A new method for fabricating ordered porous silicon is reported. A two-dimensional silica nanosphere array is used as a template with a hydrofluoric acid-hydrogen peroxide solution for etching the nanospheres. The ini...A new method for fabricating ordered porous silicon is reported. A two-dimensional silica nanosphere array is used as a template with a hydrofluoric acid-hydrogen peroxide solution for etching the nanospheres. The initial diameter and distribution of the holes in the resulting porous silicon layer are determined by the size and distribution of the silica nanospheres. The corrosion time can be used to control the depths of the holes. It is found that the presence of a SiO2 layer, formed by the oxidation of the rough internal surface of the hole, is the primary reason allowing the corrosion to proceed. Ultraviolet reflection and thermal conductivity measurements show that the diameter and distribution of the holes have a great influence on properties of the porous silicon.展开更多
Earth abundant and economical rock salt （NaC1） particles of different sizes （〈3 μm and 5-20 μm） prepared by high energy mechanical milling were used as water-soluble templates for generation of Si with novel na...Earth abundant and economical rock salt （NaC1） particles of different sizes （〈3 μm and 5-20 μm） prepared by high energy mechanical milling were used as water-soluble templates for generation of Si with novel nanoscale architectures via low pressure chemical vapor deposition （LPCVD）. Si nanoflakes （SiNF） comprising largely amorphous Si （a-Si） with a small volume fraction of nanocrystalline Si （nc-Si）, and Si nanorods （SiNR） composed of a larger volume fraction of crystalline Si （c-Si） and a small volume fraction of a-Si resulted from modification of the NaCI crystals. SiNF yielded first-cycle discharge and charge capacities of -2,830 and 2,175 mAh.g-1, respective134 at a current rate of 50 mA.g-1 with a first-cycle irreversible loss （FIR loss） of -15%-20%. SiNR displayed first-cycle discharge and charge capacities of -2,980 and -2,500 mAh-g-1, respectively, at a current rate of 50 mA-g-1 with an FIR loss of -12%-15%. However, at a current rate of 1 A.g-1, SiNF exhibited a stable discharge capacity of -810 mAh-g-1 at the end of 250 cycles with a fade rate of -0.11% loss per cycle, while SiNR showed a stable specific discharge capacity of -740 mAh.g-1 with a fade rate of -0.23% loss per cycle. The morphology of the nanostructures and compositions of the different phases/phase of Si influence the performance of SiNF and SINK, making them attractive anodes for lithium-ion batteries.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10804026 and 51101049the Natural Science Foundation of Hebei Province under Grant Nos A2013205101 and A2014205051the Hebei Talent Cultivation Foundation under Grant No A201400119
文摘A new method for fabricating ordered porous silicon is reported. A two-dimensional silica nanosphere array is used as a template with a hydrofluoric acid-hydrogen peroxide solution for etching the nanospheres. The initial diameter and distribution of the holes in the resulting porous silicon layer are determined by the size and distribution of the silica nanospheres. The corrosion time can be used to control the depths of the holes. It is found that the presence of a SiO2 layer, formed by the oxidation of the rough internal surface of the hole, is the primary reason allowing the corrosion to proceed. Ultraviolet reflection and thermal conductivity measurements show that the diameter and distribution of the holes have a great influence on properties of the porous silicon.
文摘Earth abundant and economical rock salt （NaC1） particles of different sizes （〈3 μm and 5-20 μm） prepared by high energy mechanical milling were used as water-soluble templates for generation of Si with novel nanoscale architectures via low pressure chemical vapor deposition （LPCVD）. Si nanoflakes （SiNF） comprising largely amorphous Si （a-Si） with a small volume fraction of nanocrystalline Si （nc-Si）, and Si nanorods （SiNR） composed of a larger volume fraction of crystalline Si （c-Si） and a small volume fraction of a-Si resulted from modification of the NaCI crystals. SiNF yielded first-cycle discharge and charge capacities of -2,830 and 2,175 mAh.g-1, respective134 at a current rate of 50 mA.g-1 with a first-cycle irreversible loss （FIR loss） of -15%-20%. SiNR displayed first-cycle discharge and charge capacities of -2,980 and -2,500 mAh-g-1, respectively, at a current rate of 50 mA-g-1 with an FIR loss of -12%-15%. However, at a current rate of 1 A.g-1, SiNF exhibited a stable discharge capacity of -810 mAh-g-1 at the end of 250 cycles with a fade rate of -0.11% loss per cycle, while SiNR showed a stable specific discharge capacity of -740 mAh.g-1 with a fade rate of -0.23% loss per cycle. The morphology of the nanostructures and compositions of the different phases/phase of Si influence the performance of SiNF and SINK, making them attractive anodes for lithium-ion batteries.
