Quantifying gas generation from slurries used in fabrication of Si-containing electrodes for lithium-ion cells

The high capacity of silicon motivates its use as anode material for Li-ion batteries. While such Si-based electrodes are typically processed from aqueous slurries, elemental silicon is highly susceptible to hydrolysis, yielding flammable hydrogen gas as a byproduct. This gassing can present numerous safety and quality concerns for scaling up of the production. In this study we describe a method to quantify the volume of gases generated using the Archimedes principle. We show that the gas volumes are affected by various factors, which include the characteristics of the electrode slurry and attributes (particle size, surface coatings) of the silicon powders. A catalytic effect on gas evolution is observed when a lithiated polycarboxylate binder is present in the solution. On the other hand, negligible gas generation is observed in electrode slurries containing the N-methyl-2-pyrrolidone (NMP) solvent, which could be considered as an alternative to the water-based processes presently under consideration. Our study can be used as a guide for the development of slurry mixtures that can mitigate the safety concerns associated with the silicon-electrode fabrication process.