Nanoconfined LiBH4 as a Fast Lithium Ion Conductor

Designing new functional materials is crucial for the development of efficient energy storage and conversion devices such as all solid‐state batteries. LiBH₄ is a promising solid electrolyte for Li‐ion batteries. It displays high lithium mobility, although only above 110 °C at which a transition to a high temperature hexagonal structure occurs. Herein, it is shown that confining LiBH₄ in the pores of ordered mesoporous silica scaffolds leads to high Li⁺ conductivity (0.1 mS cm^?1) at room temperature. This is a surprisingly high value, especially given that the nanocomposites comprise 42 vol% of SiO₂. Solid state ⁷Li NMR confirmed that the high conductivity can be attributed to a very high Li⁺ mobility in the solid phase at room temperature. Confinement of LiBH₄ in the pores leads also to a lower solid‐solid phase transition temperature than for bulk LiBH₄. However, the high ionic mobility is associated with a fraction of the confined borohydride that shows no phase transition, and most likely located close to the interface with the SiO₂ pore walls. These results point to a new strategy to design low‐temperature ion conducting solids for application in all solid‐state lithium ion batteries, which could enable safe use of Li‐metal anodes.     

Resolving the stability and structure of strontium chloride amines from equilibrium pressures,XRD and DFT

Strontium chloride octamine, Sr(NH₃)₈Cl₂, has been shown to be a highly efficient ammonia reservoir for selective catalytic reduction of NO_x gases in vehicle exhaust and to hold great potential for indirect hydrogen storage. The possible applications of such metal amines depend explicitly on the conditions for ammonia release and it is thus essential to understand the exact ab- and desorption mechanisms. Here, we apply equilibrium pressure measurements from ammonia desorption, X-ray powder diffraction and density functional theory calculations to identify thermodynamically stable Sr(NH₃)Cl₂, Sr(NH₃)₂Cl₂ and Sr(NH₃)₈Cl₂ phases. The crystal structures were solved in the space groups Cmcm, Aem2 and Pnma respectively. Controversy regarding the possible existence of a diamine phase is resolved on the basis of a combined structural and thermodynamic analysis of the ammonia release mechanisms, yielding a diamine structure with nearly the same stability as the monoamine. Depending on temperature and pressure, the diamine phase is found to have marginally higher or lower stability than the monoamine phase which explains why the diamine phase is found in some experiments and is not found in others.     

Improved cycling performance with ingestion of hydrolyzed marine protein depends on performance level

Background

The effect on performance of protein ingestion during or after exercise is not clear. This has largely been attributed to the utilization of different scientific protocols and the neglection of accounting for factors such as differences in physical and chemical properties of protein supplements and differences in athletic performance level.

Methods

We hypothesized that ingestion of unprocessed whey protein (15.3 g·h^-1) together with carbohydrate (60 g·h^-1), would provide no ergogenic effect on 5-min mean-power performance following 120 min cycling at 50% of maximal aerobic power (2.8 ± 0.2 W·kg^-1, corresponding to 60 ± 4% of VO_2max), compared to CHO alone (60 g·h^-1). Conversely, we hypothesized that ingestion of the hydrolyzed marine protein supplement NutriPeptin? (Np, 2.7 g·h^-1), a processed protein supplement with potentially beneficial amino acid composition, together with a PROCHO beverage (12.4 g·h^-1 and 60 g·h^-1, respectively) would provide an ergogenic effect on mean-power performance. We also hypothesized that the magnitude of the ergogenic effect of NpPROCHO would be dependent on athletic performance. As for the latter analysis, performance level was defined according to a performance factor, calculated from individual pre values of W_max, VO_2max and 5-min mean-power performance, wherein the performance of each subject was ranked relative to the superior cyclist whos performance was set to one. Twelve trained male cyclists (VO_2max = 65 ± 4 ml·kg^-1·min^-1) participated in a randomized double-blinded cross-over study.

Results and conclusions

Overall, no differences were found in 5-min mean-power performance between either of the beverages (CHO 5.4 ± 0.5 W·kg^-1; PROCHO 5.3 ± 0.5 W·kg^-1; NpPROCHO 5.4 ± 0.3 W·kg^-1) (P = 0.29). A negative correlation was found between NpPROCHO mean-power performance and athletic performance level (using CHO-performance as reference; Pearson R = -0.74, P = 0.006). Moreover, ingestion of NpPROCHO resulted in improved 5-min mean-power performance relative to ingestion of CHO in the six lesser performing subjects compared to the six superior performing subjects (P < 0.05). This suggests that with the current protocol, NpPROCHO provided an ergogenic effect on 5-min mean-power performance in athletes with a lower performance level.     

Genetic Algorithm Procreation Operators for Alloy Nanoparticle Catalysts

The long-term stability of binary nanoparticles and clusters is one of the main challenges in the development of novel (electro-)catalysts for e.g. CO₂ reduction. Here, we present a method for predicting the optimal composition and structure of alloy nanoparticles and clusters, with particular focus on the surface properties. Based on a genetic algorithm (GA) we introduce and discuss efficient permutation operations that work by interchanging positions of elements depending on their local environment and position in the cluster. We discuss the fact that in order to be efficient, the operators have to be dynamic, i.e. change their behavior during the course of an algorithm run. The implementation of the GA including the customized operators is freely available at http://svn.fysik.dtu.dk/projects/pga.