Synthesis of Lithium Boracarbonate Ion Pairs by Copper‐Catalyzed Multi‐Component Coupling of Carbon Dioxide,Diboron, and Aldehydes

The catalytic selective multi‐component coupling of CO₂, bis(pinacolato)diboron, LiOtBu, and a wide range of aldehydes has been achieved for the first time by using an NHC‐copper catalyst. This transformation has efficiently afforded a series of novel lithium cyclic boracarbonate ion pair compounds in high yields from readily available starting materials. This protocol has not only provided a new catalytic process for the utilization of CO₂, but it has also constituted a novel route for the efficient synthesis of a new class of lithium borate compounds that might be of interest as potential electrolyte candidates for lithium ion batteries.     

Strategies of Removing Residual Lithium Compounds on the Surface of Ni‐Rich Cathode Materials†

Ni‐rich cathode materials have become one of the most promising cathode materials for advanced high‐energy Li‐ion batteries (LIBs) owing to their high specific capacity. However, Ni‐rich cathode materials are sensitive to the trace H₂O and CO₂ in the air, and tend to react with them to generate LiOH and Li₂CO₃ at the particle surface region (named residual lithium compounds, labeled as RLCs). The RLCs will deteriorate the comprehensive performances of Ni‐rich cathode materials and make trouble in the subsequent manufacturing process of electrode, including causing low initial coulombic efficiency and poor storage property, bringing about potential safety hazards, and gelatinizing the electrode slurry. Therefore, it is of considerable significance to remove the RLCs. Researchers have done a lot of work on the corresponding field, such as exploring the formation mechanism and elimination methods. This paper investigates the origin of the surface residual lithium compounds on Ni‐rich cathode materials, analyzes their adverse effects on the performance and the subsequent electrode production process, and summarizes various kinds of feasible methods for removing the RLCs. Finally, we propose a new research direction of eliminating the lithium residuals after comparing and summing up the above. We hope this work can provide a reference for alleviating the adverse effects of residual lithium compounds for Ni‐rich cathode materials’ industrial production.     

A New Method for Quantitative Marking of Deposited Lithium by Chemical Treatment on Graphite Anodes in Lithium‐Ion Cells

A novel approach for the marking of deposited lithium on graphite anodes from large automotive lithium‐ion cells (≥6 Ah) is presented. Graphite anode samples were extracted from two different formats (cylindrical and pouch cells) of pristine and differently aged lithium‐ion cells. The samples present a variety of anodes with various states of lithium deposition (also known as plating). A chemical modification was performed to metallic lithium deposited on the anode surface due to previous plating with isopropanol (IPA). After this procedure an oxygenated species was detected by scanning electron microscopy (SEM), which later was confirmed as Li₂CO₃ by Fourier transform infrared spectroscopy (FTIR) and X‐ray powder diffraction (XRPD). A valuation of the covered area by Li₂CO₃ was carried out with an image analysis using energy‐dispersive X‐ray spectroscopy (EDX) and quantitative Rietveld refinement.     

Carboxylation Reactions with Carbon Dioxide Using N‐Heterocyclic Carbene‐Copper Catalysts

The development of versatile catalyst systems and new transformations for the utilization of carbon dioxide (CO₂) is of great interest and significance. This Personal Account reviews our studies on the exploration of the reactions of CO₂ with various substrates by the use of N‐heterocyclic carbene (NHC)‐copper catalysts. The carboxylation of organoboron compounds gave access to a wide range of carboxylic acids with excellent functional group tolerance. The C?H bond carboxylation with CO₂ emerged as a straightforward protocol for the preparation of a series of aromatic carboxylic esters and butenoates from simple substrates. The hydrosilylation of CO₂ with hydrosilanes provided an efficient method for the synthesis of silyl formate on gram scale. The hydrogenative or alkylative carboxylation of alkynes, ynamides and allenamides yielded useful α,β‐unsaturated carboxylic acids and α,β‐dehydro amino acid esters. The boracarboxylation of alkynes or aldehydes afforded the novel lithium cyclic boralactone or boracarbonate products, respectively. The NHC‐copper catalysts generally featured excellent functional group compatibility, broad substrate scope, high efficiency, and high regio‐ and stereoselectivity. The unique electronic and steric properties of the NHC‐copper units also enabled the isolation and structural characterization of some key intermediates for better understanding of the catalytic reaction mechanisms.     

Air‐Stable Lithium Spheres Produced by Electrochemical Plating

Lithium metal is an ideal anode for next‐generation lithium batteries owing to its very high theoretical specific capacity of 3860 mAh g^?1 but very reactive upon exposure to ambient air, rendering it difficult to handle and transport. Air‐stable lithium spheres (ASLSs) were produced by electrochemical plating under CO₂ atmosphere inside an advanced aberration‐corrected environmental transmission electron microscope. The ASLSs exhibit a core–shell structure with a Li core and a Li₂CO₃ shell. In ambient air, the ASLSs do not react with moisture and maintain their core–shell structures. Furthermore, the ASLSs can be used as anodes in lithium‐ion batteries, and they exhibit similar electrochemical behavior to metallic Li, indicating that the surface Li₂CO₃ layer is a good Li⁺ ion conductor. The air stability of the ASLSs is attributed to the surface Li₂CO₃ layer, which is barely soluble in water and does not react with oxygen and nitrogen in air at room temperature, thus passivating the Li core.     

Triazine‐based Organic Polymer‐catalysed Conversion of Epoxide to Cyclic Carbonate under Ambient CO2 Pressure

In this work we have achieved epoxide to cyclic carbonate conversion using a metal‐free polymeric catalyst under ambient CO₂ pressure (1.02 atm) using a balloon setup. The triazine containing polymer (CYA‐ANIS) was prepared from cyanuric chloride (CYA?Cl) and o‐dianisidine (ANIS) in anhydrous DMF as solvent by refluxing under the N₂ gas environment. The presence of triazine and amine functional groups in the polymer results in the adsorption of CO₂ up to 7 cc/g at 273 K. This inspired us to utilize the polymer for the conversion of a series of functionalised epoxides into their corresponding cyclic carbonates in the presence of tetrabutyl ammonium iodide (TBAI) as co‐catalyst. The product has wide range of applications like solvent in lithium ion battery, precursor for polycarbonate, etc. The catalyst was efficient for the conversion of different mono and di‐epoxides into their corresponding cyclic carbonates under atmospheric pressure in the presence of TBAI as co‐catalyst. The study indicates that epoxide attached with electron withdrawing groups (like, CH₂Cl, glycidyl ether, etc.) displayed better conversion compared to simple alkane chain attached epoxides. This is mainly due to the stabilization of electron rich intermediates produced during the reaction (e. g. epoxide ring opening or CO₂ incorporation into the halo‐alkoxide anion). This catalyst mixture was capable to maintain its reactivity up to five cycles without losing its activity. Post catalytic characterization clearly supports the heterogeneous and recyclable nature of the catalyst.     

Electrocatalytic Production of C3‐C4 Compounds by Conversion of CO2 on a Chloride‐Induced Bi‐Phasic Cu2O‐Cu Catalyst

Electrocatalytic conversion of carbon dioxide (CO₂) has recently received considerable attention as one of the most feasible CO₂ utilization techniques. In particular, copper and copper‐derived catalysts have exhibited the ability to produce a number of organic molecules from CO₂. Herein, we report a chloride (Cl)‐induced bi‐phasic cuprous oxide (Cu₂O) and metallic copper (Cu) electrode (Cu₂O_Cl) as an efficient catalyst for the formation of high‐carbon organic molecules by CO₂ conversion, and identify the origin of electroselectivity toward the formation of high‐carbon organic compounds. The Cu₂O_Cl electrocatalyst results in the preferential formation of multi‐carbon fuels, including n‐propanol and n‐butane C3–C4 compounds. We propose that the remarkable electrocatalytic conversion behavior is due to the favorable affinity between the reaction intermediates and the catalytic surface.     

A Self‐Healing Aqueous Lithium‐Ion Battery

Flexible lithium‐ion batteries are critical for the next‐generation electronics. However, during the practical application, they may break under deformations such as twisting and cutting, causing their failure to work or even serious safety problems. A new family of all‐solid‐state and flexible aqueous lithium ion batteries that can self‐heal after breaking has been created by designing aligned carbon nanotube sheets loaded with LiMn₂O₄ and LiTi₂(PO₄)₃ nanoparticles on a self‐healing polymer substrate as electrodes, and a new kind of lithium sulfate/sodium carboxymethylcellulose serves as both gel electrolyte and separator. The specific capacity, rate capability, and cycling performance can be well maintained after repeated cutting and self‐healing. These self‐healing batteries are demonstrated to be promising for wearable devices.     

Three‐Dimensional Fe2N@C Microspheres Grown on Reduced Graphite Oxide for Lithium‐Ion Batteries and the Li Storage Mechanism

Nanostructured iron compounds as lithium‐ion‐battery anode material have attracted considerable attention with respect to improved electrochemical energy storage and excellent specific capacity, so lots of iron‐based composites have been developed. Herein, a novel composite composed of three‐dimensional Fe₂N@C microspheres grown on reduced graphite oxide (denoted as Fe₂N@C‐RGO) has been synthesized through a simple and effective technique assisted by a hydrothermal and subsequent heating treatment process. As the anode material for lithium‐ion batteries, the synthetic Fe₂N@C‐RGO displayed excellent Li⁺‐ion storage performance with a considerable initial capacity of 847 mAh g^?1, a superior cycle stability (a specific discharge capacity of 760 mAh g^?1 remained after the 100th cycle), and an improved rate‐capability performance compared with those of the pure Fe₂N and Fe₂N‐RGO nanostructures. The good performance should be attributed to the existence of RGO layers that can facilitate to enhance the conductivity and shorten the lithium‐ion diffusion path; in addition, the carbon layer on the surface of Fe₂N can avert the structure decay caused by the volume change during the lithiation/delithiation process. Moreover, in situ X‐ray absorption fine‐structure analysis demonstrated that the excellent performance can be attributed to the lack of any obvious change in the coordination geometry of Fe₂N@C‐RGO during the charge/discharge processes.     

Caesium carbonate supported on hydroxyapatite‐encapsulated Ni0.5Zn0.5Fe2O4 nanocrystallites as a novel magnetically basic catalyst for the one‐pot synthesis of pyrazolo[1,2‐b]phthalazine‐5,10‐diones

A novel nanomagnetic basic catalyst of caesium carbonate supported on hydroxyapatite‐coated Ni_0.5Zn_0.5Fe₂O₄ magnetic nanoparticles (Ni_0.5Zn_0.5Fe₂O₄@HAP‐Cs₂CO₃) was prepared. This new catalyst was fully characterized using Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, X‐ray diffraction and vibrating sample magnetometry techniques, and then the catalytic activity of this catalyst was investigated in the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives. Also, Ni_0.5Zn_0.5Fe₂O₄@HAP‐Cs₂CO₃ could be reused at least five times without significant loss of activity and could be recovered easily by applying an external magnet. Thus, the developed nanomagnetic catalyst is potentially useful for the green and economic production of organic compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Palladium‐Catalyzed Coupling Reaction of Perfluoroarenes with Diarylzinc Compounds

This report describes the first Pd⁰‐catalyzed cross‐coupling of hexafluorobenzene (C₆F₆) with diarylzinc compounds to give a variety of pentafluorophenyl arenes. This reaction could be applied to other perfluoroarenes, such as octafluorotoluene, pentafluoropyridine, and perfluoronaphthalene, to give the corresponding polyfluorinated coupling products. The optimal ligand in this catalytic reaction was PCy₃, and lithium iodide was indispensable as an additive for the coupling reaction. One of the roles of lithium iodide in this catalytic reaction was to promote the oxidative addition of one C?F bond of C₆F₆ to palladium. Stoichiometric reactions revealed that an expected oxidative‐addition product, trans‐[Pd(C₆F₅)I(PCy₃)₂], generated from the reaction of [Pd(PCy₃)₂] with C₆F₆ in the presence of lithium iodide, was not involved in the catalytic cycle. Instead, a transient three‐coordinate, monophosphine‐ligated species, [Pd(C₆F₅)I(PCy₃)], emerged as a potential intermediate in the catalytic cycle. Therefore, we isolated a novel Pd^II complex, [Pd(C₆F₅)I(PCy₃)(py)], in which pyridine (py) acted as a labile ligand to generate the transient species. In fact, in the presence of lithium iodide, this Pd^II complex was found to react smoothly with diphenylzinc to give the desired pentafluorophenyl benzene, whereas the same reaction conducted in the absence of lithium iodide resulted in a decreased yield of pentafluorophenyl benzene, which indicated that the other role of lithium iodide was to enhance the reactivity of the organozinc species during the transmetalation step.     

Modified High‐Nickel Cathodes with Stable Surface Chemistry Against Ambient Air for Lithium‐Ion Batteries

High‐Ni layered oxides are promising next‐generation cathodes for lithium‐ion batteries owing to their high capacity and lower cost. However, as the Ni content increases over 70 %, they have a high dynamic affinity towards moisture and CO₂ in ambient air, primarily reacting to form LiOH, Li₂CO₃, and LiHCO₃ on the surface, which is commonly termed “residual lithium”. Air exposure occurs after synthesis as it is common practice to handle and store them under ambient conditions. The air exposure leads to significant performance losses, and hampers the electrode fabrication, impeding their practical viability. Herein, we show that substituting a small amount of Al for Ni in the crystal lattice notably improves the chemical stability against air by limiting the formation of LiOH, Li₂CO₃, LiHCO₃, and NiO in the near‐surface region. The Al‐doped high‐Ni oxides display a high capacity retention with excellent rate capability and cycling stability after being exposed to air for 30 days.     

A Switchable Domino Process for the Construction of Novel CO2‐Sourced Sulfur‐Containing Building Blocks and Polymers

α‐Alkylidene cyclic carbonates (αCCs) recently emerged as attractive CO₂‐sourced synthons for the construction of complex organic molecules. Herein, we report the transformation of αCCs into novel families of sulfur‐containing compounds by organocatalyzed chemoselective addition of thiols, following a domino process that is switched on/off depending on the desired product. The process is extremely fast and versatile in substrate scope, provides selectively linear thiocarbonates or elusive tetrasubstituted ethylene carbonates with high yields following a 100 % atom economy reaction, and valorizes CO₂ as a renewable feedstock. It is also exploited to produce a large diversity of unprecedented functional polymers. It constitutes a robust platform for the design of new sulfur‐containing organic synthons and important families of polymers.     

Generation of Aryl(2‐lithiophenyl)methanone O‐Methyl Oximes and Their Use for the Synthesis of N‐(3‐Alkyl‐1‐aryl‐ or 1,3‐diaryl‐1H‐isoindol‐1‐yl)‐O‐methylhydroxylamines via the Reaction with Nitriles

An efficient two‐step procedure for the preparation of a new type of 1H‐isoindoles, i.e., N‐(3‐alkyl‐1‐aryl‐ or 1,3‐diaryl‐1H‐isoindol‐1‐yl)‐O‐methylhydroxylamines 5 , from readily available aryl(2‐bromophenyl)methanones 1 has been developed. Aryl(2‐bromophenyl)methanone O‐methyloximes 2 , derived from the corresponding ketones, were treated with BuLi in Et₂O at 0° to generate novel lithium compounds, aryl(2‐lithiophenyl)methanone O‐methyloximes 3 , which were allowed to react with nitriles to give the desired products 5 in moderate‐to‐fair yields.     

Highly Rechargeable Lithium‐CO2 Batteries with a Boron‐ and Nitrogen‐Codoped Holey‐Graphene Cathode

Metal‐air batteries, especially Li‐air batteries, have attracted significant research attention in the past decade. However, the electrochemical reactions between CO₂ (0.04 % in ambient air) with Li anode may lead to the irreversible formation of insulating Li₂CO₃, making the battery less rechargeable. To make the Li‐CO₂ batteries usable under ambient conditions, it is critical to develop highly efficient catalysts for the CO₂ reduction and evolution reactions and investigate the electrochemical behavior of Li‐CO₂ batteries. Here, we demonstrate a rechargeable Li‐CO₂ battery with a high reversibility by using B,N‐codoped holey graphene as a highly efficient catalyst for CO₂ reduction and evolution reactions. Benefiting from the unique porous holey nanostructure and high catalytic activity of the cathode, the as‐prepared Li‐CO₂ batteries exhibit high reversibility, low polarization, excellent rate performance, and superior long‐term cycling stability over 200 cycles at a high current density of 1.0 A g⁻¹. Our results open up new possibilities for the development of long‐term Li‐air batteries reusable under ambient conditions, and the utilization and storage of CO₂.     

Metal–Organic‐Framework‐Derived Hollow N‐Doped Porous Carbon with Ultrahigh Concentrations of Single Zn Atoms for Efficient Carbon Dioxide Conversion

The development of efficient and low energy‐consumption catalysts for CO₂ conversion is desired, yet remains a great challenge. Herein, a class of novel hollow porous carbons (HPC), featuring well dispersed dopants of nitrogen and single Zn atoms, have been fabricated, based on the templated growth of a hollow metal–organic framework precursor, followed by pyrolysis. The optimized HPC‐800 achieves efficient catalytic CO₂ cycloaddition with epoxides, under light irradiation, at ambient temperature, by taking advantage of an ultrahigh loading of (11.3 wt %) single‐atom Zn and uniform N active sites, high‐efficiency photothermal conversion as well as the hierarchical pores in the carbon shell. As far as we know, this is the first report on the integration of the photothermal effect of carbon‐based materials with single metal atoms for catalytic CO₂ fixation.     

Phosphoryl‐Rich Flame‐Retardant Ions (FRIONs): Towards Safer Lithium‐Ion Batteries

The functionalized catecholate, tetraethyl (2,3‐dihydroxy‐1,4‐phenylene)bis(phosphonate) (H₂‐DPC), has been used to prepare a series of lithium salts Li[B(DPC)(oxalato)], Li[B(DPC)₂], Li[B(DPC)F₂], and Li[P(DPC)₃]. The phosphoryl‐rich character of these anions was designed to impart flame‐retardant properties for their use as potential flame‐retardant ions (FRIONs), additives, or replacements for other lithium salts for safer lithium‐ion batteries. The new materials were fully characterized, and the single‐crystal structures of Li[B(DPC)(oxalato)] and Li[P(DPC)₃] have been determined. Thermogravimetric analysis of the four lithium salts show that they are thermally stable up to around 200 °C. Pyrolysis combustion flow calorimetry reveals that these salts produce high char yields upon combustion.     

Advanced High‐Voltage Aqueous Lithium‐Ion Battery Enabled by “Water‐in‐Bisalt” Electrolyte

A new super‐concentrated aqueous electrolyte is proposed by introducing a second lithium salt. The resultant ultra‐high concentration of 28 m led to more effective formation of a protective interphase on the anode along with further suppression of water activities at both anode and cathode surfaces. The improved electrochemical stability allows the use of TiO₂ as the anode material, and a 2.5 V aqueous Li‐ion cell based on LiMn₂O₄ and carbon‐coated TiO₂ delivered the unprecedented energy density of 100 Wh kg^?1 for rechargeable aqueous Li‐ion cells, along with excellent cycling stability and high coulombic efficiency. It has been demonstrated that the introduction of a second salts into the “water‐in‐salt” electrolyte further pushed the energy densities of aqueous Li‐ion cells closer to those of the state‐of‐the‐art Li‐ion batteries.     

Ag+ selection by aza‐18‐crown‐6 ethers N‐Substituted on heterocyclic aromatics

Substitution on the nitrogen atom, where necessary by high‐pressure S_NAr reactions, of aza‐18‐crown‐6 ethers linked to heterocyclic aromatics has extended the number of potential host compounds for Ag⁺. The complexation of Ag⁺ by the new compounds has been evaluated by liquid membrane ion transport and ion extraction experiments. The nature of the binding sites of these new host compounds for Ag⁺ has been assessed, in DMF/D₂O (4/1), by ¹³C nmr titration experiments with AgClO₄.     

Structural and Electrochemical Study of Vanadium‐Doped TiO2 Ramsdellite with Superior Lithium Storage Properties for Lithium‐Ion Batteries

Titanium‐oxide‐based materials are considered attractive and safe alternatives to carbonaceous anodes in Li‐ion batteries. In particular, the ramsdellite form TiO₂(R) is known for its superior lithium‐storage ability as the bulk material when compared with other titanates. In this work, we prepared V‐doped lithium titanate ramsdellites with the formula Li_0.5Ti_1?xV_xO₂ (0≤x≤0.5) by a conventional solid‐state reaction. The lithium‐free Ti_1?xV_xO₂ compounds, in which the ramsdellite framework remains virtually unaltered, are easily obtained by a simple aqueous oxidation/ion‐extraction process. Neutron powder diffraction is used to locate the Li channel site in Li_0.5Ti_1?xV_xO₂ compounds and to follow the lithium extraction by difference‐Fourier maps. Previously delithiated Ti_1?xV_xO₂ ramsdellites are able to insert up to 0.8 Li⁺ per transition‐metal atom. The initial gravimetric capacities of 270 mAh g^?1 with good cycle stability under constant current discharge conditions are among the highest reported for bulk TiO₂‐related intercalation compounds for the threshold of one e^? per formula unit.