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In this work, we perform first-principles study to investigate the potential of two-dimensional (2D) SiS as an anode material for lithium-based batteries. Four predicted structures of 2D SiS are considered, including α-SiS, β-SiS, Pma2-SiS and silicene sulfide. Results show that among the samples studied, α-SiS exhibits: i) a negative adsorption energy to lithium of −0.44 eV; ii) the highest theoretical specific capacity of 446 mAh g−1, which is even higher than that of phosphorene (433 mAh g−1) and Ti3C2 (320 mAh g−1); iii) a low average open-circuit-voltage (OCV) of 0.20 V; iv) a fast lithium diffusivity with an energy barrier of only 0.17 eV, lower than that on MoS2 (0.25 eV), VS2 (0.22 eV) and silicene (0.23 eV); and v) a change from semiconducting to metallic state after lithiation. These advantages demonstrate that α-SiS is a promising anode material for lithium-ion batteries, and gives a choice for other lithium-based batteries such as lithium-oxygen and lithium-sulfur batteries as well.
Nanocolumnar aluminum thin films (Al nanorod films) were grown on Titanium (Ti)/glass substrates in a vacuum at different oblique inclination angles by an electron-beam evaporator. The Al nanorod/Ti/glass substrates were used as anode electrode for lithium (Li) ion batteries. The thickness of the Al nanorod thin films was controlled to be 100nm, which was confirmed by their cross-section microstructure. The X-ray diffraction (XRD) patterns showed a highly textured (111) orientation for all the films, regardless of the deposition angle, revealing that the as-synthesized products are made of high purity Al. X-ray photoelectron spectroscopy (XPS) analysis confirmed that the peak of the Al film was observed at a binding energy of 74.24eV. A three-electrode cell was employed for the Li ion battery performance tests, in which metallic Li sheets were used as counter and reference electrodes. The galvanic charge–discharge profiles were carried out at a constant current of 700mAg−1 from 0.01V to 3.00V. The aligned Al nanorod thin film demonstrated the highest specific capacity reported so far of 1293mAhg−1 in the propylene carbonate–dimethyl carbonate (PC–DMC) electrolytes, which is in close agreement with the theoretical one (1420mAhg−1). The average columbic efficiency was observed to be 91%.
Electrochemical impedance spectroscopy (EIS) is a sensitive indicator of a wide variety of chemical and physical properties. An increasing trend towards the development of impedimetric biosensors is being currently observed. Impedimetric techniques have been performed to characterize the fabrication of the biosensors and to monitor the catalyzed reactions of enzymes or the biomolecular recognition events of specific binding proteins, lectins, receptors, nucleic acids, whole cells, antibodies or antibody-related substances. However, little attention has been paid to reviewing this interesting research area. Herein, impedimetric biosensors are reviewed and many novel designs are discussed.
Prussian blue compounds have potential advantages of high working potentials and multi-electron redox capacities as Na-ion battery cathodes; however, they suffer from their poor capacity utilization in aqueous electrolytes due to the blockage of the active lattice sites by coordinating and zeolitic water for Na insertion reaction. To overcome this problem, we synthesized low-defect Prussian blue FeFe(CN)6 nanocrystals and revealed their Na-storage performance in aqueous electrolytes. Benefitting from its suppressed lattice defects and well-defined nanocubic morphology, the as-prepared Prussian blue nanocrystals exhibit a greatly improved capacity of ~125mAhg−1, a strong rate capability with 102mAhg−1 at a high rate of 20C and a remarkably long cycle life with 83% capacity retention over 500 cycles, exceeding considerably the aqueous Na-storage cathodes reported so far and capably serving as a high performance cathode for aqueous Na-ion batteries. As a model compound, the superior electrochemical performance arising from the low-defect Prussian blue nanocrystals provide a new insight into the design of high capacity Na-storage host materials for large scale electric storage applications.
The high-temperature electrochemical cell behavior of Li-stoichiometric Li–Mn–O spinel material, LiMn2O4.014, has been studied by cyclic voltammetry and coulometric titration curve measurement methods. A split of the reduction peak at x>0.5, in Li x Mn2O4.014, during Li+ insertion was found at 85°C. Correspondingly, three plateaus appeared in its coulometric titration curve, which manifest itself as three peaks in dQ/dV–V plot. The peak split phenomenon was also found for oxygen deficient spinel, LiMn2O3.986, prepared at 900°C in both reduction and oxidation branches at room and elevated temperatures using a lower scan rate of 0.02mV/s. The disproportionation dissolution of stoichiometric spinel LiMn2O4.014 intensified by the elevated temperature in slightly acidic electrolyte is considered responsible for the occurrence of the phenomenon. The finding gives a piece of evidence for oxygen deficient spinel LiMn2O4−z as the insoluble product of disproportionation dissolution.
With increasing use of lithium-ion power packs, reports of occasional incidents of severely debilitating and sometimes fatal tragedies appear in the news. This review analyzes possible scenarios that trigger such hazards before proceeding to discuss safety mechanisms such as pressure release valves, one-shot fuses, reversible and irreversible positive temperature coefficient elements, shutdown separators, chemical shuttles, non-flammable electrolytes and coatings.
The influence of carbon black distribution/arrangement in cathode composite on cathode performance is studied using three types of active materials: LiMn2O2-spinel, LiCoO2, and LiFePO4. To the active materials, carbon black is added in two different ways: (a) using a conventional mixing procedure and (b) using a novel coating technology (NCT) invented in our laboratory. Different technologies yield different arrangement (distribution) of carbon black around active particles. It is shown that the uniformity of carbon black distribution affects significantly the cathode kinetics, regardless of the type of active particles used. A simple model explaining the influence of carbon black distribution on cathode kinetics is presented.
Given the large magnitude of energy in waste heat, its efficient conversion to electrical power offers a significant opportunity to lower greenhouse gas emissions. However, it has been difficult to optimize the performance of new direct energy conversion approaches because of the coupling between entropy change and thermal and electrical transport in continuously operating devices. With electrochemical cells driving flowing electrolytes in symmetric redox reactions at different temperatures, we demonstrate two continuous electrochemical heat engines that operate at 10–50 °C and at 500–900 °C, respectively. Simulations of kilowatt-scale systems using electrochemical cells stacked in series suggest efficiencies over 30% of the Carnot limit and areal power densities competitive with solid-state thermoelectrics at maximum power. Although entropy change, thermal transport and electrical transport are inherently coupled in solid-state thermoelectrics, they can be somewhat circumvented in electrochemical systems, thus offering new opportunities to engineer efficient energy conversion systems.
In this work, we studied a destructive impact of the space electron irradiation on the promising thin film materials for optoelectronic applications, namely on pure zinc oxide (ZnO) and indium-doped (ZnO:In) thin films deposited through pulsed electrochemical deposition and Successive Ionic Layer Adsorption and Reaction technique on soda-lime glass substrates, on glass sheets covered with transparent conductive film SnO2:F (FTO), and also on flexible polyimide and polyethylene terephthalate substrates. Morphology of ZnO and ZnO:In films, both before and after their electron irradiation, and also influence of the e-irradiation treatment on the substrates were observed by scanning electron microscopy (SEM). Chemical compositions of the films were investigated by X-ray fluorescence (XRF) microanalysis. To research crystal structure we used X-ray diffraction (XRD) method. As studies have shown, the influence of electron beam irradiation in vacuum, which doses exceed the conditions of long-term space applications are manifested in the form of little ZnO and ZnO:In etching and in the slight electron-induced degradation of the film structure, which is partially offset by concomitant annealing. At the same time, such high doses of electron irradiation adversely affect all kinds of substrates we used.
We report a means by which atomic and molecular secondary ions, including cholesterol and fatty acids, can be sputtered through single-layer graphene to enable secondary ion mass spectrometry (SIMS) imaging of untreated wet cell membranes in solution at subcellular spatial resolution. We can observe the intrinsic molecular distribution of lipids, such as cholesterol, phosphoethanolamine and various fatty acids, in untreated wet cell membranes without any labeling. We show that graphene-covered cells prepared on a wet substrate with a cell culture medium reservoir are alive and that their cellular membranes do not disintegrate during SIMS imaging in an ultra-high-vacuum environment. Ab initio molecular dynamics calculations and ion dose-dependence studies suggest that sputtering through single-layer graphene occurs through a transient hole generated in the graphene layer. Cholesterol imaging shows that methyl-β-cyclodextrin preferentially extracts cholesterol molecules from the cholesterol-enriched regions in cell membranes.
A series of LiMn0.9Fe0.1−x Mg x PO4/C (x =0, 0.01, 0.02, 0.05) was synthesized by a solid state reaction, and the effect of synthesis temperature and Fe/Mg ratio on the electrochemical performance of the obtained materials was investigated by X-ray diffraction, scanning electron microscopy, Raman spectroscopy and electrochemical measurements. The electrochemical performance of the Fe and Mg co-substituted LiMnPO4 was obviously improved with increasing synthesis temperature from 650 to 800°C, but further increase led to an abrupt capacity loss due to the impurity formation. The Fe and Mg co-substitution could remarkably enhance the electrochemical activity of LiMnPO4 compared with the Fe substitution only, but too high level of Mg doping would worsen the rate capability. The LiMn0.9Fe0.09Mg0.01PO4/C synthesized at 800°C demonstrated the optimum electrochemical performance with a high capacity and an excellent rate capability. Even discharged at the rate of 10C, a capacity of 60mAhg−1 was still observed.
To assess the potential of carbon silicon composite anodes for automotive applications, C–Si anodes were fabricated and certain improvements employed. The use of a PVDF buffer layer is demonstrated for the first time with a C–Si composite material. The buffer layer increases adhesion by 89%, and increases capacity by 50–80%. Also, a limited capacity range is employed to improve cycle life by up to 200%, and enable currents as high as 2 mA cm−1. The combined use of a buffer layer and limited capacity range has not been reported before. A model is also presented for comparing C–Si performance with real-world automotive targets from USABC, including energy density, power density, specific energy, and specific power. The analysis reveals a capacity penalty that arises from pairing C–Si with a traditional cathode (NCA), and which prevents the cell from meeting all targets. Scenarios are presented in which a higher-capacity cathode (250 mAh g−1) allows all targets to be hypothetically met.
Solid-state batteries provide a safe and high energy density solution to next-generation energy storage devices. However, unsatisfactory power capability and cycling stability raised from lithium diffusion resistance and catalytic reaction at the electrode/electrolyte interface critically restrict their development. In this study, these interfacial issues are ameliorated by LiBO2 coating to achieve the successful implementation of nickel-rich LiNi0.6Co0.2Mn0.2O2 in poly(ether-acrylate) based solid-state batteries. The continuous coating acts not only as a physical barrier hindering the decomposition of polymer electrolyte but also as a buffer layer promoting lithium diffusion across the space charge layer owing to its electronic insulativity and ionic conductivity. In consequence, the LiBO2 coated nickel-rich cathode delivers superior cycling stability with a capacity retention of 84.3% during 150 cycles at 0.5C, remarkably improved lithium diffusion kinetics with an order of magnitude increase in apparent diffusion coefficient and prominent power performance with 97 mA h g−1 at 2C. The effectiveness of inserting such functional interlayer emphasizes the essentiality of interfacial chemistry in building high-performance solid-state Li metal batteries.
Background Social cognitive deficits have been proposed to be among the causes of poor functional outcome in schizophrenia. Empathy, or sharing and understanding the unique emotions and experiences of other people, is one of the key elements of social cognition, and prior studies suggest that empathic processes are impaired in schizophrenia. The current study examined whether impairments in self-reported empathy were associated with poor functioning, above and beyond the influences of neurocognitive deficits and psychopathology. Methods Individuals with schizophrenia (n=46) and healthy controls (n=37) completed the Interpersonal Reactivity Index (IRI), a measure of emotional and cognitive empathy. Participants also completed a neuropsychological test battery, clinical ratings of psychopathology, and functional outcome measures assessing both functional capacity and community functioning. After testing for between-group differences, we assessed the relationships between self-reported empathy and the measures of functioning, neurocognition, and psychopathology. Regression analyses examined whether empathic variables predicted functional outcomes. Results Individuals with schizophrenia reported lower IRI scores for perspective-taking and empathic concern, and higher IRI scores for personal distress than controls. Among individuals with schizophrenia, lower perspective-taking, greater disorganized symptoms, and deficits in working memory and episodic memory were correlated with poorer functional capacity and community functioning. Lower scores for perspective-taking explained significant incremental variance in both functional capacity (ΔR2 =.09, p <.05) and community functioning (ΔR2 =.152, p <.01) after accounting for relevant neurocognitive and psychopathological variables. Conclusions Impaired perspective-taking, a component of cognitive empathy, is associated with poor functioning even after taking into account the influences of neurocognitive deficits and psychopathology. These findings support further efforts to clarify the underlying causes of empathic disturbances and suggest that treatments for these disturbances may help functional recovery in schizophrenia.
Two series of hybrid inorganic–organic polymer electrolytes of the organically modified ceramics as polymer electrolytes (ORMOCERS-APE) type with formulas {Al[O(CH2CH2O)8.7] ρ /(LiClO4) z } n (1.85≤ ρ ≤2.24, 0≤ z ≤1.06) and {Zr[O(CH2CH2O)8.7] ρ /(LiClO4) z } n (1.80≤ ρ ≤1.99, 0≤ z ≤0.90) were treated with CO2 in subcritical conditions (293K and 5MPa). The effect of CO2 on the samples was investigated by using ESEM, thermal analysis (TG and DSC) and broad band dielectric spectroscopy (BDS). Both complexes {Al[O(CH2CH2O)8.7] ρ /(LiClO4) z } n and {Zr[O(CH2CH2O)8.7] ρ /(LiClO4) z } n after CO2 treatment exhibited a change in the segmental relaxation with respect to the untreated samples. This phenomenon has been interpreted in terms of higher portion of free volume in the samples. The CO2 treatment primarily lowered the conductivity of {Al[O(CH2CH2O)8.7] ρ /(LiClO4) z } n complexes of about one order of magnitude, as opposed to {Zr[O(CH2CH2O)8.7] ρ /(LiClO4) z } n complexes, where an increment of two orders of magnitude was observed. In both cases the conductivity of the treated and untreated materials versus the reciprocal absolute temperature presents the typical Vogel–Tamman–Fulcher (VTF) behavior. The different effects on the conductivities of the treated complexes are explained in terms of the modified anion-trapping ability of Al centers and in terms of the interactions of subcritical CO2 with the host polymer and the salt. Insight about the conductivity mechanisms were provided by the study of the VTF parameters and the relaxation times determined from the Debye peaks of the imaginary resistivity, the imaginary permittivity and the correlated motion analysis.
Although there is a strong link between the right hemisphere and understanding emotional prosody in speech, there are few data on how the right hemisphere is implicated for understanding the emotive “attitudes” of a speaker from prosody. This report describes two experiments which compared how listeners with and without focal right hemisphere damage (RHD) rate speaker attitudes of “confidence” and “politeness” which are signalled in large part by prosodic features of an utterance. The RHD listeners displayed abnormal sensitivity to both the expressed confidence and politeness of speakers, underscoring a major role for the right hemisphere in the processing of emotions and speaker attitudes from prosody, although the source of these deficits may sometimes vary.
Li-air battery using ionic liquids, N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis (trifluoromethylsulfonyl) amide (DEME-TFSA) and N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)amide (PP13-TFSA), as the solvents for electrolyte have been studied. A significant improvement of discharge capacity has been observed for DEME-TFSA (4315 mAh g−1-electrode at current density of 0.1 mA cm−2), compared with PP13-TFSA. As a discharged product, aggregates reaching 4 μm diameter in size are formed on the surface of cathode, almost 80% of the products are decomposed after charge. By using Raman spectroscopy, two typical peaks attributed to Li2O2 were detected from the discharged aggregates. From the cross sectional SEM images, vacancy occupation ratios of discharged and charged electrodes are estimated, and they are in good agreement with the theoretical calculations. The discharged products formed inside of the cathode are not decomposed completely by charge.
Gamma oscillations are key in coordinating brain activity and seem to be altered in schizophrenia. In previous work, we studied the spatial distribution of a noise power measure (scalp-recorded electroencephalographic activity unlocked to stimuli) and found higher magnitudes in the gamma band related to symptoms and cognition in schizophrenia. In the current study, we sought to replicate those findings and to study its specificity for schizophrenia in a completely independent sample. A principal component analysis (PCA) was used to determine the factorial structure of gamma noise power acquired with an electroencephalographic recording during an odd-ball P300 paradigm in the 250- to 550-ms window in 70 patients with schizophrenia (16 patients with first episode), 45 bipolar patients and 65 healthy controls. Clinical and cognitive correlates of the resulting factors were also assessed. Three factors arose from the PCA. The first displayed a midline-parietal distribution (roughly corresponding to the default mode network), the second was centro-temporal and the third anterior–frontal. Schizophrenia but not bipolar patients showed higher gamma noise power loadings in the first factor in comparison with controls. Scores for this factor were significantly and directly associated with positive and total symptoms in patients and inversely associated with global cognition in all participants. The results of this study replicate those of our previous publication and suggest an elevated midline-parietal gamma noise power specific to schizophrenia. The gamma noise power measure seems to be a useful tool for studying background oscillatory activity during performance of cognitive tasks.
For nearly two decades, research groups have attempted to increase the thermal conductivity of bulk materials by saturating them with different concentrations and types of nanoparticles. However, optimal enhancements in the thermal conductivity of these materials continue to go unrealized, primarily due to interfacial phenomena that impede phonon propagation from the bulk material to the nanoparticle or between individual, contacting nanoparticles. Though it is almost certain that interfacial resistances between contacting nanoparticles are responsible for the underwhelming thermal performance of nanoparticles in bulk materials, the physical mechanisms that limit thermal transport at nanoparticle junctions is not well understood. In this study, we investigate the effect of nanoparticle constriction size (i.e. the contact area between linked nanoparticles) on the bulk thermal conductivity of a surrounding paraffin-based phase change material. To this end, we measure the effective thermal conductivity of different Multi-walled Carbon Nanotube (MWCNT)/paraffin nanocomposites is measured with the transient plane source technique. Using a newly developed physical model, the interfacial thermal resistance between the contacting nanoparticles is determined as a function of the constriction geometry. Results suggest that the thermal conductance (i.e. the rate of heat transfer) between contacting MWCNTs can be increased by a factor of 27 by increasing their diameter by only 58nm. This is in direct conflict with effective medium approximations, which predict an increase in the bulk thermal conductivity of MWCNT–PCM composites when MWCNT diameters are reduced. Such a result indicates that the contact area between individual, contacting nanoparticles has a significant impact on thermal transport within the PCM nanocomposite, and therefore its bulk thermal conductivity. It is expected that these results will strongly impact the design of nanoparticle-laden PCMs.
AbstractSSS We fabricated asymmetric hybrid supercapacitors using binary materials composed of various ratios of H2Ti12O25 and Li4Ti5O12 as anodes and activated carbon as cathodes to investigate the tenability of their electrochemical performances. The binary materials have two advantageous properties: not only outstanding cyclability derived from Li4Ti5O12, but also excellent rate ability derived from H2Ti12O25. Because of these characteristics, hybrid supercapacitors with an 8:2 ratio of Li4Ti5O12/H2Ti12O25 as the anodes show promising electrochemical performance by complementary synergistic effects of H2Ti12O25 and Li4Ti5O12. Thus, we believe that hybrid supercapacitors containing Li4Ti5O12/H2Ti12O25 (8/2) could be used for high-grade energy storage devices that require longevity and ultrahigh electrochemical performance.