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Fibroin nanofibrils were synthesized by a pH-controlled heat denaturation method. The nanofibrils were then applied to the surface of a carbon paste electrode to prepare a novel and biocompatible electrode for electrical double-layer supercapacitor applications. The capacity per surface area at a charge/discharge current of 1.0 A was obtained as 4.68 mF cm−2. The electrode showed improved capability and charge/discharge behavior.
Spray drying method has been successfully applied to the field of lead-acid batteries. Lead powder/carbon black composite can be obtained by spray drying and subsequent calcination process. Glucose is added to increase the adhesion of carbon black and lead powder. The morphology changes before and after calcination are examined by FE-SEM. The composite negative material can enable the sum of discharge capacity increased by 8.27% from 4374.855 Ah to 4736.706 Ah at a discharge current of 25 A after 66 cycles. And the charge acceptance of the test cell also can be obviously enhanced.
A new phase of energy transition makes auxiliary technologies such as energy storage and other flexibility options more important. Economic policy that aims to steer this transition needs to grasp the complex system dynamics underlying energy and society. This conceptual article gives an overview of energy technology innovation theories that exemplify the growing importance of flexibility for electricity usage. First, the article presents different conceptualizations of technology innovation and diffusion. Second, how energy systems are embedded in physical infrastructures and social power relations is shown with a brief history of electricity in contemporary industrialized societies. Third, energy innovation is discussed in context of challenges of the upcoming energy transition. Fourth, energy technology innovations are further contextualized in light of insights from political economy and energy social sciences. Finally, the discussed approaches are synthesized to amend the holistic technology innovation system approach for studying energy technology innovations such as energy storage.
This work reports a detailed characterization of the reduction of oxygen in pyrrolidinium-based ionic liquids for application to lithium-oxygen batteries. It is found that, in the absence of Li+, all electron transfer kinetics are fast, and therefore, the reactions are limited by the mass transport rate. Reversible reduction of O2 to O2 •− and O2 •− to O2 2− take place at E 0 =2.1V and 0.8V vs. Li+/Li, respectively. In the presence of Li+, O2 is reduced to LiO2 first and then to Li2O2. The solubility product constant of Li2O2 is found to be around 10−51, corroborating the hypothesis that electrode passivation by Li2O2 deposition is an important issue that limits the capacity delivered by lithium-oxygen batteries. Enhancing the rate of Li2O2 formation by using different electrode materials would probably lead to faster electrode passivation and hence smaller charge due to oxygen reduction (smaller capacity of the battery). On the contrary, soluble redox catalysts can not only increase the reaction rate of Li2O2 formation but also avoid electrode passivation since the fast diffusion of the soluble redox catalyst would displace the formation of Li2O2 at a sufficient distance from the electrode surface.
Coal-based coke powder is a by-product when coke is smashed for metallurgy and chemical industry. There is a vast output of coke powder every year around world, most of which is combusted as cheap fuel or abandoned directly. In this work, the electrochemical performance of graphitized boron-doped coal-based coke powder as anode for lithium ion batteries was investigated. The effects of boron content and graphitization temperature on the anode performance of boron-doped coal-based coke powder were also investigated in this paper. Results showed that a reversible capacity of 360.3mAh/g of boron-doped coal-based coke powder can be obtained, while that of unboron-doped was 292.9mAh/g. X-ray diffraction (XRD) analysis for the boron-doped coal-based coke powder showed that the distance between carbon layers was lowered by a proper amount of doped boron and higher graphitization temperature. X-ray photoelectron spectrometer (XPS) analysis was carried out to explain the effect of boron doping on the electrochemical performances of coal-based coke anodes.
Low energy density and limited cyclability are preventing the commercialization of aqueous Zn–MnO2 batteries. Here, the authors combine the merits of operating Zn anodes in alkaline conditions and MnO2 cathodes in acidic conditions, via an electrolyte-decoupling strategy, to realize high-performance batteries.
Hollow Sn nanostructures were obtained by simply controlling PVP addition in a solution-based reduction process. These nanostructures are assembled by many Sn nanoparticles with an inner void structure in the center. As an anode in Na-ion battery, the hollow Sn nanoparticles present improved cycling stability and capability in comparison with solid Sn nanoparticles, clearly indicating enhanced electrochemical properties for pure Sn anode in Na-ion battery. Moreover, their electrochemical impedance spectroscopy and charge/discharge profiles reveal the hollow structure not only maintains much higher capacity at large volumetric shrinkage process, but also provides structural stability and facilitated charge transfer in Sn anodes during the electrochemical reaction. Therefore, this hollow Sn nanostructure could provide new insight towards the exploration and design of alloy anode materials in Na-ion battery.
We characterized high-power lithium-ion cells in terms of performance and cycle and calendar life at 45°C. Among other parameters, we measured the C/25 capacity every 4 weeks during the test. Differentiation of the C/25 voltage versus capacity data with respect to capacity (dV/dQ) has been used to elucidate another type of side reaction at the anode. In cycle-life cells, with their higher capacity throughput, the analysis showed that one phase transition (a peak in the profile) was disappearing with time. In contrast, this effect was not seen in calendar-life cells.
Slow-scan rate cyclic voltammetry (SSCV), potentiostatic intermittent titration (PITT) and electrochemical impedance spectroscopy (EIS) have been applied simultaneously to study Li ion intercalation into V2O5 films prepared by evaporative vacuum-deposition on Pt foils. Two different films, 1600 and 3600 Å thick, were used to study the influence of the film's thickness on the major electroanalytical characteristics of these intercalation electrodes. Modeling of the impedance spectrum related to the thin V2O5 film was performed using an equivalent circuit analog including the following elements: three R ∣∣ C semicircles (covering the high-frequency domain) and finite-length Warburg in sequence with the intercalation capacity (a straight line of unit slope at intermediate frequencies, and a sloping capacitive line at the very low frequencies). Sharp minima on D versus E plots, which are observed in the vicinity of the cyclic voltammetric peaks, present further evidence of very high, attractive electron–ion interactions during Li ion intercalation into the V2O5 electrode, as was already described for similar processes in graphite and some transition metal oxides: Li x CoO2, Li x NiO2, Li x Co y Ni1−y O2 and Li x Mn2O4. The diffusion length in these electrodes related to the V2O5 film's thickness.
The microstructure of nanometer-scale tin powder synthesized by the wire electric explosion (WEE) method is examined by transmission electron microscopy (TEM) at different Li insertion states, and then electrochemical properties of the tin power electrode are characterized by galvanostatic charge–discharge experiments. It is found that several Li/Sn inter-metalic compounds are formed during lithium insertion, namely Li1−x Sn, L13Sn5 and Li7Sn2. The passivation layer (or solid electrolyte interface, SEI) on the surface of particles cycled in an organic electrolyte electrochemical cell is characterized as Li2CO3 and ROCO2Li by FT-IR spectroscopy. A great part of the passivation layer is amorphous, but a small is poorly crystallized.
With the aim of developing lithium ion batteries with a long life and high efficiency for power storage, we experimentally evaluated combinations of cathode and anode active materials, in which batteries are able to obtain over 4000 cycles or 10 years of life. An acceleration method was evaluated using coin cells. We found that changing the current density was effective for evaluating battery life, since the logarithm of the cycle life showed a linear relationship to current density. Based on the current density increasing method, various combinations of cathode and anode active materials were tested. The cell system of LiCoO2/Li4/3Ti5/3O4 clearly showed a long life of about 4000 cycles. The energy density of the cell using the Li4/3Ti5/3O4 anode is obviously smaller than that using a graphite anode, the cell with Li4/3Ti5/3O4 anode was thought to have some merit especially in the large-scale-layer-built type battery by the applicability of the Al anode collector and a light weight battery case.
We show that anodes made by depositing thin films of polymer-derived silicon oxycarbide (SiCO) on copper have properties that are comparable to, or better than that of powder-based SiCO anodes. The great advantage of the thin film architecture is its simplicity, both in manufacturing and in application. The films are produced by spraying a film of the liquid polymer-precursor on copper, and then converting it into SiCO by heating at ∼1000°C; at this point they are ready for constructing electrochemical cells. They show a capacity of ∼1000mAhg−1, 100% coulombic efficiency, good capacity at very high C-rates, and minimal fading at ∼60 cycles. However, if the films are thick they delaminate due to the volume change as lithium is cycled in and out. The transition from thin-film to thick-film behavior occurs when the SiCO films are approximately 1μm thick. An analytical method for estimating this transition is presented.
The mechanical instability of the Solid Electrolyte Interphase (SEI) layer in lithium ion (Li-ion) batteries causes significant side reactions resulting in Li-ion consumption and cell impedance rise by forming further SEI layers, which eventually leads to battery capacity fade and power fade. In this paper, the composition-/structure-dependent elasticity of the SEI layer is investigated via Atomic Force Microscopy (AFM) measurements coupled with X-ray Photoelectron Spectroscopy (XPS) analysis, and atomistic calculations. It is observed that the inner layer is stiffer than the outer layer. The measured Young's moduli are mostly in the range of 0.2–4.5 GPa, while some values above 80 GPa are also observed. This wide variation of the observed elastic modulus is elucidated by atomistic calculations with a focus on chemical and structural analysis. The numerical analysis shows the Young's moduli range from 2.4 GPa to 58.1 GPa in the order of the polymeric, organic, and amorphous inorganic components. The crystalline inorganic component (LiF) shows the highest value (135.3 GPa) among the SEI species. This quantitative observation on the elasticity of individual components of the SEI layer must be essential to analyzing the mechanical behavior of the SEI layer and to optimizing and controlling it.
Publisher Summary This chapter reviews several energy-aware design techniques for controlling both active and standby power consumptions that are applicable to MPSoCs. The techniques discussed are for multiprocessor systems-on-chips (MPSoC) processor cores, the on-chip memory hierarchy, the on-chip communication system, and MPSoC energy-aware software. The majority of the techniques are derived from existing uni-processor energy-aware systems that take on new dimensions in the MPSoC space. Techniques for energy and power consumption reduction are successfully applied at all levels of the design space in uni-processor systems—circuit, logic gate, functional unit, processor, system software, and application software levels. The primary focus has been on reducing active power. As technology continues to scale up, accompanied by reductions in the supply and threshold voltages, the percentage of the power budget due to standby energy has driven the development of additional techniques for reducing standby energy.
Single phase Li4Ti5O12 powder with porous particle structure is synthesized via a simple, mild and productive citric-acid combustion method. The Li4Ti5O12 particle is composed of submicro-scaled grains with size of 100–200nm. The synthesized Li4Ti5O12 shows high reversible capacity (ca. 165mAhg−1 at 0.5C), excellent rate-capability (ca. 115 and 100mAhg−1 at 10 and 20C, respectively) and high temperature cycling stability (50°C). Under expanded cut-off voltage range of 0.01–2.5V, it delivers a high specific capacity of ca. 230 and 170mAhg−1 at 0.5 and 10C, respectively, while maintaining an excellent cycling stability. The synthesized Li4Ti5O12 shows fast de-lithiation but slow lithiation kinetic processes. When discharged at constant 1C while charged at 10, 20 and 30C, respectively, the specific capacity of 162, 160 and 158mAhg−1 can be achieved. The excellent electrochemical performance of the combustion synthesized Li4Ti5O12 is ascribed to the porous particle structure and small grain size feature, which ensure the good contact with electrolyte and reduce the lithium ion/electron diffusion distance, and therefore enhance the electrode reaction process.
The cells applied with a three-dimensionally (3D) patterned Li4Ti5O12 (LTO) electrode showed good performance as a rechargeable lithium-ion battery. The 3D-patterned electrode was fabricated with a printing apparatus and has many lined patterns with a high aspect ratio standing in line on a current collector. The cell using 3D-patterned electrode showed much better rate capability than that using a conventional flat electrode. In this research, cyclic voltammetry was carried out to investigate the mechanism realizing the high rates of charging and discharging in 3D-patterned electrode. Various types of line patterns were fabricated for 3D electrode by using LTO electrode slurry, and the influences of basic specifications of electrode structure (the space between two neighboring electrode lines, the height and width of electrode) on the charge and discharge characteristics were evaluated to optimize the electrode pattern. In addition, the electrode performance was discussed from the viewpoints of ohmic resistance and charge-transfer resistance of the cells with 3D-patterned and conventional flat electrodes.
The effect of potential cycling conditions on redox processes observed in the potential region of electrochemical stability window, between hydrogen and oxygen evolution reactions, of platinum, gold and glassy carbon electrodes has been investigated in aqueous lithium bis(trifluoromethylsulfonyl)imide (LITFSI) solutions with concentration ranging from 1 to 21 molal (moles of salt/kg of water). Following potential cycling to positive potential upon which oxidation of Pt is barely observable in contrast to Au, which is characterized by a well-defined oxidation wave, both electrodes showed on the return scan a cathodic wave corresponding to the electrochemical reduction of corresponding metal oxides. In the potential region more negative than about 0 V, voltammograms recorded by avoiding scanning to a positive potential limit reaching the onset of the oxygen evolution reaction, show no well-defined cathodic waves prior to hydrogen evolution reaction. This provides strong evidence that TFSI anions are not electrochemically reduced in this potential region at Pt, Au and glassy carbon electrodes. Furthermore, X-ray photoelectron spectroscopy measurements of electrode surface, following potential cycling to a value negative enough to reach the onset of hydrogen evolution, showed formation of surface layer with a high fluorine/sulfur ratio (higher than 3 expected for TFSI) that could be explained by chemical degradation of TFSI by species generated during hydrogen evolution with preferential dissolution of sulfur-based compounds.
A single phase of LiMn1−x Fe x PO4(OH) with the tavorite structure is synthesized by a H+/Li+ exchange reaction of Mn1−x Fe x PO4·H2O precursors and LiNO3 in the composition range 0≤ x ≤0.3. The materials are characterized by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and charge–discharge measurements. Rietveld refinement results of synchrotron X-ray powder diffraction data reveal that LiMn1−x Fe x PO4(OH) forms a continuous solid solution over the entire composition range with a triclinic structure (space group: P–1). A linear reduction in the unit cell dimensions a and b and a linear increase in the cell parameter c are accompanied by a local change in the bonding geometry of M 3+O6 and LiO6 octahedra with increasing iron content. Iron-substituted phases exhibit an improved charge–discharge performance with a 30% increase in capacity for voltages in the range of 2.0–4.6V as the iron content increases from x =0.0 to 0.3. The improved electrochemical properties and thermal stability reveal a correlation with distortion relaxation in the local geometry caused by partial substitution of Mn3+ by Fe3+ in LiMnPO4(OH).
Lithium–chromium–manganese oxides, LiMn x Cr1−x O2 (0≤x≤0.6), were synthesized as solid solutions by simple calcination of emulsion-dried powder precursor. The product was well crystallized to an α-NaFeO2 structure (space group: R 3 ̄ m). By combination of Rietveld analysis of X-ray diffraction data and X-ray absorption near edge structure (XANES) techniques, the final product is considered to be [LiI]3a oct[Mn x IIICr1−x III]3b oct[O2]6c (0≤x≤0.6). The prepared oxides were electrochemically active, and capacity as cathode materials for lithium-ion battery was improved with increasing Mn substitution amount.
This paper reviews the system components, modeling, and control of microgrids for future smart buildings in current literature. Microgrids are increasingly widely studied due to their reliability in the event of grid failure or emergency, their incorporation of renewable energy sources, and the potential they represent for overall cost reduction for the consumer. Greater accuracy in microgrid modeling enables the design of more advanced control methods, resulting in better objective optimization. This paper begins with an overview of microgrids and their components, their importance to both utility providers and building owners, and typical problems that they may be used to solve, as well as modeling challenges that microgrid researchers may face. An overview of microgrid control and optimization is given in terms of objectives, constraints, and optimization methods. Microgrid modeling is a complex task due to the number, variety, and complexity of microgrid components, which can include building loads, distributed energy resources, and energy storage systems. Various component modeling methods including physics-based and data-driven models are reviewed, to include battery degradation models. Furthermore, this paper provides a review of various data-driven forecasting methods for the microgrid controls. Different types of control methods including rule-based and model predictive control are reviewed, including latest occupancy-based model predictive control for buildings. Lastly, a discussion of current challenges that may be faced by researchers is presented, as well as future directions.
Thin films of lithium iron phosphate (LiFePO4, LFP), with a thickness between 80 nm and 320 nm are prepared by ion beam sputter deposition. X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy show that the films exhibit the desired structure, morphology, and chemical composition. Chrono potentiometry and cyclic voltammetry are carried out to determine the electrochemical behavior of the LFP films. Within these electrochemical measurements, a well-defined lithium intercalation/deintercalation reaction at around 3.45 V vs. Li/Li+ and a specific capacity of 104 mAh g−1 are observed. Moreover, a quite high cycling stability is found: Measurement data at 1C rate indicate a capacity fading of only 20% after ≈1700 charge–discharge cycles. In addition, the diffusion of lithium within the LFP thin films is studied by cyclic voltammetry and galvanostatic intermittent transition technique. Within these measurements it is observed that the lithium kinetics in the sputter-deposited thin films is about two orders of magnitude faster, compared to the powder material and thin films deposited by pulsed laser deposition. This behavior may be explained by the strong texture of the sputtered films.
Grafting is commonly used to relieve damage caused by soil-borne diseases and to enhance the nutrient uptake in watermelon plants. Certain reports have shown the proteomic changes of plant tissues involved in grafting, while little information about the secretome after watermelon grafting is available. To gain insight into the root-secreted protein profile, root exudates of three types of seedlings (own-root watermelon (W), grafted-root watermelon (WB) and own-root bottle gourd (B)) were collected under hydroponic conditions, desalted and concentrated using Amicon ultracentrifugal filter devices, and separated by one-dimensional SDS–PAGE. Principal component analysis revealed that the protein profile was distinctly altered after grafting, and the diversity of root-secreted proteins of WB was significantly higher than that of W and B. Moreover, analysis by LC-QTOF/MS/MS revealed that some proteins associated with biotic and abiotic stress resistance appeared in response to grafting, such as disease resistance protein At4g27190, callose synthase, HVA22, and Clp protease. These results indicate that grafting can shift the root-secreted protein profile and thus could increase stress resistance. This study would help to reveal the mechanisms of disease resistance and growth promotion achieved through grafting.
The ever-present challenge of matching polymer electrolyte to electrode in making any type of electrochemical device is addressed herein. Since fundamental experimental data on the structural nature of the polymer–inorganic interface at the atomic level is scarce (not to say non-existent), molecular dynamics simulation can give the first suggestive insights into how an idealized interface — here between PEO and double-layered V2O5 gel – can behave. The model simulated here (at a nominal 400 K) comprises ca. 20 Å-thick slabs of PEO and 15 Å-thick V2O5 gel layers arranged to form an infinite sandwich-type structure. A number of clear trends emerge: dynamical motion in both PEO and V2O5 is significantly reduced in the interface region, where it is also clear that relatively stable local structural configurations develop. These appear to be controlled by interactions between the ether oxygens of the PEO and the VO bonds which form the surface of the V2O5. Experimental confirmation of such features is lacking.
The body mass index (BMI) of breakfast eaters is frequently reported to be lower compared with that of breakfast skippers. This is not explained by differences in energy intakes, indicating there may be other mechanisms serving to drive this paradoxical association between breakfast and BMI. This study aimed to investigate the effect of eating breakfast versus morning fasting on measures predominantly of metabolism in lean and overweight participants who habitually eat or skip breakfast.