Ionic Conductivity of β-Cyclodextrin-Polyethylene-Oxide/Alkali-Metal-Salt Complex

Modulating the properties of carboxymethyl chitosan/polyethylene oxide nanocomposites with aluminium oxy hydroxide: A comprehensive study

This study explores the eco-friendly synthesis of carboxymethyl chitosan/polyethylene oxide/γ-aluminium oxyhydroxide (CMCS/PEO/γ-AlOOH) nanocomposite films through a sustainable, green preparation method. The CMCS/PEO/γ-AlOOH nanocomposites were characterized through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) to analyze their structural and morphological properties. The emergence of distinct peaks of γ-AlOOH in XRD and FTIR spectra indicated the strong interaction between γ-AlOOH and the blend. Morphological analysis revealed significant changes in the surface characteristics of the pristine blend upon incorporation of γ-AlOOH. Thermogravimteric analysis (TGA) confirmed the improved thermal stability of the nanocomposites, while differential scanning calorimetry (DSC) revealed changes in the glass transition temperature proportional to the γ-AlOOH content. The nanocomposite films demonstrated enhanced mechanical properties, exhibiting a 39.6 % increase in tensile strength at a 5 wt% γ-AlOOH loading. The temperature-dependent dielectric constant, loss tangent, AC conductivity and impedance were analyzed at varying loadings of γ-AlOOH. The 7 wt% γ-AlOOH nanocomposites showed the highest conductivity (1.23 × 10-6 S/cm at 1 MHz) and dielectric constant (244 at 100 Hz) at ambient temperature. The CMCS/PEO/γ-AlOOH nanocomposite's superior tensile strength, thermal stability, glass transition temperature, conductivity, and dielectric constant make it a strong candidate for eco-friendly, flexible electronic devices.

NMR studies of lithium and sodium battery electrolytes

This review focuses on the application of nuclear magnetic resonance (NMR) spectroscopy in the study of lithium and sodium battery electrolytes. Lithium-ion batteries are widely used in electronic devices, electric vehicles, and renewable energy systems due to their high energy density, long cycle life, and low self-discharge rate. The sodium analog is still in the research phase, but has significant potential for future development. In both cases, the electrolyte plays a critical role in the performance and safety of these batteries. NMR spectroscopy provides a non-invasive and non-destructive method for investigating the structure, dynamics, and interactions of the electrolyte components, including the salts, solvents, and additives, at the molecular level. This work attempts to give a nearly comprehensive overview of the ways that NMR spectroscopy, both liquid and solid state, has been used in past and present studies of various electrolyte systems, including liquid, gel, and solid-state electrolytes, and highlights the insights gained from these studies into the fundamental mechanisms of ion transport, electrolyte stability, and electrode-electrolyte interfaces, including interphase formation and surface microstructure growth. Overviews of the NMR methods used and of the materials covered are presented in the first two chapters. The rest of the review is divided into chapters based on the types of electrolyte materials studied, and discusses representative examples of the types of insights that NMR can provide.

Probing distribution and dynamics of lithium ions in supermolecule β-CD-PEO/Li+ solid polymer electrolytes via solid-state NMR

In this work, the distribution and dynamics of Li⁺ ions in β-CD-PEO/Li⁺ (β-CD, β-cyclodextrin; PEO, polyethylene-oxides) crystalline polymer electrolytes were investigated by solid-state NMR to enlighten the ionic conduction mechanism. Specifically, ⁷Li-⁶Li REDOR NMR and variable-contact-time ¹H-⁶Li CP/MAS NMR were adopted for the study. The results demonstrate that Li⁺ ions coordinated by polymer chains have relatively compact spatial density and fast dynamics, which facilitate the improvement of the electrochemical properties. Additionally, the variation of the distribution and dynamics of the Li⁺ ions and the ionic conduction mechanism were studied and discussed by altering the amount of the Li⁺ ions. This work deepens our understanding of the distribution and dynamics of Li⁺ ions in β-CD-PEO/Li⁺ crystals and demonstrates possible future applications of solid-state NMR on the study of the polymer electrolytes.

Supramolecular Self-Assembly of Methylated Rotaxanes for Solid Polymer Electrolyte Application

Li⁺-conducting solid polymer electrolytes (SPEs) obtained from supramolecular self-assembly of trimethylated cyclodextrin (TMCD), poly(ethylene oxide) (PEO), and lithium salt are investigated for application in lithium-metal batteries (LMBs) and lithium-ion batteries (LIBs). The considered electrolytes comprise nanochannels for fast lithium-ion transport formed by CD threaded on PEO chains. It is demonstrated that tailored modification of CD beneficially influences the structure and transport properties of solid polymer electrolytes, thereby enabling their application in LMBs. Molecular dynamics (MD) simulation and experimental data reveal that modification of CDs shifts the steady state between lithium ions inside and outside the channels, in this way improving the achievable ionic conductivity. Notably, the designed SPEs facilitated galvanostatic cycling in LMBs at fast charging and discharging rates for more than 200 cycles and high Coulombic efficiency.