Liquid metal batteries are proposed for low-cost grid scale energy storage. During their operation, solid intermetallic phases often form in the cathode and are known to limit the capacity of the cell. Fluid flow in the liquid electrodes can enhance mass transfer and reduce the formation of localized intermetallics, and fluid flow can be promoted by careful choice of the locations and topology of a battery's electrical connections. In this context we study four phenomena that drive flow: Rayleigh-B\'enard convection, internally heated convection, electro-vortex flow, and swirl flow, in both experiment and simulation. In experiments, we use ultrasound Doppler velocimetry (UDV) to measure the flow in a eutectic PbBi electrode at 160{\deg}C and subject to all four phenomena. In numerical simulations, we isolate the phenomena and simulate each separately using OpenFOAM. Comparing simulated velocities to experiments via a UDV beam model, we find that all four phenomena can enhance mass transfer in LMBs. We explain the flow direction, describe how the phenomena interact, and propose dimensionless numbers for estimating their mutual relevance. A brief discussion of electrical connections summarizes the engineering implications of our work
The low cost and high abundance of sodium make it an attractive choice for the negative electrode in a liquid metal battery. However, sodium has not found use in this application owing to the high solubility of the metal in its molten halides which results in poor coulombic efficiency and an unacceptably high rate of self discharge. In this work, we investigated the electrochemical behavior of the ternary eutectic of NaNH 2 , NaOH and NaI (m.p. 127 • C) and evaluated its usefulness as an electrolyte for sodium-based liquid metal batteries. Cyclic voltammetry revealed an electrochemical window of 1.3 V at 180 • C. The anodic limit is set by the oxidation of amide anions to form hydrazine gas. Liquid metal batteries consist of two metals of different electronegativity separated by molten salt. During discharge, the battery operates through alloying an electropositive liquid metal (e.g. Mg, Na, Li, or Ca) in an electronegative metal (e.g. Bi, Pb, Sb, or Zn). The all-liquid design allows the battery to operate at high current densities (1 A/cm 2 ) 1 with low overvoltage due to fast mass transport in the liquid state and high ionic conductivity of molten salts. Moreover, the absence of solid electrodes endows the battery with an extended service lifetime (>10,000 cycles). 2,3The negative and positive electrodes are selected based on melting point and density as well as the voltage associated with alloy formation, whereas the electrolyte is chosen based on melting point, metal solubility, density, ionic conductivity, and electrochemical window. 2Metal solubility in the electrolyte varies exponentially with operating temperature. High metal solubility in the electrolyte can influence the performance of liquid metal battery through increasing electronic conductivity, which increases the rate of self-discharge leading to lower coulombic efficiency. A low-melting electrolyte (<200• C) can substantially reduce metal solubility thereby allowing batteries to be built with low-cost negative electrodes (e.g., Na, Ca) that are otherwise inaccessible at higher temperatures (>500• C). Moreover, reducing the operating temperature below 200• C can also reduce the total battery cost through savings associated with cell container, thermal insulation, and wiring.Early work on low-melting sodium-bearing salts focused on mixtures of NaOH, NaI, and NaBr and was driven by their utility for sodium electrowinning. [4][5][6] The thought was that electrolysis at a lower temperature would reduce operating costs and improve process efficiency. More recently, in connection with work on sodium-based liquid metal batteries, Spatocco et al.7 investigated a binary eutectic of NaOH and NaI as an electrolyte operable at intermediate temperature (<280• C). An electrochemical window of 2.4 volts was measured at 250• C. In contact with liquid sodium, significantly lower values of self-discharge current were observed in this melt compared to those in early Na||Bi cells operating at much higher temperatures (necessitated by their higher-melting halide elec...
2), are found to affect elution of adsorbed semiconducting single-walled carbon nanotubes (S-SWCNTs) in a gel-based chromatographic column. The process is dramatically affected by the change in metal cation, with little effect resulting from modification of salt anion. The elution is shown to follow a logarithmic relationship between the metal ion size and the salt concentration used to achieve optimal separation. Alkaline earth ions yielded optimal S-SWCNT elutions at concentrations as low as ∼10 mM. Importantly, the method described dramatically reduces material additive costs (< $1 / L) needed for large scale amounts of electronically pure SWCNTs.
Subdural hematoma is extra-cerebral accumulation of blood between the dura matter and the subarachnoid layer. Subdural hematoma can be associated with significant long-term morbidities and high rates of mortality. The mortality following subdural hematoma can be as high as 32%, and recurrence rates can reach 33%. Acute subdural hematoma is an emergency and requires prompt diagnosis using CT most of the time, and management requires surgery as well as reversal of anticoagulants. We conducted this review using a comprehensive search of MEDLINE, PubMed, and EMBASE, January 1985, through February 2017. The following search terms were used: emergency management of subdural hematoma, subdural hematoma, CT vs. MRI in diagnosis of subdural hematoma, treatment of subdural hematoma. In this review, our aim is to study the etiology of subdural hematoma and understand how it should be diagnosed and managed. Subdural hematoma are clinical emergencies that require immediate and rapid management to prevent significant morbidity and mortality. They can be grouped into acute, subacute, or chronic, with the acute type being the most dangerous and associated with the highest mortality rates. Subdural hematoma is diagnosed using CT or MRI imaging. Management of a patient with subdural hematoma includes resuscitation followed by control of the bleeding. Controlling intracranial pressure is an important factor for predicting the outcomes of subdural hematoma, and should thus be continuously monitored and corrected.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.