Reciprocal space imaging of ionic correlations in intercalation compounds

Abstract

The intercalation of alkali ions into layered materials has played an essential role in battery technology since the development of the first lithium-ion electrodes. Coulomb repulsion between the intercalants leads to ordering of the intercalant sublattice, which hinders ionic diffusion and impacts battery performance. While conventional diffraction can identify the long-range order that can occur at discrete intercalant concentrations during the charging cycle, it cannot determine short-range order at other concentrations that also disrupt ionic mobility. In this article, we show that the use of real-space transforms of single crystal diffuse scattering, measured with high-energy synchrotron x-rays, allows a model-independent measurement of the temperature dependence of the length scale of ionic correlations along each of the crystallographic axes in a sodium-intercalated V2O5. The techniques described here provide a new way of probing the evolution of structural ordering in crystalline materials.

Ion Dynamics of Water‐in‐Salt Electrolyte with Organic Solvents in Nanoporous Supercapacitor Electrodes

“…Such non‐monotonic variation of the as‐obtained electrolyte conductivity within the nanochannels could be due to the cation‐anion Coulombic interactions. The Coulombic interactions between electrolyte ions become significant at high electrolyte concentrations . To validate the effect of cation‐anion interactions, the radial pair‐distribution function was calculated using MD simulations .…”

“…Water‐based solutions are currently considered among the most promising electrolytes for advanced energy storage devices (electrochemical double‐layer capacitors, pseudocapacitors, solid‐state supercapacitors, batteries, etc.) which may lead to a broad range of applications in industrial electrification and decarbonization, clean energy storage, electric vehicles, etc. The common critical issue of water‐based electrolytes is their narrow electrochemical stability window due to the hydrogen evolution and oxygen evolution reactions from water decomposition .…”

Acoustic phonon dispersion and diffuse scattering across the valence transition of (Pr0.85Y0.15)0.7Phelan1, Krogstad2, Schreiber3 et al. 2019Phys. Rev. B4020View full textAdd to dashboardCite

“…It is useful for understanding the diffuse scattering to consider the 3-dimensional difference pair distribution function (3D-ΔPDF), which is the Fourier transform of the diffuse scattering at a particular temperature with the average structure subtracted out by removal of the primary Bragg reflections [36,37]. The 3D-ΔPDF is a function of a real space vector connecting a pair of atoms.…”

Tuneable local order in thermoelectric crystals

“…Positive/negative features show vectors for which the real structure has more/less electron density separated by those vectors compared with the average structure. The types and signs of features can be directly related to the types of local correlations (Weber & Simonov, 2012), and indeed the 3D-ÁPDF has been used to solve the local order in several disordered crystals (Krogstad et al, 2020;Roth & Iversen, 2019;Sangiorgio et al, 2018).…”

“…The average periodic structure gives rise to sharp peaks in a diffraction experiment (Bragg peaks), which can be readily analysed. The local deviations give rise to weak diffuse scattering, which is more difficult to measure and especially to interpret on a structural basis (Keen & Goodwin, 2015;Krogstad et al, 2020;Simonov et al, 2020).…”