Rhodium(III)-Catalyzed Coupling of Quinolin-8-carboxaldehydes with CF3-Imidoyl Sulfoxonium Ylides by Chelation-Assisted C(sp2)-H Bond Activation for the Synthesis of Trifluoromethyl-Substituted Enaminones.

A rhodium(III)-catalyzed aldehydic C(sp2)-H imidoylmethylation of quinolin-8-carboxaldehydes with CF3-imidoyl sulfoxonium ylides (TFISYs) has been developed for the generation of α-imino ketones, which could be readily tautomerized to enaminones in moderate to excellent yields. In the transformation, TFISYs act as a kind of masked alkenylating reagents for the aldehyde moiety, and the obtained CF3-enaminone products have been successfully converted into other useful trifluoromethyl-substituted heterocycles.

Structural tuning of copper sulfide material for sodium-ion batteries.

In this work, single-crystal and twin-crystal copper sulfide materials are constructed in a regulatable and controlled manner. Twin boundaries are engineered into the copper sulphide material to significantly improve its electrochemical performance. The results demonstrate that structure tuning with twin crystals is an effective strategy for enhancing electrochemical reactions, and also sheds light on the design of electrode materials for sodium ion storage.

Construction of trifluoromethyl-containing heterocycles from trifluoroacetimidoyl chlorides and derivatives.

Recent advances in the direct synthesis of trifluoromethyl-containing heterocycles from trifluoroacetimidoyl chlorides (TFAICs) and derivatives, including trifluoroacetimidohydrazides (TFAIHs) and CF3-imidoyl sulfoxonium ylides (TFISYs), are systematically summarized and discussed. The cascade annulation reactions of trifluoromethyl-containing synthons with suitable coupling partners have emerged as a powerful and promising tool for the construction of a variety of trifluoromethyl-substituted heterocycles. Compared with other trifluoromethyl-containing building blocks, TFAICs and derivatives have notable merits of easy availability and handling, relative stability and safety, and high reactivity.

Rhodium(III)-catalyzed regioselective C2-alkenylation of indoles with CF3-imidoyl sulfoxonium ylides to give multi-functionalized enamines using a migratable directing group.

A rhodium(III)-catalyzed regioselective C2-alkenylation of indoles for the construction of α-CF3 substituted enamines has been developed, which utilizes CF3-imidoyl sulfoxonium ylides (TFISYs) as alkenylating agents for the first time. A wide array of indolyl- and trifluoromethyl-decorated enamine derivatives have been assembled in moderate to good yields.

Ruthenium-Catalyzed Hydroxyl-Directed peri-Selective C-H Activation and Annulation of 1-Naphthols with CF3-Imidoyl Sulfoxonium Ylides for the Synthesis of 2-(Trifluoromethyl)-2,3-dihydrobenzo[de]chromen-2-amines.

A ruthenium-catalyzed peri-selective C-H activation and annulation of 1-naphthols with CF3-substituted imidoyl sulfoxonium ylides that uses hydroxyl as a weakly coordinating directing group is disclosed. The strategy provides a facile and practical route to diverse trifluoromethyl-containing 2,3-dihydrobenzo[de]chromen-2-amines with high efficiency. Notable advantages of this protocol include readily available materials, excellent regioselectivity, good functional group compatibility, and scalability.

Formal [4+1] Annulation of Azoalkenes with CF3-Imidoyl Sulfoxonium Ylides and Dual Double Bond Isomerization Cascade: Synthesis of Trifluoromethyl-Containing Pyrazole Derivatives.

A straightforward strategy for the metal-free construction of trifluoromethyl-containing pyrazole derivatives has been achieved from readily available α-halo hydrazones and CF3-imidoyl sulfoxonium ylides. The cascade transformation proceeds through the formal [4+1] cycloaddition followed by an unexpected dual double bond isomerization. The protocol features mild conditions, easy operation, excellent substrate compatibility, and good regioselectivity. The synthetic utility is demonstrated by scale-up reaction and further elaboration of the obtained pyrazole products.

High-Performance Composite Lithium Anodes Enabled by Electronic/Ionic Dual-Conductive Paths for Solid-State Li Metal Batteries.

Solid-state lithium metal batteries (SSLMBs) promise high energy density and high safety by employing high-capacity Li metal anode and solid-state electrolytes. However, the construction of the composite Li metal electrode is a neglected but important subject when the extensive research focuses on the interface between the solid electrolyte Li6.4 La3 Zr1.4 Ta0.6 O12 and Li metal anode. Here, an electronic-ionic conducting composite Li metal anode consisting of Li-Al alloy and LiF is constructed to achieve the stable electronic-ionic transport channel and the intimate interface contact, which can realize the uniform Li deposition and the efficiency utilization of lithium in composite Li metal electrode. Therefore, the symmetric battery with composite Li metal electrode exhibits the high critical current density with 1.2 mA cm-2 and stable cycle for 1500 h at 0.3 mA cm-2 , 25 °C. Moreover, the SSLMBs matched with LiFePO4 and LiNi0.8 Co0.1 Mn0.1 O2 achieve the outstanding electrochemical performance, verifying the feasibility of composite Li metal electrode in various SSLMBs systems.

Functionalized 12 µm Polyethylene Separator to Realize Dendrite-Free Lithium Deposition toward Highly Stable Lithium-Metal Batteries.

Direct application of metallic lithium (Li) as the anode in rechargeable lithium metal batteries (LMBs) is still hindered by some annoying issues such as lithium dendrites formation, low Coulombic efficiency, and safety concerns arising therefrom. Herein, an advanced composite separator is prepared by facilely blade coating lightweight and thin functional layers on commercial 12 µm polyethylene separator to stabilize the Li anode. The composite separator simultaneously improves the Li ion transport and lithium deposition behaviors with uniform lithium ion distribution properties, enabling the dendrite-free Li deposition. As a result, the lithium anode can stably cycle up to 3000 cycles with the high capacity of 3.5 mAh cm-2 . Moreover, the composite separator exhibits wide compatibility in LMBs (Li-S and Li-ion battery) and delivers stable cycling performance and high Coulombic efficiency both in coin and lab-level soft-pack cells. Thus, this cost-effective modification strategy exhibits great application potential in high-energy LMBs.

Correction: Engineering lithiophilic Ni-Al@LDH interlayers on a garnet-type electrolyte for solid-state lithium metal batteries.

Correction for 'Engineering lithiophilic Ni-Al@LDH interlayers on a garnet-type electrolyte for solid-state lithium metal batteries' by Wei Liu et al., Chem. Commun., 2021, 57, 10214-10217, DOI: 10.1039/D1CC02932K.

Engineering lithiophilic Ni-Al@LDH interlayers on a garnet-type electrolyte for solid-state lithium metal batteries.

In this work, a lithiophilic Ni-Al@LDH interlayer is engineered at the Li6.4La3Zr1.4Ta0.6O12 (LLZTO) electrolyte and Li anode interface. The Ni-Al@LDH interlayer can significantly reduce the interfacial resistance as well as give excellent cycling performance both in a symmetric Li//Li cell and solid full lithium metal batteries.

Synthesis of 3H-1,2,4-Triazol-3-ones via NiCl2-Promoted Cascade Annulation of Hydrazonoyl Chlorides and Sodium Cyanate.

A nickel-promoted cascade annulation reaction for the facile synthesis of 3H-1,2,4-triazol-3-ones from readily available hydrazonoyl chlorides and sodium cyanate has been developed. The transformation occurs through a cascade nickel-promoted intermolecular nucleophilic addition-elimination process, intramolecular nucleophilic addition, and a hydrogen-transfer sequence. The method has been successfully applied for the construction of the core skeleton of the angiotensin II antagonist.

Universal lithiophilic interfacial layers towards dendrite-free lithium anodes for solid-state lithium-metal batteries.

Solid-state lithium-metal batteries (SSLMBs) using garnet Li6.4La3Zr1.4Ta0.6O12 (LLZTO) as the solid electrolyte are expected to conquer the safety concerns of high energy Li batteries with organic liquid electrolytes owing to its nonflammable nature and good mechanical strength. However, the poor interfacial contact between the Li anode and LLZTO greatly restrains the practical applications of the electrolyte, because large polarization, dendritic Li formation and penetration can occur at the interfaces. Here, an effective method is proposed to improve the wettability of the LLZTO toward lithium and reduce the interfacial resistance by engineering universal lithiophilic interfacial layers. Thanks to the in-situ formed lithiophilic and ionic conductive Co/Li2O interlayers, the symmetric Li/CoO-LLZTO/Li batteries present much smaller overpotential, ultra-low areal specific resistance (ASR, 12.3 Ω cm2), high critical current density (CCD, 1.1 mA cm-2), and outstanding cycling performance (1696 h at a current density of 0.3 mA cm-2) at 25 °C. Besides, the solid-state Li/CoO-LLZTO/LFP cells deliver an excellent electrochemical performance with a high coulombic efficiency of ~100% and a long cycling time over 185 times. Surprisingly, the high-voltage (4.6 V) solid state Li/CoO-LLZTO/Li1.4Mn0.6Ni0.2Co0.2O2.4 (LMNC622) batteries can also realize an ultra-high specific capacity (232.5 mAh g-1) under 0.1 C at 25 °C. This work paves an effective way for practical applications of the dendrite-free SSLMBs.

Hydrangea-Like CuS with Irreversible Amorphization Transition for High-Performance Sodium-Ion Storage.

Metal sulfides have been intensively investigated for efficient sodium-ion storage due to their high capacity. However, the mechanisms behind the reaction pathways and phase transformation are still unclear. Moreover, the effects of designed nanostructure on the electrochemical behaviors are rarely reported. Herein, a hydrangea-like CuS microsphere is prepared via a facile synthetic method and displays significantly enhanced rate and cycle performance. Unlike the traditional intercalation and conversion reactions, an irreversible amorphization process is evidenced and elucidated with the help of in situ high-resolution synchrotron radiation diffraction analyses, and transmission electron microscopy. The oriented (006) crystal plane growth of the primary CuS nanosheets provide more channels and adsorption sites for Na ions intercalation and the resultant low overpotential is beneficial for the amorphous Cu-S cluster, which is consistent with the density functional theory calculation. This study can offer new insights into the correlation between the atomic-scale phase transformation and macro-scale nanostructure design and open a new principle for the electrode materials' design.

Deciphering an Abnormal Layered-Tunnel Heterostructure Induced by Chemical Substitution for the Sodium Oxide Cathode.

Demands for large-scale energy storage systems have driven the development of layered transition-metal oxide cathodes for room-temperature rechargeable sodium ion batteries (SIBs). Now, an abnormal layered-tunnel heterostructure Na0.44 Co0.1 Mn0.9 O2 cathode material induced by chemical element substitution is reported. By virtue of beneficial synergistic effects, this layered-tunnel electrode shows outstanding electrochemical performance in sodium half-cell system and excellent compatibility with hard carbon anode in sodium full-cell system. The underlying formation process, charge compensation mechanism, phase transition, and sodium-ion storage electrochemistry are clearly articulated and confirmed through combined analyses of in situ high-energy X-ray diffraction and ex situ X-ray absorption spectroscopy as well as operando X-ray diffraction. This crystal structure engineering regulation strategy offers a future outlook into advanced cathode materials for SIBs.

Ion-Doping-Site-Variation-Induced Composite Cathode Adjustment: A Case Study of Layer-Tunnel Na0.6MnO2 with Mg2+ Doping at Na/Mn Site.

Composite cathodes have attracted great attention due to the integrated advantages of each pure structure. Also, the component ratio deserves a careful modulation to further improve the corresponding electrochemical performance. Mn-based layer-tunnel hybrid composite became a focus in sodium-ion batteries due to the superiority in terms of high performance, low cost, and nontoxicity. In the previous reports, the structure modulation was carried out via changing the synthesis condition, varying the transition-metal-element ratio, and different ion doping. Also, it is still challenging to explore a more feasible method to simplify the adjustment process. Herein, we introduced Mg2+ into Na sites or transition-metal sites in Na0.6MnO2 and first discovered the doping-site-variation-induced structural adjustment phenomenon. Specifically, Mg doping in transition-metal sites could be beneficial for the growth of the P2-type structure, while layer/tunnel component ratio decreased when locating Mg2+ in Na sites. The P2-O2 phase transformations could be effectively suppressed by locating Mg2+ in both sites in high-voltage regions and thus improve the cycling performance. The designed material, Na0.6Mn0.99Mg0.01O2, could attain a decent capacity of 100 mA h g-1 at 1000 mA g-1 and a satisfied retention of 76.6% after 500 cycles. Additionally, ex situ X-ray diffraction analysis experiments verify the excellent structural stability of Mg-substituted samples during charge-discharge processes. Moreover, the Na0.6Mn0.99Mg0.01O2 also displays superior sodium-ion full-cell properties when merged with hard carbon anode. Thus, this research may indicate a proper novel thread for designing high-performance composite electrodes.

Interpreting Abnormal Charge-Discharge Plateau Migration in Cu xS during Long-Term Cycling.

Voltage polarization during cycling, the charge potential increase of anode or discharge plateau decrease of cathode, is widely observed and would lower the output voltage. Conversely, an anomalous potential plateau negative migration phenomenon was observed in Cu xS anode of sodium-ion battery. In this study, the background mechanism was clarified from the switch of intercalation-conversion reactions and structure evolution. The dynamic cooperation between intercalation and conversion reactions may root the potential plateau negative migration during cycling. In the initial stage, the intercalation-type reaction with Na3Cu4S4 and Na4Cu2S3 products at 2.13 and 1.92 V would dominate the early migration process of potential plateaus. In the second stage, the conversion-type reaction dominated by Na2S and metallic copper formed at 1.85 and 1.53 V in the later period. The aforementioned results would provide new perspective on the electrochemical behavior of transition-metal sulfide anode and provide a clue for reducing voltage polarization.

Three-Dimensional Chestnut-Like Architecture Assembled from NaTi3O6(OH)·2H2O@N-Doped Carbon Nanosheets with Enhanced Sodium Storage Properties.

The application of sodium titanate anodes of low cost, feasible operating voltage, and nontoxic nature were severely hindered by their inferior cycling stability and poor rate capability. Here, three-dimensional (3D) chestnut-like NaTi3O6(OH)·2H2O@N-doped carbon nanospheres (NTOH@CN) with loose crystal structures were prepared by a self-sacrificed template method. The nanospheres were composed of nanosheets and linked with nanowires, which interweaved to construct a meshwork structure. The growth mechanism of unique 3D NTOH@CN nanospheres was investigated by tracking the synthesis process of different hydrothermal durations. The rate performances of 3D NTOH@CN were superior to that of NaTi3O6(OH)·2H2O irregular spheres assembled from nanosheets (3D NTOH) and NaTi3O6(OH)·2H2O nanosheets (two-dimensional NTOH). Excellent cycling and rate performance were obtained due to their open crystal structure, unique 3D nanosphere morphology with short diffusion paths, N-doped carbon surrounding, and the solid solution reaction. In addition, the reaction mechanism, morphology change, and dynamics research during the sodium insertion/desertion process have been carefully studied. Based on varying ex situ analyses, the irreversible metallic titanium formation and the excellent structural stability of nanosphere morphology have been evidenced. The pseudocapacitive phenomenon was also detected, which effectively enhanced Na+ ion storage capability. The systematical and comprehensive study provide a holograph for the design and synthesis of sodium titanate nanostructures.

Design and Synthesis of Layered Na2Ti3O7 and Tunnel Na2Ti6O13 Hybrid Structures with Enhanced Electrochemical Behavior for Sodium-Ion Batteries.

A novel complementary approach for promising anode materials is proposed. Sodium titanates with layered Na2Ti3O7 and tunnel Na2Ti6O13 hybrid structure are presented, fabricated, and characterized. The hybrid sample exhibits excellent cycling stability and superior rate performance by the inhibition of layered phase transformation and synergetic effect. The structural evolution, reaction mechanism, and reaction dynamics of hybrid electrodes during the sodium insertion/desertion process are carefully investigated. In situ synchrotron X-ray powder diffraction (SXRD) characterization is performed and the result indicates that Na+ inserts into tunnel structure with occurring solid solution reaction and intercalates into Na2Ti3O7 structure with appearing a phase transition in a low voltage. The reaction dynamics reveals that sodium ion diffusion of tunnel Na2Ti6O13 is faster than that of layered Na2Ti3O7. The synergetic complementary properties are significantly conductive to enhance electrochemical behavior of hybrid structure. This study provides a promising candidate anode for advanced sodium ion batteries (SIBs).

Insight into the Origin of Capacity Fluctuation of Na2Ti6O13 Anode in Sodium Ion Batteries.

The capacity fluctuation phenomenon during cycling, which is closely related with solid electrolyte interphase and plays a key role for the design for advanced electrode, could be frequently observed in the titanium-based anode. However, the underlying reason for capacity fluctuation still remains unclear with rare related reports. Here, the origin of capacity fluctuation is verified with a long-life Na2Ti6O13 anode. The reaction mechanism, structural evolution and reaction kinetics during the reported sodiation/desodiation processes were carefully investigated. The gradually enhanced diffusion controlled contribution resulted in the capacity increasing. And the capacity decay could be ascribed to the irreversible reaction of metallic titanium formation and the increasing potential polarization. It is worth noting that sodium ions seem to partially reduce NTO to metallic state, which is irreversible. The present study can provide more information for the design of advanced Na2Ti6O13 anode.