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Here we report the rate capability and cycling stability of NaFePO4 in aqueous electrolyte at various temperatures and voltage windows and compare it to its performance in organic electrolyte under similar conditions. In aqueous electrolyte the polarization was strongly reduced, leading to superior capacity at all tested rates compared to organic electrolyte with a comparable voltage window. Moreover, by fine tuning the voltage window, the capacity retention was notably improved, indicating that this material is a good candidate for aqueous Na-ion batteries, which we have confirmed by reporting the cycling stability of a NaFePO4/NaTi2(PO4)3 aqueous full cell.
Nano-Si embedded Si7Ti4Ni4 is synthesized with the melt spinning method, which is facile, and applicable to mass-production. Si7Ti4Ni4, the buffer material, is electrochemically inactive toward lithium. Nevertheless, Si7Ti4Ni4 has good electrical conductivity, in the order of 105 S m−1, which is more conductive than amorphous carbon that is usually used as a coating material for active material. Furthermore, the surrounding grain boundaries of Si7Ti4Ni4 effectively relax volume expansion of Si. Therefore, it plays a critical role in maintaining the structure of electrode and the integrity of active materials. As a result, nano-Si embedded in Si7Ti4Ni4 shows outstanding cycle performance over 50 cycles at 400 mA g−1, and it maintains 86% of its specific capacity at 3200 mA g−1, compared with that of 400 mA g−1. This indicates that nano-Si embedded in Si7Ti4Ni4 can be a promising anode material for lithium ion batteries.
Nanostructured spinel LiMn2O4 and super P composite with much enhanced electrochemical performance especially ultrahigh rate capability as the cathode for aqueous hybrid supercapacitors is synthesized by ball milling commercial LiMn2O4 particles together with super P. The as-prepared composite delivers a high capacitance of 306 F g−1 at the current density of 1 A g−1 and superb rate ability of 228.6 F g−1 at 40 A g−1 in 1 M Li2SO4 aqueous electrolyte. The capacitance of the nanostructured composite is 3.5 times higher than that of pristine LiMn2O4 even being charged and discharged 80 times faster. The excellent performances are ascribed to the nanosized LiMn2O4 well dispersed into the conductive carbon matrix. LiMn2O4 and super P composite//active carbon hybrid supercapacitor is assembled and the energy density can reach up to 21.58 Wh kg−1 at 293.16 W kg−1 and 13 Wh kg−1 at 5200 W kg−1. The hybrid device also shows an excellent cycling performance, which retains 85% of the initial capacitance after 4500 cycles. This work provides an effectively facile way to produce high performance LiMn2O4-based cathodes for hybrid suercapacitors in practical applications.
Retinal Müller cells exhibit the characteristics of retinal progenitor cells, and differentiate into ganglion cells under certain conditions. However, the number of ganglion cells differentiated from retinal Müller cells falls far short of therapeutic needs. This study aimed to develop a novel protocol to promote the differentiation of retinal Müller cells into ganglion cells and explore the underlying signaling mechanisms.
Platinum hollow nanospheres (HNPt) are synthesized via a galvanic replacement reaction between as-prepared cobalt nanoparticles and Pt4+ (H2PtCl6) ions. Support graphene nanosheets are also prepared using a chemical route for HNPt immobilization. Morphology and chemical composition of the as-prepared nanocomposite are characterized by transmission electron microscopy and energy dispersion X-ray spectroscopy, respectively. The prepared nanocomposite electrocatalytic activity toward sodium borohydride oxidation is studied by electrochemical techniques. To investigate the morphology effect of electrocatalytic behavior, Pt solid nanoparticles are also synthesized and immobilized on graphene support (NPt/G), and its electrocatalytic activity is studied. Results show that the electrocatalyst’s morphology has a significant effect on electrocatalytic activity, as HNPt/G shows a superior electrocatalytic activity in comparison with NPt/G toward sodium borohydride oxidation.
With a theoretical specific capacity much higher than that of traditional graphite, silicon (Si) has been considered as a promising anode material for next-generation lithium ion batteries (LIBs). Unfortunately, its practical application has been severely limited by the drawback of drastic volume expansion. In this report, we demonstrate a facile way to prepare binder-free, conductive agent-free silicon/reduced graphene oxide composite (Si/rGO) anode on nickel foam via one-step hydrothermal method followed by a post-annealing process, which delivers extraordinary cyclability and rate performance. The reversible specific capacity of the composite anode retained over 1500mAh/g at 2A/g after 2500 cycles and over 600mAh/g at 4A/g after 2500 cycles. Especially at a reasonable high current density of 16A/g, the Si/rGO anode still displayed a specific capacity of 500mAh/g.
The electrochemical performance of sodium Prussian Blue Na1-xFeIII 1+(x/3)[FeII(CN)6]·yH2O in aqueous electrolyte is here reported. Remarkable cycling stability and coulombic efficiency close to 100% have been achieved by suppressing the process at high voltage since results in Na-PB peptization and electrode disintegration. Under these conditions, this material is able to deliver 65mAhg−1 of capacity, which is slightly higher than the capacity obtained in organic electrolyte despite the voltage window used in aqueous electrolyte is narrower. This is possible thanks to the significant reduction of overpotential in aqueous medium which is here discussed and compared with previous results obtained with NaFePO4 in aqueous electrolyte.
Solid electrolytes with high ionic conductivity and excellent electrochemical stability are of prime significance to enable the application of solid-state batteries in energy storage and conversion. In this study, solid composite polymer electrolytes (CPEs) based on sodium bis(trifluorosulfonyl) imide (NaTFSI) and poly (ethylene oxide) (PEO) incorporated with active ceramic filler (NASICON) are reported for the first time. With the addition of NASICON fillers, the thermal stability and electrochemical stability of the CPEs are improved. A high conductivity of 2.8 mS/cm (at 80 °C) is readily achieved when the content of the NASICON filler in the composite polymer reaches 50 wt%. Furthermore, Na3V2(PO4)3/CPE/Na solid-state batteries using this composite electrolyte display good rate and excellent cycle performance.
In order to quantify the total Greenhouse Gas (GHG) emissions from different commodities, the contribution of emissions in all subprocess chains has to be considered. In embedded energy analysis, the higher order production processes are usually truncated due to a lack of data. To fill the truncated subprocesses up to infinite process chains, energy intensities and GHG emission factors of various final consumptions in the economy evaluated by the Input–Output Analysis (IOA) must be applied. The direct GHG emissions in final consumptions in Thailand are evaluated by imitating the approach in the energy sector of the revised 1996 Intergovernmental Panel on Climate Change (IPCC) guidelines for national GHG inventories. The indirect energy and indirect emissions are evaluated by using the 1998 Input–Output (I–O) table. Results are presented of emissions in the main process, indirect processes, and on each subprocess chain order. The trend of energy intensity and emission factors of all final consumptions for 1995, 1998, 2001 and 2006 are also presented. Results show that the highest energy intensive sector is the electricity sector where fossil fuel is primarily used, but the highest total GHG emitter is the cement industry where the major sources of the emissions are industrial processes and the combustion of fossil fuels. Implication of the emission factors on electricity generating technologies shows that various cleaner electricity generating technologies, including renewable energy technology, could help in global GHG mitigation.
There has been tremendous progress in enhancing the electrochemical performance of lithium-sulfur batteries. For example, the use of dissolved polysulfide (PS) as cathode improves sulfur (S) utilization and redox kinetics. Notably, free-standing PS cathodes have exceptional performance, but their preparation is not scalable as compared to the slurry-coating process. However, the electrochemical performance of slurry-coated PS electrodes such as Pt/graphene, Super P, metal nitrides and hierarchical porous carbon, is not satisfactory. Herein, a high-performance lithium-PS battery using inexpensive commercially available materials has been developed. Specific capacities between 1220 and 1007 mAh g−1 were achieved at charge rates of 0.2–2.0 C, having capacity fade of lower than 0.14% per cycle over 200 cycles. At higher S loading, a practical areal capacity of > 4 mAh cm-2 was achieved. The difference between PS and melt-diffusion S cathodes was also examined. Remarkably, the PS cathode offered 48% higher specific capacity and 26% lower capacity fade than the melt-diffused S cathode due to differences in morphology, surface area and ohmic resistance of the cathodes. This work provides a strong case towards a paradigm shift away from conventional cathode preparation approaches to improve the electrochemical performance of lithium-S batteries.
Robust electrospun polyimide (PI) membranes are simply fabricated by polymerization of oxidianiline (ODA) and pyromellitic dianhydride (PMDA). The as-prepared PI membranes, with reliable safety (self-extinguishing) and excellent mechanical property, exhibit highly uniform morphology with an average fiber diameter ∼ 600nm, high porosity ∼67%, high electrolyte uptake ∼534% and good relative absorption ratio ∼75% of the initial absorption (electrolyte uptake until 240min). With the presence of triethylene glycol diacetate-2-propenoic acid butyl ester (TEGDA-BA) gel electrolytes, the resulting polyimide-gel electrolytes (PI-GEL) show a high ionic conductivity up to 2.0×10−3 Scm−1 at 25°C, coupled with high electrochemical stability (>4.5V vs. Li/Li+). The Li/PI-GEL/LiFeO4 cells demonstrate remarkably stable charge/discharge performance and excellent capacity retention of ∼146.8mAhg−1 (0.1C) after 100 cycles. The results suggest a facile strategy for scalable fabrication of high-performance polymer electrolyte membrane for lithium ion batteries.
A Weight-of-evidence (WoE) evaluation should be applied in assessing all the available data for the identification of endocrine disrupting (ED) properties of chemicals. The European Commission draft acts specifying criteria under the biocidal products and plant protection products regulations require that WoE is implemented for the assessment of such products. However, only some general considerations and principles of how a WoE should be conducted are provided. This paper reviews WoE approaches to distil key recommendations specifically for the evaluation of potential ED properties of chemicals. In a manner, which is consistent with existing, published WoE frameworks, the WoE evaluation of ED properties can be divided into four phases: 1) Definition of causal questions and data gathering and selection, 2) Review of individual studies, 3) Data integration and evaluation, and 4) Drawing conclusions based on inferences. Recommendations are made on how to conduct each phase robustly and transparently to help guide the WoE evaluation of potential endocrine disrupting properties of chemicals within a European regulatory context.
In this paper, a photoelectrochemical study of hetero-junctions formed by zinc phthalocyanine (ZnPc) and semiconductor oxide nanocrystals (NCs), is reported. To this purpose, thin films composed of either size- and shape-controlled ZnO or TiO2 NCs, synthesized by both hydrolytic and non-hydrolytic colloidal methods, were investigated as photo-anodes with ZnPc as the sensitizer. The effects of the oxide nature, of the nanocrystal shape and surface chemistry, and of the modality of photo-anode preparation on the resulting photoelectrochemical response were evaluated. In general, the photoactivity was found to be significantly enhanced when ZnO NCs were used as compared to TiO2 NCs. In the latter case, the hetero-junctions based on non-hydrolytically prepared TiO2 provided remarkably lower photocurrents with respect to those formed by its hydrolytically synthesized analogous. Moreover, a slight improvement of photoactivity was observed if spherical TiO2 NCs were replaced by rod-like particles. Finally, as opposed to expectations, photo-anodes deposited from NC-ZnPc blended solutions exhibited a photoelectrochemical response comparable to that of sensitized films prepared by layer-by-layer procedure.
Na2/3Ni1/3Mn2/3O2 with a P2 phase is investigated as a cathod material for sodium ion batteries. It delivers a high discharge capacity of 228 mAh g−1 within 1.5–4.5 V in half cells, which is much higher than the theoretical value of 172 mAh g−1. Metal K-edge X-ray absorption near edge spectroscopy results show that the Mn ions remain in 4 + oxidation state during sodiation/desodiation and the charge compensation is due to the Ni2+/Ni4+ redox. Soft X-ray absorption spectroscopy results reveals a gradient in the valence state of Ni ions from bulk to surface for the charged electrode, and a change in the integrated intensity of O K-edge peak after charging, strongly suggesting that part of the charge compensation takes place at the oxygen sites. In addition, the reduction of Mn ions on the surface is observed on the discharged electrode, which indicates that the carbonate-based electrolyte reacts with the cathode material, resulting in a fast capacity drop. By utilizing an ionic liquid (IL) electrolyte (1 M NaTFSI in Pyr14TFSI) to reduce the interfacial reactions, the discharge capacity of ∼200 mAh g−1 is retained.
In the intensive search for higher performance Li-ion cathode materials the spotlight is firmly fixed on Li-rich compounds. Now, a strategy utilizing a fluorinated, disordered LiMn2O4 spinel structure shows how ultra-fast Li-ion diffusion and high energy density can be achieved with Mn and O redox.
Sputtered Pb films have been found to reversibly alloy electrochemically with magnesium in Grignard based electrolytes. The voltage curve shows a single plateau at about 125mV vs. Mg, corresponding to the formation of Mg2Pb, as confirmed by ex-situ X-ray diffraction. Pb was found to be the highest energy density Mg alloy yet reported, with the lowest voltage and highest volumetric capacity of any Mg alloy.
The commercialization of lithium–sulfur (Li–S) battery has so far hindered by the low electrochemical utilization and rapid capacity fading of sulfur cathode, which is induced by low electric/ionic conductivity, high dissolution of intermediate polysulfides and the volume expansion of sulfur. Herein, we describe an on-site adsorption strategy toward superior stability of sulfur electrode by encapsulating elemental sulfur into mesoporous TiO2 host. Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) measurements obviously indicate that elemental sulfur (S) occupy the mesopores of the TiO2 host, forming a core–shell liked nanostructure. The TiO2/S composite exhibits a superior cycling stability and high Coulombic efficiency during the charge/discharge process. Even at a high current rate of 1C, the TiO2/S composite shows an initial specific capacity of 650mAhg−1 and a specific retention of 89% after 100 cycles. The excellent electrochemical performances are critical related to the significant roles TiO2 host played during the electrochemical reaction. Firstly, the nano-sized TiO2 (∼5nm) traps the polysulfides via chemical bonding interaction to prevent their dissolution and minimize the “shuttle effect”. More importantly, the in situ formed Li x TiO2, acting as a mixed electric/ionic conductor, facilitates easier Li+/e− transport. The unique functions of the TiO2 plus its easy availability make the current study conceptually provides new opportunities to reach long-term cycling stability of sulfur cathode using carbon-free hosts.
Personality factors have been associated with Alzheimer’s disease (AD) and dementia, but they have not been examined against markers of regional brain glucose metabolism (a primary measure of brain functioning) in older adults without clinically diagnosed cognitive impairment. The relationship between personality factors derived from the five-factor model and cerebral glucose metabolism determined using positron emission tomography (PET) with [18F]-2-fluoro-2-deoxy-d-glucose (18F-FDG-PET) was examined in a cohort of 237 non-demented, community-dwelling older adults aged 60–89 years (M ± SD = 73.76 ± 6.73). Higher neuroticism and lower scores on extraversion and conscientiousness were significantly associated with decreased glucose metabolism in brain regions typically affected by AD neuropathological processes, including the hippocampus and entorhinal cortex. Furthermore, while there were significant differences between apolipoprotein E (APOE) ε4 allele carriers and non-carriers on 18F-FDG-PET results in the neocortex and other brain regions (p < 0.05), there was no significant difference between carriers and non-carriers on personality factors and no significant interactions were found between APOE ε4 carriage and personality factors on brain glucose metabolism. In conclusion, we found significant relationships between personality factors and glucose metabolism in neural regions more susceptible to AD neuropathology in older adults without clinically significant cognitive impairment. These findings support the need for longitudinal research into the potential mechanisms underlying the relationship between personality and dementia risk, including measurement of change in other AD biomarkers (amyloid and tau imaging) and how they correspond to change in personality factors. Future research is also warranted to determine whether timely psychological interventions aimed at personality facets (specific aspects or characteristics of personality factors) can affect imaging or other biomarkers of AD resulting in delay or ideally preventing the onset of the cognitive impairment.
Lithium bis(oxalate)borate (LiBOB) has many unique properties, such as thermal stability and the formation of a stable passivation layer on the surface of carbonaceous anode. In this work, the electrochemical behaviors of sulfolane (SL) with LiBOB were studied by employment of dimethyl sulfite (DMS) and diethyl sulfite (DES) as mixed solvents, respectively. When used in Li/MCMB (mesophase carbon microbeads) cells at 60°C, only LiBOB-SL/DMS electrolyte exhibits not only excellent film-forming characteristics, but also good thermal stability of the interface film on the surface of MCMB. Besides, when used in LiFePO4/Li cells at 60°C, only LiBOB-SL/DMS electrolyte simultaneously exerts several advantages, such as good thermal stability of the interface film on the surface of LiFePO4, stable cycling performance, high mean voltage, and excellent discharge rate performance. It suggests that LiBOB-SL/DMS electrolyte is an excellent candidate electrolyte for high-temperature lithium ion batteries.
The expansion and shrinkage characteristics of sulfur composite cathode electrode in rechargeable lithium batteries have been investigated. It was found that the sulfur composites electrodes expanded when discharging and shrank when charging again. The thickness change of the electrode was measured to be about 22%. The thickness of lithium metal anodes was also changed when lithium deposition and dissolution, while the sulfur composites electrodes expanded and shrank conversely. The investigation showed that the thickness changes of lithium anode and sulfur composite cathode could be compensated with each other to keep the total thickness of the cell not to change so much.
A number of recent studies utilizing both functional neuroimaging and lesion analysis techniques in neurologic patients have produced conflicting results with respect to the neural correlates of picture naming. Picture naming involves a number of cognitive processes, from visual perception/recognition to lexical-semantic retrieval to articulation. This middle process, the ability to retrieve a name associated with an object, has been attributed in some cases to posterior portions of the left lateral temporal lobe and in other cases, to anterior temporal cortex. In the current study, we used voxel-based lesion symptom mapping (VLSM) to identify neural correlates of picture naming in a large sample of well-characterized left hemisphere (LH) patients suffering from a range of naming deficits. We tested patients on the Boston Naming Test (BNT), a clinical, standardized measure of picture naming that is widely used in both clinical and research settings. We found that overall performance on the BNT was associated with a network of LH regions that included significant portions of the left anterior to posterior middle temporal gyrus (MTG) and superior temporal gyrus (STG) and underlying white matter, and extended into left inferior parietal cortex. However, when we added covariates to this analysis that controlled for deficits in visual recognition and motor speech in order to isolate brain regions specific to lexical-semantic retrieval, the significant regions that remained were confined almost exclusively to the left mid-posterior MTG and underlying white matter. These findings support the notion that a large network in left peri-Sylvian cortex supports picture naming, but that the left mid-posterior MTG and underlying white matter play a critical role in the core ability to retrieve a name associated with an object or picture.
A technique for fast impedance measurement in the time domain is presented. It is based on the Fourier transformation and includes various improvements compared to previous work in the literature. Namely, it minimizes the influence of spectral leakage and aliasing and reduces noise. This is proved by the theoretical error estimate for different model systems. The technique is independent of the excitation signal and is demonstrated by a voltage step. Measurement results for a commercial Li-ion cell are presented and compared with results obtained by electrochemical impedance spectroscopy. Finally, a combination of the two techniques is proposed to cover a wide frequency range in minimum measurement time for the characterization of electrochemical systems.
One promising preparative method that offers the potential for improved platinum (Pt) dispersion of electrocatalysts is electroless deposition (ED). In this study, the effects of multiwalled carbon nanotubes (MWCNTs) pretreatment and synthesis procedure on properties of the four catalysts, synthesized by ED method, have been considered. The results of energy-dispersive X-ray spectroscopy (EDS), X-ray dot-mapping, X-ray fluorescence (XRF) and cyclic voltammetry (CV) analyses showed that using palladium (Pd) precursor during two-step sensitization–activation coating procedure gives uniform Pt particles distribution on MWCNTs with low aggregation and high specific surface area (∼80m2 g−1). In addition, to investigate the performance of the synthesized catalysts in experimental fuel cell system, thin-film method was used to fabricate the membrane electrode assemblies (MEAs). Obtaining the polarization curves for the fabricated MEAs (Pt loading ∼0.4mgcm−2) and a commercial MEA (ElectroChem, Pt loading ∼1mgcm−2) demonstrated that the catalyst prepared by two-step sensitization–activation coating procedure possesses a good performance despite of its lower Pt content.