Tunable Redox Mediators for Li-O2 Batteries Based on Interhalide Complexes.

Li-O2 batteries can provide significantly higher gravimetric energy density than Li-ion batteries, but their practical use is limited by a number of fundamental issues associated with oxidizing discharge products such as Li2O2 and LiOH during charging. Soluble inorganic redox mediators (RMs) like LiI and LiBr have been shown to enhance round-trip efficiency where different solvents can greatly shift the redox potential of the RMs, significantly altering the overpotential during charging, as well as their oxidizing power against the discharge product. Unfortunately, other design requirements like (electro)chemical stability with the electrode as well as reactive discharge products greatly constrain the selection of solvent, making it impractical to additionally design the solvent to provide optimal RM performance. In this work, we demonstrate that interhalide RMs based on LiI/LiBr and LiI/LiCl mixtures can enable tuning of the oxidizing power of the RM in a given solvent. I-Br interhalides I2Br- to IBr2- showed increasing chemical oxidizing power toward Li2O2 and LiOH with increasing Br, and DEMS measurements during charging of Li-O2 cells demonstrated that these I-Br interhalide RMs led to increased O2 evolution with respect to LiI and reduced charging potential and CO2 evolution with respect to LiBr.

Single-Ion Lithium Conducting Polymers with High Ionic Conductivity Based on Borate Pendant Groups.

A family of single-ion lithium conducting polymer electrolytes based on highly delocalized borate groups is reported. The effect of the nature of the substituents on the boron atom on the ionic conductivity of the resultant methacrylic polymers was analyzed. To the best of our knowledge the lithium borate polymers endowed with flexible and electron-withdrawing substituents presents the highest ionic conductivity reported for a lithium single-ion conducting homopolymer (1.65×10-4  S cm-1 at 60 °C). This together with its high lithium transference number t Li + =0.93 and electrochemical stability window of 4.2 V vs Li0 /Li+ show promise for application in lithium batteries. To illustrate this, a lithium borate monomer was integrated into a single-ion gel polymer electrolyte which showed good performance on lithium symmetrical cells (<0.85 V at ±0.2 mA cm-2 for 175 h).

Nanometre-scale evidence for interfacial dissolution-reprecipitation control of silicate glass corrosion.

Silicate glasses are durable solids, and yet they are chemically unstable in contact with aqueous fluids-this has important implications for numerous industrial applications related to the corrosion resistance of glasses, or the biogeochemical weathering of volcanic glasses in seawater. The aqueous dissolution of synthetic and natural glasses results in the formation of a hydrated, cation-depleted near-surface alteration zone and, depending on alteration conditions, secondary crystalline phases on the surface. The long-standing accepted model of glass corrosion is based on diffusion-coupled hydration and selective cation release, producing a surface-altered zone. However, using a combination of advanced atomic-resolution analytical techniques, our data for the first time reveal that the structural and chemical interface between the pristine glass and altered zone is always extremely sharp, with gradients in the nanometre to sub-nanometre range. These findings support a new corrosion mechanism, interfacial dissolution-reprecipitation. Moreover, they also highlight the importance of using analytical methods with very high spatial and mass resolution for deciphering the nanometre-scale processes controlling corrosion. Our findings provide evidence that interfacial dissolution-reprecipitation may be a universal reaction mechanism that controls both silicate glass corrosion and mineral weathering.

Optimization of in-situ monolithic synthesis for immunopreconcentration in capillary.

Poly(glycidyl methacrylate-co-ethylene dimethacrylate) monoliths have been synthetized in fused-silica capillary. The monomer mixture composition, initiation mode and porogen composition were optimized in order to provide a monolith with an homogeneous morphology and able to generate an electroosmotic flow via the incorporation of a small percentage of monomers possessing sulfonate group. Anti-ochratoxin A antibodies were immobilized through a single step on the epoxy groups leading to a miniaturized immunoextraction column. In order to evaluate the specificity of the analyte-antigen interaction on this immunosorbent, the retention of ochratoxin A was examined on this support but also on two complementary sorbents: one constituted by the non-bonded monolith and another one bonded with non-specific antibodies. Only the monolith bonded with anti-ochratoxin A antibodies lead to retention, showing the specificity of the interactions involved. This affinity phase based on a monolithic polymer support exhibits a high potential for specific preconcentration of small molecules.