Influence of the Heating Temperature on the Electrochemical Performance of Coal-Based Needle Coke Anode for Lithium Ion Batteries

In this study, the effect of the heating temperature on the initial coulombic efficiency, capacity and cycle stability of the coal-based needle coke was examined. The needle cokes were heated to different temperatures, and their microstructures were characterized by the scanning electron microscope, the X-ray diffraction and Raman spectroscope. The results indicated that the defect and the degree of disorder were reduced with increasing the heating temperature. Moreover, the electrochemical properties of these needle cokes were tested. A decrease of the capacity from 368.3 to 257.3 mAh/g, while an increase of the initial coulombic efficiency was observed, when the heating temperature was improved to 1100 oC. This is because fewer defects and more ordered crystal structures reduce active sites for the storage of Li ions and decrease the irreversible consumption of Li ions, as the heating temperature was higher

Novel process for selective separation of trace artemisitene from artemisinin by ammonium functional ionic liquids

One of the challenges to obtain high-quality natural active substances is the selective separation of the target compound from its analogues. In this study, ionic liquids (ILs), with design flexibility, were proposed to separate artemisitene and artemisinin, typical examples of natural analogues. Based on COSMO-RS calculation, several ILs were selected to separate artemisitene/artemisinin by experiment. It was demonstrated that the aqueous solution of N-allyl-N,N,N-trimethylammonium chloride ([AA][Cl]) exhibited excellent capability for selective separation of the two compounds. Under the optimal conditions (40 degrees C, 1 h), the separation selectivity of artemisitene/artemisinin could reach 12.23 when the initial impurity content was only 0.8 wt%. Spectroscopic analysis and molecular dynamics indicated that pi-pi complexation between artemisitene and [AA][Cl] plays a major role in this separation process. Moreover, the process of multistage cross-flow extraction was compared with counter-flow extraction, and the latter one exhibited advantages in energy consumption and product yield

Structural Design and Synthesis of an SnO2@C@Co-NC Composite as a High-Performance Anode Material for Lithium-Ion Batteries

To overcome the drawbacks of the structural instability and poor conductivity of SnO2-based anode materials, a hollow core-shell-structured SnO2@C@Co-NC (NC=N-doped carbon) composite was designed and synthesized by employing the heteroatom-doping and multiconfinement strategies. This composite material showed a much-reduced resistance to charge transfer and excellent cycling performance compared to the bare SnO(2)nanoparticles and SnO2@C composites. The doped heteroatoms and heterostructure boost the charge transfer, and the porous structure shortens the Li-ion diffusion pathway. Also, the volume expansion of SnO(2)NPs is accommodated by the hollow space and restricted by the multishell heteroatom-doped carbon framework. As a result, this structured anode material delivered a high initial capacity of 1559.1 mA h g(-1)at 50 mA g(-1)and an initial charge capacity of 627.2 mA h g(-1)at 500 mA g(-1). Moreover, the discharge capacity could be maintained at 410.8 mA h g(-1)after 500 cycles with an attenuation rate of only 0.069 % per cycle. This multiconfined SnO2@C@Co-NC structure with superior energy density and durable lifespan is highly promising for the next-generation lithium-ion batteries

Silicon/Needle Coke Composites as Efficient Anodes for Lithium Ion Batteries

In this research, a facile method was reported to prepare silicon/carbon composites by heating Si nanosheets and coal-based needle cokes in the assistance of binder glucopyranose. The microstructures and electrochemical performances of samples were analyzed. It was found that Si nanosheets adhered to needle cokes forming silicon/carbon composites. Compared with needle cokes, the composites showed higher capacity and initial coulombic efficiency. Also, they improved the cycle stability of silicon materials. The silicon/carbon anode had a reversible capacity of 381.8 mAh/g at a current density of 100 mA/g after 170 cycles. In our work, relatively inexpensive Si nanosheets and coal-based needle cokes with low price were employed as the silicon and carbon sources respectively. Therefore, this method provides a possible strategy to reduce costs of silicon/carbon anodes, accelerating their commercial applications

Enhancement of ZIF-8 derived N-doped carbon/silicon composites for anode in lithium ions batteries

It is urgent to develop novel anode materials with high energy density and facile synthetic procedures, since the development of commercial lithium ions batteries (LIBs) is limited by the unsatisfied capacity of graphite. Herein, we propose a modified method to prepare core-shell structured ZIF-8 derived N-doped carbon/silicon (Si@NC) composites (6.6 wt% of nano-Si), featuring facile synthetic procedures and mild condition. The physicochemical properties of the ZIF-8 derived N-doped carbon are not changed when the nano-Si particles are employed as the seeds. The Si@NC composites deliver high reversible capacity of 724 mAh g(-1). Attributed to the good charge conductivity and structural stability of the ZIF-8 derived N-doped carbon, the Si@NC composites exhibit good rate performance (98.5% of the initial average capacity is retained after being cycled at different current density) and cycle stability (302 mAh g(-1) while that of commercial graphite is similar to 10 mAh g(-1) at 1000 mA g(-1) after 800 cycles). The enhancement of lithium storage capability of the ZIF-8 derived N-doped carbon shows promising application in high energy density LIBs. (C) 2021 Published by Elsevier B.V

Challenges and Solutions for Low-Temperature Lithium–Sulfur Batteries: A Review

The lithium–sulfur (Li-S) battery is considered to be one of the attractive candidates for breaking the limit of specific energy of lithium-ion batteries and has the potential to conquer the related energy storage market due to its advantages of low-cost, high-energy density, high theoretical specific energy, and environmental friendliness issues. However, the substantial decrease in the performance of Li-S batteries at low temperatures has presented a major barrier to extensive application. To this end, we have introduced the underlying mechanism of Li-S batteries in detail, and further concentrated on the challenges and progress of Li-S batteries working at low temperatures in this review. Additionally, the strategies to improve the low-temperature performance of Li-S batteries have also been summarized from the four perspectives, such as electrolyte, cathode, anode, and diaphragm. This review will provide a critical insight into enhancing the feasibility of Li-S batteries in low-temperature environments and facilitating their commercialization

Global Regulator PhoP is Necessary for Motility, Biofilm Formation, Exoenzyme Production, and Virulence of <i>Xanthomonas citri</i> Subsp. <i>citri</i> on Citrus Plants

Citrus canker caused by Xanthomonas citri subsp. citri is one of the most important bacterial diseases of citrus, impacting both plant growth and fruit quality. Identifying and elucidating the roles of genes associated with pathogenesis has aided our understanding of the molecular basis of citrus-bacteria interactions. However, the complex virulence mechanisms of X. citri subsp. citri are still not well understood. In this study, we characterized the role of PhoP in X. citri subsp. citri using a phoP deletion mutant, &#916;phoP. Compared with wild-type strain XHG3, &#916;phoP showed reduced motility, biofilm formation, as well as decreased production of cellulase, amylase, and polygalacturonase. In addition, the virulence of &#916;phoP on citrus leaves was significantly decreased. To further understand the virulence mechanisms of X. citri subsp. citri, high-throughput RNA sequencing technology (RNA-Seq) was used to compare the transcriptomes of the wild-type and mutant strains. Analysis revealed 1017 differentially-expressed genes (DEGs), of which 614 were up-regulated and 403 were down-regulated in &#916;phoP. Gene ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that the DEGs were enriched in flagellar assembly, two-component systems, histidine metabolism, bacterial chemotaxis, ABC transporters, and bacterial secretion systems. Our results showed that PhoP activates the expression of a large set of virulence genes, including 22 type III secretion system genes and 15 type III secretion system effector genes, as well as several genes involved in chemotaxis, and flagellar and histidine biosynthesis. Two-step reverse-transcription polymerase chain reaction analysis targeting 17 genes was used to validate the RNA-seq data, and confirmed that the expression of all 17 genes, except for that of virB1, decreased significantly. Our results suggest that PhoP interacts with a global signaling network to co-ordinate the expression of multiple virulence factors involved in modification and adaption to the host environment during infection

Ionic liquid assisted fabrication of cellulose-based conductive films for Li-ion battery

An imidazolium-based ionic liquid, 1-ethyl-3-methylimidazolium diethyl phosphate ([Emim]DEP) was used to dispense graphene nanoplates (GN) and multiwalled carbon nanotubes (MWCNTs) as well as dissolve cellulose for fabricating composite conductive films. The effects of GN, MWCNTs, and cellulose mass ratios on the electrical conductivity and morphology of the films were investigated. The interaction between GN, MWCNTs, and cellulose was analyzed by SEM, X-ray diffraction (XRD), TGA, and Raman spectroscopy. The results indicate that [Emim]DEP plays a vital and irreplaceable role in GN and MWCNTs dispersion, cellulose dissolution, and porous formation during the regeneration and drying processes. MWCNTs linked flaky GN and a hybrid structure was constructed elaborately to form a better conductive path and improve the conductivity as well as increase the film stability. For the XRD result, the carbonized GN-MWCNTs-cellulose films exhibited the graphitic peaks, showing that the films still retained the structure of carbon atoms or molecules. Besides, the maximum conductivity of carbonized GN-MWCNTs-cellulose (7:3:2) composite film was up to 9,009 S m(-1), due to the small carbon clusters formation and the high degree of graphitization. Further, the carbonized films were applied as anodes in Li-ion battery and showed good electrochemical performance. The best cyclic stability (i.e., discharge/charge capacity) of 438/429 mA h g(-1) and coulomb efficiency of 50.2% were obtained. This novel and sustainable design is a promising approach to obtain cellulose-based conductive films and anodes for Li-ion battery applications

Antibacterial Cellulose Fibers Spun from Ionic Liquid and Enriched with Plant Essential Oils

The COVID-19 outbreak has seen the widespread use of personal protective equipment, especially antibacterial fibers. In this work, ionic liquid (IL) is used as a solvent to fabricate antibacterial fibers combining plant essential oils (PEOs) with cellulose. PEOs are buried in microcapsules first or mixed directly with IL-cellulose spinning dopes to prepare a series of composite fibers. The internal structures, surface and cross morphologies, thermal stability, mechanical properties, antibacterial activity, washing stability, and biocompatibility of these fibers are investigated and analyzed in-depth further. Artemisia microcapsule fiber (AMCRCF) with a break strength of 30.07 MPa is obtained. Besides, the antibacterial activity rates of AMC-RCF against Escherichia coli and Staphylococcus aureus are 89.8 and 97.8%, and the fibers still have a long-lasting antibacterial effect after 30 standard washes. Furthermore, the antibacterial fibers exhibit excellent biocompatibility. This research provides a green approach for the fabrication of the antibacterial fibers with long-lasting antibacterial activity and good biocompatibility

Antibacterial Cellulose Fibers Spun from Ionic Liquid and Enriched with Plant Essential Oils

The COVID-19 outbreak has seen the widespread use of personal protective equipment, especially antibacterial fibers. In this work, ionic liquid (IL) is used as a solvent to fabricate antibacterial fibers combining plant essential oils (PEOs) with cellulose. PEOs are buried in microcapsules first or mixed directly with IL-cellulose spinning dopes to prepare a series of composite fibers. The internal structures, surface and cross morphologies, thermal stability, mechanical properties, antibacterial activity, washing stability, and biocompatibility of these fibers are investigated and analyzed in-depth further. Artemisia microcapsule fiber (AMCRCF) with a break strength of 30.07 MPa is obtained. Besides, the antibacterial activity rates of AMC-RCF against Escherichia coli and Staphylococcus aureus are 89.8 and 97.8%, and the fibers still have a long-lasting antibacterial effect after 30 standard washes. Furthermore, the antibacterial fibers exhibit excellent biocompatibility. This research provides a green approach for the fabrication of the antibacterial fibers with long-lasting antibacterial activity and good biocompatibility