High throughput production of nanocomposite SiO_xpowders by plasma spray physical vapor deposition for negative electrode of lithium ion batteries

Abstract

Nanocomposite Si/SiOx powders were produced by plasma spray physical vapor deposition (PS-PVD) at a material throughput of 480 g h−1. The powders are fundamentally an aggregate of primary ∼20 nm particles, which are composed of a crystalline Si core and SiOx shell structure. This is made possible by complete evaporation of raw SiO powders and subsequent rapid condensation of high temperature SiOx vapors, followed by disproportionation reaction of nucleated SiOx nanoparticles. When CH4 was additionally introduced to the PS-PVD, the volume of the core Si increases while reducing potentially the SiOx shell thickness as a result of the enhanced SiO reduction, although an unfavorable SiC phase emerges when the C/Si molar ratio is greater than 1. As a result of the increased amount of Si active material and reduced source for irreversible capacity, half-cell batteries made of PS-PVD powders with C/Si = 0.25 have exhibited improved initial efficiency and maintenance of capacity as high as 1000 mAh g−1 after 100 cycles at the same time.

Nano-composite Si particle formation by plasma spraying for negative electrode of Li ion batteries

“…9 In fact, this process has already been successfully applied to film deposition and/or nano-powder production via the vapor phase of various materials. [9][10][11][12] In this work, metallurgical grade silicon powders with a mean diameter of approximately 19 lm were used as raw feedstock. The powders were fed into the plasma from the top of the DC plasma torch at rates in the range of 1-6 g/min.…”

“…12. Change in the charge (CH) and discharge (DCH) gravimetric capacity (per gram of all anode material) with a cycle for batteries using PS-PVD powders with different C/Si molar ratios.…”

Dual-Size Silicon Nanocrystal-Embedded SiOx Nanocomposite as a High-Capacity Lithium Storage Material

“…Homma et al developed a SiO x nanocomposite using plasma sprayÀphysical vapor deposition (PSÀPVD) that showed a high reversible capacity of about 1770 mAh g À1 B with good cycle performance. 17 A Si/SiO x nanocomposite was also prepared and adopted as a constituent in an anode blended with graphite in some commercial LIBs by another group of researchers. 18 However, the practical use of these materials is still limited by their high production cost, because the fabrication of Si/SiO x nanocomposites requires both ultrahigh vacuum conditions and temperatures greater than 1400°C.…”

Instantaneous formation of SiOx nanocomposite for high capacity lithium ion batteries by enhanced disproportionation reaction during plasma spray physical vapor deposition

“…For comparison, CH 4 gas is also added at a fixed molar ratio of C/Si = 0.25, at which no SiC phase was detected in the previous work. [27]…”

“…SiO-NP produced by PS-PVD in industry compatible high-throughput production using metallurgy grade SiO raw powders have shown a clear increase in capacity while maintaining cyclability. [27] This characteristic process of PS-PVD further implies that the SiO-NP structure can be modified by tuning the cooling history during co-condensation of SiO-CH 4 vapor mixtures. Especially with large non-equilibrium effect by rapid gas quenching, together with CH 4 addition, a-Si core structure is expected to form by low temperature disproportionation reaction in smaller SiO-NP with reduced oxygen content.…”