Feasibility of silicon nanoparticles produced by fast-rate plasma spray PVD for high density lithium-ion storage

Abstract

Si nanoparticles with the averaged primary particle size ranging from 20 to 175 nm have been produced by plasma spray physical vapor deposition (PS-PVD) at different powder feed rates from 0.6 to 25.4 g min−1. High-order agglomerates as large as 10 µm are found to form especially at low powder feed rate, while such large agglomerates are suppressed when the particle size becomes greater than 100 nm at high powder feed rate. The electrochemical cells using Si nanoparticles smaller than 100 nm retain relatively high capacity with reasonable cycle stability, while the capacity drops rapidly for the cells with Si greater than 100 nm due partly to an increased charge transfer resistance. Moreover, ultrasonic particle breakup reveals that absence of large agglomerates as large as 10 µm are beneficial in reducing the charge-transfer resistance and in improving the cycle stability. Although oxygen content increases with decreasing the particle size, slow oxidation upon collection of the particles after PS-PVD successfully suppresses excessive oxidation, leading to negligible influence on the initial efficiency.

Influence of structural characteristics of a Si nanoparticulate anode on all-solid-state Li-ion batteries

“…Four types of Si nanoparticles (SN-1, SN-2, SN-3, and SN-4) were synthesized by PS-PVD using the hybrid plasma spraying system. The inductively-coupled plasma is generated with unique DC and RF torch [40], which is advantageous in the efficient heating and evaporation of injected powder feedstock especially at high throughput process condition [28,37,40,41]. The plasma conditions were selected referring to the previous work and confirmed to be optimal for the production of Si nanoparticles.…”

“…The plasma conditions were selected referring to the previous work and confirmed to be optimal for the production of Si nanoparticles. Details of the PS-PVD conditions can be found elsewhere [28,37]. Metallurgical grade Si (mg-Si) powders (99.7%, 16 µm) were used as raw material and injected into the plasma at a fixed rate by the powder feeder (TWIN10, Sulzer Metco).…”

“…In fact, Yamamoto et al reported that the segregation of oxygen-rich phases at the boundary between Si and SE after cycles [27]. Especially in the case of Si nanoparticle, the surface of silicon particle is easily oxidized, and the oxygen content inevitably increases due to its large specific surface area [28]. The initial coulombic efficiency (ICE) and the discharge capacity are therefore reduced for nanoparticle appreciably as lithium is consumed to form irreversible phases, such as lithium oxide and lithium silicate [29,30].…”

“…Plasma spraying physical vapor deposition (PS-PVD) is widely employed for production of nanoparticles and nanoparticulate materials at the industrial compatible throughputs from a powder source [33][34][35]. Our previous reports show that a variety of Si nanocomposite particles are produced by PS-PVD by tuning the powder feeding rates and the cooling conditions, and demonstrate the improvements in cycle performance using these Si nanoparticle in half-cells with liquid electrolyte [28,36,37]. Furthermore, composite Si/SiO x nanoparticles with varied oxygen contents are synthesized with PS-PVD from silicon monoxide (SiO) raw powder feedstock, and the improved cycle capacity and the stable cyclability for long cycles are simultaneously attained [38,39].…”

A novel self-separating silicon nanowire thin film and application in lithium-ion batteries

“…Owing to their unique and stable properties [1][2][3][4], nano silicon structures are promising materials in various applications, such as photoelectric conversion [5][6][7][8][9][10][11], thermoelectric conversion [12], and lithium-ion batteries [13]. They can be prepared using physical vapour deposition [14], chemical vapour deposition [15], laser ablation [16], thermal evaporation [17], molecular beam epitaxy [18], or chemical etching [11]. Among these methods, the metal-assisted chemical etching (MACE) has been widely used to fabricate nano silicon structures owing to its simplicity and lower cost [19][20][21][22][23].…”