Thermal Conductivities of Lithium-Ion-Conducting Solid Electrolytes

Solid electrolytes and solid-state batteries have gathered attention in recent years as a potential alternative to state-of-the-art lithium-ion batteries, given the promised increased energy density and safety following the replacement of flammable organic electrolytes with solids. While ongoing research focuses mainly on improving the ionic conductivities of solid electrolytes, little is known about the thermal transport properties of this material class. This includes fundamental studies of heat capacities and thermal conductivities, application-oriented investigations of porosity effects, and the modeling of the temperature distribution in solid-state batteries during operation. To expand the understanding of transport in solid electrolytes, in this work, thermal properties of electrolytes in the argyrodite family (Li6PS5X with X = Cl, Br, I, and Li5.5PS4.5Cl1.5) and Li10GeP2S12 as a function of temperature and porosity are reported. It is shown that the thermal conductivities of solid electrolytes are in the range of liquid electrolytes. Utilizing effective medium theory to describe the porosity-dependent results, an empirical predictive model is obtained, and the intrinsic (bulk) thermal conductivities for all electrolytes are extracted. Moreover, the temperature-independent, glass-like thermal conductivities found in all materials suggest that thermal transport in these ionic conductors occurs in a nontextbook fashion

Plasma Dimethylarginine Levels and Carotid Intima–Media Thickness are related to Atrial Fibrillation in Patients with Embolic Stroke

A relevant part of embolic strokes of undetermined source (ESUS) is assumed to be due to non-detected atrial fibrillation (AF). In this study, we aimed to investigate if markers of endothelial dysfunction and damage may indicate AF risk in embolic stroke. Eighty-eight patients with ischemic stroke confirmed by imaging were assigned to one of three groups: ESUS, AF, or micro-/macroangiopathy. ESUS patients underwent prolonged Holter electrocardiography scheduled for three days. The National Institutes of Health Stroke Scale (NIHSS), the CHA2DS2VASC score, and the carotid intima⁻media thickness (CIMT) were obtained. Markers of endothelial (dys)function (L-arginine, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA)) were measured at day seven after stroke. ESUS patients were younger and had fewer cardiovascular risk factors than patients with determined stroke etiology. Compared with AF patients, ESUS patients showed significantly lower values of SDMA (p = 0.004) and higher values of L-arginine (p = 0.031), L-arginine/ADMA ratio (p = 0.006), L-arginine/SDMA ratio (p = 0.002), and ADMA/SDMA ratio (p = 0.013). Concordant differences could be observed comparing ESUS patients with those with newly diagnosed AF (p = 0.026; p = 0.03; p = 0.009; p = 0.004; and p = 0.046, respectively). CIMT was significantly larger in AF than in ESUS patients (p < 0.001), and was identified as an AF risk factor independent from CHA2DS2VASC in the regression analysis (p = 0.014). These findings may support future stratification for AF risk in patients who have suffered embolic stroke