Vanadium pentoxide xerogel films used for lithium rechargeable batteries were prepared from crystalline c-V2O5 by melt quenching method,then the electrochemical process of lithium intercalation into vanadium pentoxide...Vanadium pentoxide xerogel films used for lithium rechargeable batteries were prepared from crystalline c-V2O5 by melt quenching method,then the electrochemical process of lithium intercalation into vanadium pentoxide xerogel films was simulated with an equivalent circuit model, which was derived from the mechanism of electrode reactions. Measured electrochemical impedance spectra at various electrode potentials were analyzed by using the complex non-linear least-squares fitting method. The results show that impedance spectra consist of 2 high-to- medium frequency depressed arcs and a low frequency straight line. The high frequency arc is attributed to the absorption reaction of lithium ions into the oxide film, the medium frequency arc is attributed to the charge transfer reaction at the vanadium oxide/electrolyte interface and the low frequency is characterized by a straight line with a phase angle of 45° corresponding to the diffusion of lithium ion through vanadium oxide phase. The experimental and calculated results are compared and discussed focusing on the electrochemical performance and the state of charge of the electrode. Moreover, the high consistence of the fitted values of the model to the experimental data indicates that this mathematical model does give a satisfying description of the intercalation process of vanadium pentoxide xerogel films.展开更多
The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigat...The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigated by cyclic voltammograms,UV-visible spectral transmittance and XPS.The results show that the cycling efficiency and the reversibility of insertion/extraction of Li + ions in (PEO) 1MoO 3·nH 2O nanocomposite film were improved.The intercalation of PEO into MoO 3 xerogel modulated the wavelength range of electrochromism and enhanced the electrochromic efficiency.Two different chemical conditions of Li + ions existing in the interlayer and interstitial positions of MoO 3 lattice were observed in MoO 3 xerogel and (PEO) 1MoO 3·nH 2O nanocomposite films.展开更多
The nanocomposite films were prepared by poly(ethylene oxide), PEO, intercalation in V2O5 xero-gel in sol-gel. The synthesis and state of the films are investigated by the XRD, IR, SEM, etc. The results show that V2O5...The nanocomposite films were prepared by poly(ethylene oxide), PEO, intercalation in V2O5 xero-gel in sol-gel. The synthesis and state of the films are investigated by the XRD, IR, SEM, etc. The results show that V2O5, xerogel is a layered structure which arranges in c-direction. The mterlayer distance of V2O5 xerogel increases remarkably when PEO is intercalated in V2O5 xero-gel interlayer. PEO has strong interaction with V2O5 host. The surface of the films is homogeneous without holes and cracks.展开更多
Vanadium pentoxide xerogel(VXG) films were prepared by rapid quenching, then coin type 2016 size lithium rechargeable batteries were assembled and tested with the VXG film electrodes and lithium anodes. Electrochemica...Vanadium pentoxide xerogel(VXG) films were prepared by rapid quenching, then coin type 2016 size lithium rechargeable batteries were assembled and tested with the VXG film electrodes and lithium anodes. Electrochemical impedance spectroscopy(EIS) analysis result reveals the expected response for intercalation, except that there is almost no Warburg (diffusion) component. Analyses results of cyclic voltammetry(CV), constant discharge(CD) and discharge-charge(DC) indicate that the sample achieves a high initial discharge specific capacity of approximate 400mA·h/g and a corresponding efficiency of 97 % in the voltage diapason of 1.54.0 V with a draining current of 60 mA/g. Its preservation ratio of capacity still keeps as high as 85 % even after 100 cycles. The good electrochemical performance indicates that VXG film material is a promising cathode for lithium rechargeable batteries.展开更多
The V 2O 5 sol was fabricated by ultra fast quenching.The vanadium with low valence (V 4+ ) was found in V 2O 5 xerogel films by XPS analysis.The technology of oxygen top blown was applied to analyze the XPS...The V 2O 5 sol was fabricated by ultra fast quenching.The vanadium with low valence (V 4+ ) was found in V 2O 5 xerogel films by XPS analysis.The technology of oxygen top blown was applied to analyze the XPS spectrum difference of V 2O 5 xerogel when the powder of V 2O 5 was melting in air or in oxygen atmosphere.The results show that the different melting atmosphere has certain influences on the chemical valence of V 2O 5 xerogel.展开更多
Five different compositions of KxV2O5-nH2O （where prepared by the sol-gel process. Electrical conductiv x=0.00, 0.0017, 0.0049, 0.0064 and 0.0091 mol） were ty and thermoelectric power were measured parallel to the s...Five different compositions of KxV2O5-nH2O （where prepared by the sol-gel process. Electrical conductiv x=0.00, 0.0017, 0.0049, 0.0064 and 0.0091 mol） were ty and thermoelectric power were measured parallel to the substrate surface in the temperature range of 300-480 K. The electrical conductivity showed that all samples were semiconductors and that conductivity increased with increasing K content. The conductivity of the present system was primarily determined by hopping carrier mobility. The carrier density was evaluated as well. The conduction was confirmed to obey non-adiabatic small polaron hopping. The thermoelectric power or Seebeck effect, increased with increasing K ions content. The results obtained indicated that an n-type semiconducting behavior within the temperature range was investigated.展开更多
文摘Vanadium pentoxide xerogel films used for lithium rechargeable batteries were prepared from crystalline c-V2O5 by melt quenching method,then the electrochemical process of lithium intercalation into vanadium pentoxide xerogel films was simulated with an equivalent circuit model, which was derived from the mechanism of electrode reactions. Measured electrochemical impedance spectra at various electrode potentials were analyzed by using the complex non-linear least-squares fitting method. The results show that impedance spectra consist of 2 high-to- medium frequency depressed arcs and a low frequency straight line. The high frequency arc is attributed to the absorption reaction of lithium ions into the oxide film, the medium frequency arc is attributed to the charge transfer reaction at the vanadium oxide/electrolyte interface and the low frequency is characterized by a straight line with a phase angle of 45° corresponding to the diffusion of lithium ion through vanadium oxide phase. The experimental and calculated results are compared and discussed focusing on the electrochemical performance and the state of charge of the electrode. Moreover, the high consistence of the fitted values of the model to the experimental data indicates that this mathematical model does give a satisfying description of the intercalation process of vanadium pentoxide xerogel films.
文摘The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigated by cyclic voltammograms,UV-visible spectral transmittance and XPS.The results show that the cycling efficiency and the reversibility of insertion/extraction of Li + ions in (PEO) 1MoO 3·nH 2O nanocomposite film were improved.The intercalation of PEO into MoO 3 xerogel modulated the wavelength range of electrochromism and enhanced the electrochromic efficiency.Two different chemical conditions of Li + ions existing in the interlayer and interstitial positions of MoO 3 lattice were observed in MoO 3 xerogel and (PEO) 1MoO 3·nH 2O nanocomposite films.
基金This project was supported by National Natural Science Foundation of China (Grant No.59802009 ) and Hubei Province Natural Science Foundation(Grant No. 99J053).
文摘The nanocomposite films were prepared by poly(ethylene oxide), PEO, intercalation in V2O5 xero-gel in sol-gel. The synthesis and state of the films are investigated by the XRD, IR, SEM, etc. The results show that V2O5, xerogel is a layered structure which arranges in c-direction. The mterlayer distance of V2O5 xerogel increases remarkably when PEO is intercalated in V2O5 xero-gel interlayer. PEO has strong interaction with V2O5 host. The surface of the films is homogeneous without holes and cracks.
文摘Vanadium pentoxide xerogel(VXG) films were prepared by rapid quenching, then coin type 2016 size lithium rechargeable batteries were assembled and tested with the VXG film electrodes and lithium anodes. Electrochemical impedance spectroscopy(EIS) analysis result reveals the expected response for intercalation, except that there is almost no Warburg (diffusion) component. Analyses results of cyclic voltammetry(CV), constant discharge(CD) and discharge-charge(DC) indicate that the sample achieves a high initial discharge specific capacity of approximate 400mA·h/g and a corresponding efficiency of 97 % in the voltage diapason of 1.54.0 V with a draining current of 60 mA/g. Its preservation ratio of capacity still keeps as high as 85 % even after 100 cycles. The good electrochemical performance indicates that VXG film material is a promising cathode for lithium rechargeable batteries.
文摘The V 2O 5 sol was fabricated by ultra fast quenching.The vanadium with low valence (V 4+ ) was found in V 2O 5 xerogel films by XPS analysis.The technology of oxygen top blown was applied to analyze the XPS spectrum difference of V 2O 5 xerogel when the powder of V 2O 5 was melting in air or in oxygen atmosphere.The results show that the different melting atmosphere has certain influences on the chemical valence of V 2O 5 xerogel.
文摘Five different compositions of KxV2O5-nH2O （where prepared by the sol-gel process. Electrical conductiv x=0.00, 0.0017, 0.0049, 0.0064 and 0.0091 mol） were ty and thermoelectric power were measured parallel to the substrate surface in the temperature range of 300-480 K. The electrical conductivity showed that all samples were semiconductors and that conductivity increased with increasing K content. The conductivity of the present system was primarily determined by hopping carrier mobility. The carrier density was evaluated as well. The conduction was confirmed to obey non-adiabatic small polaron hopping. The thermoelectric power or Seebeck effect, increased with increasing K ions content. The results obtained indicated that an n-type semiconducting behavior within the temperature range was investigated.
