428 research outputs found

    New Insights of Infiltration Process of Argyrodite Li6PS5Cl Solid Electrolyte into Conventional Lithium-Ion Electrodes for Solid-State Batteries

    Get PDF
    All-solid-state lithium-ion batteries based on solid electrolytes are attractive for electric applications due to their potential high energy density and safety. The sulfide solid electrolyte (e.g., argyrodite) shows a high ionic conductivity (10−3 S cm−1). There is an open question related to the sulfide electrode’s fabrication by simply infiltrating methods applied for conventional lithium-ion battery electrodes via homogeneous solid electrolyte solutions, the structure of electrolytes after drying, chemical stability of binders and electrolyte, the surface morphology of electrolyte, and the deepening of the infiltrated electrolyte into the active materials to provide better contact between the active material and electrolyte and favorable lithium ionic conduction. However, due to the high reactivity of sulfide-based solid electrolytes, unwanted side reactions between sulfide electrolytes and polar solvents may occur. In this work, we explore the chemical and electrochemical properties of the argyrodite-based film produced by infiltration mode by combining electrochemical and structural characterizations

    ARCHModels.jl: Estimating ARCH Models in Julia

    Get PDF
    This paper introduces ARCHModels.jl, a package for the Julia programming language that implements a number of univariate and multivariate autoregressive conditional heteroskedasticity models. This model class is the workhorse tool for modeling the conditional volatility of financial assets. The distinguishing feature of these models is that they model the latent volatility as a (deterministic) function of past returns and volatilities. This recursive structure results in loop-heavy code which, due to its just-in-time compiler, Julia is well-equipped to handle. As such, the entire package is written in Julia, without any binary dependencies. We benchmark the performance of ARCHModels.jl against popular implementations in MATLAB, R, and Python, and illustrate its use in a detailed case study

    Public assistance: The development of social security

    Get PDF
    Thesis (B.A.) in Political Science--University of Illinois at Urbana-Champaign, 1982.Bibliography: leaves 47-48.Microfiche of typescript. [Urbana, Ill.] : Photographic Services, University of Illinois, U of I Library, [1982]. 2 microfiches (54 frames) : negative ; 11 x 15 cm

    Brief history of early lithium-battery development

    Get PDF
    Lithium batteries are electrochemical devices that are widely used as power sources. This history of their development focuses on the original development of lithium-ion batteries. In particular, we highlight the contributions of Professor Michel Armand related to the electrodes and electrolytes for lithium-ion batteries

    Application of operando X-ray diffraction and Raman spectroscopies in elucidating the behavior of cathode in lithium-ion batteries

    Get PDF
    With the advances in characterization techniques, various operando/in-situ methods were applied in studying rechargeable batteries in order to improve the electrochemical properties of electrode materials, prolonging the battery life and developing new battery materials. In the present review, we focus on the characterization of electrode materials with operando/in-situ X-ray diffraction and Raman spectroscopies. By correlating the results obtained via these two techniques in different electrode chemistry: (a) intercalation materials, such as layered metal oxides and (b) conversion materials, such as elemental sulfur. We demonstrate the importance of using operando/in-situ techniques in examining the microstructural changes of the electrodes under various operating conditions, in both macro and micro-scales. These techniques also reveal the working and the degradation mechanisms of the electrodes and the possible side reactions involved. The comprehension of these mechanisms is fundamental for ameliorating the electrode materials, enhancing the battery performance and lengthening its cycling life

    Redox Centers Evolution in Phospho-Olivine Type (LiFe0. 5Mn0. 5 PO4) Nanoplatelets with Uniform Cation Distribution

    Get PDF
    Accepted Version of the publication: Nano Lett. 2014, 14, 3, 1477–1483. Publication Date: February 24, 2014. https://doi.org/10.1021/nl4046697 © 2014 American Chemical Society. In phospho-olivine type structures with mixed cations (LiM1M2PO4), the octahedral M1 and M2 sites that dictate the degree of intersites order/disorder play a key role in determining their electrochemical redox potentials. In the case of LiFexMn1−xPO4, for example, in micrometer-sized particles synthesized via hydrothermal route, two separate redox centers corresponding to Fe2+/Fe3+ (3.5 V vs Li/Li+) and Mn2+/Mn3+ (4.1 V vs Li/Li+), due to the collective Mn−O−Fe interactions in the olivine lattice, are commonly observed in the electrochemical measurements. These two redox processes are directly reflected as two distinct peak potentials in cyclic voltammetry (CV) and equivalently as two voltage plateaus in their standard charge/discharge characteristics (in Li ion batteries). On the contrary, we observed a single broad peak in CV from LiFe0.5Mn0.5PO4 platelet-shaped (∌10 nm thick) nanocrystals that we are reporting in this work. Structural and compositional analysis showed that in these nanoplatelets the cations (Fe, Mn) are rather homogeneously distributed in the lattice, which is apparently the reason for a synergetic effect on the redox potentials, in contrast to LiFe0.5Mn0.5PO4 samples obtained via hydrothermal routes. After a typical carbon-coating process in a reducing atmosphere (Ar/H2), these LiFe0.5Mn0.5PO4 nanoplatelets undergo a rearrangement of their cations into Mn-rich and Fe-rich domains. Only after such cation rearrangement (via segregation) in the nanocrystals, the redox processes evolved at two distinct potentials, corresponding to the standard Fe2+/Fe3+ and Mn2+/Mn3+ redox centers. Our experimental findings provide new insight into mixed-cation olivine structures in which the degree of cations mixing in the olivine lattice directly influences the redox potentials, which in turn determine their charge/discharge characteristics
    • 

    corecore