type of chiral stationary phase is discussed in detail.
Metallic bismuth has drawn attention as a promising alloying anode for advanced potassium ion batteries (PIBs). However, serious volume expansion/electrode pulverization and sluggish kinetics always ...lead to its inferior cycling and rate properties for practical applications. Therefore, advanced Bi‐based anodes via structural/compositional optimization and sur‐/interface design are needed. Herein, we develop a bottom‐up avenue to fabricate nanoscale Bi encapsulated in a 3D N‐doped carbon nanocages (Bi@N‐CNCs) framework with a void space by using a novel Bi‐based metal‐organic framework as the precursor. With elaborate regulation in annealing temperatures, the optimized Bi@N‐CNCs electrode exhibits large reversible capacities and long‐duration cyclic stability at high rates when evaluated as competitive anodes for PIBs. Insights into the intrinsic K+‐storage processes of the Bi@N‐CNCs anode are put forward from comprehensive in situ characterizations.
A hierarchical nano Bi@N‐doped carbon nanocage framework with an interior void space was smartly fabricated as competitive anode for K‐ion batteries. Its intrinsic potassium storage behaviors are unveiled via comprehensive in situ characterizations.
Potassium‐ion batteries (PIBs) are promising alternatives to lithium‐ion batteries because of the advantage of abundant, low‐cost potassium resources. However, PIBs are facing a pivotal challenge to ...develop suitable electrode materials for efficient insertion/extraction of large‐radius potassium ions (K+). Here, a viable anode material composed of uniform, hollow porous bowl‐like hard carbon dual doped with nitrogen (N) and phosphorus (P) (denoted as N/P‐HPCB) is developed for high‐performance PIBs. With prominent merits in structure, the as‐fabricated N/P‐HPCB electrode manifests extraordinary potassium storage performance in terms of high reversible capacity (458.3 mAh g−1 after 100 cycles at 0.1 A g−1), superior rate performance (213.6 mAh g−1 at 4 A g−1), and long‐term cyclability (205.2 mAh g−1 after 1000 cycles at 2 A g−1). Density‐functional theory calculations reveal the merits of N/P dual doping in favor of facilitating the adsorption/diffusion of K+ and enhancing the electronic conductivity, guaranteeing improved capacity, and rate capability. Moreover, in situ transmission electron microscopy in conjunction with ex situ microscopy and Raman spectroscopy confirms the exceptional cycling stability originating from the excellent phase reversibility and robust structure integrity of N/P‐HPCB electrode during cycling. Overall, the findings shed light on the development of high‐performance, durable carbon anodes for advanced PIBs.
A viable anode material composed of nitrogen/phosphorus co‐doped hollow porous bowl‐like hard carbon is developed for potassium ion batteries. The resulting anode manifests prominent merits in structure, endowing it with extraordinary K+ storage capability. The K+ storage mechanisms are revealed through in‐depth studies by combining in situ TEM studies, ex situ microscopic, and Raman spectroscopy in conjunction with DFT calculations.
With the development of flexible electronic devices and large‐scale energy storage technologies, functional polymer‐matrix nanocomposites with high permittivity (high‐k) are attracting more attention ...due to their ease of processing, flexibility, and low cost. The percolation effect is often used to explain the high‐k characteristic of polymer composites when the conducting functional fillers are dispersed into polymers, which gives the polymer composite excellent flexibility due to the very low loading of fillers. Carbon nanotubes (CNTs) and graphene nanosheets (GNs), as one‐dimensional (1D) and two‐dimensional (2D) carbon nanomaterials respectively, have great potential for realizing flexible high‐k dielectric nanocomposites. They are becoming more attractive for many fields, owing to their unique and excellent advantages. The progress in dielectric fields by using 1D/2D carbon nanomaterials as functional fillers in polymer composites is introduced, and the methods and mechanisms for improving dielectric properties, breakdown strength and energy storage density of their dielectric nanocomposites are examined. Achieving a uniform dispersion state of carbon nanomaterials and preventing the development of conductive networks in their polymer composites are the two main issues that still need to be solved in dielectric fields for power energy storage. Recent findings, current problems, and future perspectives are summarized.
1D/2D carbon nanomaterial‐polymer dielectric composites are a promising way to realize excellent dielectric properties and high energy density with low filler concentration, which are essential in power energy storage application. Progress in recent years is summarized and the advantages and disadvantages of different strategies are identified to provide clearer paths for researchers in this field.
Dielectric capacitors with a high operating temperature applied in electric vehicles, aerospace and underground exploration require dielectric materials with high temperature resistance and high ...energy density. Polyimide (PI) turns out to be a potential dielectric material for capacitor applications at high temperatures. In this review, the key parameters related to high temperature resistance and energy storage characteristics were introduced and recent developments in all-organic PI dielectrics and PI-matrix dielectric nanocomposites were discussed. Synthetic strategies for new functional PI
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modification at the molecular level together with the design engineering of nanofillers and multilayer structures of PIs were also analysed. Finally, a systematic summary of the current challenges and future developments for capacitor materials used at high temperatures were presented.
Dielectric capacitors with a high operating temperature applied in electric vehicles, aerospace and underground exploration require dielectric materials with high temperature resistance and high energy density.
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