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Lithium difluoro(oxalato)borate (LiFOB) is investigated as an additive for enhancing the electrochemical performance of high-voltage lithium cobalt oxide (LiCoO2, LCO)/lithium nickel manganese cobalt oxide (LiNi0.6Co0.2Mn0.2O2, NMC) cathodes and high-capacity silicon/graphite (Si-C) anodes. LCO-NMC/Si-C full cells with a LiFOB additive have been found to exhibit improved high temperature electrochemical performance. To confirm the effects of LiFOB on the cathode and the anode, the surface chemistry of the anodes and cathodes cycled in electrolytes with and without the LiFOB additive are examined using ex-situ X-ray photoelectron spectroscopy (XPS). The LiFOB additive produces a LiF-based solid electrolyte interphase (SEI) on the Si-C anode and a carboxylate-based SEI on the LCO-NMC cathode.
Electrochemical supercapacitors provide electrical energy storage systems complementary to batteries. Based on the double layer capacitance of high area porous electrode materials, e.g. carbon powders, felts, foams, aerogels or on the redox pseudocapacitance of oxide or polymer films, specific capacitances of the order of 50∼100 F g−1 are realizable. However, the porous nature of the electrode structures introduces a distribution of resistive and capacitative elements giving rise to electrical behaviour like that of a transmission line, as treated by de Levie, with a resulting complex power spectrum depending on charging or discharging rates. The present paper examines the cyclic voltammetry behaviour of de Levie type wire brush electrodes as models for porous electrodes, in comparison with that of single wire electrodes of the same metal. Comparisons are also made with constant current charging behaviour and with the electrochemical behaviour of specially made, 3 V, non aqueous solution, double layer capacitor modules, examined under similar conditions in relation to the current response profiles of a 5 RC element hardware model circuit. These approaches enable the effects of the distribution of R and C elements on charge acceptance and delivery at various rates to be quantitatively evaluated for various resistivities of the conducting electrolyte in pores.
Understanding the nature and consequences of the competitive dynamics among firms is a key objective of the strategic management field. We review recent developments in six research streams relevant to competitive dynamics: competitive action and response, first-mover advantage, co-opetition, multipoint competition, strategic groups, and regional clusters. As a first step toward filling gaps in knowledge identified in our review, we provide suggestions for future inquiry within each research stream. We also describe opportunities for conceptual integration across the streams that could significantly advance the understanding of competitive dynamics.
A practical artificial heart has been sought for >50 years. An increasing number of people succumb to heart disease each year, but the number of hearts available for transplantation remains small. Early total artificial hearts mimicked the pumping action of the native heart. These positive-displacement pumps could provide adequate haemodynamic support and maintain the human circulation for short periods, but large size and limited durability adversely affected recipients' quality of life. Subsequent research into left ventricular assist devices led to the use of continuous-flow blood pumps with rotating impellers. Researchers have attempted to integrate this technology into modern total artificial hearts with moderate clinical success. The importance of pulsatile circulation remains unclear. Future research is, therefore, needed into positive-displacement and rotary total artificial hearts.
This is the first targeted review of the synthesis – microstructure – electrochemical performance relations of MoS2 – based anodes and cathodes for secondary lithium ion batteries (LIBs). Molybdenum disulfide is a highly promising material for LIBs that compensates for its intermediate insertion voltage (∼2 V vs. Li/Li+) with a high reversible capacity (up to 1290 mA h g−1) and an excellent rate capability (e.g. 554 mA h g−1 after 20 cycles at 50 C). Several themes emerge when surveying the scientific literature on the subject: first, we argue that there is excellent data to show that truly nanoscale structures, which often contain a nanodispersed carbon phase, consistently possess superior charge storage capacity and cycling performance. We provide several hypotheses regarding why the measured capacities in such architectures are well above the theoretical predictions of the known MoS2 intercalation and conversion reactions. Second, we highlight the growing microstructural and electrochemical evidence that the layered MoS2 structure does not survive past the initial lithiation cycle, and that subsequently the electrochemically active material is actually elemental sulfur. Third, we show that certain synthesis techniques are consistently demonstrated to be the most promising for battery applications, and describe these in detail. Fourth, we present our selection of synthesis methods that we believe to have a high potential for creating improved MoS2 LIB electrodes, but are yet to be tried.
In this chapter papers reporting preparations, formations, or some more important transformations of compounds containing tetracoordinated carbon atoms, bearing one or two halogen atoms (fluorine, chlorine, or bromine) and respectively two or one other functions attached, have shortly been reviewed. The review mainly covers the literature published since 1995 up to 2003, not reported in the first edition of COFGT (1995). Some older references not included in COFGT (1995) are also provided.
Composition design and morphology control can lead to high performance electrode materials for energy storage devices. In this work a graphene/porous Fe2O3 nanocomposite anode material is fabricated via a template-assisted nanocasting process. This nanocomposite consists of graphene scaffold with high electronic conductivity and interconnected Fe2O3 with porous structure, thus exposing ample active sites for redox reactions and offering sufficient contacts with the electrolyte. Owing to these morphological advantages, the nanocomposite outperforms nearly all the reported Fe-based anode materials by delivering a high specific capacitance of 1095Fg−1 at a current density of 3Ag−1. In addition, the material shows great rate capability and good cycling stability. Asymmetric supercapacitors are fabricated by assembling the graphene/porous Fe2O3 nanocomposite (as the anode material) with a CoNi-layered double hydroxide/carbon nanotube composite (as the cathode material). The devices exhibit high energy and power densities of 98.0Whkg−1 and 22,826Wkg−1, which are among the best performances reported to date for asymmetric supercapacitors.
Supercapacitors known as typical electrochemical capacitors have been considered as one of the most promising candidates of energy storage systems owing to their advantages such as high-power density, long life span and lower production cost. The electrode materials play a crucial role on properties of supercapacitors. Hence, many researches have been focused on the development of novel electrode materials for high-performance supercapacitors. NiCo2O4 as supercapacitor electrode material has drawn more and more attentions in recent years due to its outstanding advantages, such as high theoretical capacity, low cost, natural abundance and easy of synthesis. However, the NiCo2O4 always suffer from severe capacity deterioration because of the low electrical conductivity and small surface area. Hence, it is necessary to systematically and comprehensively summarize the progress in understanding and modifying NiCo2O4-based materials from various aspects. In this review, the structure and synthesis method of NiCo2O4-based materials are discussed in detail. And then, the major goal of this review is to highlight new progress in using proposed strategies to improve the cycling stability and rate capacity of NiCo2O4-based materials, including synthesis, control of special morphologies and design of composite materials. Finally, an insight into the future research and development of NiCo2O4-based materials for supercapacitors is prospected.
In Al-air batteries, the self-corrosion of Al electrodes and the parasitic hydrogen evolution during battery discharge are the major defects that lead to the degradation in the performance of the battery. Here, the ionic liquid (1-Allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) (IL) is used as an organic additive to minimize the H2 gas evolution and corrosion rate in the alkaline electrolyte (4.0M NaOH) for Al-air battery. The efficiency of IL compound is investigated using H2 gas evolution, polarization, electrochemical frequency modulation (EFM) and battery performance measurements. The surface morphology of Al electrode was characterized by scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis. The results presented below show that the IL compound inhibits both the H2 gas evolution and the self-corrosion of Al electrode. In addition to this, the presence of IL compound enhances the capacity density of battery reaching to the maximum value (2554 mAhg-1) at 1.5mM of IL.
Uniform flow distribution through the porous electrodes in a flow battery cell is very important for reducing Ohmic and mass transport polarization. A segmented cell approach can be used to obtain in-situ information on flow behaviour, through the local voltage or current mapping. Lateral flow of current within the thick felts in the flow battery can hamper the interpretation of the data. In this study, a new method of segmenting a conventional flow cell is introduced, which for the first time, splits up both the porous felt as well as the current collector. This dual segmentation results in higher resolution and distinct separation of voltages between flow inlet to outlet. To study the flow behavior for an undivided felt, monitoring the OCV is found to be a reliable method, instead of voltage or current mapping during charging and discharging. Our approach to segmentation is simple and applicable to any size of the cell.
Publisher Summary Ceramic materials play an important role in the field of battery technology. The Li-ion battery is a typical case in which ceramic materials are applied. In Li-ion batteries, lithium oxides are used for positive active material and carbons for negative active material. Both of the active materials are considered ceramics prepared by normal ceramic-production processes. They are used in powder form in Li-ion batteries. Typical cylindrical cell structure and electrode configuration of Li-ion battery are illustrated. When Li ions are intercalated to graphite, the Li ions penetrate not into the basal plane, but into the edge plane of the graphite crystal structure. Battery reaction of Li-ion battery is given. The production process of Li-ion battery is illustrated. Compared to conventional batteries such as lead-acid, Ni-Cd, and Ni-MH, Li-ion batteries provide higher energy density and higher power density.
Li-rich layered material Li1.1Ni0.35Mn0.65O2 was synthesized by a two-step calcination method, the relationship between the calcination conditions and the cyclic performance was studied. The results show the calcination conditions of the second step exhibiting great influences on the cyclic performance of the material. As the calcination temperature increases from 970°C to 1030°C, the discharge capacity of the prepared material increases firstly and then decreases, so does the discharge voltage fading. The material obtained at the temperature (The second step calcination) of 990°C exhibits the highest discharge capacity and the highest discharge voltage fading. The material with longer second calcination time shows lower stable discharge capacity but smaller discharge voltage fading. The variation of the cyclic performance with the calcination conditions should be ascribed to the structural change, the electrochemical active area change and the electrochemical impedance.
Developing practically meaningful conductive- and binder- free electrode material for lithium ion battery has been of great interest in recently years. In this study, we describe a facile synthesis of cyclized-Polyacrylonitrile (PAN)/Li4Ti5O12 (LTO) nanosheet lithium ion battery anode material by one-pot hydrothermal approach followed by cyclization of the polymer at intermediate temperature. The obtained product was thoroughly characterized by powder XRD, Raman, TG-DSC, XPS, electron microscopy, EDS, BET and electrochemical methods The cyclized polymer does not alter crystal structure of LTO but goes through turbostratic transition to create sp2-π bonding and graphitic carbon at it course of conjugation. Electrochemical tests revealed the composite heightened electronic and ionic conductivity, rate capability, cycling performance, and significantly reduced charge transfer resistance than pure LTO, especially under the low temperatures. The boosted battery performance is on the ground that sp2-π bonding and graphitic carbon during the cyclization of PAN contribute significantly to charge transfer process. These results strongly suggest this method a cost-effective way producing high performance LTO material and may be applied to other lithium ion battery electrode material as well.
Composite materials containing Co–Sn alloys and polyacrylonitrile (PAN) have been prepared by reduction of Co(II) and Sn(II) in dimethylformamide with NaBH4. The resulting cobalt and tin form an amorphous alloy and the PAN molecules hinder the growth and crystallization of the metallic grains. After heating the composite material obtained at 300°C in Ar-atmosphere, the amorphous alloy leads to poorly crystallized CoSn2, and the PAN molecules are partially pyrolyzed. In contrast, the reduction of Fe(II) and Sn(II) leads to crystalline Sn. The electrode containing nanosized CoSn2 and PAN shows an excellent electrochemical behavior in lithium cells due to the structural stability of the PAN matrix and the small size of the metallic grains.
Data suggest that culinary spices are a potent, low-calorie modality for improving physiological responses to high fat meals. In a pilot study (N = 6 healthy adults), we showed that a meal containing a high antioxidant spice blend attenuated postprandial lipemia by 30% compared to a low spice meal. Our goal was to confirm this effect in a larger sample and to consider the influence of acute psychological stress on fat metabolism. Further, we used in vitro methods to evaluate the inhibitory effect of spices on digestive enzymes.
Mesoporous V2O5 nanofibers were fabricated by a method combining sol–gel processing with electrospinning followed by annealing in air. The resultant nanofibers were 350 nm in diameter and consisted of porous polycrystalline vanadium oxide with a specific surface area of ∼97 m2 g−1. The mesoporous V2O5 nanofibers demonstrated a significantly enhanced Li ion storage capacity of above 370 mA h g−1 and a high charge/discharge rate of up to 800 mA g−1 with little cyclic degradation.
This article in honor of 60th anniversary of Prof. Dr. J. Garche shows some historical and general aspects of batteries and fuel cells. Our most innovative product PoLiFlex™ will be highlighted and compared with the direct methanol fuel cell (DMFC), which is sometimes considered as a replacement for batteries.
The preparation and the structural, morphological and electrochemical characterization of a Silicon/V2O5 nanosheets composite (Si@V2O5), as an active anode material for Li-ion batteries, are here reported. The nanocomposite material, aimed at mitigating the morphological instability issues commonly plaguing Si-based anodes, is prepared by a H2O2-based low-impact synthesis, while the electrode processing involves the use of Polyacrylic Acid (PAA) binder. The electrolyte formulation is optimized as well, by employing Vinylene Carbonate (VC) additive, in order to maximize cycling stability and performance. Preliminary results report specific capacities of 932 mAhg−1 and 759 mAhg−1 after 50 cycles at 500 mA g−1 and 1000 mA g−1, respectively. The Si@V2O5 electrode also shows remarkable rate capability performance.
The efficacy of current antidepressant (AD) drugs for the treatment of major depressive disorder (MDD) lays behind expectations. The correct genetic differentiation between severe and less severe cases before treatment may pave the way to the most correct clinical choices in clinical practice. Genetics may pave the way such identification, which in turns may provide perspectives for the synthesis of new ADs by correcting the molecular unbalances that differentiate severe and less severe depressive patients. We investigated 1,903 MDD patients from the STAR*D study. Outcome was the number of severe depressive records, defined as a Quick Inventory of Depressive Symptomatology (QIDS)-Clinician rated (C) total score >15, corrected for the number of observations for each patient during the first 14 weeks of citalopram treatment. Predictors were the genetic variations harbored by genes involved in the glutamatergic–monoaminergic interplay as defined in a previous work published by our group. Clinical and socio-demographic stratification factor analyses were taken in cases and controls. Covariated linear regression was the statistical model for the analysis. SNPs were analyzed in groups (molecular pathway analysis) testing the hypothesis that the distribution of significant (p < 0.05) associations between SNPs and the outcome segregates within each pathway/gene subset. The best associated results are relative to two signle SNPs, (rs7744492 in AKAP12p = 0.0004 and rs17046113 in CAMK2Dp = 0.0006) and a molecular pathway (cAMP biosynthetic process p = 0.005). After correction for multitesting, none of them resulted to be significantly associated. These results are consistent with previous findings in literature and further stress that the molecular mechanisms targeted by current ADs may not be the key biological variables that differentiate severe from mild depression.
The structural changes of the composite cathode made by mixing spinel LiMn2O4 and layered LiNi1/3Co1/3Mn1/3O2 in 1:1wt% in both Li-half and Li-ion cells during charge/discharge are studied by in situ XRD. During the first charge up to ∼5.2V vs. Li/Li+, the in situ XRD spectra for the composite cathode in the Li-half cell track the structural changes of each component. At the early stage of charge, the lithium extraction takes place in the LiNi1/3Co1/3Mn1/3O2 component only. When the cell voltage reaches at ∼4.0V vs. Li/Li+, lithium extraction from the spinel LiMn2O4 component starts and becomes the major contributor for the cell capacity due to the higher rate capability of LiMn2O4. When the voltage passed 4.3V, the major structural changes are from the LiNi1/3Co1/3Mn1/3O2 component, while the LiMn2O4 component is almost unchanged. In the Li-ion cell using a MCMB anode and a composite cathode cycled between 2.5V and 4.2V, the structural changes are dominated by the spinel LiMn2O4 component, with much less changes in the layered LiNi1/3Co1/3Mn1/3O2 component, comparing with the Li-half cell results. These results give us valuable information about the structural changes relating to the contributions of each individual component to the cell capacity at certain charge/discharge state, which are helpful in designing and optimizing the composite cathode using spinel- and layered-type materials for Li-ion battery research.
Introduction Music perception involves processing of melodic, temporal and emotional dimensions that have been found to dissociate in healthy individuals and after brain injury. Two components of the temporal dimension have been distinguished, namely rhythm and metre. We describe an 18 year old male musician ‘JM’ who showed apperceptive music agnosia with selectively preserved metre perception, and impaired recognition of sad and peaceful music relative to age and music experience matched controls after resection of a right temporoparietal tumour. Method Two months post-surgery JM underwent a comprehensive neuropsychological evaluation including assessment of his music perception abilities using the Montreal Battery for Evaluation of Amusia (MBEA, Peretz, Champod, & Hyde, 2003). He also completed several experimental tasks to explore his ability to recognise famous songs and melodies, emotions portrayed by music and a broader range of environmental sounds. Five age-, gender-, education- and musical experienced-matched controls were administered the same experimental tasks. Results JM showed selective preservation of metre perception, with impaired performances compared to controls and scoring below the 5% cut-off on all MBEA subtests, except for the metric condition. He could identify his favourite songs and environmental sounds. He showed impaired recognition of sad and peaceful emotions portrayed in music relative to controls but intact ability to identify happy and scary music. Conclusion This case study contributes to the scarce literature documenting a dissociation between rhythmic and metric processing, and the rare observation of selectively preserved metric interpretation in the context of apperceptive music agnosia. It supports the notion that the anterior portion of the superior temporal gyrus (STG) plays a role in metric processing and provides the novel observation that selectively preserved metre is sufficient to identify happy and scary, but not sad or peaceful emotions portrayed in music.
Materials design and synthesis is critical for reliable fabrication of stable and high-performance lithium-air batteries that are competitive with other energy delivery systems. Intensive research activities have focused on the development of efficient cathode catalysts and stable electrolytes in the past several years and many review articles are already available. This review aims on lithium ion conducting membranes that are barely studied although they are essentially indispensible for building batteries composed of aqueous electrolytes and batteries composed of non-aqueous electrolytes for long-term operation. In a typical lithium-air battery cell, a lithium ion conducting membrane is sandwiched between the lithium metal anode and the air cathode to prevent the lithium metal anode from reacting with poison species (e.g., water, oxygen, etc.) diffused from cathode to anode, leading to a significant increase in lifetime of the battery. A number of solid materials including polymer/polymer-ceramic composites, non-oxide inorganic compounds, perovskite-type oxides, garnet-type oxides, γ-Li3PO4 oxides, NASICON-type oxides, and single-crystalline silicon that exhibit good lithium-ion conductivity are comprehensively summarized and discussed in this review. Although only a few of NASICON-type oxides and single-crystalline silicon have been evaluated as the lithium ion conducting membranes in lithium-air battery cells, all of the solid materials summarized in this review and their possible derivative composites are also promising to be developed as lithium ion conducting membranes for lithium-air batteries. This review is also expected to be an advocate for research in lithium ion conducting membranes.