The discovery of superconductivity in magnesium diboride (MgB2) has opened up a new field in materials science research. It offers a possibility of a new class of high performance superconducting materials for practic...The discovery of superconductivity in magnesium diboride (MgB2) has opened up a new field in materials science research. It offers a possibility of a new class of high performance superconducting materials for practical applications because of the relatively low cost of fabrication, high critical current densities (Jc) and fields, large coherence length, absence of weak links, higher Tc(TC = 39K) compared with Nb3Sn and Nb-Ti alloys (two or four times that of Nb,,Sn and Nb-Ti alloys). However, the weak flux pinning in the magnetic field remains a major challenge. This paper reports the most interesting results on nanomaterial (SiC and Si) doping in magnesium diboride. The high density of nano-scale defects introduced by doping is responsible for the enhanced pinning. The fabrication method, critical current density, microstructures, flux pinning and cost for magnesium diboride bulks, wires and tapes are also discussed. It is believed that high performance SiC doped MgB2 will have a great potential for many practical applications at 5K to 25K up to 5T.展开更多
An available surface modification process of nano-Si3N4 was given using KH-5 60 as modifying agent and acetone as dispersion medium. Nano-Si3N4 suspension w as of the greatest stability when the nano-Si3N4 powder was ...An available surface modification process of nano-Si3N4 was given using KH-5 60 as modifying agent and acetone as dispersion medium. Nano-Si3N4 suspension w as of the greatest stability when the nano-Si3N4 powder was modified with prope r amount of KH-560, which was 1%(wt) of the amount of nano-Si3N4 powder. Elem ents of C, O and Si were detected on the surface of the modified nano-Si3N4 pow der by means of XPS. The TEM of the suspension showed that the average particle size of nano-Si3N4 became smaller and dispersibility of nano-Si3N4 was improve d in the medium of acetone when the nano-Si3N4 powder was modified with proper amount of KH-560. The results obtained showed that KH-560 had been bound on th e surface of nano-Si3N4 particles.展开更多
纳米硅碳材料主要成分为纳米硅与碳材料,纳米硅具有较小的颗粒尺寸,其储锂容量较高,碳材料具有较高的电子电导,为复合材料提供较好的电子通道;同时将碳与硅材料复合后能缓和硅材料体积形变带来的应力变化;此外,碳作为包覆材料能有效稳...纳米硅碳材料主要成分为纳米硅与碳材料,纳米硅具有较小的颗粒尺寸,其储锂容量较高,碳材料具有较高的电子电导,为复合材料提供较好的电子通道;同时将碳与硅材料复合后能缓和硅材料体积形变带来的应力变化;此外,碳作为包覆材料能有效稳定电极材料与电解液的界面,使SEI膜稳定生长。因此,硅碳复合材料有望替代石墨成为下一代高能量密度锂离子电池负极。本文简要介绍了纳米先导专项硅负极研究团队在纳米硅碳材料方面的研究进展。通过持续的研发与技术更新,目前低容量复合材料（380-450 m A·h/g）的反弹系数、效率、压实密度、加工性能皆不亚于目前商品石墨的水平;在高容量及超高容量材料（500-2000 m A·h/g）方面,通过精细的结构设计,循环性能和倍率性能等得到了较大提升。展开更多
文摘The discovery of superconductivity in magnesium diboride (MgB2) has opened up a new field in materials science research. It offers a possibility of a new class of high performance superconducting materials for practical applications because of the relatively low cost of fabrication, high critical current densities (Jc) and fields, large coherence length, absence of weak links, higher Tc(TC = 39K) compared with Nb3Sn and Nb-Ti alloys (two or four times that of Nb,,Sn and Nb-Ti alloys). However, the weak flux pinning in the magnetic field remains a major challenge. This paper reports the most interesting results on nanomaterial (SiC and Si) doping in magnesium diboride. The high density of nano-scale defects introduced by doping is responsible for the enhanced pinning. The fabrication method, critical current density, microstructures, flux pinning and cost for magnesium diboride bulks, wires and tapes are also discussed. It is believed that high performance SiC doped MgB2 will have a great potential for many practical applications at 5K to 25K up to 5T.
文摘An available surface modification process of nano-Si3N4 was given using KH-5 60 as modifying agent and acetone as dispersion medium. Nano-Si3N4 suspension w as of the greatest stability when the nano-Si3N4 powder was modified with prope r amount of KH-560, which was 1%(wt) of the amount of nano-Si3N4 powder. Elem ents of C, O and Si were detected on the surface of the modified nano-Si3N4 pow der by means of XPS. The TEM of the suspension showed that the average particle size of nano-Si3N4 became smaller and dispersibility of nano-Si3N4 was improve d in the medium of acetone when the nano-Si3N4 powder was modified with proper amount of KH-560. The results obtained showed that KH-560 had been bound on th e surface of nano-Si3N4 particles.
文摘纳米硅碳材料主要成分为纳米硅与碳材料,纳米硅具有较小的颗粒尺寸,其储锂容量较高,碳材料具有较高的电子电导,为复合材料提供较好的电子通道;同时将碳与硅材料复合后能缓和硅材料体积形变带来的应力变化;此外,碳作为包覆材料能有效稳定电极材料与电解液的界面,使SEI膜稳定生长。因此,硅碳复合材料有望替代石墨成为下一代高能量密度锂离子电池负极。本文简要介绍了纳米先导专项硅负极研究团队在纳米硅碳材料方面的研究进展。通过持续的研发与技术更新,目前低容量复合材料（380-450 m A·h/g）的反弹系数、效率、压实密度、加工性能皆不亚于目前商品石墨的水平;在高容量及超高容量材料（500-2000 m A·h/g）方面,通过精细的结构设计,循环性能和倍率性能等得到了较大提升。
