Search Results (3)

The aim of this work was to study the purification of silicon kerf loss waste (KLW) by a combination of single-acid leaching followed by inductive melting at high temperatures with an addition of fluidized bed reactor (FBR) silicon granules. The KLW indicated an average particle size (D50) of approximately 1.6 µm, and a BET surface area of 30.4 m²/g. Acid leaching by 1 M HCl indicated significant removal of impurities such as Ni (77%), Fe (91%) and P (75%). The combined two-stage treatment resulted in significant removal of the major impurities: Al (78%), Ni (79%), Ca (85%), P (92%) and Fe (99%). The general material loss during melting decreased with an increasing amount of FBR silicon granules which aided in the melting process and indicated better melting. It was observed that the melting behavior of the samples improved as the temperature increased, with complete melting being observed throughout the crucibles at the highest temperature (1800 °C) used, even without any additives. At lower temperatures (1600 °C–1700 °C) and lower FBR-Si (<30 wt.%) additions, the melting was incomplete, with patches of molten silicon and a lot of surface oxidation as confirmed by both visual observation and electron microscopy. In addition, it was indicated that more reactive and volatile elements (Ga, Mg and P) compared to silicon are partially removed in the melting process (51–87%), while the less reactive elements end up in the final silicon melt. It was concluded that if optimized, the combined treatment of single-acid leaching and inductive melting with the addition of granular FBR silicon has great potential for the recycling of KLW to solar cells and similar applications. Moreover, the application of higher melting temperatures is accompanied by a higher silicon yield of the process, and the involved mechanisms are presented. Full article

The recovery of massive kerf loss silicon waste into silicon anodes is an attractive approach to efficiently utilizing resources and protect the environment. Tens-of-nanometers-scale-thickness Si waste particles enable the high feasibility of high-rate Li-ion storage, but continuous oxidation leads to a gradual loss of electrochemical activity. Understanding the relationship between this oxidation and Li-ion storage properties is key to efficiently recovering silicon wastes into silicon anodes. However, corresponding research is rare. Herein, a series of silicon waste samples with different oxidation states were synthesized and their Li-ion storage characters were investigated. By analyzing their Li-ion storage properties and kinetics, we found that oxidation has absolutely detrimental effects on Li-ion storage performance, which is different to previously reported results of nano-silicon materials. The 2.5 wt.% Si provides a substantial initial discharge capacity of 3519 mAh/g at 0.5 A/g. The capacity retention of 2.5 wt.% Si is almost 70% after 500 cycles at 1 A/g. However, the 35.8 wt.% Si presents a modest initial discharge capacity of merely 170 mAh/g. Additionally, oxidation leads the Li-ion storage kinetics to transform from Li-ion diffusion-controlled to charge transfer-controlled behaviors. For kerf loss silicon waste with an oxygen content over 35.8 wt.%, Li-ion storage capability is lost due to a high charge transfer resistance and a low Li-ion diffusion coefficient. Full article

Silicon is considered to have significant potential for anode materials in lithium–ion batteries (LIBs) with a theoretical specific capacity of 4200 mAh g⁻¹. However, the development of commercial applications is impacted by the volume shift that happens in silicon when charging and discharging. In this paper, a yolk–shell–structured Si@void@C anode material has been developed to address this problem. The silicon nanoparticle yolk material is obtained by recycling kerf loss (KL) Si waste from the process of slicing silicon block casts into wafers in the photovoltaic industry; the carbon shell is prepared by a hydrothermal method with glucose, and the sacrificial interlayer is Al₂O₃. The produced material is employed in the production of anodes, exhibiting a reversible capacity of 836 mAh g⁻¹ at 0.1 A g⁻¹ after 100 cycles, accompanied by a Coulomb efficiency of 71.4%. This study demonstrates an economical way of transforming KL Si waste into materials with an enhanced value for LIBs. Full article