Based on three different kinds of conductive paths in microstructure of soil and theory of electrochemical impedance spectroscopy(EIS), an integrated equivalent circuit model and impedance formula for soils were propo...Based on three different kinds of conductive paths in microstructure of soil and theory of electrochemical impedance spectroscopy(EIS), an integrated equivalent circuit model and impedance formula for soils were proposed, which contain 6 meaningful resistance and reactance parameters. Considering the conductive properties of soils and dispersion effects, mathematical equations for impedance under various circuit models were deduced and studied. The mathematical expression presents two semicircles for theoretical EIS Nyquist spectrum, in which the center of one semicircle is degraded to simply the equivalent model. Based on the measured parameters of EIS Nyquist spectrum, meaningful soil parameters can easily be determined. Additionally, EIS was used to investigate the soil properties with different water contents along with the mathematical relationships and mechanism between the physical parameters and water content. Magnitude of the impedance decreases with the increase of testing frequency and water content for Bode graphs. The proposed model would help us to better understand the soil microstructure and properties and offer more reasonable explanations for EIS spectra.展开更多
Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge...Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge/discharge process of commercial lithium-ion batteries of mobile telephone, degradation analysis and related mechanisms are put forward and discussed in the paper. The impedance spectra of prismatic commercial lithium-ion batteries are measured at various state of charge after different charge/discharge cycles. The incastared impedance spectra are discussed with a proposed equivalent circuit. Results indicated that the structure change of electrode materials or swell and shrink of crystal lattice, decompose of electrolyte, dissolution of active materials and solid electrolyte interphase film formation are the main reasons leading to the capacity degradation.展开更多
基金Projects(5120833351078253)supported by the National Natural Science Foundation of China+4 种基金Projects(2014011036-12014131019TYUT2014YQ017OIT2015)supported by the Natural Science Foundation of Shanxi ProvinceChina
文摘Based on three different kinds of conductive paths in microstructure of soil and theory of electrochemical impedance spectroscopy(EIS), an integrated equivalent circuit model and impedance formula for soils were proposed, which contain 6 meaningful resistance and reactance parameters. Considering the conductive properties of soils and dispersion effects, mathematical equations for impedance under various circuit models were deduced and studied. The mathematical expression presents two semicircles for theoretical EIS Nyquist spectrum, in which the center of one semicircle is degraded to simply the equivalent model. Based on the measured parameters of EIS Nyquist spectrum, meaningful soil parameters can easily be determined. Additionally, EIS was used to investigate the soil properties with different water contents along with the mathematical relationships and mechanism between the physical parameters and water content. Magnitude of the impedance decreases with the increase of testing frequency and water content for Bode graphs. The proposed model would help us to better understand the soil microstructure and properties and offer more reasonable explanations for EIS spectra.
基金"973"Project (2002CB211800)Teaching and Research Fund of Beijing Institute of Technology(20070542008)
文摘Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge/discharge process of commercial lithium-ion batteries of mobile telephone, degradation analysis and related mechanisms are put forward and discussed in the paper. The impedance spectra of prismatic commercial lithium-ion batteries are measured at various state of charge after different charge/discharge cycles. The incastared impedance spectra are discussed with a proposed equivalent circuit. Results indicated that the structure change of electrode materials or swell and shrink of crystal lattice, decompose of electrolyte, dissolution of active materials and solid electrolyte interphase film formation are the main reasons leading to the capacity degradation.
