Alternative Host Material Research Articles

Improving Room Temperature Performance of All-Solid-State Polymer Batteries through Cell Activation

Solid polymer electrolytes (SPE) are gaining increasing attention for use in all-solid-state lithium batteries (ASSLB) due to their enhanced safety and simplified processing.[1] However, their conventional operation requires elevated temperatures.[2, 3] Here, we propose a straightforward hot-press activation method to facilitate cell operation at room temperature (r.t., 30 °C) for SPE-based ASSLB. This activation method induces grain amorphization, leading to a substantial reduction in grain boundary resistance within the SPE and achieving a fourfold increase in r.t. ionic conductivity. Furthermore, by decoupling Li-ion transport processes, the activation significantly diminishes the electrode-electrolyte interfacial resistances for both the cathode and anode, thereby enhancing kinetics and overall cell performance at r.t.. Through the application of an optimized activation procedure, all-solid-state LiFeO4 (LFP)|SPE|Li cells exhibit noteworthy performance enhancements, demonstrating both high specific capacity and stable cycling at r.t.References Mauger, A., et al., Building Better Batteries in the Solid State: A Review. Materials, 2019. 12(23).Chen, R.J., et al., The pursuit of solid-state electrolytes for lithium batteries: from comprehensive insight to emerging horizons. Materials Horizons, 2016. 3(6): p. 487-516.Mindemark, J., et al., Beyond PEO—Alternative host materials for Li + -conducting solid polymer electrolytes. Progress in Polymer Science, 2018. 81: p. 114-143.

Emerging Carbonyl Polymers as Sustainable Electrode Materials for Lithium‐Free Metal‐Ion Batteries

Lithium‐ion batteries using inorganic electrode materials have been long demonstrated as the most promising power supplies for portable electronics, electric vehicles, and smart grids. However, the increasing cost and descending availability of lithium resources in combination with the limited electrochemical performance and eco‐sustainability have created serious concerns with the competitiveness of lithium‐ion batteries. There is a pressing need for the discovery of new redox chemistries between the alternative host materials and charge carriers. Organic nonlithium batteries using organic electrodes have recently attracted considerable interests as the future substitutes for energy storage systems, because of their combined merits (e.g., natural abundance, rich chemistry of organics, rapid kinetics, and multielectron redox) of Li‐free batteries and organic electrodes. Herein, an overview on the state‐of‐the‐art developments of emerging carbonyl polymers for nonlithium metal‐ion batteries is comprehensively presented with a primary focus on polyquinones and polyimides from the perspective of chain engineering. Six distinct categories, including monovalent (Na+, K+) and multivalent (Mg2+, Zn2+, Ca2+, Al3+) metal‐ions batteries are individually outlined. Advantages of polymer electrode materials and characteristics of charge storage mechanisms are highlighted. Some key performance parameters such as specific capacity, rate capability, and cycle stability are carefully discussed. Moreover, aqueous nonlithium batteries based on carbonyl polymers are specially scrutinized due to the less reactivity of Li‐free metals when exposed in aqueous electrolytes and ambient atmosphere. Current challenges and future prospects of developing polymer‐based batteries are proposed finally. This review provides a fundamental guidance for the future advancement of next‐generation sustainable batteries beyond lithium‐ion batteries.

Material gain concentration quenching in organic dye-doped polymer thin films

The optimization of material gain in optically pumped dye-doped polymer thin films is an important task in the development of organic solid-state lasers. In this work, we present a theoretical model that accommodates the influence of concentration quenching on material gain and employ it to study the novel dye molecule 2-(4-(bis(4-(tert-butyl)phenyl)amino)benzylidene)malononitrile (PMN) and the well-established dye molecule 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) embedded in poly(methyl methacrylate) (PMMA). Polycarbonate was tested as an alternative host material for PMN. The material gain in these dye-doped polymer thin films was determined by the variable stripe length method. The inclusion of concentration quenching in the material gain expression is able to significantly reduce the overestimation of the gain efficiency inherent to a linear model.

Li-ion batteries using electrolytes based on mixtures of poly(vinyl alcohol) and lithium bis(triflouromethane) sulfonamide salt

Poly(vinyl alcohol) (PVA) has, to a limited degree, previously been investigated as an alternative host material to the dominating poly(ethylene oxide)-(PEO)-based polymer electrolytes used in electrochemical applications. These PVA-materials were found to be highly ionically conducting for a number of different salts at temperatures below the glass transition temperature, but in the presence of DMSO (dimethyl sulfoxide) residues. Here, we investigate the PVA:LiTFSI (lithium bis(triflouromethane)sulfonamide) electrolytes system, thereby for the first time using the salt most commonly explored in PEO-based systems also in PVA. It is shown that this results in significantly higher conductivities than for alternative Li salts. Comparisons between electrolytes casted in DMSO, H2O and hot-pressed samples confirm the necessity of solvent residues present in the DMSO casted films for the ionic transport, although no obvious liquid phase is formed. Moreover, we also show the feasibility of PVA-based electrolytes by construction of functional Li-metal | PVA-LiTFSI (DMSO) | LiFePO4 batteries operating at 60°C, displaying stable capacities of 136mAh/g LiFePO4 at a rate of C/20.

An Alternative Host Material for Long-Lifespan Blue Organic Light-Emitting Diodes Using Thermally Activated Delayed Fluorescence.

It has been challenging to find stable blue organic light emitting diodes (OLEDs) that rely on thermally activated delayed fluorescence (TADF). Lack of stable host materials well‐fitted to the TADF emitters is one of the critical reasons. The most popular host for blue TADF, bis[2‐(diphenylphosphino)phenyl] ether oxide (DPEPO), leads to unrealistically high maximum external quantum efficiency. DPEPO is however an unstable material and has a poor charge transporting ability, which in turn induces an intrinsic short OLED operating lifespan. Here, an alternative host material is introduced which educes the potential efficiency and device lifespan of given TADF emitters with the appropriateness of replacing the most popular host material, DPEPO, in developing blue TADF emitters. It simultaneously provides much longer device lifespan and higher external quantum efficiency at a practical brightness due to its high material stability and electron‐transport‐type character well‐fitted for hole‐transport‐type TADF emitters.

Up-conversion emission of Er3+/Yb3+co-doped BaBi2Nb2O9 (BBN) phosphors

On this paper, polycrystalline samples of the tetragonal systems BaBi2Nb2O9 (BBN) and BBN co-doped with Er3+/Yb3+ (BBN: 0.04Er3+yYb3+, where y=0.02, 0.04, 0.06 and 0.08mol%) were synthesized by the solid state method. The crystalline structure and photoluminescent properties of the ceramic phosphors were investigated by powder X-ray diffraction (PXRD), Raman spectroscopy and spectral analysis of up-conversion (UC) emission. The results reveal that all compositions crystallize in the I4/mmm space group at room temperature, and show UC green emissions (centered at 525nm and 550nm) and red (around 660nm) coming from (2H11/2, 4S3/2→4I15/2) and (4F9/2→4I15/2) transitions, respectively, under excitation at 980nm. Increasing variations of the Yb3+ sensitizer concentration in the host BBN, lead to a significant intensity increase in both UC emissions due to the efficiency of the energy-transfer process. The BBN: 0.04mol%Er3+0.08mol%Yb3+ composition showed the higher intensity bands, thus establishing the BBN as an alternative host material for luminescent centers.

Ion transport in polycarbonate based solid polymer electrolytes: experimental and computational investigations.

Among the alternative host materials for solid polymer electrolytes (SPEs), polycarbonates have recently shown promising functionality in all-solid-state lithium batteries from ambient to elevated temperatures. While the computational and experimental investigations of ion conduction in conventional polyethers have been extensive, the ion transport in polycarbonates has been much less studied. The present work investigates the ionic transport behavior in SPEs based on poly(trimethylene carbonate) (PTMC) and its co-polymer with ε-caprolactone (CL) via both experimental and computational approaches. FTIR spectra indicated a preferential local coordination between Li(+) and ester carbonyl oxygen atoms in the P(TMC20CL80) co-polymer SPE. Diffusion NMR revealed that the co-polymer SPE also displays higher ion mobilities than PTMC. For both systems, locally oriented polymer domains, a few hundred nanometers in size and with limited connections between them, were inferred from the NMR spin relaxation and diffusion data. Potentiostatic polarization experiments revealed notably higher cationic transference numbers in the polycarbonate based SPEs as compared to conventional polyether based SPEs. In addition, MD simulations provided atomic-scale insight into the structure-dynamics properties, including confirmation of a preferential Li(+)-carbonyl oxygen atom coordination, with a preference in coordination to the ester based monomers. A coupling of the Li-ion dynamics to the polymer chain dynamics was indicated by both simulations and experiments.

Understanding the infrared to visible upconversion luminescence properties of Er3+/Yb3+ co-doped BaMoO4 nanocrystals

In this paper we report the infrared to visible upconversion luminescence properties of Er3+/Yb3+ co-doped BaMoO4 nanocrystals synthesized via microwave assisted sol–gel processing route. Structural, morphological and upconversion luminescence properties were investigated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and Upconversion Photoluminescence spectra analysis. Results revealed that the oval shaped BaMoO4 nanocrystals ranging in size from 40 to 60nm having tetragonal scheelite crystal structure were obtained by sol–gel route. The infrared to visible upconversion luminescence has been investigated in Er3+/Yb3+ co-doped in BaMoO4with different Yb3+ concentrations. Intense green upconversion emissions around 528, 550nm, and red emission at 657nm corresponding to the 2H11/2, 4S3/2, and 4F9/2 transitions, respectively to the 4I15/2 ground state were observed when excited by CW laser radiation at 980nm. The green emissions were greatly enhanced after the addition of sensitizer (Yb3+ ions). The effect of Yb3+ on the upconversion luminescence intensity was analyzed and explained in terms of the energy transfer process based. The reported work establishes the understanding of molybdates as an alternative host material for upconversion luminescence.

Synthesis and photo- and electroluminescence properties of 3,6-disubstituted phenanthrenes: alternative host material for blue fluorophores

Three deep-blue fluorescent 9,10-bis(4-tert-butylphenyl)phenanthrenes with diphenyl, -naphthyl, and -pyrenyl moieties at C3 and C6 positions were synthesized and used as the host for doped blue fluorescent devices; one of these devices reveals excellent external quantum efficiency of 7.7% and current efficiency of 9.8 cd A(-1) with low efficiency roll-off, deep-blue color coordinates (0.14, 0.14) and long operational lifetime.

Dispersal of the spruce beetle, Dendroctonus rufipennis Kirby (Col., Scolytidae) from an experimental log deck

AbstractDispersal of spruce beetles from a log deck composed of infested (brood) and uninfested spruce logs was assessed by trapping emerged beetles and sampling logs for fresh attacks. The brood logs were dusted with fluorescent powder in order to mark beetles as they emerged. Two other log decks, composed of uninfested spruce, were built 25 m distant on opposite sides of the brood log deck to provide alternative host material for the dispersing beetles. About 14% of the emerged beetles attacked uninfested logs in the central deck and 25% attacked logs in the other two decks. The balance of the beetles dispersed beyond the experimental area.

Excited-state-absorption cross sections and amplifier modeling in the 1300-nm region for Nd-doped glasses

The performance of Nd/sup 3+/-doped fibre amplifiers is limited by strong excited-state absorption (ESA) of the signal, and, even for fluorozirconate glasses, ESA prevents the important region below 1320 nm from being used. To quantify this limitation and explore alternative host materials, ESA and stimulated-emission cross sections have been measured for a representative group of glass compositions. These parameters have been used in an accurate fiber-amplifier model to provide the first quantitative comparisons of performance for Nd/sup 3+/-doped glasses in the 1300-nm band as a function of host.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Excited-State-Absorption Cross Sections and Amplifier Modeling in the 1300-nm Region for Nd-Doped Glasses

ABSTRACTThe performance of Nd3+-doped fiber amplifiers is limited by strong excited state absorption (ESA) of the signal, even for fluorozirconate glasses where ESA prevents the important region below 1320 nm from being used. To quantify this and explore alternative host materials, ESA and stimulated-emission cross sections have been measured for a representative group of glass compositions. These parameters have been used in an accurate, fiber-amplifier model to provide the first quantitative comparisons of performance for Nd3+-doped glasses in the 1300-nm band as a function of host. A high-fluorine fluorophosphate is predicted to extend the short-wavelength boundary of the gain spectrum to 1295 nm but only at reduced gain levels and at the cost of having lower gains at longer wavelengths than fluorozirconates. A substantial increase in small-signal gain is predicted if the amplified spontaneous emission for the 1050-nm band is suppressed.

Sol-gel glasses: a new material for solar fluorescent planar concentrators?

Inorganic glasses prepared by the “cold” chemical sol-gel process can present an alternative host material for organic fluorescent dyes. We report on measurements done on thin SiO 2 layers prepared as sol-gels and doped with various dyes on a glass substrate. The preparation is done by dip-coating of the substrate in the corresponding alcoxide solutions. Good-quality layers without crazing after drying are achieved with a thickness of up to 1–2 μm. The measurements include absorption measurements (UV to IR), fluorescence and excitation measurements (visible to NIR), and measurements of photo-decomposition. The optical properties of the dye molecules in the layer and in the sol-gel solutions are studied as a function of dye concentration and changes in the thermal treatment of the layers. The results are examined for their applicability to fluorescent planar concentrators. Further we report on small silver islands (submicron size) brought into the sol-gel solution as stabilised colloids or by chemical reduction of Ag + salts. According to theoretical predictions, the electromagnetic interaction between silver surface plasmons and dye molecules can result, under certain conditions, in an enhanced fluorescence quantum efficiency and photostability of the dye.

Reactions of ALK-1-enes over ion-exchanged montmorillonites

Straight-chain alk-1-enes react over ion-exchanged montmorillonites below 100 °C to give the di(2,2'-alkyl) ether. The water which is added to the alkene is that present initially in the interlayer of the clay, and essentially the whole of this water can be converted to ether with 1.5 g of di(2,2'hexyl) ether being produced from 1 g of clay catalyst. The most efficacious interlayer cations are those that give high interlayer acidity, i.e. Al 3+,, Fe 3+ and Cr 3+, but use of Cu 2+ leads to very clean ether production. The reaction is pseudo-autocatalytic and accelerates until all the interlayer water is consumed, after which degradation of the ether occurs to give predominantly alk-1-ene, alk-2-ene and alkan-2-ol. Attempts to regenerate the clay catalyst were unsuccessful. It is noteworthy that alternative host materials, even closely related layer silicates, do not give good yields. The reaction displays a high degree of shape selectivity. When this is taken in conjunction with infrared evidence of carbocation formation which intimately involves hydrogen atoms (of the interlayer water molecules) which do not form hydrogen bonds to the silicate sheets, it suggests carbocation intermediates bound at the primary coordination sphere of the interlayer cation. The reaction is viable with alkenes from at least C 5 to C 16, although the efficiency varies with chain length and source of montmorillonite employed.