Etching Anode Foil with Branch Tunnels for Aluminum Electrolytic Capacitors.

Al foil for high-voltage aluminum electrolytic capacitor was first D.C. etched in HCl-H2SO4 mixed acidic solution to form main tunnels and then D.C. etched in natural NaCl solution containing 0.1% H2C2O4 and different trace amounts of Zn(NO3)2. Between the two etching processes, Zn nuclei were deposited on the interior surface of the main tunnels by the natural occluded corrosion cell effect to form micro Zn-Al galvanic local cells. The effects of Zn nuclei on the cross-section etching and electrochemical behavior of Al foil were investigated using scanning electron microscopy, polarization curve measurement, and electrochemical impedance spectroscopy. The sub-branch tunnels can form along the main tunnels owing to the formation of Zn-Al micro-batteries, in which Zn is the cathode and Al is the anode. Increasing Zn(NO3)2 concentration increases the number of Zn nuclei that can serve as sites for branch tunnel initiation along the main tunnels, thereby enhancing the specific capacitance of etched Al foil.

Halbach array assisted assembly of orderly aligned nickel nanowire networks as transparent conductive films.

The aspect ratio and arrangement of nanowires play an important role in achieving excellent optoelectronic performance for metal nanowire-based transparent conductive films (TCFs). However, limited to the technology and material properties, studies are always focused on only one of the issues. Here, a novel strategy for manipulating the relative aspect ratio and arrangement of nickel nanowires (NiNWs) at nanoscale by Halbach array assisted assembly technology is introduced. Head-to-tail nickel nanowire chains as large as hundreds of micrometers are formed as a result of the dipole-dipole interactions of wire-wire. The arrangement of nickel nanowires can be preciously controlled by layer-by-layer deposition. Notably, the alignment create a significant improvement on the optoelectronic performance of nickel nanowire TCFs. The optimized orderly aligned NiNWs TCFs demonstrate super optoelectronic performance (90 Ω sq-1, 86%) than disordered NiNW TCFs (200 Ω sq-1, 80%). Moreover, NiNW-based TCFs exhibit outstanding long-term oxidation stability at 80 °C over 30 d as well as high-temperature oxidization stability even up to 300 °C, that is the most stable metal nanowire-based TCFs in air as far as we know. The low-cost, good optoelectronic performance and excellent oxidation resistance of aligned NiNWs will make them as attractive alternatives to silver nanowires for TCFs application.

Nitrogen self-doped porous carbon with layered structure derived from porcine bladders for high-performance supercapacitors.

Nitrogen-doped layered porous carbon has been successfully fabricated from the biomass of porcine bladders via carbonization and KOH activation. The effects of KOH dosage on the structure, composition and capacitive property of carbon were investigated by a variety of means (SEM, HRTEM, XRD, Raman, XPS, BET and electrochemical test). Owing to the unique layered structure and rich heteroatom content of porcine bladders, the sample obtained at a KOH/carbon mass ratio of 2 were endowed with appropriate pore structure, large specific surface area (1881.7 m2 g-1) and high nitrogen content (5.38%). Meanwhile, the sample exhibits the best electrochemical performance in 6 M KOH electrolyte, including high specific capacitance (322.5 F g-1 at a current density of 0.5 A g-1), desirable rate capability (79% capacitance retention when current density increases from 0.5 to 10 A g-1) and superior cycling stability (96% capacitance retention after 5000 cycles). Furthermore, the symmetric supercapacitor assembled with this carbon electrode can deliver 10.9 Wh kg-1 energy density at 0.15 kW kg-1 power density, and maintain 95% capacitance after 5000 cycles. The prominent performance of this material suggests its promising application in supercapacitor electrode.

Fabrication of honeycomb-patterned porous films from PS-b-PNIPAM amphiphilic diblock copolymers synthesized via RITP.

Poly(styrene)-b-poly(N-isopropylacrylamide) (PS-b-PNIPAM) amphiphilic diblock copolymers were synthesized via reverse iodine transfer polymerization (RITP) firstly. And then the honeycomb structured porous films were fabricated by drop the amphiphilic diblock copolymer solutions on glass substrates. The porous films were characterized using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), respectively. The results showed that the regular honeycomb patterned porous film was achieved successfully by employing the block copolymer with a significantly larger polystyrene block proportion into the solution and the pore diameter of the film decreases obviously with the polymer concentration increased. The effects of airflow speed and Ag particles on porous films are also discussed in this study.