Solvent-free NMC electrodes for Li-ion batteries: unravelling the microstructure and formation of the PTFE nano-fibril network

The microstructure and electrochemical performance of solvent-free processed and slurry cast Li(Ni0.6Co0.2Mn0.2)O2 (NMC622) based electrodes for Li-ion batteries has been investigated. In contrast to a moss-like PVDF-based carbon binder domain in slurry cast electrodes, the PTFE binder in solvent-free electrodes had a hierarchical morphology composed of primary fibrils of a few µm in diameter and 100’s µm in length that branched into secondary and then ever finer fibrils, down to diameters of 10s nm or below. A mechanism for the formation of the branch-like morphology observed in PTFE-based solvent-free electrodes is also presented. Even the finest fibrils were confirmed to survive typical cathode cycling conditions. The solvent-free electrodes showed progressive improvement in capacity with increasing charge-discharge rate (up to 150% at 2C) compared with slurry cast equivalents. The capacity of solvent-free electrodes faded 40% slower over 200 cycles at C/3. Impedance analysis showed the solvent-free microstructure enabled reduced charge transfer resistance and ionic resistance, arising from minimal obscuration of the active material surface and no pore blockage

Iron fluoride-lithium metal batteries in bis(fluorosulfonyl)imide-based ionic liquid electrolytes

The aviation industry's shift toward electrification demands greater energy density and enhanced cell safety compared to commercial lithium-ion batteries. Transition metal fluoride cathodes can store multiple lithium ions per metal center through a conversion reaction mechanism, resulting in a 3-fold increase in capacity compared to intercalation compounds. Additionally, fluoride cathodes exhibit remarkable thermal stability due to the ionic nature of the metal-fluoride bond. However, their practical implementation faces challenges due to their limited electronic and ionic conductivity. In this study, we conducted a comprehensive investigation of FeF2-Li metal cells in a lithium bis(fluorosulfonyl)imide N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ionic liquid electrolyte. We explored the effects of FeF2 particle size, the distribution of conductive additives within the electrode, and the influence of the bis(fluorosulfonyl)imide anion on electrochemical behavior and its evolution throughout cycling. Our findings suggest that the rate requirements for electric aviation could be met at 80°C

Advancing fluoride-ion batteries with a Pb-PbF2 counter electrode and a diluted liquid electrolyte

Fluoride ion batteries (FIB) are a promising post lithium-ion technology thanks to their high theoretical energy densities and Earth-abundant materials. However, the flooded cells commonly used to test liquid electrolyte FIBs severely affect the overall performance and impede comparability across different studies, hindering FIB progress. Here, we report a reliable Pb-PbF2 counter electrode that enables the use of two-electrode coin cells. To test this setup, we first introduce a liquid electrolyte that combines the advantages of a highly concentrated electrolyte (tetramethylammonium fluoride in methanol) while addressing its transport and high-cost shortcomings by introducing a diluent (propionitrile). We then demonstrate the viability of this system by reporting a BiF3–Pb-PbF2 cell with the highest capacity retention to date

Combined spectroscopy and intensity interferometry to determine the distances of the blue supergiants P Cygni and Rigel

In this paper, we report on the spatial intensity interferometry measurements within the H$\alpha$ line on two stars: the Luminous Blue Variable (LBV) supergiant \PCygni\,and the late-type B supergiant Rigel. The experimental setup has been upgraded to allow simultaneous measurement of two polarization channels and the zero baseline correlation function. Combined with simultaneous spectra measurements and based on radiative transfer models calculated with the code CMFGEN, we were able to fit our measured visibility curves to extract the stellar distances. Our distance determinations for both \PCygni\ (1.61 $\pm$ 0.18 kpc) and Rigel (0.26 $\pm$ 0.02 kpc) agree very well with the values provided by astrometry with the Gaia and Hipparcos missions, respectively. This is the first successful step towards extending the application of the Wind Momentum Luminosity Relation method for distance calibration from an LBV supergiant to a more normal late-type B supergiant

Removal and Reoccurrence of LLZTO Surface Contaminants under Glovebox Conditions

The reactivity of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) solid electrolytes to form lithio-phobic species such as Li2CO3 on their surface when exposed to trace amounts of H2O and CO2 limits the progress of LLZTO-based solid-state batteries. Various treatments, such as annealing LLZTO within a glovebox or acid etching, aim at removing the surface contaminants, but a comprehensive understanding of the evolving LLZTO surface chemistry during and after these treatments is lacking. Here, glovebox-like H2O and CO2 conditions were recreated in a near ambient pressure X-ray photoelectron spectroscopy chamber to analyze the LLZTO surface under realistic conditions. We find that annealing LLZTO at 600 °C in this atmosphere effectively removes the surface contaminants, but a significant level of contamination reappears upon cooling down. In contrast, HCl(aq) acid etching demonstrates superior Li2CO3 removal and stable surface chemistry post treatment. To avoid air exposure during the acid treatment, an anhydrous HCl solution in diethyl ether was used directly within the glovebox. This novel acid etching strategy delivers the lowest lithium/LLZTO interfacial resistance and the highest critical current density

The BLAST View of the Star Forming Region in Aquila (ell=45deg,b=0deg)

We have carried out the first general submillimeter analysis of the field towards GRSMC 45.46+0.05, a massive star forming region in Aquila. The deconvolved 6 deg^2 (3\degree X 2\degree) maps provided by BLAST in 2005 at 250, 350, and 500 micron were used to perform a preliminary characterization of the clump population previously investigated in the infrared, radio, and molecular maps. Interferometric CORNISH data at 4.8 GHz have also been used to characterize the Ultracompact HII regions (UCHIIRs) within the main clumps. By means of the BLAST maps we have produced an initial census of the submillimeter structures that will be observed by Herschel, several of which are known Infrared Dark Clouds (IRDCs). Our spectral energy distributions of the main clumps in the field, located at ~7 kpc, reveal an active population with temperatures of T~35-40 K and masses of ~10^3 Msun for a dust emissivity index beta=1.5. The clump evolutionary stages range from evolved sources, with extended HII regions and prominent IR stellar population, to massive young stellar objects, prior to the formation of an UCHIIR.The CORNISH data have revealed the details of the stellar content and structure of the UCHIIRs. In most cases, the ionizing stars corresponding to the brightest radio detections are capable of accounting for the clump bolometric luminosity, in most cases powered by embedded OB stellar clusters

COOL-LAMPS III: Discovery of a 25".9 Separation Quasar Lensed by a Merging Galaxy Cluster

In the third paper from the COOL-LAMPS Collaboration, we report the discovery of COOL J0542-2125, a gravitationally lensed quasar at $z=1.84$, observed as three images due to an intervening massive galaxy cluster at $z=0.61$. The lensed quasar images were identified in a search for lens systems in recent public optical imaging data and have separations on the sky up to 25".9, wider than any previously known lensed quasar. The galaxy cluster acting as a strong lens appears to be in the process of merging, with two sub-clusters separated by $\sim 1$ Mpc in the plane of the sky, and their central galaxies showing a radial velocity difference of $\sim 1000$ km/s. Both cluster cores show strongly lensed images of an assortment of background sources, as does the region between them. A preliminary strong lens model implies masses of $M(<250\ \rm{kpc}) = 1.79^{+0.16} _{-0.01} \times 10^{14} M_{\odot}$and$M(<250\ \rm{kpc}) = 1.48^{+0.04}_{-0.10} \times 10^{14} M_{\odot}$ for the East and West sub-clusters, respectively. This line of sight is also coincident with a ROSAT ALL-sky Survey source, centered between the two confirmed cluster halos reminiscent of other major cluster-scale mergers.Comment: 13 pages, 6 figures. Submitted to Ap

COOL-LAMPS. VI. Lens Model and New Constraints on the Properties of COOL J1241+2219, a Bright z = 5 Lyman Break Galaxy and its z = 1 Cluster Lens

We present a strong lensing analysis of COOL J1241+2219, the brightest known gravitationally lensed galaxy at z ≥ 5, based on new multiband Hubble Space Telescope (HST) imaging data. The lensed galaxy has a redshift of z = 5.043, placing it shortly after the end of the “Epoch of Reionization,” and an AB magnitude z AB = 20.47 mag (Khullar et al.). As such, it serves as a touchstone for future research of that epoch. The high spatial resolution of HST reveals internal structure in the giant arc, from which we identify 15 constraints and construct a robust lens model. We use the lens model to extract the cluster mass and lensing magnification. We find that the mass enclosed within the Einstein radius of the z = 1.001 cluster lens is M(<5.″77)=1.079−0.007+0.023×1013M☉ , significantly lower than other known strong lensing clusters at its redshift. The average magnification of the giant arc is 〈μ arc〉 = 76−20+40 , a factor of 2.4−0.7+1.4 greater than previously estimated from ground-based data; the flux-weighted average magnification is 〈μ arc〉 = 92−31+37 . We update the current measurements of the stellar mass and star formation rate (SFR) of the source for the revised magnification to log(M⋆/M⊙)= 9.7 ± 0.3 and SFR = 10.3−4.4+7.0 M ⊙ yr−1, respectively. The powerful lensing magnification acting upon COOL J1241+2219 resolves the source and enables future studies of the properties of its star formation on a clump-by-clump basis. The lensing analysis presented here will support upcoming multiwavelength characterization with HST and JWST data of the stellar mass assembly and physical properties of this high-redshift lensed galaxy