A novel hierarchical architecture—N-doped hollow carbon fibers decorated with N-doped carbon clusters(NHCF@NCC)—was synthesized for high-performance anode material of potassium ion batteries(PIBs).The material is fo...A novel hierarchical architecture—N-doped hollow carbon fibers decorated with N-doped carbon clusters(NHCF@NCC)—was synthesized for high-performance anode material of potassium ion batteries(PIBs).The material is formulated with porous N-doped hollow carbon fibers as the backbone,which effectively shortens the diffusion length of potassium ion and increases the interface between the electrode and electrolyte.In addition,the N-doped carbon clusters attached on the hollow carbon fibers can provide abundant reactive sites.Specially,NHCF@NCC could form a freestanding electrode with a three dimensional interconnected conductive network owing to the ultrahigh aspect ratio.In this way,NHCF@NCC delivers an excellent electrochemical performance as free-standing anode materials of PIBs,exhibiting a high reversible capacity of 310 mA h g^−1 at a current density of 100 mA g^−1,a long cycling stability of 1000 cycles with negligible degradation,and a superior rate performance of 153 mA h g^−1 at a large current density of 2000 mA g^−1.展开更多
In this paper,we report a high-performance selfsupported supercapacitor electrode composed of a cracked bark-shaped Ni-Co-Mn ternary metallic sulfide(NiCoMnS4)nanostructure on carbon cloth prepared by a simple one-ste...In this paper,we report a high-performance selfsupported supercapacitor electrode composed of a cracked bark-shaped Ni-Co-Mn ternary metallic sulfide(NiCoMnS4)nanostructure on carbon cloth prepared by a simple one-step hydrothermal process and subsequent electrochemical treatment.The electrode delivers a high specific discharge capacity of up to 2470.4 F g^(-1) at 1 A g^(-1) and high rate performances of1635.6 F g^(-1) at 10 A g^(-1) and 910.2 F g^(-1) even at 32 A g^(-1).Cycling tests indicate that NiCoMnS_(4) could maintain >91.1% of its initial capacity and nearly 100% Coulombic efficiency over10,000 cycles at 8 A g^(-1).An aqueous asymmetric supercapacitor assembled with NiCoMnS_(4) as the cathode,activated carbon as the anode,and 1 mol L^(-1) KOH as the electrolyte delivers an energy density of 68.2 W h kg^(-1)at 850.1 W kg^(-1) and capacity retention of 92.5% after 10,000 cycles at 4 A g^(-1).Given the excellent performance and simple material preparation of our proposed device,this study provides a valuable foundation for the development of self-supported metallic sulfide-based electrodes with high electrochemical properties for potential application in aqueous asymmetric supercapacitors.展开更多
Polypyrrole (PPy) films were prepared by multi-potential steps polymerization in an aqueous pyrrole solution, with lithium perchlorate and oxalic acid as supporting electrolytes. Morphology and structure of PPy films ...Polypyrrole (PPy) films were prepared by multi-potential steps polymerization in an aqueous pyrrole solution, with lithium perchlorate and oxalic acid as supporting electrolytes. Morphology and structure of PPy films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Electrochemical behaviors of PPy films were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that multi-potential steps polymerization improves the conductivity of PPy films and large polymer films can be peeled off easily from the electrode without cracking. Lithium perchlorate and oxalic acid provide appropriate dopants for PPy polymerization. It was observed that the polymerization time and the current density have a crucial influence on the surface morphology of PPy films. Smooth and compact PPy films could be generated under long polymerization time and low current density. Multi-potential steps polymerization decreases the occurrence of peroxidation, which improves the conductivity of PPy films. The parameters for multi-potential steps polymerization have been optimized.展开更多
基金financially supported by the National Natural Science Foundation of China (51672078)Hunan Natural Science Foundation (2019JJ40031)+1 种基金Hunan Provincial Innovation Foundation for Postgraduate (CX20190321)China Scholarship Council (201906130035)
文摘A novel hierarchical architecture—N-doped hollow carbon fibers decorated with N-doped carbon clusters(NHCF@NCC)—was synthesized for high-performance anode material of potassium ion batteries(PIBs).The material is formulated with porous N-doped hollow carbon fibers as the backbone,which effectively shortens the diffusion length of potassium ion and increases the interface between the electrode and electrolyte.In addition,the N-doped carbon clusters attached on the hollow carbon fibers can provide abundant reactive sites.Specially,NHCF@NCC could form a freestanding electrode with a three dimensional interconnected conductive network owing to the ultrahigh aspect ratio.In this way,NHCF@NCC delivers an excellent electrochemical performance as free-standing anode materials of PIBs,exhibiting a high reversible capacity of 310 mA h g^−1 at a current density of 100 mA g^−1,a long cycling stability of 1000 cycles with negligible degradation,and a superior rate performance of 153 mA h g^−1 at a large current density of 2000 mA g^−1.
基金supported by the National Natural Science Foundation of China(61376068,11304132,11304133 and11504147)the Fundamental Research Funds for the Central Universities(lzujbky-2017-178 and lzujbky-2017-181)。
文摘In this paper,we report a high-performance selfsupported supercapacitor electrode composed of a cracked bark-shaped Ni-Co-Mn ternary metallic sulfide(NiCoMnS4)nanostructure on carbon cloth prepared by a simple one-step hydrothermal process and subsequent electrochemical treatment.The electrode delivers a high specific discharge capacity of up to 2470.4 F g^(-1) at 1 A g^(-1) and high rate performances of1635.6 F g^(-1) at 10 A g^(-1) and 910.2 F g^(-1) even at 32 A g^(-1).Cycling tests indicate that NiCoMnS_(4) could maintain >91.1% of its initial capacity and nearly 100% Coulombic efficiency over10,000 cycles at 8 A g^(-1).An aqueous asymmetric supercapacitor assembled with NiCoMnS_(4) as the cathode,activated carbon as the anode,and 1 mol L^(-1) KOH as the electrolyte delivers an energy density of 68.2 W h kg^(-1)at 850.1 W kg^(-1) and capacity retention of 92.5% after 10,000 cycles at 4 A g^(-1).Given the excellent performance and simple material preparation of our proposed device,this study provides a valuable foundation for the development of self-supported metallic sulfide-based electrodes with high electrochemical properties for potential application in aqueous asymmetric supercapacitors.
基金supported by the National Basic Research Program of China ("973"Program) (Grant No. 2011CB935701)the National Science Foundation for Post-doctoral Scientists of China (Grant No. 20100480251)
文摘Polypyrrole (PPy) films were prepared by multi-potential steps polymerization in an aqueous pyrrole solution, with lithium perchlorate and oxalic acid as supporting electrolytes. Morphology and structure of PPy films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Electrochemical behaviors of PPy films were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that multi-potential steps polymerization improves the conductivity of PPy films and large polymer films can be peeled off easily from the electrode without cracking. Lithium perchlorate and oxalic acid provide appropriate dopants for PPy polymerization. It was observed that the polymerization time and the current density have a crucial influence on the surface morphology of PPy films. Smooth and compact PPy films could be generated under long polymerization time and low current density. Multi-potential steps polymerization decreases the occurrence of peroxidation, which improves the conductivity of PPy films. The parameters for multi-potential steps polymerization have been optimized.
