Showing papers by "Jianming Lin published in 2014"

Improving the energy density of quasi-solid-state electric double-layer capacitors by introducing redox additives into gel polymer electrolytes

Abstract: A redox-active gel polymer electrolyte was prepared by introducing KI/VOSO4 redox additives into a polyvinyl alcohol–H2SO4 gel electrolyte for application in a quasi-solid-state electric double-layer capacitor (EDLC) based on activated carbon. The EDLC obtained had a high electrode-specific capacitance of 1232.8 F g−1 and a high energy density of 25.4 W h kg−1; these values are higher than that of an EDLC with a conventional gel electrolyte. The improved energy storage is attributed to Faradaic pseudocapacitance related to the redox-active ions in the gel polymer electrolyte.

A redox‐mediator‐doped gel polymer electrolyte applied in quasi‐solid‐state supercapacitors

Abstract: Methylene blue (MB) redox mediator was introduced into polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blend host to prepare a gel polymer electrolyte (PVA-PVP-H2SO4-MB) for a quasi-solid-state supercapacitor. The electrochemical properties of the supercapacitor with the prepared gel polymer electrolyte were evaluated by cyclic voltammetry, galvanostatic charge–discharge, electrochemical impedance spectroscopy, and self-discharge measurements. With the addition of MB mediator, the ionic conductivity of gel polymer electrolyte increased by 56% up to 36.3 mS·cm−1, and the series resistance reduced, because of the more efficient ionic conduction and higher charge transfer rate, respectively. The electrode specific capacitance of the supercapacitor with PVA-PVP-H2SO4-MB electrolyte is 328 F·g−1, increasing by 164% compared to that of MB-undoped system at the same current density of 1 A·g−1. Meanwhile, the energy density of the supercapacitor increases from 3.2 to 10.3 Wh·kg−1. The quasi-solid-state supercapacitor showed excellent cyclability over 2000 charge/discharge cycles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39784.

Efficient Mn-doped CdS quantum dot sensitized solar cells based on SnO2 microsphere photoelectrodes

Abstract: Mn-doped CdS quantum dot sensitized solar cells based on SnO2 microsphere photoelectrodes are prepared with successive ionic layer adsorption and reaction method. It is found that with Mn-doped CdS quantum dot sensitizers, the photovoltaic performance of the cells based on SnO2 microsphere photoelectrodes can obviously be enhanced. The reasons are owing to the improved light absorption and the expanded light absorption edge by doping Mn in CdS quantum dots. The electrochemical impedance spectroscopy analysis found that the cells with Mn-doped CdS quantum dot sensitized SnO2 microsphere photoelectrodes can efficiently suppress dark reaction, owing to the increased related resistance. Moreover, it is also found that the Mn-doped CdS quantum dot sensitized SnO2 microsphere photoelectrode can increase the electron diffusion lifetime in the cell. The power conversion efficiency of the cell with 4 wt% Mn-doped CdS quantum dot sensitizers can attain to 2.80 %, with 53 % enhancement compared with that of the CdS quantum dot sensitized cell (1.83 %).

Template-free synthesis of polyaniline nanobelts as a catalytic counter electrode in dye-sensitized solar cells

Abstract: Polyaniline (PAn) nanobelts were synthesized by simply mixing aniline and hydrochloric acid aqueous solution with ammonium peroxydisulfate and hydrochloric acid aqueous solution at room temperature without any templates. The PAn nanobelt paste with polytetrafluoroethylene as binder is proper for low-cost and efficient casting processes such as doctor blade method, screen printing, spin-casting, and even roll-to-roll painting. The porous network structure of the PAn nanobelt counter electrode was obtained after drying the paste on the conductive glass. The as-prepared PAn nanobelt counter electrode showed nearly equivalent electrochemical catalytic activity as that of thermal decomposed Pt counter electrode, owing to the well-connected conductive network and high active surface area. The power conversion efficiency of dye-sensitized solar cell with PAn nanobelt counter electrode attained 90% of the value of the cell with Pt counter electrode. Copyright © 2014 John Wiley & Sons, Ltd.

Room temperature polymerization of poly(3,4‐ethylenedioxythiophene) as transparent counter electrodes for dye‐sensitized solar cells

Abstract: Poly(3,4-ethylenedioxythiophene) (PEDOT) counter electrode is prepared with in situ polymerization of 3,4-ethylenedioxythiophene on a fluorine-doped tin oxide over-layer glass at room temperature. The cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization are measured to evaluate the catalytic activity of PEDOT counter electrode for I3−/I− redox couple. Comparing the data with that of traditional thermal decomposed Pt counter electrode, it is found that PEDOT has higher catalytic activity than that of Pt counterpart. Power conversion efficiency of the dye-sensitized solar cell (DSC) with PEDOT counter electrode can attain to 7.713%, a little higher than that of the cell with Pt counter electrode (7.300%). Taking the advantage of high transparency of PEDOT counter electrode, an Ag mirror is put on the back side of PEDOT counter electrode of the DSC to reflect light back for power conversion. Power conversion efficiency of the DSC with this special structure can be further enhanced to 8.359%, which mainly stems from the improved short-circuit current density by the increased irradiated light intensity. Copyright © 2014 John Wiley & Sons, Ltd.

Improving photoelectrical performance of dye sensitized solar cells by doping Y2O3:Tb3+ nanorods

Abstract: Y2O3:Tb3+ nanorods have been successfully synthesized via a hydrothermal method and then introduced into the photoanode of dye-sensitized solar cell. As a p-type dopant, Y2O3:Tb3+ enhances the Fermi level of TiO2 film. Meanwhile, it also improves the short-circuit current density and the light-to-electric energy conversion efficiency by acting as a luminescence medium which can convert ultraviolet light to visible light efficiently. As a result, the conversion efficiency can reach 7.942 % when the doping amount is 4 wt%. The light-to-electric conversion efficiency is increased by a factor of 2.051 compared to that of a cell without Y2O3:Tb3+ doping. The mechanism has been discussed as well.

TiCl 4 assisted formation of nano-TiO 2 secondary structure in photoactive electrodes for high efficiency dye-sensitized solar cells

Abstract: A new kind of photoactive electrodes with nanocrystalline TiO2 (nano-TiO2) secondary structure is successfully prepared via a simple method of adding a small amount of TiCl4 2-propanol solution in conventional nano-TiO2 paste to form micro-sized nano-TiO2 aggregates. The benefits of this special structure include improved optical absorption, increased light scattering ability, and enhanced electron transport and collection efficiency. Dye-sensitized solar cells (DSCs) based on these photoactive electrodes show improved performance. The power conversion efficiency of the cells can be increased from 5.03% to 7.30% by substituting 6 μm conventional nano-TiO2 thin film with the same thickness of as-prepared nano-TiO2 aggregates film in the photoactive electrodes. A higher power conversion efficiency of the cells can be obtained by further increasing the thickness of the nano-TiO2 aggregates film.