Shibiao Zhou

Hydrothermal synthesis of porous Co(OH)2 nanoflake array film and its supercapacitor application

Porous α-Co(OH)2 nanoflake array film is prepared by a facile hydrothermal synthesis method. The α-Co(OH)2 nanoflake array film exhibits a highly porous net-like structure composed of interconnected nanoflakes with a thickness of 15 nm. The pseudo-capacitive behaviour of the Co(OH)2 nanoflake array film is investigated by cyclic voltammograms (CV) and galvanostatic charge–discharge tests in 2 M KOH. The α-Co(OH)2 nanoflake array film exhibits high capacitances of 1017 F g − 1 at 2 A g − 1 and 890 F g − 1 at 40 A g − 1 as well as rather good cycling stability for supercapacitor application. The porous architecture is responsible for the enhancement of the electrochemical properties because it provides fast ion and electron transfer, large reaction surface area and good strain accommodation.

Recent Research Progress of Branched and Functional Branched Polyethylene Prepared Using Ni- and Pd–Based Catalysts

In this paper, the recent development of branched and functional branched polyethylene prepared using Ni- and Pd-based catalysts are reviewed. The influence of ligand species, steric effect, electronic effect and polymerization condition on branching density of resultant polymer prepared using Ni- and Pd-based catalysts is discussed. In addition, the review is also focused on functional branched polyethylene produced by copolymerization of ethylene and polar monomer and copolymerization mechanism.

High performance Li4Ti5O12/CN anode material promoted by melamine–formaldehyde resin as carbon–nitrogen precursor

A carbon–nitrogen coating approach using melamine–formaldehyde resin as carbon–nitrogen source is introduced in this work with the aim of getting high rate Li4Ti5O12/CN composite. Li4Ti5O12/CN composite, particle size of 50–100 nm in diameter, is well dispersed and the carbon–nitrogen layers are 2 nm in thickness. The composite delivers much higher electrochemical performance than those of Li4Ti5O12. At 0.2 C and 10 C, it exhibits a discharge capacity of 172 mA h g−1 and 160 mA h g−1, respectively, and after 250 cycles at 10 C, 97.4% of its initial capacity is retained. The superior electrochemical performance can be attributed to the improved ionic and electronic conductivity in the electrode due to the uniform and ultrathin carbon–nitrogen coating layer.

Fabrication of three-dimensional porous cobalt network-supported cobalt oxides nanoflake arrays for electrochemical energy storage

Smart combination of porous metal with metal oxides is important for the construction of high-performance electrochemical devices. Herein, we report three-dimensional Co network-supported Co3O4 nanoflake arrays by a facile electrodeposition and following hydrothermal process. 3D Co networks with porous branches and interconnected pores are well formed and used as the skeleton for the growth of porous Co3O4 nanoflake arrays. High porosity and integrated growth are combined in the composite electrode. As an anode material for lithium ion batteries, the Co network-supported Co3O4 nanoflake array electrode exhibits a high first discharge capacity (1164 mAh g−1 at 0.5 A g−1), good cycling stability (714 mAh g−1 after 100 cycles) and enhanced rate capability. The proposed method is useful for the construction of other porous metal/metal oxide composite films for application in electrochemical energy storage and catalysis.

Mechanical Properties of Elastomeric Terpolymer Composites Containing Carbon Nanotubes

Nanocomposites were obtained by mixing terpolymer and carbon nanotubes (CNTs) in a twin-screw extruder at 135–155°C. The results indicated that increasing the amount of PSt, the molecular weight of PSt macromonomer of terpolymers and CNTs charged resulted in improving the tensile strength and modulus at 300% elongation of nanocomposites.

Na+ and Zr4+ co-doped Li4Ti5O12 as anode materials with superior electrochemical performance for lithium ion batteries

Na+ and Zr4+ co-doped lithium titanates with the formula Li4−xNaxTi5−xZrxO12 (x = 0, 0.01, 0.03, 0.05, 0.10, 0.15 and 0.20) were successfully synthesized via a solid-state reaction in air. XRD analysis indicates that Na+ and Zr4+ co-doping does not change the spinel structure of Li4Ti5O12 and the lattice parameter slightly increases with the enhancement of doping amount. Smaller particle size and larger BET surface areas are obtained for Na+ and Zr4+ co-doped Li4Ti5O12 samples. The four-point probe method and electrochemical impedance spectroscopy (EIS) results demonstrate that the Na+ and Zr4+ co-doped Li4Ti5O12 samples possess higher electrical conductivity and smaller charge transfer resistance compared with undoped Li4Ti5O12, resulting in improved electrochemical performance. Particularly, Li3.97Na0.03Ti4.97Zr0.03O12 exhibits the best rate capability and cycling stability. Even at 20C, it delivers a discharge capacity of 140 mA h g−1, and after 100 cycles at 10C, 97.7% of its initial capacity is retained.

Synthesis, Electrochemical Behaviors and Anion Recognition of A Novel Star-[Polystyrene-b-poly(ferrocenyloxy ethyl acrylate)]6 with Hexafunctional Cyclotriphosphazene Core

A novel star-[polystyrene-b-poly(ferrocenyloxy ethyl acryl ate)]6 with hexa- functional cyclotriphosphazene core (star-(PS-b-PFcEA)6) was synthesized by atom -transfer radical polymerization(ATRP) and its electrochemical behaviors and anion recognition was investigated through CV. The results indicated that increasing of molecular weight resulted in obvious decreasing of reduction peak potential Epc, and the oxidation peak potential Epa kept comparatively stable. Moreover, when titrating anion into polymer solution, Epc increased while Epa reduced evidently, which suggested that star-(PS-b-PFcEA)6 provided with high anion recognition capacity of .

Mechanical Properties of Nanocomposites Prepared Using Elastomeric Terpolymer and Nano-SiO2

Nanocomposites were obtained by mixing elastomeric terpolymer and nano-SiO2 in double-screw extruder at 130–150°C, in which elastomeric terpolymer was prepared by terpolymerization of poly(methyl methacrylate (PMMA) macromonomer, butyl acrylate (BA), and acrylic acid (AA) in benzene using azobisisobutyronitrile (AIBN) as initiator. The results indicated that increasing the amount of PMMA, the molecular weight of PMMA and terpolymers as well as the content of carboxylic acid were favorable to increase the mechanical properties of nanocomposites. In addition, the tensile strength and the modulus at 300% elongation of nanocomposites reach to a maximum while the mass ratio of nano-SiO2 to terpolymer is 3%.