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This article introduces a continuous, gas-phase method for depositing thin metallic coatings onto (nano)particles using a type of physical vapor deposition (PVD) at ambient pressure and temperature. An aerosol of core particles is mixed with a metal vapor cloud formed by spark ablation by passing the aerosol through the spark zone using a hollow electrode configuration. The mixing process rapidly quenches the vapor, which condenses onto the core particles at a timescale of several tens of milliseconds in a manner that can be modeled as bimodal coagulation. Gold was deposited onto core nanoparticles consisting of silver or polystyrene latex, and silver was deposited onto gold nanoparticles. The coating morphology depends on the relative surface energies of the core and coating materials, similar to the growth mechanisms known for thin films: a coating made of a substance having a high surface energy typically results in a patchy coverage, while a coating material with a low surface energy will normally “wet” the surface of a core particle. The coated particles remain gas-borne, allowing further processing., ChemE/Chemical Engineering, Applied Sciences

This article introduces a continuous, gas-phase method for depositing thin metallic coatings onto (nano)particles using a type of physical vapor deposition (PVD) at ambient pressure and temperature. An aerosol of core particles is mixed with a metal vapor cloud formed by spark ablation by passing the aerosol through the spark zone using a hollow electrode configuration. The mixing process rapidly quenches the vapor, which condenses onto the core particles at a timescale of several tens of milliseconds in a manner that can be modeled as bimodal coagulation. Gold was deposited onto core nanoparticles consisting of silver or polystyrene latex, and silver was deposited onto gold nanoparticles. The coating morphology depends on the relative surface energies of the core and coating materials, similar to the growth mechanisms known for thin films: a coating made of a substance having a high surface energy typically results in a patchy coverage, while a coating material with a low surface energy will normally “wet” the surface of a core particle. The coated particles remain gas-borne, allowing further processing., ChemE/Chemical Engineering, Applied Sciences

Aerospace Structures and Materials, Aerospace Engineering

Aerospace Structures and Materials, Aerospace Engineering

ChemE/Chemical Engineering, Applied Sciences

ChemE/Chemical Engineering, Applied Sciences

This PhD thesis focuses on the synthesis of nanostructured materials via an aerosol-assisted route based on electrospraying of liquid precursors. Electrospraying is a powerful technique for the production of nearly-monodispersed, highly-charged droplets. The possibility of tailoring the droplet size, as well as coupling the process to different chemical reactions makes this technique attractive for the production of a wide variety of nanostructured functional materials in a simple, direct and cost-effective way. The materials investigated in this work are directly related to applications in advanced Li-ion battery negative electrodes. The electrospray process has been implemented in two novel approaches for the production of different materials. The first one consists in the production of nanoparticles via an alternative method that combines charged aerosols with red-ox reactions in liquids, while the second one develops a single-step process for complete synthesis and assembly of nanocomposite coated electrodes by pyrolysis and/or deposition of precursor solutions and suspensions. In this way advanced negative electrodes containing active nanoparticles dispersed in polymer binders have been directly fabricated in one step at relatively low temperature without any further processing. The resulting materials show enhanced electrochemical performances and could replace graphite in commercial electrodes, due to their high capacities. It should be stressed that this approach is extremely general and it has the potential to be implemented in a roll-to-roll process for the continuous production of nanocomposite coatings for various purposes, not necessarily restricted to Li-ion batteries., Chem E, Applied Sciences

ChemE/Chemical Engineering, Applied Sciences

ChemE/Chemical Engineering, Applied Sciences

This PhD thesis focuses on the synthesis of nanostructured materials via an aerosol-assisted route based on electrospraying of liquid precursors. Electrospraying is a powerful technique for the production of nearly-monodispersed, highly-charged droplets. The possibility of tailoring the droplet size, as well as coupling the process to different chemical reactions makes this technique attractive for the production of a wide variety of nanostructured functional materials in a simple, direct and cost-effective way. The materials investigated in this work are directly related to applications in advanced Li-ion battery negative electrodes. The electrospray process has been implemented in two novel approaches for the production of different materials. The first one consists in the production of nanoparticles via an alternative method that combines charged aerosols with red-ox reactions in liquids, while the second one develops a single-step process for complete synthesis and assembly of nanocomposite coated electrodes by pyrolysis and/or deposition of precursor solutions and suspensions. In this way advanced negative electrodes containing active nanoparticles dispersed in polymer binders have been directly fabricated in one step at relatively low temperature without any further processing. The resulting materials show enhanced electrochemical performances and could replace graphite in commercial electrodes, due to their high capacities. It should be stressed that this approach is extremely general and it has the potential to be implemented in a roll-to-roll process for the continuous production of nanocomposite coatings for various purposes, not necessarily restricted to Li-ion batteries., Chem E, Applied Sciences