31,735 research outputs found
Cl-Doped Li<sub>10</sub>SnP<sub>2</sub>S<sub>12</sub> with Enhanced Ionic Conductivity and Lower Li-Ion Migration Barrier
No full textAll-solid-state
lithium batteries based on sulfide solid electrolytes
have attracted much attention because of their high ionic conductivity.
Li10SnP2S12 (LSPS) has the same structure
as Li10GeP2S12, and there is little
difference in ionic conductivity between them, but the preparation
cost of LSPS is lower. Here, Cl doping is used to improve the electrochemical
stability of the LSPS to the anode and the Li-ion transport performance.
Among them, Li9.9SnP2S11.9Cl0.1 had a high ion conductivity of 2.62 mS cm–1 after cold pressure. On the crystal structure, X-ray diffraction
Rietveld refinement indicated that the Cl-substituted portion S is
successfully incorporated into the lattice of the LSPS, increasing
Li-ion vacancies and reducing the distance between adjacent Li-ion
distributed along the c-axis, these are conducive
to Li-ion transmission. The temperature-dependent AC impedance experiment
and density functional theory calculation show that doping with Cl
makes Li9.9SnP2S11.9Cl0.1 have a lower activation energy. The assembled lithium symmetric
batteries show that the doping of Cl promotes the stability of the
interface between LSPS and the lithium metal anode. The charge–discharge
tests of all-solid-state batteries using Li9.9SnP2S11.9Cl0.1 as electrolyte have confirmed that
Cl doping can improve the electrochemical performance of LSPS, which
have a higher specific capacity and cycle life
Theoretical Study on Cyclopeptides as the Nanocarriers for Li+, Na+, K+ and F-, Cl-, Br-
No full text
The interaction process between a series of cyclopeptide compounds cyclo(Gly)(n) (n = 4, 6, 8) and monovalent ions (Li+, Na+, K+, F-, Cl-, and Br-) was studied using theoretical calculation. The mechanism of combination between the cyclo(Gly)(n) and ions was discussed through binding energy, Mulliken electron population, and hydrogen bond. It was found that for the same cyclopeptide the binding energy has the order of cyclo(Gly)(n)-Li+ > cyclo(Gly)(n)-Na+ > cyclo(Gly)(n)-K+ and cyclo(Gly)(n)-F- > cyclo(Gly)(n)-Br- > cyclo(Gly)(n)-Cl-. The binding energy manifests the stable complex of cyclo(Gly)(n) and ions can be formed, and the different energy shows the potential use of cyclo(Gly)(n) as nanocarriers for metal ions or the extractant for ions separation.</p
The fate of B, Cl and Li in the subducted oceanic mantle and in the antigorite breakdown fluids
No full textWe present an inventory of B, Cl and Li concentrations in (a) key minerals from a set of ultramafic samples featuring the
main evolutionary stages encountered by the subducted oceanic mantle, and in (b) fluid inclusions produced during high-pressure breakdown of antigorite serpentinite. Samples correspond to (i) nonsubducted serpentinites (Northern Apennine and Alpine ophiolites), (ii) high-pressure olivine-bearing antigorite serpentinites (Western Alps and Betic Cordillera), (iii) high-pressure olivine–orthopyroxene rocks recording the subduction breakdown of antigorite serpentinites (Betic Cordillera). Two main dehydration episodes are recorded by the sample suite: partial serpentinite dewatering during formation of metamorphic
olivine, followed by full breakdown of antigorite serpentine to olivine + orthopyroxene + fluid. Ion probe and laser ablation ICPMS (LA ICP-MS) analyses of Cl, B and Li in the rock-forming minerals indicate that the hydrous mantle is an important carrier of light elements. The estimated bulk-rock B and Cl concentrations progressively decrease from oceanic serpentinites (46.7 ppm B and 729 ppm Cl) to antigorite serpentinites (20 ppm B and 221 ppm Cl) to olivine–orthopyroxene rocks (9.4 ppm B and 45 ppm Cl). This suggests release of oceanic Cl and B in subduction fluids, apparently without inputs from external sources.
Lithium is less abundant in oceanic serpentinites (1.3 ppm) and the initial concentrations are still preserved in high-pressure antigorite serpentinites. Higher Li contents in olivine, Ti-clinohumite of the olivine–orthopyroxene rocks (4.9 ppm bulk rock Li), as well as in the coexisting fluid inclusions, suggest that their budget may not be uniquely related to recycling of oceanic Li, but may require input from external sources.
Laser ablation ICP-MS analyses of fluid inclusions in the olivine–orthopyroxene rocks enabled an estimate of the Li and
B concentrations in the antigorite breakdown fluid. The inclusion compositions were quantified using a range of salinity
values (0.4–2 wt.% NaClequiv) as internal standards, yielding maximum average fluid/rock DB = 5 and fluid/rockDLi = 3.5. We also performed model calculations to estimate the B and Cl loss during the two dehydration episodes of serpentinite subduction. The first event is characterized by high fluid/rock partition coefficients for Cl (f100) and B (f60) and by formation of a fluid with salinity of 4–8 wt.% NaClequiv. The antigorite breakdown produces less saline fluids (0.4–2 wt.% NaClequiv) and is characterized by lower partition coefficients for Cl (25–60) and B (12–30). Our calculations indicate that the salinity of the subduction fluids decreases with increasing depths. Fluid/rockDB/fluid/rockDCl<1 ( about 0.5) indicates that Cl
preferentially partitions into the evolved fluids relative to B and that the B/Cl of fluids progressively increases with
increasing depths and temperatures.
Despite light element release in fluids, appreciable B, Cl and Li are still retained in chlorite, olivine and Ti-clinohumite
beyond the antigorite stability field. This permits a bulk storage of about 10 ppm B, 45 ppm Cl and 5 ppm Li, i.e.,
concentrations much higher than in mantle reservoirs. Chlorite is the Cl repository and its stability controls the Cl and H2O budget beyond the antigorite stability; B and Li are bound in olivine and clinohumite. The subducted oceanic mantle thus retains light elements beyond the depths of arc magma sources, potentially introducing anomalies in the upper mantle
Li-Rich and Halide-Deficient Argyrodite Fast Ion Conductors
No full textWe report on a new family of halide-deficient and Li-rich
argyrodite
fast-ion conductors, Li6+xPS5+x(Cl/Br/I)1–x (0
≤ x ≤ 0.85). Exploration of the influence
of aliovalent anion substitution in Li6PS5X
(X = Cl, Br, I)using a combination of high-resolution powder
neutron diffraction and electrochemical impedance spectroscopyreveals
that aliovalent anion substitution induces higher Li-ion concentration
and Li site disorder, and creates S2–/I– anion site disorder on the 4a site. In the series
Li6+xPS5+xI1–x (0 ≤ x ≤ 0.4), the resulting conductivity for Li6.4PS5.4I0.6 (0.13 mS·cm–1) represents
almost a 100-fold increase over that of the parent phase, Li6PS5I (0.0033 mS·cm–1), and establishes
one of the first fast-ion conducting argyrodite thiophosphate iodides.
For Cl-argyrodites, the ionic conductivity decreases a little with
lower halide-content but ionic conductivity for the Br-argyrodites
is almost unchanged. Overall, all Cl/Br-argyrodites Li6+xPS5+x(Cl/Br)1–x (0 ≤ x ≤ 0.75) with
a low halide content exhibit surprisingly high ionic conductivities
> 1 mS·cm–1 despite a very low degree of
sulfur/halogen
anion site disorder. Our findings highlight the importance of attaining
a disordered Li-ion sublattice and sulfur/halogen anion site disorder
(anionic charge homogeneity) in argyrodites, where Li ions occupy
high energy sites and activate concerted ion migration that drives
the ionic conductivity
Li-Promoted La<sub><i>x</i></sub>Sr<sub>2–<i>x</i></sub>FeO<sub>4−δ</sub> Core–Shell Redox Catalysts for Oxidative Dehydrogenation of Ethane under a Cyclic Redox Scheme
No full textChemical
looping oxidative dehydrogenation (CL-ODH) of ethane utilizes
a transition metal oxide based oxygen carrier, also known as a redox
catalyst, to convert ethane into ethylene under an autothermal cyclic
redox scheme. The current study investigates a Li-promoted LaxSr2–xFeO4−δ (LaSrFe) redox catalyst for CL-ODH reactions.
While LaSrFe without Li promoter exhibits low ethylene selectivity,
addition of Li leads to high selectivity/yield and good regenerability.
Up to 61% ethane conversion and 90% ethylene selectivity are achieved
with Li-promoted LaSrFe. Further characterization indicates that the
Li-promoted LaSrFe redox catalyst consists of LiFeO2 (disordered
rock salt) and LaSrFe (Ruddlesden–Popper) phases. Moreover,
the surface of the redox catalysts is enriched with Li cations. It
is also determined the LaSrFe phase contributes to oxygen storage
and donation, whereas the activity and selectivity of the redox catalysts
are modified by the Li promoter: while oxygen for the CL-ODH reaction
is supplied from the lattice of the LaSrFe phase, the enrichment of
Li cations on the surface increases the resistance for O2– diffusion from the bulk and its subsequent evolution into electrophilic
oxygen species on the surface. The nonselective nature of the surface
oxygen species and the inhibition effects of Li promoter on O2– diffusion are further confirmed by pulse experiments.
On the basis of such findings, it is concluded that Li-promoted LaxSr2–xFeO4−δ is an effective redox catalyst for ethane
ODH in the absence of gaseous oxygen. Moreover, the selectivity of
the redox catalysts can be enhanced by the alkali metal oxide promoters
A scalable Li-Al-Cl stratified structure for stable all-solid-state lithium metal batteries
No full textAbstract Sulfides are promising electrolyte materials for all-solid-state Li metal batteries due to their high ionic conductivity and machinability. However, compatibility issues at the negative electrode/sulfide electrolyte interface hinder their practical implementation. Despite previous studies have proposed considerable strategies to improve the negative electrode/sulfide electrolyte interfacial stability, industrial-scale engineering solutions remain elusive. Here, we introduce a scalable Li-Al-Cl stratified structure, formed through the strain-activated separating behavior of thermodynamically unfavorable Li/Li9Al4 and Li/LiCl interfaces, to stabilize the negative electrode/sulfide electrolyte interface. In the Li-Al-Cl stratified structure, Li9Al4 and LiCl are enriched at the surface to serve as a robust solid electrolyte interphase and are diluted in bulk by Li metal to construct a skeleton. Enabled by its unique structural characteristic, the Li-Al-Cl stratified structure significantly enhances the stability of negative electrode/sulfide electrolyte interface. This work reports a strain-activated phase separation phenomenon and proposes a practical pathway for negative electrode/sulfide electrolyte interface engineering
Thermodynamics of salt system: , , // , .
No full textIn this work, a new thermodynamic database of the Li+, Na+, K+//Cl-, CO32- system was generated using the Calphad method with FactSage. After collecting and analyzing the available thermodynamic data in the literature, experiments were designed to improve the comprehensiveness of the new database. Differential Thermal Analysis (DTA) and high temperature X-ray diffraction (HTXRD) were used to determine the phase transition temperatures. Different types of Differential Scanning Calorimetry (DSC) were used to investigate the heat capacity of pure salts and intermediate compounds. The controversial solid-solid phase transition of Li2CO3 was proved to be caused by impurities. The accuracy of the heat capacity of Li2CO3, LiKCO3 was improved, the heat capacity of LiNaCO3 was measured for the first time. The eutectic temperature of the K2CO3-KCl system was measured, the solid solubility in the K2CO3-Li2CO3 system based on K2CO3 was checked. The phase diagram of the subsystem Li2CO3-Na2CO3 was further completed, three solid solution phases based on the three solid modifications of pure Na2CO3 were determined. For the reciprocal systems Li+, K+//Cl-, CO32- and Li+, Na+//Cl-, CO32-, phase diagrams of diagonal systems Li2CO3-K2Cl2, K2CO3-Li2Cl2, Li2Cl2-Na2CO3 and Li2CO3-Na2Cl2 were measured. The Gibbs energy data of stoichiometric compounds (Li2CO3, LiKCO3 and LiNaCO3) and the Gibbs energy functions of the solutions (liquid and solid solutions) of the mentioned systems were reassessed according to the literature and own experimental data for the new database. Mainly based on the literature data, the Gibbs energy of pure salt LiCl, the Gibbs energy of the liquid phase of binary LiCl-NaCl, LiCl-KCl, LiCl-Li2CO3, KCl-K2CO3, NaCl-Na2CO3 systems and the reciprocal system Na+, K+//Cl-, CO32- and the ternary systems Li+, K+, Na+//Cl- and Li+, K+, Na+//CO32- were reassessed. A new database was developed, which can calculate and predict the thermodynamic properties of the whole system more precisely and reliably
LINK CAPACITY ALLOCATION AND NETWORK CONTROL BY FILTERED INPUT RATE IN HIGH-SPEED NETWORKS
No full textWe study link capacity allocation for a finite buffer system to transmit multimedia traffic. The queueing process is simulated with real video traffic. Two key concepts are eplored in this study. First, the link capacity requirement at each node is essentially captured by its low-frequency input traffic (filtered at a properly selected cut-off frequency). Second, the low-frequency traffic stays intact as it travels through a finite-buffer system without significant loss. Hence, one may overlook the queueing process at each node for network-wide traffic flow in the low-frequency band. We propose a simple, effective method for link capacity allocation and network control using on-line observation of traffic flow in the low-frequency band. The study explores a new direction for measurement-based traffic control in high-speed networks.National Science
Foundation under grant NCR9015757 and
by the Texas Advanced Research Program
Link Capacity Allocation and Network Control by Filtered Input Rate in High-speed Networks
No full textThis work was supported by the National Science Foundation under Grant
NCR9015757 and by the Texas Advanced Research Program under Grant
TARP- 179
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