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Lithium-ion batteries (LIBs) are the most important electrochemical energy storage devices due to their high energy density, long cycle life, and low cost. During the past decades, many review papers outlining the advantages of state-of-the-art LIBs have been published, and extensive efforts have been devoted to improving their specific energy density and cycle life performance. These papers are primarily focused on the design and development of various advanced cathode and anode electrode materials, with less attention given to the other important components of the battery. The “nonelectroconductive” components are of equal importance to electrode active materials and can significantly affect the performance of LIBs. They could directly impact the capacity, safety, charging time, and cycle life of batteries and thus affect their commercial application. This review summarizes the recent progress in the development of nonaqueous electrolytes, binders, and separators for LIBs and discusses their impact on the battery performance. In addition, the challenges and perspectives for future development of LIBs are discussed, and new avenues for state-of-the-art LIBs to reach their full potential for a wide range of practical applications are outlined. Graphic Abstract

The incorporation of metal ions in dielectric layers by means of electric field assisted film dissolution is investigated. The samples consist of alkali-containing glass substrates coated first with SiO 2 and then Ag thin films. The application of moderately elevated temperatures and DC voltages induces thermal poling in the glass matrix and metal film dissolution, resulting in the incorporation of metal ions in both dielectric layer and glass matrix. First, the process dynamics are simulated by modelling the migration of metal film ions and alkali species under an applied electric field. Numerical solution of the model indicates that metal ions progressively dope the dielectric layer until they reach the glass matrix. Then the dopant distribution in the layer becomes steady-state and further injection of ions contributes to increase the dopant concentration in glass. The influence on the process of alkali and dopant ion mobilities and alkali ion concentration is analysed. Additionally, Ag doping of SiO 2 layers deposited on soda-lime and borosilicate glasses is experimentally carried out and characterized using spectroscopic ellipsometry. The evolution of refractive index profiles through both, SiO 2 layer and glass substrate, is correlated with ion migration and confirms the model trends. Overall, this study shows that glass poling and film dissolution can be used to control metal doping of dielectric layers, with potential application in optical and photonic devices.

Carbon black additive, which combines high specific surface area and high purity, was designed to improve gravimetric capacitance and cycle life of electrochemical double layer capacitors. In this study, acid extraction method is employed to remove the impurities in the base carbon black (SC2) and the electrochemical performance of the product materials (SC2A) are evaluated in comparison with other commercially available conductive additives. Results suggest that carbon black with high purity and optimized morphology can not only provide desired electrical conductivity but also improve capacitance and cycle life of the electrochemical cells made with this material.

Pure silicon nano-powder was successfully synthesized via gas-phase sodium reduction of silicon tetrachloride, exhibiting 100% conversion of the reactants and achieving >95% yield of the final product. The interactions of the process conditions and tin-doping with the particle morphology were investigated. The produced powders were analyzed by nitrogen adsorption, transmission and scanning electron microscopy, X-ray diffraction, inert gas fusion analysis and glow discharge mass spectroscopy. The washed polycrystalline silicon particles had a BET surface area in the range of 23–44 m 2 /g. The silicon aciniform aggregates consisted of relatively homogeneous primary particles in the range of 20–100 nm. The silicon was protected by a 2–3 nm thick passivation layer established during the washing step resulting in an oxygen content of less than 3 wt.%. Electrochemical testing demonstrated a high inherent capacity for the pure Si powders. The initial capacity and 1st cycle charge efficiency of Si-containing anode electrodes was dependent on the initial powder surface area. The highest capacity was achieved for Si powders with intermediate BET surface area of 28.5 m 2 /g and cells with this anode material delivered capacity of 2651 mA h/g (normalized to Si) and 82.4% efficiency at first charge.

Conductive carbon additives with different surface area and particle size, alone or in different combinations, were tested as conductive additives for LiFePO 4 cathode materials in lithium ion batteries. Their influence on the conductivity, rate capability as well as the structure of the resulting electrodes was investigated. Mercury porosimetry was carried out to define the porosity and pore size distribution of electrodes, and scanning electron microscopy was used to image their morphology. By comparing the discharge capacity, especially at higher rates, it can be concluded that the electrochemical performance of LiFePO 4 cathode material is significantly affected by the surface area, particle size and morphology of the used carbon additives. The best rate performance is achieved with the electrode containing a carbon additive with a specific surface area of 180 m 2 g −1 . This work reveals that the choice of conductive additive influences discharge capacity of LiFePO 4 Li-ion battery cells by as much as 20–30%. This is due to conductive additive’s influence on both electronic conductivity and porosity (which determines ionic conductivity) of LiFePO 4 electrodes. A system approach to lithium ion battery material research should always consider inactive materials, such as conductive additives and binders, in addition to active materials.

In this paper we report the physical investigation and the electrochemical performance of the carbon black SC3 from Cabot Corporation. The SC3 carbon black was investigated in terms of BET surface area, pore size distribution, resistivity and morphology. Composite electrodes containing SC3 as active material were prepared and used for the realization of electrochemical double layer capacitor (EDLC) and lithium-ion capacitor (LIC). In EDLC, at 5 mA cm−2 charge–discharge currents, the carbon black displays a specific capacity of 40 mAh g−1 and a specific capacitance of 115 F g−1. It also displays a very good cycling stability for over 50,000 cycles and excellent performance retention at currents up to 50 mA cm−2. The performance retention at high currents outstandingly differentiates this carbon black from a few commercially available EDLC-grade activated carbons. Because of the high specific capacity of SC3, the carbon black electrodes were also used in combination with LiFePO4 electrodes in LIC. The results of this study indicate that SC3 carbon black is an interesting carbonaceous candidate for the realization of LIC.

Optical distortion through a plane shear layer between two uniform streams of unequal temperatures is investigated using imaging of scalar mixing by planar laser-induced fluorescence (LIF). Simultaneous fluorescence intensity measurements of disodium fluorescein and rhodamine B (the fluorescence of the latter is temperature dependent) are used to extract the temperature distribution within the plane of a laser sheet. This planar imaging technique allows a direct measurement of the index of refraction field, which is used to determine optical distortions in the imaging plane. While a given ray within the sheet is refracted at a cumulative angle that depends on the local index of refraction gradient along its path, LIF measurements in the cross-stream plane of the flow show substantial optical distortions near the upstream and downstream edges of the primary vortices where the angle between the local temperature (or index) gradient and the wavevector of the incident light is large. These distortions are manifested by the appearance of low- and high-intensity streaks that are advected with the flow and whose characteristic spatial scales significantly diminish with the onset of small-scale (mixing) transition. The formation of secondary (streamwise) vortical structures leads to substantial spanwise variations in index of refraction and consequently to optical distortions that vary with the phase of the base flow and can exceed the distortions in the cross-stream plane. An important aim of the present research is the investigation of the effects of direct actuation of small-scale motions on the mixing and consequently on optical distortion within the shear layer. The actuation suppresses the formation of the large coherent vortical structures and leads to localized enhancement of dissipation and reduction in turbulent kinetic energy. The actuation enhances mixing across the entire width of the forced shear layer and leads to significant reduction of optical distortion, suggesting that active small-scale mixing can play a significant role in the mitigation of aero-optical effects through turbulent shear flows.

Combustion chemical vapor condensation (ccvc) is described for production of metal oxide nanoparticles by decomposing metalorganic precursors in NanoSpraySM diffusion flames. CCVC involves atomization and controlled thermal decomposition of liquid precursors that can yield crystalline nanopowders with sizes ranging from 2 to 50 nm. The atomization of liquid precursors into an ultrafine mist of submicron-size droplets enables rapid evaporation and formation of vaporous material in the flame. The synthesized nanopowders are then collected by continuous baghouse filtering. This article describes the flame synthesis of pure and doped ZnO and CeO2 nanopowders. Nanopowder particle size, crystallinity, morphology, and composition were characterized by x-ray diffraction analysis, surface area analysis, and transmission electron microscopy. Flame-made nanopowders are of high purity, and appear to be made of individual nanoparticles and loose aggregates, with surface area ranging from 50 to more than 200 m2/g.

Graphitized carbon blacks have shown a more promising electrochemical performance than the non-treated ones when being applied in small amounts as conductive additives in composite cathode electrodes for lithium ion batteries, due to the absence of surface functional groups which contribute to detrimental side-reactions with the electrolyte. Here, we report that at high potentials of4.5 V vs. Li/Li(+), graphitic structures in carbon black can provide host sites for the partially reversible intercalation of electrolyte salt anions. This process is in analogy to the charge reaction of graphite positive electrodes in dual-ion cells. A standard furnace carbon black with small graphitic structural units, as well as slightly and highly graphitized carbon blacks, were characterized and analyzed with regard to anion intercalation. A LiPF6 containing organic solvent based electrolyte as well as a state-of-the-art ionic liquid based electrolyte composed of LiTFSI in PYR14TFSI were applied. The intercalation of both PF6(-) and TFSI(-) could be confirmed by cyclic voltammetry in electrodes made of carbon blacks. When exposed to high potentials, carbon blacks experienced strong activation in the 1st cycle, which promotes the perception for anion intercalation, and thus increases the anion intercalation capacity in the following cycles. The specific capacity from anion intercalation was evaluated by constant current charge-discharge cycling. The obtained capacity was proportional to the graphitization degree. As anion intercalation might be accompanied by decomposition reactions of the electrolyte, e.g., by co-intercalation of solvent molecules, it could induce the decomposition of the electrolyte inside the carbon and thus degradation of the carbon black graphitic structure. In order to avoid side reactions from surface groups and from anion intercalation, the thermal treatment of carbon blacks must be optimized.

Recent analytical work has shown that when an acoustic plane wave propagates through a rotational flow field there is a linear relationship between the Fourier component of the scattered acoustic pressure and the Fourier transform in space and time of the vorticity component that is normal to the plane defined by the wave vectors of the incident and scattered acoustic waves. Hence, ultrasound scattering can be used as a non-intrusive spectral probe of vorticity and potentially as a tool for direct measurements of vorticity distributions. Some aspects of this technique have been tested in a swirling air jet emanating from a 2.54 cm diameter nozzle where the swirl is generated upstream of the jet nozzle by a rotating paddle. For a given exit volume flow rate, swirl numbers up to 0.4 are realized. Radial distributions of the streamwise and tangential velocity components downstream of the jet exit plane are measured using two-component hot-wire anemometry and the corresponding distributions of streamwise vort...

An integral method, using Coles combined inner and outer law as the velocity profile, is developed for calculation of turbulent boundary layers with blowing or suction and pressure gradients. The resulting ordinary differential equations are solved numerically for the distribution of skin friction coefficient and integral thickness along the surface. Comparisons of predicted skin friction coefficients with experimental data are made for a wide range of blowing and suction rates and for various pressure gradients, including adverse, zero and a strong favorable gradient. In addition to good agreement with experimental data for constant blowing fractions F, the method is also successfully tested on cases where the blowing fraction is variable with position. Predictions, in general, exhibit satisfactory agreement with the data. The integral method predictions are comparable to, or better than, a number of finite difference procedures in a limited number of cases where comparisons were made.

The integral form of the momentum equation is solved by use of a combined law of the wall and wake for the velocity profile appropriate to a transpired turbulent boundary layer. This gives a nonlinear ordinary differential equation which is solved numerically to predict the skin friction coefficient, Cf, variation with distance, as well as integral thicknesses, for both constant blowing fraction, F, and for F variable with x along the surface. Predicted skin friction coefficients are compared to experimental data for both blowing and suction in both zero and nonzero pressure gradients. Predictions compare well with the experimental values.

*† ‡ § ** †† This paper describes experimental investigation of subcritical and supercritical liquid fuel injection and combustion in a high-pressure combustor. The back-scattered laser light diagnostics was implemented for online monitoring and characterization of heat release oscillations and spray quality. The change in spray quality in the subcritical regime affects combustor dynamics causing various regimes of stable and unstable combustor operation. Thus, spray quality optimization can be used to suppress combustor instabilities in subcritical regime, with the particular mode of instability depending on the incoming air temperature. Supercritical injection of heptane resulted in gradual decrease in combustor oscillatory pressure amplitude. The back-scattered laser light intensity gradually decreased with decreasing droplet size in subcritical regime and disappeared altogether when fuel became supercritical. The CO emission was reduced to an insignificant level for supercritical injection indicating complete combustion.

A novel fuel atomization device (Nanomiser™) was evaluated under laboratory conditions with respect to its ability to reduce SI engine cold-start hydrocarbon emissions. First, comparisons between the level of atomization using the conventional, pintle-type fuel injector and the novel atomizer were carried out using flow visualization in a spray chamber and particle size distribution. The novel atomizer is capable of producing sub-micron fuel droplets, which form an ultra-fine mist with outstanding non-wetting characteristics. To capitalize on these atomization characteristics, this device was compared to a conventional fuel injector in a small, two-cylinder, SI engine under a number of operating conditions. Results show a slightly enhanced combustion quality and lean limit under warm operating conditions and a dramatic reduction in unburned HC emission under cold operating conditions, with cold emissions with the Nanomiser™ matching those with a conventional injector under fully warm conditions.Copyright © 2002 by ASME

Ceria and doped ceria nanopowders synthesized in flames from submicrometer-sized droplets of precursor solutions demonstrate several characteristics that promise superior performance when used to fabricate electrolytes for solid oxide fuel cells relative to powders synthesized using other technologies. Combustion chemical vapor condensation has been used to produce CeO 2 . Ce 0 . 8 S m 0 . 2 O 2 - x (SDC), and Ce 0 . 8 Gd 0 . 2 O 2 - x (GDC) nanopowders, with an average particle size below 20 nm. These nanopowders have been used to fabricate electrolyte test specimens. The effect of particle size, dopant, and sintering temperature on electrolyte morphology, density, and ac conductivity have been measured. Sintering of pressed nanopowder specimens at temperatures below 1150°C resulted in electrolytes with densities higher than 99% of theoretical density. The resulting sintered grain sizes range from 150 to 500 nm for CeO 2 and GDC. and from 150 to 300 nm for SDC AC impedance measurements show conductivities of 8 and 10 S/m at 800°C for SDC and GDC electrolytes, respectively. Conductivities at 500°Capproached 2 S/m for both SDC and GDC.