Compared with antiferroelectric(AFE)orthothombic R phases,AFE orthothombic P phases in Na NbO_(3)(NN)ceramics have been rarely investigated,particularly in the field of energy-storage capadtors.The main bottlenedk is ...Compared with antiferroelectric(AFE)orthothombic R phases,AFE orthothombic P phases in Na NbO_(3)(NN)ceramics have been rarely investigated,particularly in the field of energy-storage capadtors.The main bottlenedk is closely related to the contradiction between d fficultly achieved stable relaxor AFE P phase and easily induced P-R phase transition during modifying dhemical compositions.Herein,we reporta novel lead-free AFE ceramic of(1-x)NN-x(Bi_(0.5)K_(0.5))ZrO_(3)((1-x)NN-xBKZ)with a pure AFE P phase str ucture,which exhibits excellent energy-storage characteristics,such as an ultrahigh recoverable energy density(W_(rec))-4.4 J/cm^(3) at x=0.11,a large powder density P_(D)-104 MW/cm^(3) and a fast discharge rate t_(0.9)-45 ns.The analysis of polarization-field response,Raman spectrum and transmission elecron microscopy demonstrates that the giant amplification of W_(rec) by≥177% should be ma inly ascribed to the simultaneously and effectively enhanced AFE P phase stbility and its relaxor dharacteristics,resulting in a diffused reversible electric field-induced AFE P-ferroelectric phase transition with concurrently incre.ased driving electric fields.Different from mast(1-x)NN-xABO_(3) systems,it was found that the reduced polarizability of B-site cations dominates the enhanced AFE P-phase stability in(1-x)NN-xBKZ ceramics,but the almost unchanged tolerance factor tends to ause the AFE R phase to be induced at a relatively high x value.展开更多
Metal-ion capacitors(including Li^(+),Na^(+),and K^(+))effectively combine a battery negative electrode capable of reversibly intercalating metal cations,together with an electrical double-layer positive electrode.How...Metal-ion capacitors(including Li^(+),Na^(+),and K^(+))effectively combine a battery negative electrode capable of reversibly intercalating metal cations,together with an electrical double-layer positive electrode.However,such novel cell design has a birth defect,namely kinetics mismatch between sluggish negative electrode and fast positive electrode,thus limiting the energy-power performance.Herein,we design a MoS_(2)-carbon composite anode with the ordered macroporous architecture and interlayer-expanded feature,exhibiting the fast and reversible Na^(+)redox processes.This kinetically favored anode is coupled with a homemade activated carbon cathode that allows for the excellent electrochemical performance of sodiumion capacitor with respect to large specific capacity,high-rate capability,and robust cycling.Through quantification of the potential swings of anode and cathode via a three-electrode Swagelok cell,we for the first time observe the abnormal variation law of potential swings and thus directly providing the evidence that the kinetics gap has been filled up by this kinetically favored anode.Our results represent a crucial step toward understanding the key issues of kinetics mismatch for hybrid cell,thus propelling the development of design of kinetically favored anode materials for high-performance metalion capacitors.展开更多
A novel three-phase active power filter （APF） circuit with photovoltaic （PV） system to improve the quality of service and to reduce the capacity of energy storage capacitor is presented. The energy balance concept...A novel three-phase active power filter （APF） circuit with photovoltaic （PV） system to improve the quality of service and to reduce the capacity of energy storage capacitor is presented. The energy balance concept and sampling technique were used to simplify the calculation algorithm for the required utility source current and to control the voltage of the energy storage capacitor. The feasibility was verified by using the Pspice simulations and experiments. When the APF mode was used during non-operational period, not only the utilization rate, power factor and power quality could be improved, but also the capacity of energy storage capacitor could sparing. As the results, the advantages of the APF circuit are simplicity of control circuits, low cost, and good transient response.展开更多
基金Financial support from the National Natural Science Foundation of China(Grant No.52072103 and U19A2087)the AHPU innovation team project(S022021058)is gratefully acknowledged.
文摘Compared with antiferroelectric(AFE)orthothombic R phases,AFE orthothombic P phases in Na NbO_(3)(NN)ceramics have been rarely investigated,particularly in the field of energy-storage capadtors.The main bottlenedk is closely related to the contradiction between d fficultly achieved stable relaxor AFE P phase and easily induced P-R phase transition during modifying dhemical compositions.Herein,we reporta novel lead-free AFE ceramic of(1-x)NN-x(Bi_(0.5)K_(0.5))ZrO_(3)((1-x)NN-xBKZ)with a pure AFE P phase str ucture,which exhibits excellent energy-storage characteristics,such as an ultrahigh recoverable energy density(W_(rec))-4.4 J/cm^(3) at x=0.11,a large powder density P_(D)-104 MW/cm^(3) and a fast discharge rate t_(0.9)-45 ns.The analysis of polarization-field response,Raman spectrum and transmission elecron microscopy demonstrates that the giant amplification of W_(rec) by≥177% should be ma inly ascribed to the simultaneously and effectively enhanced AFE P phase stbility and its relaxor dharacteristics,resulting in a diffused reversible electric field-induced AFE P-ferroelectric phase transition with concurrently incre.ased driving electric fields.Different from mast(1-x)NN-xABO_(3) systems,it was found that the reduced polarizability of B-site cations dominates the enhanced AFE P-phase stability in(1-x)NN-xBKZ ceramics,but the almost unchanged tolerance factor tends to ause the AFE R phase to be induced at a relatively high x value.
基金supported by National Natural Science Foundation of China(No.51902188)Natural Science Foundation of Jiangsu Province(No.BK20190207)+1 种基金Natural Science Doctoral Foundation of Shandong Province(No.ZR2019BB057)the CAS Key Laboratory of Carbon Materials(No.KLCMKFJJ2006).
文摘Metal-ion capacitors(including Li^(+),Na^(+),and K^(+))effectively combine a battery negative electrode capable of reversibly intercalating metal cations,together with an electrical double-layer positive electrode.However,such novel cell design has a birth defect,namely kinetics mismatch between sluggish negative electrode and fast positive electrode,thus limiting the energy-power performance.Herein,we design a MoS_(2)-carbon composite anode with the ordered macroporous architecture and interlayer-expanded feature,exhibiting the fast and reversible Na^(+)redox processes.This kinetically favored anode is coupled with a homemade activated carbon cathode that allows for the excellent electrochemical performance of sodiumion capacitor with respect to large specific capacity,high-rate capability,and robust cycling.Through quantification of the potential swings of anode and cathode via a three-electrode Swagelok cell,we for the first time observe the abnormal variation law of potential swings and thus directly providing the evidence that the kinetics gap has been filled up by this kinetically favored anode.Our results represent a crucial step toward understanding the key issues of kinetics mismatch for hybrid cell,thus propelling the development of design of kinetically favored anode materials for high-performance metalion capacitors.
文摘A novel three-phase active power filter （APF） circuit with photovoltaic （PV） system to improve the quality of service and to reduce the capacity of energy storage capacitor is presented. The energy balance concept and sampling technique were used to simplify the calculation algorithm for the required utility source current and to control the voltage of the energy storage capacitor. The feasibility was verified by using the Pspice simulations and experiments. When the APF mode was used during non-operational period, not only the utilization rate, power factor and power quality could be improved, but also the capacity of energy storage capacitor could sparing. As the results, the advantages of the APF circuit are simplicity of control circuits, low cost, and good transient response.
