Silicon is emerging as a promising next-generation lithium-ion battery anode because of its high theoretical capacity and low cost.However,the poor cyclability and inferior rate performance hinder its largescale appli...Silicon is emerging as a promising next-generation lithium-ion battery anode because of its high theoretical capacity and low cost.However,the poor cyclability and inferior rate performance hinder its largescale applications.Here,hollow silicon/germanium(H-SiGe)nanospheres with a binary-active component and heterogeneous structure combined with porous carbon(pC)reinforcing are synthesized as lithium-ion battery anodes.Experimental studies demonstrate that the H-SiGe/pC anodes possess tiny volume expansion,high ion/electron conductivity,and stable electrode interface.Theoretical calculations confirm that through the replacement of Si using Ge with rational component control,the diffusion energy barrier of lithium will be reduced and lithium storage ability can be improved because of the slight charge polarization.Benefiting from these unique merits,the H-SiGe/pC anodes display a high initial specific capacity of 2922.2 mA h g^(-1)at 0.1 A g^(-1),superior rate capability(59.4%capacity retention from 0.5 to 8 A g^(-1)),and excellent cycling stability(81%retention after 700 cycles at 5 A g^(-1)at 1.0–1.2 mg cm^(-2)).An outstanding stability is preserved even at a high loading of 3.2 mg cm^(-2)with an improved reversible capacity of 429.1 mA h g^(-1)after 500 cycles at 4 A g^(-1).Furthermore,the full-cell with the prelithiated H-SiGe/pC anode and LiFePO4cathode exhibits an impressive capacity performance.展开更多
There are some new results about photovoltaic transient response in the new effect. We suggest a theoretical model to explain the effect reasonably. The theoretical calculation results agree with that in experiments.
Lattice dynamics of strained(Si)_(4)/(Ge)_(4) superlattice grown pseudomorphically on (001)-oriented Si_(1-x)Ge_(x)(0≤x≤1)substrate is investigated.In the present calculations,the effects of strain and substrate are...Lattice dynamics of strained(Si)_(4)/(Ge)_(4) superlattice grown pseudomorphically on (001)-oriented Si_(1-x)Ge_(x)(0≤x≤1)substrate is investigated.In the present calculations,the effects of strain and substrate are discussed.展开更多
The effect of strains on the thermal conductivity of Si/Ge superlattices was investigated by nonequilibrium molecular dynamics（NEMD） simulation. The thermal conductivities experienced a near linear drop with increas...The effect of strains on the thermal conductivity of Si/Ge superlattices was investigated by nonequilibrium molecular dynamics（NEMD） simulation. The thermal conductivities experienced a near linear drop with increasing tensile and compressive strains. It was explained by the fact that the decrease of the phonons velocities and a mass of structural defects generated under strains. Meanwhile, a theoretical calculation based on Modified-Callaway model was performed,and it was found that the theoretical results were in good agreement with the molecular dynamics results.展开更多
Self-assembled Si/Ge quantum dot (QD) structures have been intensively studied in the last years for potential applications in Si based integrated optoelectronics [1]. For the demand of many technical applications, Ge...Self-assembled Si/Ge quantum dot (QD) structures have been intensively studied in the last years for potential applications in Si based integrated optoelectronics [1]. For the demand of many technical applications, Ge dot superlattices separated by Si can be deposited in order to increase the optical and electronic response. Raman scattering has proven to be an essential technique to characterize Si/Ge superlattices and Si/Ge dot superlattices [2,3,4]. However, most of Raman studies were concentrated on their optical modes of Si/Ge dot superlattices, but few of them were carried out to characterize the detail structural properties of Si/Ge dot superlattice structures. Here, Self-assembled Si/Ge dot multilayers with small, uncorrelated dots fabricated by molecular beam epitaxy in the Stranski-Krastanov growth mode are studied by Raman scattering of folded longitudinal acoustic (FLA) modes.展开更多
基金supported by the National Natural Science Foundation of China programs(52007110,22078179,21901146)the Natural Science Foundation of Shandong Province(ZR2020QB048)the Taishan Scholar Foundation(tsqn201812063)。
文摘Silicon is emerging as a promising next-generation lithium-ion battery anode because of its high theoretical capacity and low cost.However,the poor cyclability and inferior rate performance hinder its largescale applications.Here,hollow silicon/germanium(H-SiGe)nanospheres with a binary-active component and heterogeneous structure combined with porous carbon(pC)reinforcing are synthesized as lithium-ion battery anodes.Experimental studies demonstrate that the H-SiGe/pC anodes possess tiny volume expansion,high ion/electron conductivity,and stable electrode interface.Theoretical calculations confirm that through the replacement of Si using Ge with rational component control,the diffusion energy barrier of lithium will be reduced and lithium storage ability can be improved because of the slight charge polarization.Benefiting from these unique merits,the H-SiGe/pC anodes display a high initial specific capacity of 2922.2 mA h g^(-1)at 0.1 A g^(-1),superior rate capability(59.4%capacity retention from 0.5 to 8 A g^(-1)),and excellent cycling stability(81%retention after 700 cycles at 5 A g^(-1)at 1.0–1.2 mg cm^(-2)).An outstanding stability is preserved even at a high loading of 3.2 mg cm^(-2)with an improved reversible capacity of 429.1 mA h g^(-1)after 500 cycles at 4 A g^(-1).Furthermore,the full-cell with the prelithiated H-SiGe/pC anode and LiFePO4cathode exhibits an impressive capacity performance.
文摘There are some new results about photovoltaic transient response in the new effect. We suggest a theoretical model to explain the effect reasonably. The theoretical calculation results agree with that in experiments.
文摘Lattice dynamics of strained(Si)_(4)/(Ge)_(4) superlattice grown pseudomorphically on (001)-oriented Si_(1-x)Ge_(x)(0≤x≤1)substrate is investigated.In the present calculations,the effects of strain and substrate are discussed.
基金Supported by the National Natural Science Foundation of China(No.51706039)
文摘The effect of strains on the thermal conductivity of Si/Ge superlattices was investigated by nonequilibrium molecular dynamics（NEMD） simulation. The thermal conductivities experienced a near linear drop with increasing tensile and compressive strains. It was explained by the fact that the decrease of the phonons velocities and a mass of structural defects generated under strains. Meanwhile, a theoretical calculation based on Modified-Callaway model was performed,and it was found that the theoretical results were in good agreement with the molecular dynamics results.
文摘Self-assembled Si/Ge quantum dot (QD) structures have been intensively studied in the last years for potential applications in Si based integrated optoelectronics [1]. For the demand of many technical applications, Ge dot superlattices separated by Si can be deposited in order to increase the optical and electronic response. Raman scattering has proven to be an essential technique to characterize Si/Ge superlattices and Si/Ge dot superlattices [2,3,4]. However, most of Raman studies were concentrated on their optical modes of Si/Ge dot superlattices, but few of them were carried out to characterize the detail structural properties of Si/Ge dot superlattice structures. Here, Self-assembled Si/Ge dot multilayers with small, uncorrelated dots fabricated by molecular beam epitaxy in the Stranski-Krastanov growth mode are studied by Raman scattering of folded longitudinal acoustic (FLA) modes.
