Coordinatively Cross-Linked Binders for Silicon-Based Electrodes for Li-Ion Batteries: Beneficial Impact on Mechanical Properties and Electrochemical Performance.

A simple and versatile preparation of Zn(II)-poly(carboxylates) reticulated binders by the addition of Zn(II) precursors (ZnSO4, ZnO, or Zn(NO3)2) into a preoptimized poly(carboxylic acids) binder solution is proposed. These binders lead systematically to a significantly improved electrochemical performance when used for the formulation of silicon-based negative electrodes. The formation of carboxylate-Zn(II) coordination bonds formation is investigated by rheology and FTIR and NMR spectroscopies. Mechanical characterizations reveal that the coordinated binder offers a better electrode coating cohesion and adhesion to the current collector, as well as higher hardness and elastic modulus, which are even preserved in the presence of a carbonate solvent (i.e., in battery operation conditions). Ultimately, as shown from operando dilatometry experiments, the electrode expansion during lithiation is reduced, mitigating electrode mechanical failure. Such coordinatively reticulated electrodes outperform their uncoordinated counterparts with an improved capacity retention of over 30% after 60 cycles.

Influence of the Polyacrylic Acid Binder Neutralization Degree on the Initial Electrochemical Behavior of a Silicon/Graphite Electrode.

The role of the physicochemical properties of the water-soluble polyacrylic acid (PAA) binder in the electrochemical performance of highly loaded silicon/graphite 50/50 wt % negative electrodes has been examined as a function of the neutralization degree x in PAAH1-xLix at the initial cycle in an electrolyte not containing ethylene carbonate. Electrode processing in the acidic PAAH binder at pH 2.5 leads to a deep copper corrosion, resulting in a significant electrode cohesion and adhesion to the current collector surface, but the strong binder rigidity may explain the big cracks occurring on the electrode surface at the first cycle. The nonuniform binder coating on the material surface leads to an important degradation of the electrolyte, explaining the lowest initial Coulombic efficiency and the lowest reversible capacity among the studied electrodes. When processed in neutral pH, the PAAH0.22Li0.78 binder forms a conformal artificial solid electrolyte interphase layer on the material surface, which minimizes the electrolyte reduction at the first cycle and then maximizes the initial Coulombic efficiency. However, the low mechanical resistance of the electrode and its strong cracking explain its low reversible capacity. Electrodes prepared at intermediate pH 4 combine the positive assets of electrodes prepared at acidic and neutral pH. They lead to the best initial performance with a notable areal capacity of 7.2 mA h cm-2 and the highest initial Coulombic efficiency of around 90%, a value much larger than the usual range reported for silicon/graphite anodes. All data obtained with complementary characterization techniques were discussed as a function of the PAA polymeric chain molecular conformation, microstructure, and surface adsorption or grafting, emphasizing the tremendous role of the binder in the electrode initial performance.

Tuning the Formation and Structure of the Silicon Electrode/Ionic Liquid Electrolyte Interphase in Superconcentrated Ionic Liquids.

The latest advances in the stabilization of Li/Na metal battery and Li-ion battery cycling have highlighted the importance of electrode/electrolyte interface [solid electrolyte interphase (SEI)] and its direct link to cycling behavior. To understand the structure and properties of the SEI, we used combined experimental and computational studies to unveil how the ionic liquid (IL) cation nature and salt concentration impact the silicon/IL electrolyte interfacial structure and the formed SEI. The nature of the IL cation is found to be important to control the electrolyte reductive decomposition that influences the SEI composition and properties and the reversibility of the Li-Si alloying process. Also, increasing the Li salt concentration changes the interface structure for a favorable and less resistive SEI. The most promising interface for the Si-based battery was found to be in P1222FSI with 3.2 m LiFSI, which leads to an optimal SEI after 100 cycles in which LiF and trapped LiFSI are the only distinguishable lithiated and fluorinated products detected. This study shows a clear link between the nanostructure of the IL electrolyte near the electrode surface, the resulting SEI, and the Si negative electrode cycling performance. More importantly, this work will aid the rational design of Si-based Li-ion batteries using IL electrolytes in an area that has so far been neglected, reinforcing the benefits of superconcentrated electrolyte systems.

AFM and FluidFM Technologies: Recent Applications in Molecular and Cellular Biology.

Atomic force microscopy (AFM) is a widely used imaging technique in material sciences. After becoming a standard surface-imaging tool, AFM has been proven to be useful in addressing several biological issues such as the characterization of cell organelles, quantification of DNA-protein interactions, cell adhesion forces, and electromechanical properties of living cells. AFM technique has undergone many successful improvements since its invention, including fluidic force microscopy (FluidFM), which combines conventional AFM with microchanneled cantilevers for local liquid dispensing. This technology permitted to overcome challenges linked to single-cell analyses. Indeed, FluidFM allows isolation and injection of single cells, force-controlled patch clamping of beating cardiac cells, serial weighting of micro-objects, and single-cell extraction for molecular analyses. This work aims to review the recent studies of AFM implementation in molecular and cellular biology.

In Silico Evaluation of the Potential Antiarrhythmic Effect of Epigallocatechin-3-Gallate on Cardiac Channelopathies.

Ion channels are transmembrane proteins that allow the passage of ions according to the direction of their electrochemical gradients. Mutations in more than 30 genes encoding ion channels have been associated with an increasingly wide range of inherited cardiac arrhythmias. In this line, ion channels become one of the most important molecular targets for several classes of drugs, including antiarrhythmics. Nevertheless, antiarrhythmic drugs are usually accompanied by some serious side effects. Thus, developing new approaches could offer added values to prevent and treat the episodes of arrhythmia. In this sense, green tea catechins seem to be a promising alternative because of the significant effect of Epigallocatechin-3-Gallate (E3G) on the electrocardiographic wave forms of guinea pig hearts. Thus, the aim of this study was to evaluate the benefits-risks balance of E3G consumption in the setting of ion channel mutations linked with aberrant cardiac excitability phenotypes. Two gain-of-function mutations, Nav1.5-p.R222Q and Nav1.5-p.I141V, which are linked with cardiac hyperexcitability phenotypes were studied. Computer simulations of action potentials (APs) show that 30 µM E3G reduces and suppresses AP abnormalities characteristics of these phenotypes. These results suggest that E3G may have a beneficial effect in the setting of cardiac sodium channelopathies displaying a hyperexcitability phenotype.

Surface Modification of Halogenated Polymers. 7. Local Reduction of Poly(tetrafluoroethylene) and Poly(chlorotrifluoroethylene) by a Scanning Electrochemical Microscope in the Feedback Mode.

Fluoropolymers have been reduced locally by the radical anion of a redox mediator electrogenerated at a microelectrode operating in the configuration of a scanning electrochemical microscope. Approach curves with different redox mediators were used to investigate the reduction mechanism of the fluoropolymer. Different factors are discussed, such as the monomer reduction mechanism, the kinetic control by the surface modification growth, and the conductivity of the modified surface. The fluoropolymers' reduction parallels the trends observed in organic electrochemistry in solution within the haloalkane series.