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Insertion polynorbornenes (PBNEs) are rigid-rod polymers that have very high glass transition temperatures (T

Organic cathode materials for lithium batteries are becoming increasingly popular because they have high theoretical redox voltage, high gravimetric capacity, low cost, easy processing and sustainability. However, their development is limited by their solubility in the electrolyte, which leads to rapid deterioration of the battery upon cycling. We developed a Janus membrane, which consists of two layers – a commercial polypropylene separator (Celgard) and a 300–600 nm layer of exfoliated graphite that was applied by a simple and environmentally friendly process. The submicron graphite layer is only permeable to Li+ and it drastically improves the battery performance, as measured by capacity retention and high coulombic efficiency, even at 2C rates. Post-mortem analysis of the battery indicates that the new membrane protects the anode against corrosion, and cathode dissolution is reduced. This graphite-based membrane is expected to greatly expedite the deployment of batteries with organic cathodes.

Summary High-energy-density batteries use lithium electrodes because they provide the highest theoretical capacity and widest electrochemical potential window of all the possible anodes for rechargeable lithium batteries. However, adoption of metallic lithium leads to safety problems and low cycling performance due to the reactivity of lithium with standard liquid electrolytes (LEs). Solid electrolytes (SEs) are a promising solution to replace LEs due to their high thermal and chemical stability. They also possess numerous other advantages such as light-weight, flexibility, low-cost and a high operating window voltage. The aim of this review is to present a summary of recent advances in polymer and inorganic SEs for all-solid lithium metal batteries (LMBs). We will discuss the replacement of polyethylene oxide (PEO) and the crucial parameters for achieving a suitable combination of polymer matrix with inorganic ceramic fillers to obtain viable SE composites for high-voltage and high-capacity cell.

The catalytic insertion polymerization of substituted norbornenes (NBEs) leads to the formation of a family of polymers which combine extreme thermomechanical properties as well as unique optical and electronic properties. However, this reaction is marred by the lack of reactivity of endo substituted monomers. It has long been assumed that these monomers chelate the metallic catalyst, leading to species which are inactive in polymerization. Here we examine the polymerization of cis-5-norbornene-2,3-dicarboxylic anhydride (so-called carbic anhydride, CA) with a naked cationic Pd catalyst. Although exo-CA can be polymerized, the polymerization of endo-CA stops after a single insertion. Surprisingly, no chelate is formed between the catalyst and endo-CA. Using DFT calculation, it is shown that while the insertion of exo-NBEs is exergonic, the insertion of two endo-CA in a row is endergonic. In this latter case, the enthalpy gain corresponding to the insertion of a double bond is not sufficient to overcome th...

Aqueous lithium-ion batteries are emerging as strong candidates for a great variety of energy storage applications because of their low cost, high-rate capability, and high safety. Exciting progress has been made in the search for anode materials with high capacity, low toxicity, and high conductivity; yet, most of the anode materials, because of their low equilibrium voltages, facilitate hydrogen evolution. Here, we show the application of olivine FePO4 and amorphous FePO4·2H2O as anode materials for aqueous lithium-ion batteries. Their capacities reached 163 and 82 mA h/g at a current rate of 0.2 C, respectively. The full cell with an amorphous FePO4·2H2O anode maintained 92% capacity after 500 cycles at a current rate of 0.2 C. The acidic aqueous electrolyte in the full cells prevented cathodic oxygen evolution, while the higher equilibrium voltage of FePO4 avoided hydrogen evolution as well, making them highly stable. A combination of in situ X-ray diffraction analyses and computational studies reveal...

Recently many observations related to the catalytic effects of layered metal disulfide versus polysulfide electrochemistry were documented. In this work, we investigated the reactivity of layered WS2 in a Li-S battery and observed a chemical reaction involving the removal of W ions by polysulfides. The presence of metallic tungsten nanoparticles in the sulfur cathode is the result of W ion oxidation reaction and subsequent recrystallization during cycling. In situ Raman spectroscopy and ex situ transmission electron microscopy were used in order to clarify the reaction mechanism.

A simple method to synthesize high Tg sulfonated ionomers based on catalytic insertion polynorbornene is reported. Copolymers of norbornene and 5-methyl alcohol norbornene (endo:exo = 82:18) or 5-methyl bromide norbornene (endo:exo = 86:14) as well as terpolymers of norbornene, 5-methyl alcohol norbornene and 5-hexyl norbornene are prepared using a cationic Pd catalyst. These copolymers are then thioacetylated. Using hydrogen peroxide as oxidant, a sulfonated polynorbornene is obtained. Ionomers containing as much as 30 mol% SO3H and with Tgs above 200 °C are obtained in a four-step procedure of overall 40–75% yield.

Thermosetting materials (thermosets) are widely used organic materials derived from 3D-network forming monomers. Achieving high glass transition temperature (Tg) thermosets is often a challenging task due to the complexity of designing efficiently and cheaply monomers which are rigid enough to prevent molecular motions within the thermoset. We report here a very simple route to prepare epoxy thermosets with Tg as high as 350 °C, based on insertion polynorbornenes. The epoxy monomer (PNBE(epoxy)) is prepared by the epoxidation of poly(5-vinylnorbornene) obtained by catalytic insertion polymerization of 5-vinylnorbornene. PNBE(epoxy) can be cross-linked with simple biosourced compounds. Alternatively, polar insertion polynorbornene can also be used as cross-linker in the formulation of an epoxy resin, once again resulting in epoxy resins with Tg higher than 300 °C and devoid of degradation at this temperature. Thus, this study clearly demonstrates the viability of catalytic polymerization to access epoxy th...

Energy storage technology is a critical research area for the success of portable electronic devices and electrical transportation. Such applications need affordable, durable, safe and environmentally friendly battery materials with high energy density. Organic cathode materials are currently promising candidates because they fulfill most of these requirements for an active battery material1. However, they usually suffer from a major limitation, namely their solubility in organic electrolytes2. Even a very low solubility translates into a decreased capacity upon cycling due to the loss of active material. Among organic cathode materials, conjugated carbonyl compounds have been intensively scrutinized because of a combination of desirable properties, such as low cost, good theoretical capacity, reversible oxidative behavior, high discharge potential and commercial availability. For example, 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) is an inexpensive red pigment that is widely investigated as an active material for energy devices. However, Li-PTCDA batteries suffer from poor and irreversible cycling stability due to the dissolution in the electrolyte. Even more problematic, the dissolved PTCDA migrates through the porous separator and deposits on the anode surface causing irreversible damage3. In order to solve this problem, chemical modifications such as polymerisation, functionalization and immobilization on carbon materials have improved cycling stability. However, these modified cathode materials, which are often prepared by complex processes, contain considerable amounts of inactive mass that cause a decreases of the energy density. We developed a Janus membrane, which consists of two layers – a commercial polypropylene separator (CelgardTM) and a 300-600 nm layer of exfoliated graphite that was applied by a simple and environmentally friendly process. The submicron graphite layer is only permeable to Li+ and it drastically improves the battery performance, as measured by capacity retention and high coulombic efficiency, even at 2C rates. Post-mortem analysis of the battery indicates that the new membrane protects the anode against corrosion, and cathode dissolution is reduced. This graphite-based membrane is expected to greatly expedite the deployment of lithium batteries using organic moities as active materials. References [1] Armand, M. & Tarascon, J. M. Building better batteries. Nature 451, 652–657 (2008). [2] Zhao, Q., Zhu, Z. & Chen, J. Molecular Engineering with Organic Carbonyl Electrode Materials for Advanced Stationary and Redox Flow Rechargeable Batteries. Adv. Mater. 29, 1–25 (2017). [3] Wang, J., Wang, X., Li, H., Yang, X. & Zhang, Y. Intrinsic factors attenuate the performance of anhydride organic cathode materials of lithium battery. J. Electroanal. Chem. 773, 22–26 (2016).

A commercial low molecular weight poly(ε-caprolactone) was chain-extended with acrylate moieties to create a macromonomer, which was then polymerized by radical reaction in the presence of different amounts of lithium bis(trifluoromethanesulfonyl)imide, LiTFSI, to obtain a 3D network Solid Polymer Electrolyte (SPE). The SPE with the largest ionic conductivity (24 μS cm−1 at 50 °C) had a high transference number of 0.78 and could form a self-standing film. Lithium Iron Phosphate (LFP)/SPE/Li cells made with this SPE attained a specific capacity of 120 mA.h.g−1. At 50 °C, the initial capacity declined by less than 15% after 150 cycles at 0.2 C. No evidence of degradation and dendrite growth was observed, indicating that the 3D network was stable. Thus, caprolactone-based 3D networks are promising materials for the fabrication of all solid-state batteries with high stability and cyclability, at near room temperature.

Aqueous lithium-ion batteries are emerging as strong candidates for a great variety of energy storage applications because of their low cost, high-rate capability, and high safety. Exciting progress has been made in the search for anode materials with high capacity, low toxicity, and high conductivity; yet, most of the anode materials, because of their low equilibrium voltages, facilitate hydrogen evolution. Here, we show the application of olivine FePO

The catalytic 1,2-insertion polymerization of polar norbornenes (NBEs) leads to the formation of functional rigid macromolecules with exceptional thermal, optical and mechanical properties. However, this remarkable reaction is plagued by the low reactivity of the polar monomers, and most notably of those bearing a functional group in endo position. We have examined the polymerization mechanism of NBEs bearing one or two CO2Me groups either in exo or endo position catalyzed by the so-called naked allyl Pd+ SbF6- catalyst (1). Although endo dimethyl ester of 5-norbornene-2,3-dicarboxylic acid (NBE(CO2Me)2) is polymerized by 1, two endo units are never inserted consecutively along the polymer chain. Indeed, 1 is a tandem catalyst which not only catalyzes the insertion of the monomer but also the isomerization of endo and exo isomers. Thus, the polymerization of endo monomers proceeds via a novel mechanism, coined rectification-insertion mechanism, whereby half of the endo monomers are rectified into exo ones prior insertion, leading to the formation of an alternating endo-exo copolymer using an endo only feedstock. With this mechanism, the lack of reactivity of endo norbornenes is bypassed, and the polymerization of predominantly endo polar NBEs bearing a variety of functionalities such as esters, imides, acids, aldehydes, alcohols, anhydrides, or alkyl bromides proceeds with catalyst loadings as low as 0.002 mol%.

Recently, intensive efforts are dedicated to convert and store the solar energy in a single device. Herein, dye-synthesized solar cell technology is combined with lithium-ion materials to investigate light-assisted battery charging. In particular we report the direct photo-oxidation of lithium iron phosphate nanocrystals in the presence of a dye as a hybrid photo-cathode in a two-electrode system, with lithium metal as anode and lithium hexafluorophosphate in carbonate-based electrolyte; a configuration corresponding to lithium ion battery charging. Dye-sensitization generates electron–hole pairs with the holes aiding the delithiation of lithium iron phosphate at the cathode and electrons utilized in the formation of a solid electrolyte interface at the anode via oxygen reduction. Lithium iron phosphate acts effectively as a reversible redox agent for the regeneration of the dye. Our findings provide possibilities in advancing the design principles for photo-rechargeable lithium ion batteries., Photo-rechargable energy storage cells can provide plug-free power for various applications. Here the authors integrate a photo-absorbing dye complex with LiFePO4 nanocrystals as a lithium-ion battery cathode in a two-electrode system demonstrating its photo-charging and galvanostatic discharging.

In this work, we analyzed the thermal stability of polycarbonate: lithium trifluoromethane sulphonylimide (LiTFSI) systems. Polyethylene carbonate (PEC) and polypropylene carbonate (PPC) undergo depolymerization to ethylene carbonate (EC) and propylene carbonate (PC), respectively, in the presence of Li salt under annealing treatment. The decomposition reaction can explain the surprising high ionic conductivity recently reported for solid polymer electrolyte (SPE) polycarbonate-based systems. Because this phenomenon can strongly impact the results of SPE research, it is essential to control the depolymerization of polymers to avoid inaccurate electrochemical performance. In addition, we observed that the standard drying procedure for the preparation of high-salt-concentration polymer (polymer-in-salt) SPEs traps a high amount of residual solvent, e.g., acetonitrile (ACN), due to the strong bond between the solvent and ionic species. This finding represents another factor influencing the remarkably high ionic conductivity.

Polymer nanocrystals have attracted considerable attention because of their potential applications in future technology and their fascinating properties which differ from those of corresponding bulk materials. The essential influence of the nanointerface in nanocrystals is apparent in the linear dependence of the melting temperature with the inverse sheet thickness, i.e. the Gibbs–Thomson behaviour. Yet, few experimental and theoretical works have been attempted to highlight the influence of nanointerfaces on the thermal properties of nanocrystals. In this work, simulations were used to evaluate the melting temperature of crystalline polymer nanosheets. Ensuing results were compared favourably to experimental melting temperatures stemming from alkane chains and functional polyolefins, thus validating our simulation approach. Both experimental and simulated results followed Gibbs–Thomson behaviour and a procedure was devised to extract the heat of melting as well as the surface energy from these results. Thus, surface energy of various nanocrystals was found to be widely different for various experimental systems, demonstrating the significance of the environment on thermal properties of nanocrystals.

The novel rectification–insertion mechanism for the polymerization of polar norbornenes: making alternating copolymers from a single monomer., The catalytic 1,2-insertion polymerization of polar norbornenes (NBEs) leads to the formation of functional rigid macromolecules with exceptional thermal, optical and mechanical properties. However, this remarkable reaction is plagued by the low reactivity of the polar monomers, and most notably of those bearing a functional group in endo position. We have examined the polymerization mechanism of NBEs bearing one or two CO2Me groups either in exo or endo position catalyzed by the so-called naked allyl Pd+ SbF6– catalyst (1). Although endo dimethyl ester of 5-norbornene-2,3-dicarboxylic acid (NBE(CO2Me)2) is polymerized by 1, two endo units are never inserted consecutively along the polymer chain. Indeed, 1 is a tandem catalyst which not only catalyzes the insertion of the monomer but also the isomerization of endo and exo isomers. Thus, the polymerization of endo monomers proceeds via a novel mechanism, coined rectification–insertion mechanism, whereby half of the endo monomers are rectified into exo ones prior insertion, leading to the formation of an alternating endo–exo copolymer using an endo only feedstock. With this mechanism, the lack of reactivity of endo norbornenes is bypassed, and the polymerization of predominantly endo polar NBEs bearing a variety of functionalities such as esters, imides, acids, aldehydes, alcohols, anhydrides, or alkyl bromides proceeds with catalyst loadings as low as 0.002 mol%.