The activated carbon wound supercapacitors with TEABF4/propylene carbonate （PC） and TEABF4/acetonitrile （AN） electrolytes were prepared. The effects of the electrolyte and temperature on the capacitance behavior w...The activated carbon wound supercapacitors with TEABF4/propylene carbonate （PC） and TEABF4/acetonitrile （AN） electrolytes were prepared. The effects of the electrolyte and temperature on the capacitance behavior were investigated by cyclic voltammetry （CV） and constant current charge-discharge. Compared with the PC-based supercapacitor, the AN-based supercapacitor has higher capacitance and lower equivalent serial resistance （RES） at discharge currents ranging from 5 to 1 000 mA and 25 ℃. Moreover, temperature effects are more prominent for PC-based supercapacitor than for AN-based supereapacitor. When the measurement temperature ranges from 60 ℃to -40 ℃ the capacitance changes from 5.1 to 2.5 F and RES changes from 135 to 876 mΩ for the PC-based supercapacior, while the AN-based supercapacitor shows less change in capacitance and RES. Thus AN-based supercapacitor exhibits excellent power characteristics and temperature property.展开更多
Potassium-ion batteries(PIBs) hold great potential as an alternative to lithium-ion batteries due to the abundant reserves of potassium and similar redox potentials of K+/K and Li+/Li. Unfortunately, PIBs with carbona...Potassium-ion batteries(PIBs) hold great potential as an alternative to lithium-ion batteries due to the abundant reserves of potassium and similar redox potentials of K+/K and Li+/Li. Unfortunately, PIBs with carbonaceous electrodes present sluggish kinetics, resulting in unsatisfactory cycling stability and poor rate capability. Herein, we demonstrate that the synergistic effects of the enlarged interlayer spacing and enhanced capacitive behavior induced by the co-doping of nitrogen and sulfur atoms into a carbon structure(NSC) can improve its potassium storage capability. Based on the capacitive contribution calculations, electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique, and density functional theory results, the NSC electrode is found to exhibit favorable electronic conductivity,enhanced capacitive adsorption behavior, and fast K+ ion diffusion kinetics. Additionally, a series of exsitu characterizations demonstrate that NSC exhibits superior structural stability during the(de)potassiation process. As a result, NSC displays a high reversible capacity of 302.8 mAh g-1 at 0.1 Ag-1 and a stable capacity of 105.2 m Ahg-1 even at 2 Ag-1 after 600 cycles. This work may offer new insight into the effects of the heteroatom doping of carbon materials on their potassium storage properties and facilitate their application in PIBs.展开更多
Zn-air batteries are promising energy storage and conversion systems to replace the conventional lithiumbased ones.However,their applications have been greatly hindered by the formation of Zn dendrites and ZnO passiva...Zn-air batteries are promising energy storage and conversion systems to replace the conventional lithiumbased ones.However,their applications have been greatly hindered by the formation of Zn dendrites and ZnO passivation layer on the Zn anodes.Herein,we report the fabrication of an artificial protective layer comprised of N-doped threedimensional hollow porous multi-nanochannel carbon fiber with well-dispersed TiO_(2) nanoparticles(HMCNF).The incorporated TiO;nanoparticles and N dopants improve the ion flux distribution and promote the surface adsorption,facilitating the interfacial pseudocapacitive behaviors during Zn deposition.The hierarchical architecture also induces homogenous electric field distribution at the anode/electrolyte interface.Accordingly,the deposition behavior of Zn is regulated,giving rise to enhanced utilization and rechargeability of Zn.When integrated in alkaline Zn-air batteries,the HMCNF-coated Zn anodes exhibit improved electrochemical performances relative to those with the bare Zn anodes,demonstrating a versatile strategy to boost energy storage of metal anodes through optimizing surface adsorption properties.展开更多
Magnesium and its alloys have attracted great attention as biocompatible and degradable biomaterials recent years.But their corrosion rate has been proved to be too high,which limits their biomedical application great...Magnesium and its alloys have attracted great attention as biocompatible and degradable biomaterials recent years.But their corrosion rate has been proved to be too high,which limits their biomedical application greatly.In order to improve the corrosion resistance,nano-fluoridated apatite(FA) coating was prepared on ZK60 magnesium alloy by a simple chemical conversion method.The FA coating showed a needle-like morphology.The polarization curves and EIS plots indicated that the FA coating improved the corrosion potential by 125 mV and doubled the polarization resistance of the magnesium alloy,meanwhile decreasing the corrosion current by two orders of magnitude of the substrate in simulated body fluid.The MTT assay indicated good cytocompatibility of L-929 cells with the fluoridated apatite coated magnesium alloy.展开更多
The charging kinetics of electric double layers （EDLs） is closely related to the performance of a wide variety of nanostructured devices including supercapacitors, electro-actuators, and electrolyte-gated transistor...The charging kinetics of electric double layers （EDLs） is closely related to the performance of a wide variety of nanostructured devices including supercapacitors, electro-actuators, and electrolyte-gated transistors. While room temperature ionic liquids （RTIL） are often used as the charge carrier in these new applications, the theoretical analyses are mostly based on conventional electrokinetic theories suitable for macroscopic electrochemical phenomena in aqueous solutions. In this work, we study the charging behavior of RTIL-EDLs using a coarse-grained molecular model and constant-potential molecular dynamics （MD） simulations. In stark contrast to the predictions of conventional theories, the MD results show oscillatory variations of ionic distributions and electrochemical properties in response to the separation between electrodes. The rate of EDL charging exhibits non-monotonic behavior revealing strong electrostatic correlations in RTIL under confinement.展开更多
基金Project(20803095)supported by the National Natural Science Foundation of ChinaProject(2008AA03Z207)supported by the National High Technology Research and Development Program of China
文摘The activated carbon wound supercapacitors with TEABF4/propylene carbonate （PC） and TEABF4/acetonitrile （AN） electrolytes were prepared. The effects of the electrolyte and temperature on the capacitance behavior were investigated by cyclic voltammetry （CV） and constant current charge-discharge. Compared with the PC-based supercapacitor, the AN-based supercapacitor has higher capacitance and lower equivalent serial resistance （RES） at discharge currents ranging from 5 to 1 000 mA and 25 ℃. Moreover, temperature effects are more prominent for PC-based supercapacitor than for AN-based supereapacitor. When the measurement temperature ranges from 60 ℃to -40 ℃ the capacitance changes from 5.1 to 2.5 F and RES changes from 135 to 876 mΩ for the PC-based supercapacior, while the AN-based supercapacitor shows less change in capacitance and RES. Thus AN-based supercapacitor exhibits excellent power characteristics and temperature property.
基金supported by the National Natural Science Foundation of China (51932011, 51972346, 51802356, and 51872334)Innovation-Driven Project of Central South University (2020CX024)the Fundamental Research Funds for the Central Universities of Central South University (2020zzts075)。
文摘Potassium-ion batteries(PIBs) hold great potential as an alternative to lithium-ion batteries due to the abundant reserves of potassium and similar redox potentials of K+/K and Li+/Li. Unfortunately, PIBs with carbonaceous electrodes present sluggish kinetics, resulting in unsatisfactory cycling stability and poor rate capability. Herein, we demonstrate that the synergistic effects of the enlarged interlayer spacing and enhanced capacitive behavior induced by the co-doping of nitrogen and sulfur atoms into a carbon structure(NSC) can improve its potassium storage capability. Based on the capacitive contribution calculations, electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique, and density functional theory results, the NSC electrode is found to exhibit favorable electronic conductivity,enhanced capacitive adsorption behavior, and fast K+ ion diffusion kinetics. Additionally, a series of exsitu characterizations demonstrate that NSC exhibits superior structural stability during the(de)potassiation process. As a result, NSC displays a high reversible capacity of 302.8 mAh g-1 at 0.1 Ag-1 and a stable capacity of 105.2 m Ahg-1 even at 2 Ag-1 after 600 cycles. This work may offer new insight into the effects of the heteroatom doping of carbon materials on their potassium storage properties and facilitate their application in PIBs.
基金supported by the National Natural Science Foundation of China(52002060)Shanghai Sailing Program(20YF1400600)the Fundamental Research Funds for the Central Universities(2232021D-06)。
文摘Zn-air batteries are promising energy storage and conversion systems to replace the conventional lithiumbased ones.However,their applications have been greatly hindered by the formation of Zn dendrites and ZnO passivation layer on the Zn anodes.Herein,we report the fabrication of an artificial protective layer comprised of N-doped threedimensional hollow porous multi-nanochannel carbon fiber with well-dispersed TiO_(2) nanoparticles(HMCNF).The incorporated TiO;nanoparticles and N dopants improve the ion flux distribution and promote the surface adsorption,facilitating the interfacial pseudocapacitive behaviors during Zn deposition.The hierarchical architecture also induces homogenous electric field distribution at the anode/electrolyte interface.Accordingly,the deposition behavior of Zn is regulated,giving rise to enhanced utilization and rechargeability of Zn.When integrated in alkaline Zn-air batteries,the HMCNF-coated Zn anodes exhibit improved electrochemical performances relative to those with the bare Zn anodes,demonstrating a versatile strategy to boost energy storage of metal anodes through optimizing surface adsorption properties.
基金supported by the Program for Young Excellent Talents in Tongji University (Grant No. 2009KJ003)"Chen Guang" project(Grant No. 10CG21) supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation
文摘Magnesium and its alloys have attracted great attention as biocompatible and degradable biomaterials recent years.But their corrosion rate has been proved to be too high,which limits their biomedical application greatly.In order to improve the corrosion resistance,nano-fluoridated apatite(FA) coating was prepared on ZK60 magnesium alloy by a simple chemical conversion method.The FA coating showed a needle-like morphology.The polarization curves and EIS plots indicated that the FA coating improved the corrosion potential by 125 mV and doubled the polarization resistance of the magnesium alloy,meanwhile decreasing the corrosion current by two orders of magnitude of the substrate in simulated body fluid.The MTT assay indicated good cytocompatibility of L-929 cells with the fluoridated apatite coated magnesium alloy.
基金This work was supported as part of the Fluid Interface Reactions, Structures and Transport （FIRST） Center, an Energy Frontier Research Center funded by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences. K. X. is grateful to the Chinese Scholarship Council for a visiting fellowship. Additional support was provided by National Natural Science foundation of China （No. 21276138） and Tsinghua University Foundation （No. 2013108930）. The numerical calculations were performed at the National Energy Research Sdentific Computing Center （NERSC）.
文摘The charging kinetics of electric double layers （EDLs） is closely related to the performance of a wide variety of nanostructured devices including supercapacitors, electro-actuators, and electrolyte-gated transistors. While room temperature ionic liquids （RTIL） are often used as the charge carrier in these new applications, the theoretical analyses are mostly based on conventional electrokinetic theories suitable for macroscopic electrochemical phenomena in aqueous solutions. In this work, we study the charging behavior of RTIL-EDLs using a coarse-grained molecular model and constant-potential molecular dynamics （MD） simulations. In stark contrast to the predictions of conventional theories, the MD results show oscillatory variations of ionic distributions and electrochemical properties in response to the separation between electrodes. The rate of EDL charging exhibits non-monotonic behavior revealing strong electrostatic correlations in RTIL under confinement.
