Germanium (Ge)-carbon (C) core-shell nanowires (NWs), 15 - 80 nm thick and <1 μm long, were grown using continuous-wave laser vaporization of Ge-graphite composite targets in high pressure (0.1 - 0.9 MPa) Ar gas. ...Germanium (Ge)-carbon (C) core-shell nanowires (NWs), 15 - 80 nm thick and <1 μm long, were grown using continuous-wave laser vaporization of Ge-graphite composite targets in high pressure (0.1 - 0.9 MPa) Ar gas. The NW core was crystalline Ge and the shell was amorphous C. The fraction of the NWs in deposits was changed significantly by the Ge content in the targets and had a maximum at the Ge content of 40 atomic %. With increasing Ar pressure, thicker NWs were grown. A strong correlation was evident between the two diameters of the NW and nanoparticle (NP) attached with the tip of the NW. The growth of the NWs can be explained by the formation of Ge-C liquid-like molten NPs having a specific range of size and composition and precipitation of Ge and C followed by phase separation.展开更多
采用高温石墨化处理和原位沉淀法,首次将高度石墨化空心碳球(HGS)与纳米锗(Ge)球复合制备锂离子电池负极材料。所制备复合材料中Ge的负载量为57.9%,表现出较高的循环稳定性和优异的倍率性能,特别是具有较高的首次库仑效率。在0.2 C下,...采用高温石墨化处理和原位沉淀法,首次将高度石墨化空心碳球(HGS)与纳米锗(Ge)球复合制备锂离子电池负极材料。所制备复合材料中Ge的负载量为57.9%,表现出较高的循环稳定性和优异的倍率性能,特别是具有较高的首次库仑效率。在0.2 C下,首次充放电比容量分别为1 427.4和1 153.3 m Ah/g,首次库仑效率高达80.8%;在4 C倍率下可逆比容量可达600 m Ah/g;经过100次循环后,平均每次循环容量衰减量小于0.46%。展开更多
The binary cluster ions Ge2Cn+/Ge2Cn? and GeCn+ have been produced by laser ablation. The parity ef- fect is present in the negative ions Ge2Cn?, though it is not very prominent. While the experiments tell that the pa...The binary cluster ions Ge2Cn+/Ge2Cn? and GeCn+ have been produced by laser ablation. The parity ef- fect is present in the negative ions Ge2Cn?, though it is not very prominent. While the experiments tell that the parity effect is totally not shown in the positive ions Ge2Cn+. An extensive theoretical investigation on GeCn/GeCn+/GeCn?(n = 1?10) and Ge2Cn/Ge2Cn+/Ge2Cn?(n = 1?9) has been carried out by density functional theory at B3LPY level. The calcula- tion shows that the low-lying states of GeCn/GeCn+/GeCn?(n = 1?10) and Ge2Cn/Ge2Cn+/Ge2Cn? (n = 1?9) are linear structure with germanium atoms locating at terminals respectively. The electronic distributions, ionization potential (IPad), elec- tron affinity (EA) and increasing bonding energy reveal that the parity effect of neutral species is much stronger than that of ions, which is attributed to the valence π-electrons. It is explained that the differences between experiments and cal- culations are due to the kinetic factor in the formation of Ge2Cn±.展开更多
文摘Germanium (Ge)-carbon (C) core-shell nanowires (NWs), 15 - 80 nm thick and <1 μm long, were grown using continuous-wave laser vaporization of Ge-graphite composite targets in high pressure (0.1 - 0.9 MPa) Ar gas. The NW core was crystalline Ge and the shell was amorphous C. The fraction of the NWs in deposits was changed significantly by the Ge content in the targets and had a maximum at the Ge content of 40 atomic %. With increasing Ar pressure, thicker NWs were grown. A strong correlation was evident between the two diameters of the NW and nanoparticle (NP) attached with the tip of the NW. The growth of the NWs can be explained by the formation of Ge-C liquid-like molten NPs having a specific range of size and composition and precipitation of Ge and C followed by phase separation.
基金Supported by National Natural Science Foundation of China(61235011)the Science and Technology Commission of Tianjin Municipality(13JCYBJC17300,12JCQNIC01200)
文摘采用高温石墨化处理和原位沉淀法,首次将高度石墨化空心碳球(HGS)与纳米锗(Ge)球复合制备锂离子电池负极材料。所制备复合材料中Ge的负载量为57.9%,表现出较高的循环稳定性和优异的倍率性能,特别是具有较高的首次库仑效率。在0.2 C下,首次充放电比容量分别为1 427.4和1 153.3 m Ah/g,首次库仑效率高达80.8%;在4 C倍率下可逆比容量可达600 m Ah/g;经过100次循环后,平均每次循环容量衰减量小于0.46%。
基金supported by the National Natural Science Foundation of China(Grant No.20302020)
文摘The binary cluster ions Ge2Cn+/Ge2Cn? and GeCn+ have been produced by laser ablation. The parity ef- fect is present in the negative ions Ge2Cn?, though it is not very prominent. While the experiments tell that the parity effect is totally not shown in the positive ions Ge2Cn+. An extensive theoretical investigation on GeCn/GeCn+/GeCn?(n = 1?10) and Ge2Cn/Ge2Cn+/Ge2Cn?(n = 1?9) has been carried out by density functional theory at B3LPY level. The calcula- tion shows that the low-lying states of GeCn/GeCn+/GeCn?(n = 1?10) and Ge2Cn/Ge2Cn+/Ge2Cn? (n = 1?9) are linear structure with germanium atoms locating at terminals respectively. The electronic distributions, ionization potential (IPad), elec- tron affinity (EA) and increasing bonding energy reveal that the parity effect of neutral species is much stronger than that of ions, which is attributed to the valence π-electrons. It is explained that the differences between experiments and cal- culations are due to the kinetic factor in the formation of Ge2Cn±.
