No abstract

Silicon nanoparticles (Si-NPs) have been produced by plasma spray physical vapor deposition at throughput as high as 1 kg h−1 (17 g min−1) and the effect on the battery performance is investigated. When the Si powder feed-rate is changed from 1 to 17 g min−1, although the average primary particle size increases to 50 nm, the cycle capacity of the batteries using these Si-NPs is improved slightly owing to their less agglomerated structure. In contrast, when Ni is added to Si feedstock, the cycle capacity is improved at 1 g min−1 due to modified Si-NP structure having SiNi2 interface. Whereas, the batteries with the Si-NP produced at 17 g min−1 shows significant decrease in the cycle capacity because of the excess Ni silicide formation that is resulted from the elevated co-condensation point and the increased reaction area at high throughputs despite the constant Ni concentration in the feedstock.

Nanocomposite SiOx particles have been produced by a single step plasma spray physical vapor deposition (PS-PVD) through rapid condensation of SiO vapors and the subsequent disproportionation reaction. Core-shell nanoparticles, in which 15 nm crystalline Si is embedded within the amorphous SiOx matrix, form under typical PS-PVD conditions, while 10 nm amorphous particles are formed when processed with an increased degree of non-equilibrium effect. Addition of CH4 promotes reduction in the oxygen content x of SiOx, and thereby increases the Si volume in a nanocomposite particle. As a result, core-shell nanoparticles with x = 0.46 as anode exhibit increased initial efficiency and the capacity of lithium ion batteries while maintaining cyclability. Furthermore, it is revealed that the disproportionation reaction of SiO is promoted in nanosized particles attaining increased Si diffusivity by two orders of magnitude compared to that in bulk, which facilitates instantaneous composite nanoparticle formation during PS-PVD.

We derive the non-Maxwellian distribution of self-gravitating N-body systems around the core by a model based on the random process with the additive and the multiplicative noise. The number density can be obtained through the steady state solution of the Fokker-Planck equation corresponding to the random process. We exhibit that the number density becomes equal to that of the King model around the core by adjusting the friction coefficient and the intensity of the multiplicative noise. We also show that our model can be applied in the system which has a heavier particle. Moreover, we confirm the validity of our model by comparing with our numerical simulation.How relevant is the equilibrium statistical mechanics when we describe the steady state of a self-gravitating system (SGS) where many particles interact via the gravitational force? Let's assume that the state of the SGS with equal mass m becomes isothermal with temperature T and the particles of the system will be distributed spherically symmetrically. Then, the structure in the phase space can be determined by the Maxwell-Boltzmann distribution. For example, the number density at a radial distance r in the real space iswhere Φ(r) is the mean gravitational potential per mass generated by this whole system at r and k B is the Boltzmann constant. This potential should satisfy a relation with the number density by the Poisson equation △Φ(r) = 4πGmn MB (r) where G is the gravitational constant. A special solution of eq.(1) and this Poisson equation is n MB (r) = k B T /2πGm 2 r 2 known as the singular isothermal sphere. 1) This solution has *