Diankai Li

Lysine-assisted hydrothermal synthesis of urchin-like ordered arrays of mesoporous Co(OH)2 nanowires and their application in electrochemical capacitors

In the work, a novel lysine-assisted hydrothermal process is first developed to produce urchin-like ordered Co(OH)2 arrays, which are assembled from mesoporous Co(OH)2 nanowires. The synergistic contributions from lysine and Cl− ions to the formation of the unique arrays was also tentatively proposed. Electrochemical results show that the unique urchin-like ordered Co(OH)2 arrays show the ability to deliver large specific capacitance and good electrochemical stability at large current densities, which is reasonably ascribed to their ordered microstructure, hierarchical (meso- and macro-) porosity and good electronic conductivity. Moreover, the method we proposed here provides a universal green chemistry approach to large-scale production of Co(OH)2 and even other metal hydroxides oriented arrays with hierarchical porosity for fast energy storage.

Facile interfacial synthesis of flower-like hierarchical a-MnO2 sub-microspherical superstructures constructed by two-dimension mesoporous nanosheets and their application in electrochemical capacitors

In this work, flower-like hierarchical a-MnO2 sub-microspherical superstructures were synthesized by means of a novel interfacial strategy, where the amphiphilic tri-block poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) was used both as a reaction material and a template in an acidic media. Further physical characterizations revealed that the flower-like MnO2 hierarchical superstructures with a specific surface area of 216 m2 g−1 were assembled by two-dimension mesoporous nanosheet building blocks and greatly depended upon the synthesis condition. Electrochemical results demonstrated that the unique MnO2 superstructures delivered a specific capacitance of 298 F g−1 at a current density of 0.117 A g−1, and even 236 F g−1 at 2.353 A g−1, demonstrating their great ability of delivering large energy density at high rates. The good electrochemical capacitance mainly resulted from their unique hierarchical porous structure and rich MnO2-electrolyte interfaces. The unique hierarchical porous structure provided convenient ion transport paths for K+ ions to contact their rich electroactive sites for fast and efficient energy storage.

Large-scale Co3O4 nanoparticles growing on nickel sheets via a one-step strategy and their ultra-highly reversible redox reaction toward supercapacitors

Ultra-high electrochemical reversible redox reactions for energy storage at high rates are realized from large-scale Co3O4 nanoparticles growing on a nickel sheet pretreated with HNO3via a facile one-step hydrothermal strategy.

Interface-hydrothermal synthesis and electrochemical properties of CoSx nanodots/poly(sodium-4-styrene sulfonate) functionalized multi-walled carbon nanotubes nanocomposite

In the work, amorphous CoS(x) nanodots were highly dispersed onto poly(sodium-4-styrene sulfonate) (PSS) functionalized multi-walled carbon nanotubes (FMWCNTs) by a interface-hydrothermal method. Electrochemical data demonstrated a specific capacitance (SC) of 300Fg(-1) was delivered at 3Ag(-1) by the nanocomposite, which was 90% of that at 0.4Ag(-1), indicating its good rate response. The good dispersion of the electroactive CoS(x) nanodots onto the FMWCNTs should be responsible for its better supercapacitive performance. Such unique structure made the abundant electroactive surface atoms of the CoS(x) phase contacted by OH(-) ions and electrons easily through the three-dimensional mesoporous conducting matrix of FMWCNTs for fast energy storage. Furthermore, the SC retention of ca. 95% reveals a good electrochemical stability of the nanocomposite.

Facile synthesis of Co2P2O7 nanorods as a promising pseudocapacitive material towards high-performance electrochemical capacitors

In the present work, we developed an efficient one-step template-free strategy to fabricate intriguing one-dimensional (1D) Co2P2O7 nanorods (NRs) at room temperature, and utilized the unique monoclinic Co2P2O7 NRs as an excellent electrode material for high-performance pseudocapacitors using 3 M KOH as an electrolyte. Strikingly, the as-synthesized 1D Co2P2O7 NR electrode delivered a specific capacitance (SC) of 483 F g−1 at 1 A g−1, and even at 402 F g−1 a high current loading of 10 A g−1. And the SC retention of ∼90% over continuous 3000 charge–discharge cycles at a current density of 6 A g−1confirmed its stable long-term cycling ability at high current density. More significantly, the underlying electrochemical energy-storage mechanism of the Co2P2O7 NR electrode in alkaline KOH aqueous solution was tentatively proposed. And the appealing strategy was proposed for future exploration and development of other low-cost pseudocapacitive materials for next-generation ECs.

Synthesis of Ru0.58In0.42Oy⋅nH2O nanoparticles dispersed onto poly(sodium-4-styrene sulfonate)-functionalized multi-walled carbon nanotubes and their application for electrochemical capacitors

In this work, poly(sodium-4-styrene sulfonate) (PSS)-functionalized multi-walled carbon nanotubes (FMWCNTs) were first synthesized via a polymer-assisted technique. Then, Ru(0.58)In(0.42)O(y)⋅nH(2)O nanoparticles (NPs) were mono-dispersed onto the FMWCNTs surfaces under mild hydrothermal condition. Here, PSS with negative charge serves as a bifunctional molecule both for solubilizing and dispersing MWCNTs into aqueous solution and for tethering Ru(3+) and In(3+) to facilitate the good dispersion of Ru(1-)(x)In(x)O(y)⋅nH(2)O NPs onto their surfaces. The good dispersion of Ru(0.58)In(0.42)O(y)⋅nH(2)O NPs onto FMWCNTs makes OH(-) ions and electrons easily contact these NPs with abundant electroactive sites, which results in a large specific capacitance (SC) of 319Fg(-1) for the naocomposites. Moreover, a symmetric electrochemical capacitor (EC) is constructed by using the nanocomposites as electrodes and delivers large specific energy density of 18.1Whkg(-1), desirable power property of 1302Wkg(-1), high electrochemical reversibility and good SC retention of 84.7%.

Enhanced Supercapacitance of Hydrous Ruthenium Oxide/Mesocarbon Microbeads Composites toward Electrochemical Capacitors

A facile hydrothermal strategy was proposed to synthesize RuO2⋅nH2O/mesocarbon microbeads (MCMBs) composites. Further physical characterizations revealed that RuO2⋅nH2O nanoparticles (NPs) were well dispersed upon the surfaces of the MCMB pretreated in 6 M KOH solution. Electrochemical data indicated that the RuO2⋅nH2O/MCMB composites owned higher electrochemical utilization of RuO2 species, better power property, and better electrochemical stability, compared with the single RuO2 phase. The good dispersion of RuO2⋅nH2O NPs and enhanced electronic conductivity made the H