216,215 research outputs found
C-H-activated aluminum hydroxide via molecular oxygen
No full textThe reaction of LAl[eta(2)-(C-2(SiMe3)(2))] (1; L = HC[(CMe)(NDipp)](2), Dipp = 2,6-iPr(2)C(6)H(3)) with dioxygen leads to the elimination of bis(trimethylsilyl)acetylene and the formation of the corresponding aluminum monohydroxide via the oxidation of one of the CHMe2 groups on the Dipp ring
ljt-uiuc/H-k-c: H-k-c
No full textH-k-c package:
Generalized H-k after harmonic correction on receiver functions
a modification of H-k method by Zhu and Kanamori (2000)
by Jiangtao Li, Xiaodong Song, Pan Wang, and Lupei Zhu
Reference: Li, J., Song, X., Wang, P., & Zhu, L. (2019). A generalized H-k method with harmonic corrections on Ps and its crustal multiples in receiver functions. J. Geophys. Res. Solid Earth, 124(4), 3782-3801
Contact: [email protected]; [email protected]
Bis(arylimido) molybdenum(VI) amidinate and guanidinate complexes; Molecular structures of [(ArN)(2)MoMe{N(Cy)C[N(i-Pr)(2)]N(Cy)}] (Ar=2,6-i-Pr2C6H3; Cy = cyclohexyl) and [(2,6-i-Pr2C6H3N)(2)MoCl2]center dot[NH=C(C6H5)CH(SiMe3)(2)]
No full textThe reaction of [(ArN)(2)MoCl2]. DME (Ar = 2,6-i-Pr6C6H3) (1) with lithium amidinates or guanidinates resulted in molybdenum(VI) complexes [(ArN)(2)-MoCl(N(R-1)C(R-2)N(R-1))] (R-1 = Cy (cyclohexyl), R-2 = Me (2); R-1 = Cy, R-2 = N(i-Pr)(2) (3); R-1 = Cy, R-2 = N(SiMe3)(2) (4); R-1 = SiMe3, R-2 = C6H5 (5)) with five coordinated molybdenum atoms. Methylation of these compounds was exemplified by the reactions of 2 and 3 with MeLi affording the corresponding methylates [(ArN)(2)MoMe(N(R-1)C(R-2)N(R-1))] (R-1 = Cy, R-2 = Me (6); R-1 = Cy, R-2 = N(i-Pr)(2) (7)). The analogous reaction of 1 with bulky [N(SiMe3)C(C6H5)-C(SiMe3)(2)]Li . THF did not give the corresponding metathesis product, but a Schiff base adduct [(ArN)(2)MoCl2]. [NH=C(C6H5)CH(SiMe3)(2)] (8) in low yield. The molecular structures of 7 and 8 are established by the X-ray single crystal structural analysis
Electrochemical Properties and Crystal Structure of Li+/H+ Cation-Exchanged LiNiO2
No full textLiNiO2 has high energy density but easily reacts with moisture in the atmosphere and deteriorates. We performed qualitative and quantitative evaluations of the degraded phase of LiNiO2 and the influence of the structural change on the electrochemical properties of the phase. Li1-xHxNiO2 phase with cation exchange between Li+ and H+ was confirmed by thermogravimetric analysis and Karl Fischer titration measurement. As the H concentration in LiNiO2 increased, the rate capability deteriorated, especially in the low-temperature range and under low state of charge. Experimental and density functional theory (DFT) calculation results suggested that this outcome was due to increased activation energy of Li+ diffusion owing to cation exchange. Rietveld analysis of X-ray diffraction and DFT calculation confirmed that the c lattice parameter and Li-O layer reduced because of the Li+/H+ cation exchange. These results indicate that LiNiO2 modified in the atmosphere has a narrowed Li-O layer, which is the Li diffusion path, and the rate characteristics are degraded
Missing-mass spectroscopy with the Li-6(pi(-), K+)X reaction to search for H-6(Lambda)
No full textWe searched for the bound state of the neutron-rich Lambda-hypernucleus H-6(Lambda), using the Li-6(pi(-), K+)X double charge-exchange reaction at a pi-beam momentum of 1.2 GeV/c at J-PARC. A total of 1.4 x 10(12) pi(-) was driven onto a Li-6 target of 3.5-g/cm(2) thickness. No event was observed below the bound threshold, i.e., the mass of H-4(Lambda) + 2n, in the missing-mass spectrum of the Li-6(pi(-), K+) X reaction in the 2 degrees < theta(pi K) < 20 degrees angular range. Furthermore, no event was found up to 2.8 MeV/c(2) above the bound threshold. We obtained the double-differential cross section spectra of the Li-6(pi(-), K+)X reaction in the angular range of 2 degrees < theta(pi K) < 14 degrees. An upper limit of 0.56 nb/sr (90% C.L.) was obtained for the production cross section of the H-6(Lambda) hypernucleus bound state. In addition, not only the bound state region, but also the Lambda continuum region and part of the Sigma(-) quasifree production region of the Li-6(pi(-), K+) reaction were obtained with high statistics. The present missing-mass spectrum will facilitate the investigation of the Sigma(-) -nucleus optical potential for Sigma(-) -He-5 through spectrum shape analysis
Improved measurement of the branching fraction of h c → γη′/η and search for h c → γπ 0
No full textAbstract The processes h c → γP (P = η′, η, π 0) are studied with a sample of (27.12 ± 0.14) × 108 ψ(3686) events collected by the BESIII detector at the BEPCII collider. The decay h c → γη is observed for the first time with the significance of 9.0 σ, and the branching fraction is determined to be (3.77 ± 0.55 ± 0.13 ± 0.26) × 10 −4, while B (h c → γη′) is measured to be (1.40 ± 0.11 ± 0.04 ± 0.10) × 10 −3, where the first uncertainties are statistical, the second systematic, and the third from the branching fraction of ψ(3686) → π 0 h c . The combination of these results allows for a precise determination of R h c = B h c → γη B h c → γ η ′ , which is calculated to be (27.0 ± 4.4 ± 1.0)%. The results are valuable for gaining a deeper understanding of η − η′ mixing, and its manifestation within quantum chromodynamics. No significant signal is found for the decay h c → γπ 0, and an upper limit is placed on its branching fraction of B (h c → γπ 0) < 5.0 × 10 −5, at the 90% confidence level
Tuning Work Function of Fe2N@C Nanosheets by Co Doping for Enhanced Lithium Storage
No full textTransition metal nitrides (TMNs) with high theoretical capacity and excellent electrical conductivity have great potential as anode materials for lithium-ion batteries (LIBs), but suffer from poor rate performance due to the slow kinetics. Herein, taking the Fe2N for instance, Co doping is utilized to enhance the work function of Fe2N, which accelerates the charge transfer and strengthens the adsorption of Li+ ions. The Fe2N nanoparticles with various Co dopants are anchoring on the surface of honeycomb porous carbon foam (named Co-x-Fe2N@C). Co-doping can enlarge the work function of pristine Fe2N and thereby optimize the charging/discharging kinetics. The work function can be increased from 5.23 eV (pristine Fe2N) to 5.67 eV for Co-0.3-Fe2N@C and 5.56 eV for Co-0.1-Fe2N@C. As expected, the Co-0.1-Fe2N@C electrode exhibits the highest specific capacity (673 mA h g(-1) at 100 mA g(-1)) and remarkable rate capability (375 mA h g(-1) at 5 000 mA g(-1)), outperforming most reported TMNs electrodes. Therefore, this work provides a promising strategy to design and regulate anode materials for high-performance and even commercially available LIBs.Y.C. and Q.H. contributed equally to this work. This work was supported by National Natural Science Foundation of China (Nos. 22372127), Natural Science Foundation of Hubei Province (Nos. ZRM2023000271 and
2023AFB608)
Unusual Activation of Cation Disordering by Li/Fe Rearrangement in Triplite LiFeSO4F
No full textIt is reported that cation disordering in triplite LiFeSO4F can be activated by Li/Fe rearrangement that results from irreversible and nondestructive structural changes during the 1st charge/discharge cycle, especially during the charge. This rearrangement decreases the number of edge-shared FeO4F2 connection environments, compared to the pristine material. With this activation, triplite LiFeSO4F exhibits several unexpected electrochemical features in subsequent cycles; a decrease in open-circuit voltage indicating the change in thermodynamic property, negligible volumetric change, enhanced Li diffusion, and facile phase transformation pathway. As a consequence, the cation-disordered triplite LiFeSO4F achieves superior rate capability up to approximate to 66 mA h g(-1) at 40 C rate (1.5 min discharge) and has excellent capacity retention for 500 cycles at 5 C charge/5 C discharge rate and for 1200 cycles at 2 C charge/2 C discharge rate. Therefore, triplite LiFeSO4F can be one of the most promising electrode materials for Li ion batteries.11Nsciescopu
Interfacial “Single-Atom-in-Defects” Catalysts Accelerating Li+ Desolvation Kinetics for Long-Lifespan Lithium-Metal Batteries
No full textThe lithium-metal anode is a promising candidate for realizing high-energy-density batteries owing to its high capacity and low potential. However, several rate-limiting kinetic obstacles, such as the desolvation of Li+ solvation structure to liberate Li+, Li0 nucleation, and atom diffusion, cause heterogeneous spatial Li-ion distribution and fractal plating morphology with dendrite formation, leading to low Coulombic efficiency and depressive electrochemical stability. Herein, differing from pore sieving effect or electrolyte engineering, atomic iron anchors to cation vacancy-rich Co1−xS embedded in 3D porous carbon (SAFe/CVRCS@3DPC) is proposed and demonstrated as catalytic kinetic promoters. Numerous free Li ions are electrocatalytically dissociated from the Li+ solvation complex structure for uniform lateral diffusion by reducing desolvation and diffusion barriers via SAFe/CVRCS@3DPC, realizing smooth dendrite-free Li morphologies, as comprehensively understood by combined in situ/ex situ characterizations. Encouraged by SAFe/CVRCS@3DPC catalytic promotor, the modified Li-metal anodes achieve smooth plating with a long lifespan (1600 h) and high Coulombic efficiency without any dendrite formation. Paired with the LiFePO4 cathode, the full cell (10.7 mg cm−2) stabilizes a capacity retention of 90.3% after 300 cycles at 0.5 C, signifying the feasibility of using interfacial catalysts for modulating Li behaviors toward practical applications
- …
