Silicon nano-particle based electrodes are attractive for implementation in lithium ion batteries due to the improvement in specific capacity over the currently used graphite based electrodes. Here we investigate polyacrylic acid (PAA) and lithium polyacrylate (Li-PAA) polymer binders' role in the electrochemical performance of silicon nanoparticle based electrodes. The binders are evaluated in comparison to sodium carboxymethyl cellulose (Na-CMC), and polyether imide (PEI). Large variations in the cumulative irreversible capacity is observed for the different binders after 20 cycles while limiting the alloying capacity to 1000 mA h g −1 . Coulombic efficiencies at the first cycle and upon cycling are optimized for PAA and Li-PAA binders considering the binder proportion and the molecular weight. Coulombic efficiencies greater than 99% are obtained after 5 cycles. In depth physico-chemical characterizations of the binders, electrode slurries, and electrodes are performed. From these characterizations the polymers' mechanical properties, binder partitioning in the electrode, and binder interactions with the silicon particles are elucidated. Through correlation of these results with electrochemical performance, the basis for PAA and Li-PAA binders' behavior is proposed in silicon nano-particle electrodes.

The H 2 bubbles resulting from the reaction of freshly prepared Si powders with water were found to impede the large-scale preparation of aqueous-based Si/CMC (Na-Carboxy-Methyl-Cellulose)/C slurries and could consequently prevent the large-scale production of composite electrode films. To understand and possibly control this reaction, silicon particles (Si ref ) have been partially oxidized either by contact with water or by air heating at elevated temperatures. By coupling kinetics, XRD, (HR)TEM/EELS, TGA/DSC, IR and gas adsorption data, the porosity/texture/surface chemistry of the resulting silica-based coating layers were found to be highly dependent on the oxidation process, while the extent of oxidation is tuned by the time-temperature of the treatment. Although fully oxidized samples are totally inactive vs. Li, the high porosity of the water-formed silica coating contrasts with the dense air-formed one that can limit access to the Si core and can block its reactivity if too thick. Controlled and optimized air-oxidative pre-treatments can prevent the H 2 evolution during the slurry preparation, hence enabling the reproducible production of high-quality electrode coatings on Cu current collectors. Such treatments do not impact the reversibility of the Si-Li electrochemical reaction, even with no capacity constraints and with or without FEC addition in commercial EC/DMC/LiPF 6 electrolytes.