MnO2/MnO cathode material with superior Zn^2+storage performance is prepared through a simple physical mixing method.The MnO2/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity(36...MnO2/MnO cathode material with superior Zn^2+storage performance is prepared through a simple physical mixing method.The MnO2/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity(364.2 mA·h/g at 0.2C),good cycle performance(170.4 mA·h/g after 100 cycles)and excellent rate performance(205.7 mA·h/g at 2C).Analysis of cyclic voltammetry(CV)data at various scan rates shows that both diffusioncontrolled insertion behavior and surface capacitive behavior contribute to the Zn2+storage performance of MnO2/MnO cathodes.And the capacitive behavior contributes more at high discharge rates,due to the short paths of ion diffusion and the rapid transfer of electrons.展开更多
Although the application of various nonprecious compounds as the air cathodes of Zn-air batteries has been explored, the construction of highly efficient selfsupported Co-based electrodes remains challenging and highl...Although the application of various nonprecious compounds as the air cathodes of Zn-air batteries has been explored, the construction of highly efficient selfsupported Co-based electrodes remains challenging and highly desired given their outstanding electrocatalytic activity and cost-effectiveness. Herein, we fabricated a three-dimensional(3D) self-supported electrode based on N-doped,carbon-coated Co3O4 nanosheets grown on a carbon cloth(i.e., NC-Co3O4/CC) through the electrochemical deposition and carbonization. When used as a binder-free electrode for oxygen evolution reaction(OER), the NC–Co3O4/CC electrode demonstrated excellent electrocatalytic activity with an overpotential of 210 mV at 10 mA cm^-2 and a Tafel slope of79.6 mV dec^-1. In the Zn-air battery test, the electrode delivered a small charge/discharge voltage gap(0.87 V at 10 mA cm^-2) and exhibited high durability without degradation after 93 cycles at the large current density of 25 mA cm^-2.The durability of our electrode was superior to that of a commercial Pt/C+RuO2 catalyst. The excellent performance of NC–Co3O4/CC could be attributed to the presence of 3D structures that promoted electron/ion transfer. By the absence of a binder, the carbon coating improved electron conductivity and promoted electrochemical stability. Moreover, N doping could be used to adjust the C electron structure and accelerate electron transfer. The present study provides a facile and effective route for the synthesis of various self-supported electrodes that fulfill the requirements of different energy storage and conversion devices.展开更多
基金Anhui Provincial Natural Science Foundation(2008085ME155)USTC Research Funds of the Double First-Class Initiative(YD2090002006)+1 种基金Joint Laboratory for USTC and Yanchang Petroleum(ES2090130110)USTC Tang Scholar(KY2090000065).
基金Project(21905304)supported by the National Natural Science Foundation of ChinaProject(ZR2019BEM031)supported by the Natural Science Foundation of Shandong Province,ChinaProjects(18CX02158A,19CX05001A)supported by the Fundamental Research Funds for the Central Universities,China。
文摘MnO2/MnO cathode material with superior Zn^2+storage performance is prepared through a simple physical mixing method.The MnO2/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity(364.2 mA·h/g at 0.2C),good cycle performance(170.4 mA·h/g after 100 cycles)and excellent rate performance(205.7 mA·h/g at 2C).Analysis of cyclic voltammetry(CV)data at various scan rates shows that both diffusioncontrolled insertion behavior and surface capacitive behavior contribute to the Zn2+storage performance of MnO2/MnO cathodes.And the capacitive behavior contributes more at high discharge rates,due to the short paths of ion diffusion and the rapid transfer of electrons.
基金the support from the National Natural Science Foundation of China (21631004, 21771059 and 21571054)Heilongjiang Provincial Postdoctoral Science Foundation (LBH-Q16194)
文摘Although the application of various nonprecious compounds as the air cathodes of Zn-air batteries has been explored, the construction of highly efficient selfsupported Co-based electrodes remains challenging and highly desired given their outstanding electrocatalytic activity and cost-effectiveness. Herein, we fabricated a three-dimensional(3D) self-supported electrode based on N-doped,carbon-coated Co3O4 nanosheets grown on a carbon cloth(i.e., NC-Co3O4/CC) through the electrochemical deposition and carbonization. When used as a binder-free electrode for oxygen evolution reaction(OER), the NC–Co3O4/CC electrode demonstrated excellent electrocatalytic activity with an overpotential of 210 mV at 10 mA cm^-2 and a Tafel slope of79.6 mV dec^-1. In the Zn-air battery test, the electrode delivered a small charge/discharge voltage gap(0.87 V at 10 mA cm^-2) and exhibited high durability without degradation after 93 cycles at the large current density of 25 mA cm^-2.The durability of our electrode was superior to that of a commercial Pt/C+RuO2 catalyst. The excellent performance of NC–Co3O4/CC could be attributed to the presence of 3D structures that promoted electron/ion transfer. By the absence of a binder, the carbon coating improved electron conductivity and promoted electrochemical stability. Moreover, N doping could be used to adjust the C electron structure and accelerate electron transfer. The present study provides a facile and effective route for the synthesis of various self-supported electrodes that fulfill the requirements of different energy storage and conversion devices.
