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Abstract A facile method is proposed to prepare Si nanoparticles encapsulated in polymeric carbon (SiNPs-PC) as anode materials for lithium ion batteries. Si nanoparticles (SiNPs) with average diameter of 125 nm are prepared. Under the aid of silane coupling agent, SiNPs are coated with phenolic resin, and SiNPs-PC composite is prepared after carbonization engineering. The SiNPs-PC anode with 63.7 wt% of Si exhibits greatly strengthened electronic conductivity and relatively stable electrode interface. The SiNPs-PC anode delivers a reversible capacity of 984 mA h g−1 with 84% capacity retention after 100 cycles at a current density of 0.1 A g−1 and 710 mA h g−1 after 800 cycles at a current density of 1 A g−1. When cycled at a very larger current density of 10 A g−1, a decent reversible capacity of 404 mA h g−1 can be harvested, which is still higher than the theoretical capacity of commercial graphite anode. The electrochemical performances are systematically discussed on microstructure and morphology of electrode materials. The feedstock of SiNPs is recycled from waste Si, and the preparation of SiNPs-PC composite is facile, cost-effective and environmentally benign, which shows great potential of industrial production. [ABSTRACT FROM AUTHOR]

Highlights • Residual Si is recycled to prepare Si-SiO x nanoparticles. • Si-SiO x nanoparticles as anode materials have good electrochemical performances. • Water is a key role to obtain Si-SiO x nanoparticles. • Deposition pattern of residual Si agrees with model of three-dimension growth. Abstract Residual Si was produced on a furnace wall when upgraded metallurgical grade Si was refined by electron beam melting. It was then recycled to prepare Si-SiO x nanoparticles with an average size of 100 nm by planetary ball milling. The obtained Si-SiO x nanoparticles mainly consist of amorphous Si, crystalline Si and amorphous SiO x , which was confirmed by XRD, FTIR, XPS and TEM. SiO x is mainly composed of SiO 2 and SiO 1.35. Distilled water used as a grinding aid not only enhances milling efficiency, but also plays a key role in obtaining SiO x. During refining of upgraded metallurgical grade Si, the deposition pattern of residual Si on furnace wall agrees with model of three-dimension growth. Growth of Si-SiO x nanoparticles is the mutual effect of distilled water and ball milling. Si-SiO x nanoparticles were doped into phenolic resin pyrolysis carbon as anode materials for lithium ion batteries, and 10% doping was observed to improve the specific capacity. After 500 cycles, specific capacity of delithiation remained around 550 mA h/g. It suggests the residual Si is a value-added by-product, and it can be recycled as anode materials for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Corrosion behavior of crystalline silicon (C-Si) solar cells was investigated. For this purpose, three groups of cells were conducted with three kinds of aging test which cells setting in indoor environment (25 °C, 45% RH, 0– 2 months), cells immersing in moisture atmosphere (25 °C, 85% RH, 0– 240 h) and cells immersing in acetic acid atmosphere (25 °C, 85% RH, 0– 240 h). Subsequently the microstructure characteristic of the alumina paste layer (APL), rear electrode and soldered connection of cells and the corrosion production during aging test were analyzed and compared. The results show that the smooth oxide coating and looser structure were found in the APL of cell after aging test. In addition the discoloration and elements diffusion were found on the rear electrode. And the corrosion region expanded gradually from the edge to the center of soldered connection along the interface between Ag electrode and Sn 37 Pb alloy. Thereafter, a model was put forward to try to explain the degradation mechanism of traditional photovoltaic (PV) modules during damp-heat (DH) test based on corrosion behavior of C-Si cells in this experiment. [ABSTRACT FROM AUTHOR]

The mass transfer behavior of vapor silicon (Si) and volatile impurities during refining of Si by electron beam melting is still unclear. In present work, with gas flow guidance, the mass transfer mechanism of vapor Si and volatile impurities, and corresponding heat transfer rule in the furnace chamber are investigated by simulation and experiment. Numerical simulation shows that vapor Si is preferentially transferred to the outlet, and temperature in the outlet is lower than the solidification temperature of vapor Si when gas flow is fixed at 0° and 1.16 m s−1 (optimal conditions). Experimental results show that volatile impurities are effectively removed (P and Al both are less than 0.01 ppmw in the refined Si ingot with >99% of removal efficiency). Moreover, volatile impurities flux positively increases with increase of vapor Si flux. Gas flow significantly gathers the vapor Si in the outlet, reinforcing evaporation kinetics of molten Si and volatile impurities, which demonstrates the numerical simulation model is feasible to control the mass transfer and evaporation kinetics. Gas flow guidance may be a promising way to improve volatile impurities removal from Si. Image 1 • Gas flow guidance is a promising method to control mass transfer of vapor Si/volatile impurities. • The optimal conditions for argon guide vapor Si/volatile impurities are 0° and 1.16 m s−1. • Volatile impurities flux positively increases with vapor Si flux. [ABSTRACT FROM AUTHOR]

A purification method using copper (Cu) alloying and CaO–SiO 2 –CaCl 2 slag treatment had been studied in connection with the purification of metallurgical grade silicon (MG-Si). The principle of this method was that low-purity MG-Si alloyed with Cu to form Si–Cu alloy phase, and then the Si–Cu alloy was treated using CaO–SiO 2 –CaCl 2 slag to remove impurities. Finally, selective acid leaching was applied to remove the Si–Cu alloy phase, whereupon high-purity silicon could be recovered from the Si–Cu alloy. Effects of slag composition and Cu content on the removal of boron (B) and phosphorus (P) were also investigated. When the Si–50 wt% Cu alloy treated with 45 wt% CaO–45 wt% SiO 2 –10 wt% CaCl 2 slag for 30 min at 1550 °C, the final concentrations of B and P in the purified Si decreased from 3.12 to 0.35 ppmw and 17.14 to 7.27 ppmw, respectively. Furthermore, the corresponding removal mechanism was investigated. It was found that the reaction kinetics followed a first-order rate law with respect to B and P, and were controlled by mass transfer with mass transfer coefficients of 6.25 × 10 −4 cm s −1 and 2.55 × 10 −4 cm s −1 , respectively. [ABSTRACT FROM AUTHOR]

The effect of hydrogen peroxide as a novel oxidizing agent on purifying metallurgical grade silicon (MG-Si) by leaching with hydrofluoric acid was investigated as a function of temperature, leaching duration, stirring and hydrofluoric acid concentration. It was found that adding oxidizing agent resulted in enhancing the extraction of impurities from MG-Si as compared to that without oxidizing agent, especially for some non-dissolving elements in the acid like copper. After 2 h of leaching MG-Si with an acid mixture composed of 1 mol L − 1 hydrofluoric acid and 2 mol L − 1 hydrogen peroxide, the purity of MG-Si increased from 99.74 to 99.99%, which was higher than 99.97% obtained without hydrogen peroxide addition. Based on cracking shrinking model, the leaching MG-Si with the mixture was under chemical reaction control. Furthermore, to investigate the reaction mechanism on leaching MG-Si, the micro-structural evolutions of MG-Si before and after exposure to each etchants were revealed. [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) are promising materials for next‐generation lithium‐ion batteries while the lithium storage and cycling stability of TMOs are still limited. Herein, a novel Co3O4/MnO2/C composite using metal‐organic frameworks (MOFs) as sacrificial templates is reported. MnO2 and C shells are layer by layer coated on the MOF‐derived Co3O4/C samples via hydrothermal technique and heat treatment. When employed as anode materials for LIBs, the hierarchically heterostructured Co3O4/MnO2/C composites incorporate the merits of Co3O4, MnO2, and C, showing high Li storage performances at a current density of 0.2 A g−1 with an initial capacity of ∼1245.7 mAh g−1 and a reversible capacity of ∼854.9 mAh g−1 after 100 cycles, remarkable cycling stability, and excellent rate capability (almost 98 % recovery as the current density returns to the initial 0.2 A g−1, and especially, the specific capacity remains ∼587.6 mAh g−1 at a high current density of 2.0 A g−1). [ABSTRACT FROM AUTHOR]

Combination chemotherapy is widely exploited for suppressing drug resistance and achieving synergistic anticancer efficacy in the clinic. In this paper, the nanostructured targeting methotrexate (MTX) plus pemetrexed (PMX) chitosan nanoparticles (CNPs) were developed by modifying methoxy polye (thylene glycol) (mPEG), in which PEGylation CNPs was used as stealth nanocarriers (PCNPs) and MTX was employed as a targeting ligand and chemotherapeutic agent as well. Studies were undertaken on human lung adenocarcinoma epithelial (A549) and Lewis lung carcinoma (LLC) cell lines, revealing the anti-tumor efficacy of nanoparticle drug delivery system. The co-delivery nanoparticles (MTX-PMX-PCNPs) had well-dispersed with sustained release behavior. Cell counting kit-8 (CCK8) has been used to measure A549 cell viability and the research showed that MTX-PMX-PCNPs were much more effective than free drugs when it came to the inhibition of growth and proliferation. Cell cycle assay by flow cytometry manifested that the MTX-PMX-PCNPs exhibited stronger intracellular taken up ability than free drugs at the same concentration. In vivo anticancer effect results indicated that MTX-PMX-PCNPs exhibited a significantly prolong blood circulation, more tumoral location accumulation, and resulted in a robust synergistic anticancer efficacy in lung cancer in mice. The results clearly demonstrated that such unique synergistic anticancer efficacy of co-delivery of MTX and PMX via stealth nanocarriers, providing a prospective strategy for lung cancer treatment. [ABSTRACT FROM AUTHOR]

Metallurgical grade silicon was purified through solvent refining method by adding tin to the Si–Al alloy. The distribution of phosphorus and metallic impurities in the resulting Si–Al–Sn melts was investigated. Compared with the primary Si and the eutectic αAl+Si, the phosphorus and metallic impurities were more distinctly distributed in the βSn phase, which was always accompanied by needle-like intermetallic β-Al 5 SiFe compounds. To improve the phosphorus and metallic impurity removal ratios, Si–Al–Sn ternary alloys with different composition were investigated. The phosphorus removal ratio increased with the aluminum and tin content in the Si–Al–Sn ternary alloy. Compared to increasing the Al content and keeping the Si/Sn ratio fixed, the impurity removal ratios were higher when the Sn content was increased to the same mass percentage and the Si/Al ratio was kept fixed in the Si–Al–Sn melt. [ABSTRACT FROM AUTHOR]

Impurity removal from metallurgical grade silicon (MG-Si) is an important issue for solar-grade silicon production, and solvent refining is used as an effective method to purify silicon. To evaluate the purification ability of solvent refining with Si Cu melt at 1343–1603 K, the effective segregation ratio of the main impurity element Fe between solid Si and Si Cu melt was experimentally and theoretically determined. The results demonstrated that the effective segregation ratio of Fe increased with the increasing temperature at the range of 1343–1603 K. The corresponding removal mechanism of Fe was investigated in detail. It was found that the effective segregation ratio of Fe calculated by Scheil equation presented the same tendency with experimental results, and the theoretical calculation was more consistent with experimental results when back diffusion was considered. Moreover, Fe was found to form Si Fe Mn and Fe Mn Ti phases into Si Cu alloy phase from MG-Si with the presence of Cu. It can be concluded that removal mechanism of Fe was not only a segregation process, but also a recombining process of impurity phase transformation. [ABSTRACT FROM AUTHOR]

A numerical model is proposed to investigate influences of process parameters, including crucible pulling down rates and heater temperature, on crystal growth rates for silicon purification by vacuum directional solidification. The crystal growth rates of a silicon ingot are analyzed based on the interface energy balance equation combining with the temperature field calculated by software of ProCAST, and the segregation behavior of impurities is investigated with the Scheil's equation. The results show that the crystal growth rates decrease linearly with the increase of heater temperature at a fixed value of the crucible pulling down rate, and increase exponentially with the increase of the crucible pulling down rates at a fixed value of the heater temperature. The numerical model is verified by removal of iron impurity from 300 ppmw to 1 ppmw and by the temperature of melt silicon which is recorded by a thermocouple. The results show that numerical results agree well with experimental results. This research is used for adjusting process parameters to control crystal growth during silicon purification by directional solidification. [ABSTRACT FROM AUTHOR]