Y. Glukhoy
Nanocoating Plasma Systems Inc,
United States
Keywords: 3D printing, Li-ion battery, plasma, discharge, beam
Summary:
Silicon anodes are able to make an impact for high-energy storage technologies due to ultrahigh theoretical specific capacity 3579 mA h g−1 However, the mechanical stress induced by Si expansion upon alloying with Li-ions causes pulverization, capacity loss and rupture of Solid Electrolyte Interphase on Si surface, contributing electrolyte depletion. the Fabrication the large-format Si anodes is complicated by fundamental limitations to scalability because of absence of environmentally -friendly technology and equipment. Nanocoating Plasma Systems Inc (NPS) specializing in the plasma beam printing technology choses the strategy to reduce particle size in the nanoscale regime. Well-nanosized silicon nanoparticles (SiNP) have a variety of merits such as shortened lengths for Li+ diffusion/electron mobility (high-power ability) and enhanced electrode/electrolyte interface area (high capacity). NPS has developed the 3D plasma beam printer where the commercial SiNPs are vaporized in the axial high-temperature atmospheric Inductively Coupled Plasma (ICP) discharge to print the 3D architecture of the Si anode. Because this powder is subjected to agglomeration, therefore, before injection into the ICP torch it should be de-aggregated through negative charging in the atmospheric Dielectric Barrier Discharge (DBD). Next strategy is the 3D alienated structure fabricated through the Si lamination of carbon nanofibers (CNF) in the fly, It is provided through the injection of CNFs into the ICP plasma beam saturated by Si vapor droplets. As a core CNF provides free space to load the high capacity SiNP shell , alleviate their volume expansion, promote electron transfer, and maintain the structural stability of anode during cycling. This Si shell may suffer exfoliation during lithiation/de-lithiation. Therefore, the surface of CNF is pre-heated for adhesion. Also, SiNP should be bound to this surface by the Si thin film. Therefore, CNFs are injected initially into the surrounding axial ICP atmospheric ICP torus-like torch. After circulation in this torus torch CNFs are injected tangentially into the axial beam. But the Si thin-film deposition is provided through a high-temperature dissociation of silane (SiH4) Injected into the axial torch simultaneously with SiNP. The Si/CNF composites are fabricated in the fly in the reactor with a saturated by Si vapor and droplets high-temperature plasma beam. Nozzle at the end of the reactor with the orifice and with the grounded extractor in proximity to this orifice comprise the plasma gun focusing the ejected plasma beam on the current collector. Carrying Si/CNFs this beam builds up the 3D lattice architecture. The resilient arrays of this lattice withstand stresses and redirect swelling laterally into the intervals. This architecture provides the high surface area, offering more lithium insertion channels and pathways for fast diffusion of Li-ions and good accommodation of strain induced by repeated lithiation/delithiation.