As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation ...As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.展开更多
Organic electrode materials have high capacity,and environmentally friendly advantages for the next generation lithium-ion batteries(LIBs).However,organic electrode materials face many challenges,such as low reduction...Organic electrode materials have high capacity,and environmentally friendly advantages for the next generation lithium-ion batteries(LIBs).However,organic electrode materials face many challenges,such as low reduction potential as cathode materials or high reduction potential as anode materials.Here,the influence of chemical functionalities that are capable of either electron donating or electron withdrawing groups on the reduction potential and charge-discharge performance of anthraquinone(AQ)based system is studied.The cyclic voltammetry results show that the introduction of two-OH groups,two-NO2 groups and one-CH3 group on anthraquinone structure has a little impact on the reduction potential,which is found to be 2.1 V.But when three or four-OH groups are introduced on AQ structure,the reduction potential is increased to about 3.1 V.The charge-discharge tests show that these materials exhibit moderate cycling stability.展开更多
Vanadates and vanadium oxides are potential lithium-ion electrode materials because of their easy preparation and high capacity properties.This paper reports the electrochemical lithium-storage performance of VO2 and ...Vanadates and vanadium oxides are potential lithium-ion electrode materials because of their easy preparation and high capacity properties.This paper reports the electrochemical lithium-storage performance of VO2 and NaV2O5 composite nanowire arrays.Firstly,Na5V12O32 nanowire arrays are fabricated by a hydrothermal method,and then VO2 and NaV2O5 composite nanowire arrays are prepared by a reduction reaction of Na5V12O32 nanowire arrays in hydrogen atmosphere.Crystal structure,chemical composition and morphology of the prepared samples are characterized in detail.The obtained composite is used as an electrode of a lithium-ion battery,which exhibits high reversible capacity and good cycle stability.The composite obtained at 500℃presents a specific discharge capacity up to 345.1 mA·h/g after 50 cycles at a current density of 30 mA/g.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(WK2090000055)Anhui Provincial Natural Science Foundation of China(2308085QG231).
文摘As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.
基金Project(21875076)supported by the National Natural Science Foundation of ChinaProjects(2018A050506077,2017A050506048)supported by the Scientific and Technological Plan of Guangdong Province,ChinaProject(201910574037)supported by the Undergraduates’ Innovating Experimentation Project of China
文摘Organic electrode materials have high capacity,and environmentally friendly advantages for the next generation lithium-ion batteries(LIBs).However,organic electrode materials face many challenges,such as low reduction potential as cathode materials or high reduction potential as anode materials.Here,the influence of chemical functionalities that are capable of either electron donating or electron withdrawing groups on the reduction potential and charge-discharge performance of anthraquinone(AQ)based system is studied.The cyclic voltammetry results show that the introduction of two-OH groups,two-NO2 groups and one-CH3 group on anthraquinone structure has a little impact on the reduction potential,which is found to be 2.1 V.But when three or four-OH groups are introduced on AQ structure,the reduction potential is increased to about 3.1 V.The charge-discharge tests show that these materials exhibit moderate cycling stability.
基金Project(51201117)supported by the National Natural Science Foundation of China
文摘Vanadates and vanadium oxides are potential lithium-ion electrode materials because of their easy preparation and high capacity properties.This paper reports the electrochemical lithium-storage performance of VO2 and NaV2O5 composite nanowire arrays.Firstly,Na5V12O32 nanowire arrays are fabricated by a hydrothermal method,and then VO2 and NaV2O5 composite nanowire arrays are prepared by a reduction reaction of Na5V12O32 nanowire arrays in hydrogen atmosphere.Crystal structure,chemical composition and morphology of the prepared samples are characterized in detail.The obtained composite is used as an electrode of a lithium-ion battery,which exhibits high reversible capacity and good cycle stability.The composite obtained at 500℃presents a specific discharge capacity up to 345.1 mA·h/g after 50 cycles at a current density of 30 mA/g.
