Phosphorus-carbon nanocomposite anodes for lithium-ion and sodium-ion batteries

With the expected theoretical capacity of 2596 mA h g-1, phosphorus is considered to be the highest capacity anode material for sodium-ion batteries and one of the most attractive anode materials for lithium-ion systems. This work presents a comprehensive study of phosphorus-carbon nanocomposite anodes for both lithium-ion and sodium-ion batteries. The composite electrodes are able to display high initial capacities of approximately 1700 and 1300 mA h g-1 in lithium and sodium half-cells, respectively, when the cells are tested within a larger potential windows of 2.0-0.01 V vs. Li/Li+ and Na/Na+. The level of demonstrated capacity is underpinned by the storage mechanism, based on the transformation of phosphorus to Li3P phase for lithium cells and an incomplete transformation to Na3P phase for sodium cells. The capacity deteriorates upon cycling, which is shown to originate from disintegration of electrodes and their delamination from current collectors by post-cycling ex situ electron microscopy. Stable cyclic performance at the level of ∼700 and ∼350-400 mA h g-1 can be achieved if the potential windows are restricted to 2.0-0.67 V vs. Li/Li+ for lithium and 2-0.33 vs. Na/Na+ for sodium half-cells. The results are critically discussed in light of existing literature reports

Nanostructured composite anodes and cathodes for lithium-ion and sodium-ion batteries

The thesis was focused on developing alloy based anode materials for Li-ion and Na-ion batteries. It helps to reduce the size and increase the energy density of the batteries. Furthermore, a novel cathode material was developed for Na-ion batteries which showed good cycling performance over a period of 100 cycles.

Suppression of bitterness using sodium salts

Bitterness is an ongoing taste problem for both the pharmaceutical and food industries. This paper reports on how salts (NaCI, NaAcetate, NaGluconate, LiCI, KCI) and bitter compounds (urea, quinine-HCI, caffeine, amiloride-HCI, magnesium sulfate, KCI) interact to influence bitter perception. Sodium salts differentially suppress bitterness of these compounds; for example urea bitterness was suppressed by over 70% by sodium salts, while MgSO4 bitterness was not reduced. This study indicated that lithium ions had the same bitter suppressing ability as sodium ions, however the potassium cation had no bitter suppression ability. Changing the anion attached to the sodium did not affect bitter suppression, however, as the anion increased in size, perceived saltiness decreased. This indicates that sodium's mode of action is at the peripheral taste level, rather than a cognitive affect. A second experiment revealed that suppressing bitterness with a sodium salt in a bitter/sweet mixture causes an increase in sweetness. This suggests adding salt to a food matrix will not only increase salt perception, but also potentiate flavor by differential suppression of undesirable tastes such as bitter, while increasing more desirable tastes such as sweet.

Physicochemical properties of N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide for sodium metal battery applications.

The physicochemical properties of a range of NaNTf2 (or NaTFSI) salt concentrations in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (or C3mpyrFSI) ionic liquid were investigated by DSC, conductivity, cyclic voltammetry and diffusivity studies. Cyclic voltammetry indicated a stable sodium plating behavior with a current of 5 mA cm(-2) at 25 °C to 20 mA cm(-2) at 100 °C, along with high reversibility identifying this electrolyte as a possible candidate for sodium-ion or sodium metal battery applications. (23)Na NMR chemical shifts and spectral linewidths (FWHM) indicate a complex coordination of the Na(+) ion which is dependent on both temperature and salt concentration with an apparently stronger coordination to the NTf2 anion upon increasing the NaNTf2 concentration. Temperature dependent PFG-NMR diffusion measurements show that both FSI and NTf2 have a comparable behaviour although the smaller FSI anion is more diffusive.

A study of phase behavior and conductivity of mixtures of the organic ionic plastic crystal N-methyl-N-methyl-pyrrolidinium dicyanamide with sodium dicyanamide

We report on the thermal, structural and conductivity properties of the organic ionic plastic crystal (OIPC) N-methyl-N-methyl-pyrrolidinium dicyanamide [C1mpyr][N(CN)2] mixed with the sodium salt Na[N(CN)2]. The DSC thermal traces indicate that an isothermal transition, which may be a eutectic melting, occurs at ~ 89 °C, below which all compositions are entirely in the solid phase. At 20 mol% Na[N(CN)2], this transition is the final melt for this mixture, and a new liquidus peak grows beyond 20 mol% Na[N(CN)2]. The III- > II solid-solid phase transition continues to be evident at ~- 2 °C. The microstructure for all the mixtures indicated a phase separated morphology where precipitates can be clearly observed. Most likely, these precipitates consist of a Na-rich second phase. This was also suggested from the vibrational spectroscopy and the 23Na NMR spectra. The lower concentrations of Na[N(CN)2] present complex 23Na MAS spectra, suggesting more than one sodium ion environment is present in these mixtures consistent with complex phase behavior. Unlike other OIPCs where the ionic conductivity usually increases upon doping or mixing in a second component, the conductivity of these mixtures remains relatively constant and above 10- 4 S cm- 1 at ∼ 80 °C, even in the solid state. Such high conductivities suggest these materials may be promising to be used for all solid-state electrochemical devices.

Gelled ionic liquid sodium ion conductors for sodium batteries

Owing to the unique properties of certain Ionic liquids (ILs) as safe and green solvents, as well as the potential of sodium as an alternative to lithium as charge carriers, we investigate gel sodium electrolytes as safe, low cost and high performance materials with sufficient mechanical properties for application in sodium battery technologies. We investigate the effect of formation of two types of gel electrolytes on the properties of IL electrolytes known to support Na/Na⁺ electrochemistry. The ionic conductivity is only slightly decreased by 0.0005 and 0.0002 S cm^-1 in the case of 0.3 and 0.5 M NaNTf2 systems respectively as the physical properties transition from liquid to gel. We observed facile plating and stripping of Na metal around 0 V vs. Na/Na⁺ through the cyclic voltammetry. A wide-temperature range of the gelled IL state, of more than 100 K around room temperature, is achieved in the case of 0.3 and 0.5 M NaNTf2. We conclude that the formation of a gel does not significantly affect the liquid-like ion dynamics in these materials, as further evidenced by DSC and FTIR analysis.

Ex situ electrochemical sodiation/desodiation observation of Co₃O₄ anchored carbon nanotubes: a high performance sodium-ion battery anode produced by pulsed plasma in a liquid

Liquid plasma, produced by nanosecond pulses, provides an efficient and simple way to fabricate a nanocomposite architecture of Co3O4/CNTs from carbon nanotubes (CNTs) and clusters of Co3O4 nanoparticles in deionized water. The crucial feature of the composite's structure is that Co3O4 nanoparticle clusters are uniformly dispersed and anchored to CNT networks in which Co3O4 guarantees high electrochemical reactivity towards sodium, and CNTs provide conductivity and stabilize the anode structure. We demonstrated that the Co3O4/CNT nanocomposite is capable of delivering a stable and high capacity of 403 mA h g(-1) at 50 mA g(-1) after 100 cycles where the sodium uptake/extract is confirmed in the way of reversible conversion reaction by adopting ex situ techniques. The rate capability of the composite is significantly improved and its reversible capacity is measured to be 212 mA h g(-1) at 1.6 A g(-1) and 190 mA h g(-1) at 3.2 A g(-1), respectively. Due to the simple synthesis technique with high electrochemical performance, Co3O4/CNT nanocomposites have great potential as anode materials for sodium-ion batteries.

Immunolocalisation of sodium/proton exchanger-like proteins in the gills of elasmobranchs

Na⁺/H⁺ exchangers are integral membrane proteins that exchange Na⁺ and H⁺ across cell membranes. The Na⁺/H⁺ exchangers 2 and 3 are epithelial isoforms in mammals and contribute to acid–base homeostasis. The gills of fishes, including elasmobranchs, are also associated with acid/base balance, and are probably the primary acid/base regulatory organ. This study examines the presence of Na⁺/H⁺ exchangers 2 and 3 using immunohistochemistry and immunoblotting in the gills of four species of elasmobranchs, the banjo ray (Trygonorrhina fasciata), southern eagle ray (Myliobatis australis), the gummy shark (Mustelus antarcticus) and the Australian angel shark (Squatina australis) using heterologous antibodies. Na⁺/H⁺ exchanger 2-like immunoreactivity was observed in the gills of the banjo ray, eagle ray and angel shark. In the banjo and eagle rays, this Na⁺/H⁺ exchanger-like immunoreactivity co-localised with immunoreactivity to Na⁺/K⁺-ATPase, a marker for the mitochondrial-rich cells of fishes. Na⁺/H⁺ exchanger 3-like immunoreactivity was only observed in the gills of the angel and gummy sharks, some Na⁺/H⁺ exchanger 3-like cells also showed Na⁺/K⁺-ATPase immunoreactivity. However, immunoblotting of banjo and eagle ray gill membranes demonstrated Na⁺/H⁺ exchanger 3-like immunoreactivity, which was not consistent with the immunohistochemical results. These data demonstrate the presence of epithelial Na⁺/H⁺ exchangers 2 and 3 in the gills of elasmobranchs and a link with acid/base regulation is suggested.

Determination of sodium oxalate in Bayer liquor using flow-analysis incorporating an anion exchange column and tris(2,2`-bipyridyl)ruthenium(II) chemiluminescence detection

Semi-automated flow injection instrumentation, incorporating a small anion exchange column coupled with tris(2,2′-bipyridyl)ruthenium(II) (Ru(bipy)₃²⁺) chemiluminescence detection, was configured and utilised to develop rapid methodology for the determination of sodium oxalate in Bayer liquors. The elimination of both negative and positive interferences from aluminium(III) and, as yet, unknown concomitant organic species, respectively are discussed. The robustness of the methodology was considerably enhanced by using the temporally stable form of the chemiluminescence reagent, tris(2,2′-bipyridyl)ruthenium(III) perchlorate in dry acetonitrile. Real Bayer process samples were analysed and the results obtained compared well with those performed using standard methods within industrial laboratories.

Decreasing dietary sodium while following a self-selected potassium-rich diet reduces blood pressure

Reducing dietary sodium reduces blood pressure (BP), a major risk factor for cardiovascular disease, but few studies have specifically examined the effect on BP of altering dietary sodium in the context of a high potassium diet. This randomized, crossover study compared BP values in volunteer subjects self-selecting food intake and consuming low levels of sodium (Na+; 50 mmol/d) with those consuming high levels of sodium (> or =20 mmol/d), in the context of a diet rich in potassium (K+). Sodium supplementation (NaSp) produced the difference in Na+ intake. Subjects (n = 108; 64 women, 44 men; 16 on antihypertensive therapy) had a mean age of 47.0 ± 10.1 y. Subjects were given dietary advice to achieve a low sodium (LS) diet with high potassium intake (50 mmol Na+/d, >80 mmol K+/d) and were allocated to NaSp (120 mmol Na+/d) or placebo treatment for 4 wk before crossover. The LS diet decreased urinary Na+ from baseline, 138.7 ± 5.3 mmol/d to 57.8 ± 3.8 mmol/d (P < 0.001). The NaSp treatment returned urinary Na+ to baseline levels 142.4 ± 3.7 mmol/d. Urinary K+ increased from baseline, 78.6 ± 2.3 to 86.6 ± 2.1 mmol/d with the LS diet and to 87.1 ± 2.1 mmol/d with NaSp treatment (P < 0.001). The LS diet reduced home systolic blood pressure (SBP) by 2.5 ± 0.8 mm Hg (P = 0.004), compared with the NaSp treatment. Hence, reducing Na+ intake from 140 to 60 mmol/d significantly decreased home SBP in subjects dwelling in a community setting who consumed a self-selected K+-rich diet, and this dietary modification could assist in lowering blood pressure in the general population.

New light from an old reagent: chemiluminescence from the reaction of potassium permanganate with sodium borohydride

When aqueous sodium borohydride (50 mM) is added to a solution of potassium permanganate (1mM, in sodium hexametaphosphate) at acidic pH, bright red-orange emission is easily visible in a darkened room. This chemiluminescence emission is due to an excited state of manganese (II) that undergoes solution phase phosphorescence and provides an excellent opportunity for students to explore the relationship between the initial oxidation state of the manganese and the likelihood of luminescence. Not surprisingly Mn(VII), Mn(IV) and Mn(III) all give rise to chemiluminescence where as Mn(II) fails to react.

The influence of sodium salts on binary mixtures of bitter-tasting compounds

In order to study potential mixture interactions among bitter compounds, selected sodium salts were added to five compounds presented either alone or as binary bitter- ompound mixtures. Each compound was tested at a concentration that elicited ‘weak’ perceived bitterness. The bitter compounds were mixed at these concentrations to form a subset of possible binary mixtures. For comparison, the concentration of each solitary compound was doubled to measure bitterness inhibition at the higher intensity level elicited by the mixtures. The following sodium salts were tested for bitterness inhibition: 100 mM sodium chloride (salty), 100 mM sodium gluconate (salty), 100 and 20 mM monosodium glutamate (umami), and 50 mM adenosine monophosphate disodium salt (umami). Sucrose (sweet) was also employed as a bitterness suppressor. The sodium salts differentially suppressed the bitterness of compounds and their binary combinations. Although most bitter compounds were suppressed, the bitterness of tetralone was not suppressed, nor was the bitterness of the binary mixtures that contained it. In general, the percent suppression of binary mixtures of compounds was predicted by the average percent suppression of its two components. Within the constraints of the present study, the bitterness of mixtures was suppressed by sodium salts and sucrose independently, with few bitter interactions. This is consistent with observations that the bitter taste system integrates the bitterness of multi-compound solutions linearly.

Sodium adsorption using activated alumina for application in the dairy industry

Basic activated alumina with negatively charged surface is considered as a potential adsorbent for a targeted molecule with positive polarity. Adsorption of sodium by basic activated alumina was investigated as a method for desalting dairy waste streams, in which sodium ion concentration averaged 600 mg/L. Sodium equilibrium and kinetic adsorption were investigated using basic activated alumina with synthetic brines. The results of equilibrium adsorption show that uptake of sodium by activated alumina is significantly higher when the pH is greater than 8 and increases as the pH of the brines increases until pH reaches around 10. The results of kinetic adsorption show that 90 hours were needed to reach equilibrium for sodium adsorption. Binding and diffusion processes are suggested to have taken place within the activated alumina.

Gender differences in adherence to sodium-restricted diet patients with heart failure.

Background

Despite the importance of the sodium-restricted diet (SRD) to heart failure (HF) management, patient adherence is poor. Little is known about gender differences in adherence or factors that affect patients' ability to follow SRD recommendations. The purposes of this study were to determine whether there were gender differences in (1) adherence to the SRD; (2) knowledge about SRD and HF self-care; and (3) perceived barriers to following the SRD.
Methods and Results

Forty-one men and 27 women completed the Heart Failure Attitudes and Barriers questionnaire that measured HF self-care, knowledge, and perceived barriers to follow an SRD. Diet adherence was measured by 24-hour urinary sodium excretion (UNa). Women were more adherent to the SRD than men as reflected by 24-hour urine excretion (2713 versus 3859 mg UNa, P = .01). Women recognized signs of excess sodium intake such as fluid buildup (P = .001) and edema (P = .01) more often than men and had better understanding of appropriate actions to take related to following an SRD. There were no gender differences in perceived barriers to follow an SRD.
Conclusions

Although men and women perceived similar barriers, women were more adherent to the SRD and had greater knowledge about following an SRD. Further investigation of this phenomenon is warranted to determine if better adherence contributes to improved outcomes in women.

Effect of sodium bicarbonate on muscle metabolism during intense endurance cycling

Introduction: Sodium bicarbonate (NaHCO₃) ingestion has been shown to increase both muscle glycogenolysis and glycolysis during brief submaximal exercise. These changes may be detrimental to performance during more prolonged, exhaustive exercise. This study examined the effect of NaHCO₃ ingestion on muscle metabolism and performance during intense endurance exercise of ~60 min in seven endurance-trained men. Methods: Subjects ingested 0.3 g·kg^-1 body mass of either NaHCO₃ or CaCO₃ (CON) 2 h before performing 30 min of cycling exercise at 77 ± 1% [latin capital V with dot above]O_2peak followed by completion of 469 ± 21 kJ as quickly as possible (~30 min, ~80% [latin capital V with dot above]O_2peak). Results: Immediately before, and throughout exercise, arterialized-venous plasma HCO₃- concentrations were higher (P < 0.05) whereas plasma and muscle H⁺ concentrations were lower (P < 0.05) in NaHCO₃ compared with CON. Blood lactate concentrations were higher (P < 0.05) during exercise in NaHCO₃, but there was no difference between trials in muscle glycogen utilization or muscle lactate content during exercise. Reductions in PCr and ATP and increases in muscle Cr during exercise were also unaffected by NaHCO₃ ingestion. Accordingly, exercise performance time was not different between treatments. Conclusion: NaHCO₃ ingestion resulted in a small muscle alkalosis but had no effect on muscle metabolism or intense endurance exercise performance in well-trained men.