Electrolyte Volume Research Articles

Effects of Polysulfide Solubility and Li Ion Transport on Performance of Li–S Batteries Using Sparingly Solvating Electrolytes

Sparingly solvating electrolytes are an emerging class of electrolytes used in Li–S batteries. In this type of electrolytes, polysulfide dissolution and shuttling can be suppressed, resulting in high Coulombic efficiency and cycle life. To optimize the electrolytes for high energy density cells, effects of polysulfide solubility and Li ion transport properties on Li–S battery performance were investigated for tetraglyme (G4)-based solvate ionic liquids [Li(G4)x][TFSA] and a sulfolane (SL)-based concentrated electrolyte [Li(SL)2][TFSA], which are both diluted with a hydrofluoroether (HFE). The Li2S8 solubility is low (1 mM in atomic S concentration) in [Li(G4)0.8][TFSA]−4.3HFE and [Li(SL)2][TFSA]−4.0HFE. Cells with [Li(SL)2][TFSA]−4.0HFE exhibited better rate capability despite their lower ionic conductivity. The higher transference number (tLi+) of [Li(SL)2][TFSA]−4.0HFE may predominantly contribute to the rate performance, rather than polysulfide solubility and ionic conductivity. Furthermore, [Li(SL)2][TFSA]−4.0HFE demonstrated an initial discharge capacity of 1130 mAh g−1 at a low electrolyte volume to sulfur weight ratio of 4, whereas a typical organic electrolyte failed to achieve such a high capacity owing to limitations of the redox mechanism mediated by dissolved polysulfides. In addition to the low solubility of polysulfides, the high tLi+ is crucial for achieving high energy density Li–S batteries by reducing the electrolyte amount.

A crucial incorrect understanding in the traditional solution theory

In this work, thermodynamically we demonstrate that the partial molar volume of a substance in a mixture always is positive. Therefore, in the past hundred years, the obtained so-called partial molar quantity of a solute within the framework of the traditional solution theory all were not the real partial molar quantity of the solute because the obtained limiting partial molar volumes of many electrolytes in water within the framework of the same theory were negative. The comparative study shows that hydrophilic molecules, especially ions in solvents such as water have been chemically solvated, no more naked because few solvent molecules in the traditional so-called first solvation shell of the molecule have belonged to the molecule.

Novel nontoxic electrochemical method for the detection of cefadroxil in pharmaceutical formulations and biological samples

The current study represented a novel nano-silver amalgam pastes microelectrode (nano-Ag-APME) as a suitable alternative for the assay of cefadroxil contents in pharmaceutical formulations and biological specimen. The proposed electrode prepared in a plastic tip of micropipette tied with the nano-silver amalgam pastes mainly comprise of silver nano-powder and pure mercury (1:9, w/w). The commercial silver nanopowder and nano-silver amalgam paste were characterized using scanning electron microscope–energy dispersive X-ray spectrometer and X-Ray Diffraction (XRD). These analyses depicted that nano-Ag amalgam paste formed Ag-Hg clusters consisting of a crystalline solid. The EDX analysis showed that all the chemical composition of the starting materials (silver nanopowder) consisted of the nano-Ag amalgam paste having Ag and Hg only. The optimization of different characteristics such as voltammetric modes, pH, type of supporting electrolytes, electrolyte volume, stirring rate, accumulation potential, and accumulation time for the determination of cefadroxil by SW-AdSV examined in detailed. The proposed method based on the square-wave stripping voltammetry for the measurement of cefadroxil at pH 4 in Britton–Robinson buffer, manifested a well-defined reduction peak at −0.160 V. The comparative study of SW-AdSV and spectrophotometric methods showed the linear response for CFL at a linear dynamic ranged from 0.033–0.304 and 10–70 µM, respectively. The analytical performance for the quantification of CFL by the SW-AdSV method was significantly good as compared to the spectrophotometric method (p < 0.01). Moreover, it has been indicated that the SW-AdSV is more sensitive and selective for precise routine analysis of CFL than the spectrophotometric method.

Polyoxyethylene (PEO)|PEO-Perovskite|PEO Composite Electrolyte for All-Solid-State Lithium Metal Batteries.

Composite solid electrolytes (CSEs) are regarded as one of the most promising candidates for all-solid-state lithium metal batteries (ASSLMBs) due to inherited desirable features from both ceramic and polymer materials. However, poor interfacial contact/compatibility between the electrodes and solid electrolytes remains a critical challenge. In this work, we prepare a flexible CSE composed of polyoxyethylene (PEO)-perovskite composite with a layer of PEO on either side. This PEO|PEO-perovskite|PEO structure prevents direct contact between theperovskite and lithium metal at the anode side, avoiding the undesired reaction between the two materials (Ti4+ + Li → Ti3+ + Li+). Moreover, the design incorporating the PEO surface on either side enables superb contact between the electrolyte and the electrodes and buffers the change in electrolyte volume from the cathode and lithium metal during repeated cycling, resulting in low interfacial resistances and excellent cycling stability. Meanwhile, perovskite inorganic electrolyte Li0.33La0.557TiO3 (LLTO) 3D nanofiber networks formed by electrospinning enable the CSE to achieve enhanced mechanical strength and high ionic conductivity of 0.16 mS cm-1 at 24 °C. As a result, a Li|PEO-LiTFSI-LLTO|Li symmetric cell remains stable after 400 h of operation without short-circuiting. Most notably, a Li|PEO-LiTFSI-LLTO|LiFePO4 full battery is capable of delivering a high capacity of 135.0 mAh g-1 even at 2 C with a retention rate of 79.0% after 300 cycles at 60 °C. These results demonstrate that the integrated sandwich structure proposed in this work is effective in developing high-performance composite solid electrolytes for ASSLMBs.

Variable current strategy for boosting the effective energy capacity in vanadium redox flow batteries

Abstract Recognizing the importance of the cost to the wider adoption of redox flow batteries, it is critical to achieve the higher utilization of electrolytes and thus reduce the required electrolyte volume. Although the effects of the applied current on the battery performance were extensively explored in previous studies, few of them investigated how to dynamically optimize the applied current with varying state-of-charge conditions during the (dis-)charging process. A variable current strategy is proposed in the present study to dynamically vary the applied current density according to the real-time state-of-charge conditions in a vanadium redox flow battery system. Both simulations and experiments are conducted to confirm the feasibility and practicality of the proposed strategy. The results show that the concentration overpotentials and ohmic losses can be reduced at relatively large or low state-of-charge conditions under the proposed strategy, leading to a more than 10% increment in the effective energy capacity at the required power density, compared to the constant current strategy. In addition, the strategy is further improved by incorporating the variable flowrate, which is shown to further enhance the performance of the battery system.

Composition-dependent thermodynamic and mass-transport characterization of lithium hexafluorophosphate in propylene carbonate

A complete set of thermodynamic and mass-transport properties is determined for solutions of LiPF6 in propylene carbonate at 25°C, elucidating the composition dependences of six independent primary material parameters. Mass density is correlated with concentration to parameterize the partial molar volumes of electrolyte and solvent. Conductometry and Hittorf experiments yield correlations for equivalent conductance and cation transference number, respectively. A theoretical analysis connects the measured transference number to transport numbers measured by other standard approaches. Concentration-cell measurements yield the thermodynamic Darken factor; voltammetric restricted diffusion quantifies diffusivity. A Bruggeman factor is measured to relate true transport properties to the effective properties in polarization cells with glass-fiber separators. Taken together, the data reveal how the three Stefan–Maxwell diffusivities vary with composition, in terms of functions that interpolate between 0.2 M and 2 M. The property set is validated by simulations, which match voltage-relaxation experiments excluded from the parameterization.

Can Electrolytic Capacitors Meet the Demands of High Reliability Applications?

Abstract Electrolytic capacitors have long been identified as a weak link for long term high reliability applications. However, capacitor manufacturers have made significant improvements to the materials and manufacturing processes to enhance their reliability. This paper will discuss those changes, provide insight into the various failure mechanisms for electrolytic capacitors and describe appropriate accelerated tests to validate performance. We will take a deeper dive into the methodologies utilized to improve capacitor performance, e.g. foil purity and electrolyte volume. We will also discuss, from a reliability perspective, the impact of changing to a higher temperature electrolyte (from ethylene glycol to DMF, DMA and GBL) and also changes in the bung material (from butyl to EPDM). There are several environmental factors involved in the aging of electrolytic capacitors. Electrolyte loss due to drying out and leakage current due to oxide degradation are thermally related as is the self-heating associated with ripple current. The impact of the applied voltage level is also a driver as it can cause leakage current increases as well. All of these issues result in a capacitance decrease, an increase in ESR, and a change to the dissipation factor. Many other failure mechanisms associated with manufacturing will also be discussed.

RESOLUTION OF AKI AFTER LARGE VOLUME PARACENTESIS AND CORRECTION OF INTRA-ABDOMINAL HYPERTENSION

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Intra-abdominal pressure (IAP) is the pressure within the abdominal cavity. Elevated IAP can lead to Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS). This is caused by a wide variety of causes including ascites. This entity can cause low abdominal perfusion pressures (AAP) and result in end organ damage. We present a case of AKI caused by tense ascites, which resolved after drainage CASE PRESENTATION: A 52-year-old man was transferred to our ICU for the management of hyponatremia and AKI. He presented initially with confusion, weakness, and fall. He has a history of systolic heart failure and alcohol abuse. On presentation, he was significantly volume overloaded with ascites, pitting lower extremity edema and significant electrolyte abnormalities including severe hyponatremia, hypokalemia and an AKI with creatinine of 1.35mg/dL (baseline = 0.6). Urine electrolytes were consistent with pre-renal AKI and his echo showed a normal LV function, RV and RA dilation with no signs of pulmonary hypertension. He was initially treated with hypertonic saline infusion. He was found to have liver cirrhosis on abdominal ultrasound. Given his tense abdomen, a paracentesis was performed in conjunction with IAP monitoring via an arterial line monitoring system. After zeroing the pressure at the insertion of the paracentesis catheter, an initial IAP of 22 mmHg was obtained. IAPs were documented at end expiration following each liter of ascites fluid removed (figure 1). A total of 8.75L were removed and a final IAP of 6mmHg was recorded. Mean arterial pressure prior to paracentesis was 73mmHg and AAP was 51mmHg. Over the following 24 hours, patient’s urinary output increased dramatically to over 4L without diuretics and his creatinine normalized (figure 2). Over the course of the hospital stay, the patient’s electrolyte abnormalities, volume overload, weakness and confusion resolved and he was discharged without complication DISCUSSION: We demonstrate a case of a patient who developed AKI and electrolyte derangements from tense ascites causing IAH that resolved after fluid removal. We illustrate that there may be a linear decrease in IAP with ascites volume removal. The most likely cause the the dramatic increase in UOP following the paracentesis is restoration of renal blood flow with normalization of IAP. CONCLUSIONS: IAH and ACS can be dramatic consequences of elevated IAP and clinicians should be aware of more subtle presentations of organ damage that are due to IAH Reference #1: Papavramidis, Theodossis S et al. “Abdominal compliance, linearity between abdominal pressure and ascitic fluid volume” Journal of emergencies, trauma, and shock vol. 4,2 (2011): 194-7. Reference #2: Caldwell CB, Ricotta JJ. Changes in visceral blood flow with elevated intraabdominal pressure.J Surg Res. 1987;43(1):14. Reference #3: Caldwell CB, Ricotta JJ.Changes in visceral blood flow with elevated intraabdominal pressure. J Surg Res. 1987 Jul;43(1):14-20. DISCLOSURES: No relevant relationships by Amit Chopra, source=Web Response No relevant relationships by Kurt Hu, source=Web Response No relevant relationships by Ali Wazir, source=Web Response No relevant relationships by Robert Wilcott, source=Web Response

Characterization of Flagellar Filaments and Flagellin through Optical Microscopy and Label-Free Nanopore Responsiveness.

In this study, we investigated the translocation characteristics of flagellar filaments (Salmonella typhimurium) and flagellin subunits through silicon nitride nanopores in tandem with optical microscopy analysis. Even though untagged flagella are dark to the optical method, the label-free nature of the nanopore sensor allows it to characterize both tagged (Cy3) and pristine forms of flagella (including real-time developments). Flagella were depolymerized to flagellin subunits at ∼65 °C (most commonly reported temperature), ∼70 °C, ∼75 °C, and ∼80 °C to investigate the effect of temperature (Tdepol)on depolymerization. The change in conductance (ΔG) profiles corresponding to Tdepol ∼65 °C and ∼70 °C were bracketed within the flagellin monomer profile whereas those of ∼75 °C and ∼80 °C extended beyond this profile, suggesting a change to the native protein state. The molecular radius calculated from the excluded electrolyte volume of flagellin through nanopore-based ΔG characteristics for each Tdepol of ∼65 °C, ∼70 °C, ∼75 °C, and ∼80 °C yielded ∼4.2 ± 0.2 nm, ∼4.3 ± 0.3 nm, ∼4.1 ± 0.2 nm, and ∼4.7 ± 0.5 nm, respectively. This, along with ΔG (plateaued values) and translocation time profiles, points to the possibility offlagellin misfolding at ∼80 °C.

Role of Lattice Oxygen in the Oxygen Evolution Reaction on Co3O4: Isotope Exchange Determined Using a Small-Volume Differential Electrochemical Mass Spectrometry Cell Design

This work demonstrates the roleof lattice oxygen of metal oxide catalysts in the oxygen evolution reaction (OER) as evidenced by isotope labeling together with the differential electrochemical mass spectrometry (DEMS) method. Our recent report assessed this role for Co3O4 using a flow-through DEMS cell, which requires a large volume of electrolyte. Herein, we extend this procedure to different Co3O4 catalyst loadings and particle sizes as well as the mixed Ag + Co3O4 catalyst. We introduce, for the first time, a novel small-volume DEMS cell design capable of using disc electrodes and only <0.5 mL of electrolyte. The reliability of the cell is demonstrated by monitoring gas evolution during OER in real time. This cell shows high sensitivity, high collection efficiency, and very short delay time. DEMS results reveal that only the interfacial part (∼0.2% of the total loading or 25% of surface atoms) of the catalyst is active for OER. Interestingly, the amount of oxygen exchanged on the mixed Ag + Co3O4 catalyst is higher than that on the single Co3O4 catalyst, which illustrates the improved electrocatalytic activity previously reported on this mixed catalyst. Furthermore, the real surface area of the catalysts is estimated using different methods (namely, the ball model, double layer capacitance, isotope exchange, and redox peak methods). The surface areas estimated from the Brunauer-Emmett-Teller (BET) and ball models are comparable but roughly three times higher than that of the redox peak method. Our method represents an alternative approach for probing the mechanism and real surface area of catalysts.

(Invited) Investigating Failure in Anode-Free Lithium-Metal Pouch Cells with Liquid Electrolytes

Anode-free, or zero-excess lithium-metal cells, promise higher energy density than existing lithium-ion batteries. However, the abysmal performance of cells with lithium-metal electrodes prevents them from being used in commercial products that require long-life: electric cars and energy storage products. Many researchers believe all-solid state cells are necessary to achieve the lifetime required for these applications, but solid electrolytes complicate cell manufacturing and incur the huge costs required to rebuild existing production facilities designed to handle cells with liquid electrolytes. If a long-life anode-free cell could be made using a liquid electrolyte, this would be the best path forward for fast and inexpensive introduction into the existing market. In this work, baseline NMC532/Cu anode-free pouch cells with 1M LiPF6 in FEC:DEC (1:2 vol) were tested at 40°C, with C/5 charge and C/2 discharge between 3.6 V – 4.5 V. Cells with this electrolyte lose 80% of their initial capacity before 20 charge-discharge cycles. Liquid electrolytes with different lithium salts are tested and show improved performance. To investigate the capacity loss mechanisms, SEM is used to track lithium morphology, XPS is used to compare SEI composition, and liquid NMR is used to track the electrolyte volume and degradation at various points throughout cycling. The results of these experiments are used to guide further optimization of the electrolyte composition which give incremental improvements in capacity retention. With continued works towards understanding the failure of these cells, a commercializable anode-free lithium-metal cell with liquid electrolyte may be realized.

The indefinite cycle life via a method of mixing and online electrolysis for vanadium redox flow batteries

To restore unavoidable capacity losses, we propose a method of mixing and online electrolysis that resolves the imbalance of electrolyte concentration, volume and valence simultaneously. The cycle life of all-vanadium redox flow batteries is effectively prolonged at various current densities (120, 180, 240 and 300 mA cm−2) using different Nafion membranes (Nafion 212, Nafion 115 and Nafion 117). Besides, the total vanadium concentrations of the electrolytes detected by the titrator indicates minimal influence of electrolysis on the batteries. Although the capacity recovery decreases over long-term cycles, especially at the higher current density, this decrease is mainly due to the attenuation of the electrochemical performance of the electrodes, as evidenced by cyclic voltammetry curves. In addition, we conduct long-term cycle tests of 4140 and 5100 cycles, and we observe capacity retentions of 89.87% and 81.39% on batteries with Nafion 115 and Nafion 117, respectively, at the current density of 120 mA cm−2. Based on these results, we speculate that the method of mixing and online electrolysis can operate over indefinite cycles. This low-cost, convenient method, which does not need replacement of electrolytes, is beneficial to prospective applications in large-scale energy storage.

Determination of current homogeneity on the electrodes of lead-acid batteries through electrochemical impedance spectroscopy

This work explores a qualitative appraisal of lead acid battery electrodes by Electrochemical Impedance Spectroscopy. Lead acid cells behavior has been examined by gathering data of impedance modifications in distinct electrolyte volumes, from a full one to a battery filled at about 20% of the total volume of acid. Since the current between electrodes is inhomogeneous around the collector by varying the quantity of the electrolyte, we have associated numerical values of the elements in the battery equivalent circuit, to the homogeneity of the current in the electrodes. Theoretical considerations dealing with modeling, equivalent circuits and corresponding equations are provided. As a function of the electrolyte quantity, we investigated the dependence of the values for components of the Randle circuit. A particular attention has been devoted to constant phase element (CPE) peculiarities, as this parameter was found essential for a good quality fit over an extended range of batteries. The stability depending on current homogeneity at a certain battery state of charge was analysed in order to assess the effect of electrolyte volumes, and thereby to provide new quality requirements for improvement of lead-acid battery performance.

On the Capacity Losses Seen for Optimized Nano‐Si Composite Electrodes in Li‐Metal Half‐Cells

AbstractWhile the use of silicon‐based electrodes can increase the capacity of Li‐ion batteries considerably, their application is associated with significant capacity losses. In this work, the influences of solid electrolyte interphase (SEI) formation, volume expansion, and lithium trapping are evaluated for two different electrochemical cycling schemes using lithium‐metal half‐cells containing silicon nanoparticle–based composite electrodes. Lithium trapping, caused by incomplete delithiation, is demonstrated to be the main reason for the capacity loss while SEI formation and dissolution affect the accumulated capacity loss due to a decreased coulombic efficiency. The capacity losses can be explained by the increasing lithium concentration in the electrode causing a decreasing lithiation potential and the lithiation cut‐off limit being reached faster. A lithium‐to‐silicon atomic ratio of 3.28 is found for a silicon electrode after 650 cycles using 1200 mAhg−1 capacity limited cycling. The results further show that the lithiation step is the capacity‐limiting step and that the capacity losses can be minimized by increasing the efficiency of the delithiation step via the inclusion of constant voltage delithiation steps. Lithium trapping due to incomplete delithiation consequently constitutes a very important capacity loss phenomenon for silicon composite electrodes.

SUBCLINICAL ATHEROSCLEROSIS, SERUM URIC ACID AND PLASMA ALDOSTERONE IN HYPERTENSIVE ADULTS

Objective: aldosterone has long been classically considered to play a central role in the regulation of electrolyte and fluid volume and the maintenance of blood pressure (BP) homeostasis. Moreover, the aldosterone/mineralocorticoid system plays a key role in cardiovascular, metabolic and renal damage. This study aimed to assess the relationship between plasma aldosterone concentration (PAC) and some surrogate markers of subclinical atherosclerosis, such as carotid intima-media thickness (cIMT), ankle-brachial index (ABI) and biochemical parameters (i. e. serum uric acid – SUA, 24-h urinary albumin excretion - UAE) in subjects with essential hypertension (EH). Design and method: from January 2014 to December 2017 we consecutively enrolled 804 EH patients (407 males and 397 females, mean age 50 ± 14.5 yrs) without evident cardiovascular complications. Patients were divided in quartiles according to PAC levels. Results: Compared to the first quartile, the highest PAC quartile was associated with the highest levels of SUA (5.3 ± 1.34 vs 5.0 ± 1 mg/dl; p = 0.01) triglycerides (117.5 ± 15.7 vs 106.8 ± 10.5 mg/dl; p < 0.05), UAE (38.8 vs 17.6 mg/24ore; p < 0.05) and cIMT (0.87 ± 0.22 mm vs 0.8 ± 0.21 mm; p = 0.001). Patients of the fourth quartile also exhibited increased prevalence of carotid plaques, compared to the first quartile (26% vs. 16%; p < 0.005). Moreover, we found that in patients with PAC >160 pg/ml ABI was significantly lower compared to those with PAC < 160 pg/ml (1.01 ± 0.09 vs 1.1 ± 0.09; p < 0.022). Binary logistic regression analysis showed that PAC was an independent predictor of the presence of carotid plaques and pathological ABI (< 0.9) in the population examined. Conclusions: These findings suggest that higher values of PAC are strongly associated with higher values of SUA, triglycerides, UAE, cIMT, worse ABI and major prevalence of carotid plaques that, together with elevated BP values, are strictly correlated with higher risk of atherosclerosis and cardiovascular complications.

Low‐Cost Self‐Assembled Oxide Separator for Rechargeable Batteries

AbstractRechargeable battery cells having a liquid electrolyte require a separator permeable to the electrolyte between the two electrodes. Because the electrodes change their volume during charge and discharge, the porous separators are flexible polymers with an electronic energy gap Eg large enough for the Fermi levels of the two electrodes to be within it. In this work, a porous film of self‐assembled SiO2 nanoparticles is developed as the separator for a Li‐ion battery with a liquid electrolyte. This coating does not require the plasticity of a polymer membrane and has the required large Eg. If adsorbed water is removed from the SiO2 surface, the nanoparticles bond to one another and to an oxide cathode to form a plastic self‐assembling porous layer into which the liquid electrolyte can penetrate. The Li‐ion batteries with a LiCoO2 cathode coated with SiO2 as a separator show similar performance to cells with a traditional polypropylene separator and improved cyclability with a reduced volume of liquid electrolyte owing to the electrolyte wetting properties of the SiO2 nanoparticles. The SiO2 nanoparticles are easy to prepare, cheap, and environmentally friendly.

Effect of confined electrolyte volumes on galvanic corrosion kinetics in statically loaded materials

Abstract This work investigates the effects that the confined volume of atmospheric electrolytes has on the galvanic corrosion kinetics of a martensitic stainless steel alloy, UNS S13800, coupled with UNS A97075 in simulated atmospheric environments at relative humidity values that span the range of operational exposures. Restricted volumes found in thin films and droplets have been shown to control reduction reaction kinetics and are an ongoing challenge to characterize and standardize. This, along with the dynamic and high concentration of aggressive ions found in confined electrolytes, creates a unique corrosion system that requires a multifaceted approach to evaluate varied conditions, compare them with traditional measurements, and more accurately predict galvanic atmospheric corrosion. In this work, corrosion currents in galvanic couples were obtained under two environmental conditions: (1) bulk electrolytes, in a standardized test configuration, with chemistries relevant to atmospheric electrolytes; and (2) deliquesced droplets formed and equilibrated at a given temperature and relative humidity value. The corrosion currents for the same galvanic couple specimens were evaluated, using an atmospheric corrosion model, under a thin film electrolyte while statically loaded and unloaded, at two nominally different locations, e.g. Alexandria, VA, and Miami, FL, on the same date, using recorded weather conditions. The modeled corrosion currents were then compared with the currents obtained from the experimental conditions.

A No-Mixing Design of Vanadium Redox Flow Batteries

Vanadium redox flow batteries are expected to play an important role in the future energy systems with increasing intermittent renewables. Over the past few decades, the performance of vanadium redox flow batteries has improved significantly in terms of such as power density, voltage and columbic efficiencies. However, the effective energy capacity has not yet reached the theoretical value, partly because of the large concentration discrepancies of the active species in the tank and stack during the (dis-)charging processes. In order to alleviate this concentration discrepancy and thus enhance the effective energy capacity and economics of the vanadium redox flow battery, the authors develop a no-mixing design with two additional tanks and two extra pumps being added to the battery system. As such, the mixing of the (dis-)charged and un(dis-)charged electrolytes in tanks during (dis-)charge processes can be alleviated to certain extent. Some main findings include: First, both experimental and simulative results show that the no-mixing design can effectively improve the effective capacity and voltage efficiency by more than 10% and 2%, respectively, compared to the conventional two-tank system. In addition, the efficiency increment in the effective capacity rises with increasing electrolyte volumes and decreasing flow rates. Moreover, an analytical approach for estimating the benchmarked enhancement of the effective energy capacity in the no-mixing design is also provided in the present study. With the alleviated concentration discrepancy and increased benchmarked enhancement of the effective energy capacity, the no-mixing design is recommended to be adopted in the applications that require a large amount of electrolytes, i.e., relatively large electrolyte volume. And last, some new industrial setups based on the no-mixing design are proposed, such as gravity-driven or pressure-driven setups, to enhance the industrial practicability of the no-mixing design. The no-mixing design is also shown to be one of the possibilities to achieve pumpless system for reduced pump consumption in the future, especially for non-aqueous redox flow batteries with high viscosity electrolytes.

Improvement of ferning patterns of lubricant eye drops mixed with various electrolytes and carboxymethylcellulose

PurposeTo investigate the effect of the addition of electrolytes, basic tear solution (BTS), and sodium carboxymethylcellulose (SCMS) on the tear ferning (TF) patterns of Blink Contact Soothing Eye Drops® and Refresh Plus Tears®. MethodSamples of Blink Contact Soothing Eye Drops® and Refresh Plus Tears® (10 μL) were mixed with different volumes (3–30 μL) of several electrolytes, namely sodium chloride, potassium chloride, calcium chloride, magnesium chloride hexahydrate, sodium hydrogen carbonate, and sodium dihydrogen phosphate, BTS, and SCMS. Samples (1 μL) of the mixtures were dried on a glass slide at room temperature and the TF patterns were inspected using a light microscope, graded using the Masmali five-point grading scale and compared to the corresponding TF grades of the artificial tears. ResultsThe TF grades of Blink Contact Soothing Eye Drops® and Refresh Plus Tears® improved from 1.2 and 1.5, respectively to 0.2 when calcium chloride was used as the electrolyte. Improvements in TF grades were also observed when other electrolytes (e.g., sodium dihydrogen phosphate), BTS, and SCMS were used. ConclusionThe tear ferning test can be used to evaluate the effect of the addition of electrolytes to an artificial tear in-vitro. The TF patterns of artificial tear solutions such as Blink Contact Soothing Eye Drops® and Refresh Plus Tears® can be improved with the addition of various concentrations of electrolytes, BTS, and SCMS, however further research is still needed to understand the clinical relevance of TF patterns with respect to the management of dry eye symptoms and their potential role in the development of new artificial tears.

No-mixing design of vanadium redox flow battery for enhanced effective energy capacity

Abstract The increasing proliferation of intermittent renewables is driving great attention to grid-scale energy storage, particularly vanadium redox flow batteries. The performance of vanadium redox flow batteries has improved remarkably over the last few decades. However, due to the premature cut-off resulting from growing concentration overpotentials at low or high states-of-charge and the discrepancy of active reactants in the tank and stack, the energy capacity of the electrolytes has not yet been fully utilized. In this study, we develop a method for enhancing effective energy capacity of vanadium redox flow batteries, especially in applications with large amounts of electrolytes. The developed system uses four electrolyte tanks to achieve the objective through the avoidance of the mixing of the (dis-)charged and un(dis-)charged electrolytes in tanks. Both experimental and simulative studies are conducted to investigate the performance of the proposed system, which is confirmed to afford a significant increase in the effective energy capacity of more than 10% compared with a two-tank setup. And the enhancement increases with decreasing electrolyte flowrate and increasing electrolyte volume. Besides, the voltage efficiency can be also enhanced by more than 2%. The underlying mechanisms are analyzed in the present study.