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Lithium-ion batteries (LIBs) are extensively used in electric vehicles and portable electronics due to their high energy density. However, conventional carbonate electrolytes suffer from potential Li plating at high current density and high flammability, which hinder their fast charging capability. Herein, a multi-functional electrolyte additive, namely ethoxy(pentafluoro)cyclotriphosphazene (PFPN), is explored to realize extreme fast charging of graphite‖LiFePO4 (LFP) cells with enhanced safety. The addition of PFPN into the baseline electrolyte comprising 1 M lithium bisfluorosulfonimide salt (LiFSI) in 1,3-dioxolane not only enhances the bulk ionic conductivity but also promotes the generation of a robust and ionic-conductive solid electrolyte interphase, hence enabling superior fast-charging performance of LIBs. In addition, the PFPN additive improves the nonflammability of electrolytes and inhibits the corrosion of Al foil caused by the LiFSI salt. As a result, graphite anodes deliver reversible capacities of 314.2 mA h g−1 and 164.4 mA h g−1 at 20C and 50C, respectively. Furthermore, the graphite‖LFP full pouch cells maintain a reversible capacity of 127.9 mA h g−1 and a high capacity retention of 99.68% over 500 cycles under 1C. This work provides a viable pathway to designing fast-charging electrolytes with remarkable cycling stability and excellent flame retardancy. [ABSTRACT FROM AUTHOR]

ZnO-based memristors are considered to be promising candidates in neuromorphic computing because of their nonvolatile resistive switching characteristics. Biological synaptic plasticity processes such as long-term potentiation (LTP) and long-term depression (LTD) require the application of driving voltages with different polarity, which inescapably leads to an increase in the operational costs of memristor circuits. In this study, we have successfully introduced a strategic innovation by incorporating a TiO2 thin layer, thereby achieving unipolar-enhanced bilayer and unipolar-weakened monolayer memristors. In the context of monolayer memristors, the unipolar weakening mechanism primarily arises from the thermal disruption of conduction filaments (CFs) caused by oxygen vacancies. Additionally, the incorporation of a thin TiO2 layer on the ZnO layer confines Joule heat within the TiO2 film, inhibiting the promotion of oxygen vacancy diffusion and preventing the occurrence of ZnO CF fracture. Moreover, a two transistor–two memristor (2T2R) unit based on the given memristors is introduced to achieve LTP and LTD characteristics under unipolar voltage pulse excitation. Simulation results show that the 2T2R structure unit can achieve an approximately 50% reduction in time and power consumption during the weight update process. [ABSTRACT FROM AUTHOR]

Metal oxide memristors are highly desirable for bionic synaptic applications. Recently, negative differential resistance (NDR) effects have been found in the resistance switching (RS) region for some oxide memristors, which provide a basis for multifunctional devices. Here, the mechanisms of the coexistence of NDR and RS behaviors in a W/WOx/Ti memristor are analyzed. The WOx-based memristor shows good synaptic plasticity behavior with a bipolar RS effect, and the NDR behavior during reverse voltage scanning is due to the dual role of conductive filaments (CFs) and trap-assisted transport (TAT) mechanisms. As the number of scans increases, fracture of the CFs is accelerated, while oxygen vacancy concentrations are reduced. The TAT mechanism is not enough to assist the electronic transition, thus leading to change in the NDR effect. In addition, replacing WOx with Al2O3 can lead to the disappearance of the NDR behavior, and the RS effect is switched from digital to analog type. This work provides a promising pathway to understand the coexistence mechanisms of NDR and RS effects in metal oxide memristors and promotes their application in bifunctional devices. [ABSTRACT FROM AUTHOR]

Sulfurized polyacrylonitrile (SPAN) has attracted considerable interest for high-energy lithium–sulfur batteries owing to its high specific capacity and remarkable cyclic stability. However, common electrolytes fail to stabilize both the lithium (Li) metal anode and SPAN cathode, thus affecting their practical applications. Herein, a lightweight siloxane solvent-based electrolyte (below 1 g mL−1) comprising 1.5 M lithium bis(fluorosuflonyl) imide (LiFSI) in dimethyldimethoxysilane (DMMS) has been designed for linking metallic Li and high-capacity SPAN cathode simultaneously. The weakly solvating DMMS electrolyte with a moderate salt concentration of 1.5 M not only allows a remarkable Li stripping/plating CE of 99.6% but also retards the dissolution of polysulfides. As a result, the assembled Li‖SPAN cells delivered a superior cyclic stability of 513 mA h g−1 at 0.2 A g−1 with 96.9% capacity retention after 300 cycles. Depth-profiling X-ray photoelectron spectroscopy results confirm the generation of an inorganic-rich inner layer in electrode–electrolyte interphases with trace DMMS decomposition in the outer layer, thus enabling uniform Li deposition. Density functional theory result suggests weak affinity between the DMMS solvent and polysulfides, which minimizes polysulfide shuttling. This study provides a new avenue to explore novel solvents to simultaneously stabilize metallic Li and SPAN cathodes. [ABSTRACT FROM AUTHOR]

Rechargeable potassium (K) batteries that are of low cost, with high energy densities and long cycle lives have attracted tremendous interest in affordable and large-scale energy storage. However, the large size of the K-ion leads to sluggish reaction kinetics and causes a large volume variation during the ion insertion/extraction processes, thus hindering the utilization of active electrode materials, triggering a serious structural collapse, and deteriorating the cycling performance. Therefore, the exploration of suitable materials/hosts that can reversibly and sustainably accommodate K-ions and host K metals are urgently needed. Electrospun carbon-based materials have been extensively studied as electrode/host materials for rechargeable K batteries owing to their designable structures, tunable composition, hierarchical pores, high conductivity, large surface areas, and good flexibility. Here, we present the recent developments in electrospun CNF-based nanomaterials for various K batteries (e.g., K-ion batteries, K metal batteries, K–chalcogen batteries), including their fabrication methods, structural modulation, and electrochemical performance. This Feature Article is expected to offer guidelines for the rational design of novel electrospun electrodes for the next-generation K batteries. [ABSTRACT FROM AUTHOR]

Sodium/potassium-ion batteries (SIBs/PIBs) are expected to replace conventional lithium-ion batteries (LIBs) soon in view of their lower cost and the abundant reserves of sodium/potassium resources. However, it remains a challenge to explore suitable anode materials for SIBs/PIBs with high energy/power density and long lifespan due to the sluggish kinetics during the insertion/extraction of Na+/K+ ions with larger ionic sizes. Herein, ultra-small SnS2 nanocrystals encapsulated in sulphurized polyacrylonitrile (SPAN) fibres have been fabricated via electrospinning paired with sulphuration treatment. Density functional theory (DFT) calculations demonstrate that SPAN fibre can concentrate Na+ on the surface and offer additional storage sites with enhanced reaction kinetics. Consequently, this composite electrode manifests superb sodium/potassium-ion storage performance with high capacities (613 mA h g−1 after 50 cycles under 0.1 A g−1 for SIBs; 565 mA h g−1 at 0.05 A g−1 and 226 mA h g−1 at 5 A g−1 after 50 and 2000 cycles for PIBs) and superior long-life cycling capability (261 mA h g−1 after 30 000 cycles at 10 A g−1 for SIBs). Additionally, a sodium full cell assembled with Na3V2(PO4)3 as the cathode and SnS2-SPAN-470-1 as the anode displays excellent cycling performance. This work can provide new insights into the construction of novel transition metal dichalcogenide-based nanostructures and nanocomposites for high-performance electrochemical energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

A sustainable and easy method for the fabrication of a composite of ultra-fine few-layer MoS2 structures embedded on N,P-co-doped bio-carbon (MoS2-N/P-C) was developed by using natural chlorella as an adsorbent and reactor. This MoS2-N/P-C composite was easily synthesized by carrying out a biosorption of chlorella and a subsequent calcination process. This bio-carbon made from chlorella acted as a nanoreactor to prevent the MoS2 nanoparticles from agglomerating with each other during the calcination process. Besides, the N,P-codoped bio-carbon contributed to the relatively high conductivity and surface wettability of this composite and accommodated the large radius of Na+. When used as an anode for sodium ion batteries, it showed significant superiority with a high rate and long-duration cycling performance, evidenced by a measured capacity of 175 mA h g−1 after 2000 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]

Rational fabrication of anode electrodes for sodium-ion batteries remains a challenge due to the problem of sluggish Na+ diffusion kinetics, large volume expansion etc. Significant efforts, such as fabricating carbon composites and novel nanostructures, have been devoted to the development of anode materials. Herein, an ultra-small few-layer MoS2 nanostructure confined on a hierarchical porous carbon fiber composite was synthesized through the nanocasting route using a novel hierarchical porous carbon fiber as the template. As an anode material, the composite displays outstanding electrochemical performance for sodium-ion batteries. For instance, it delivers high reversible capacities (491 mA h g−1 after 50 cycles at 0.1 A g−1), high rate performance (387 mA h g−1 at 2 A g−1) and long-term cycling stability (234 mA h g−1 at 1 A g−1 after 3000 cycles). Note that it shows one of the best long-term cycling properties reported to date for MoS2-based anode materials for sodium-ion batteries. This regulation strategy may offer new insights into the fabrication of high-performance anode materials for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

The first asymmetric synthesis of (-)-penostatins B and D and the practical synthesis of (+)-penostatins A and C have been accomplished through a flexible strategy. The features of the synthesis are a BF 3 ·OEt 2 -mediated Diels-Alder reaction of chiral dienophiles and methylcyclopentadienes with high chemo-, regio-, and stereoselectivity, followed by ozonolysis to install the common trisubstituted cyclopentane intermediate, and a hetero-Diels-Alder reaction with easily tunable facial selectivity, followed by sulfonate elimination to construct both enantiomeric tricyclic systems for penostatins A/C and B/D, respectively.

An efficient synthesis of ECH, epoxyquinols A and B, and two bioactive analogs EqM and RKTS-33 has been completed starting from (-)-shikimic acid. Rapid establishment of the desired epoxyquinol core is facilitated through a key allylic oxidation with high stereoselectivity, which is achieved by fine tuning the cyclohexene substrate structure and reaction conditions.

Stilbene derivatives have long been known to undergo "acid-catalyzed" Z → E isomerization, where a strong mineral acid at high concentration is practically necessary. Such severe reaction conditions often cause undesired by-reactions and limit their potential application. Herein, we present a trace mild acid-catalyzed Z → E isomerization found with stilbene derivatives fused with a norbornene moiety. By-reactions, such as the migration of the C[double bond, length as m-dash]C double bond and electrophilic addition reactions, were completely inhibited because of the ring strain caused by the fused norbornene component. Direct photolysis of the E isomers at selected wavelengths led to the E → Z photoisomerization of these stilbene derivatives and thus constituted a unique class of molecular switches orthogonally controllable by light and acid. The catalytic amount of acid could be readily removed, and the Z → E isomerization could be controlled by turning on/off the irradiation of a photoacid, which allowed repeated isomerization in a non-invasive manner. Moreover, the Z isomer produced by photoisomerization could spontaneously self-recover to the E isomer in the presence of a catalytic amount of acid. The kinetics of Z → E isomerization were adjustable by manipulating catalytic factors and, therefore, unprecedented molecular photoswitches with adjustable self-recovery were realized., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Rational fabrication of anode electrodes for sodium-ion batteries remains a challenge due to the problem of sluggish Na+ diffusion kinetics, large volume expansion etc. Significant efforts, such as fabricating carbon composites and novel nanostructures, have been devoted to the development of anode materials. Herein, an ultra-small few-layer MoS2 nanostructure confined on a hierarchical porous carbon fiber composite was synthesized through the nanocasting route using a novel hierarchical porous carbon fiber as the template. As an anode material, the composite displays outstanding electrochemical performance for sodium-ion batteries. For instance, it delivers high reversible capacities (491 mA h g-1 after 50 cycles at 0.1 A g-1), high rate performance (387 mA h g-1 at 2 A g-1) and long-term cycling stability (234 mA h g-1 at 1 A g-1 after 3000 cycles). Note that it shows one of the best long-term cycling properties reported to date for MoS2-based anode materials for sodium-ion batteries. This regulation strategy may offer new insights into the fabrication of high-performance anode materials for sodium-ion batteries.

(-)-Renieramycin T, an interesting tetrahydroisoquinolinequinone alkaloid with a novel renieramycin-ecteinascidin mixed framework, is synthesized from the known phenol 16 in 22 steps with 6.2% overall yield. In the convergent route, the key cyclocondensation between the isoquinoline moiety 27 and trisubstituted phenylalaninol 14 is achieved with good selectivity to furnish bistetrahydroisoquinoline 29, which permits a rapid construction of the pentacyclic framework having a fully substituted aromatic A ring.

Two superaromatic terpyridine ligands (1 and 2) incorporating a corannulene unit at the 4'-position are reported. The optical and metal sensing properties of both ligands were investigated by the naked eye, and UV-vis and fluorescence spectroscopy in this work. In 1, the corannulene motif is directly connected to the 4'-phenylterpyridine domain, while in 2, the corannulene motif and the 4'-phenylterpyridine domain are separated by an acetylene linker. Both 1 and 2 can work as chemosensors for metal ions and display different optical responses to various metal ions. It is shown that both ligands exhibit a colorimetric sensing ability for Fe(2+) through an obvious color change from colorless to magenta, and this color change can be observed easily by the naked eye. The addition of Fe(2+) also leads to significant changes in the absorption spectra of the ligands. A characteristic red shift in the emission spectra is observed in the presence of Zn(2+), which facilitates the discrimination of Zn(2+) from other metal ions. In addition, density functional theory (DFT) and time-dependent-density functional theory (TD-DFT) calculations were performed and shown to be consistent with the observed experimental results.