直接涂膜技术用于质子交换膜燃料电池膜电极制备 (Ⅱ)

研究了直接涂膜过程中 ,催化剂液组成对电池性能的影响 .异丙醇在催化剂墨水中起到溶剂和造孔剂的作用 ,当催化剂墨水中催化剂、异丙醇的质量比为 1∶10时电池性能最好 .Nafion是催化剂层中良好的黏结剂和质子传导载体 .由于直接涂膜 ,使Nafion液与Nafion膜直接接触 ,从而增加了质子传导性 .实验结果表明 ,最佳的Nafion含量 (干基 )为NFP =33% .通过对不同金属含量的Pt/C催化剂的研究发现 ,金属含量不同 ,异丙醇和Nafion的最优含量亦随之改变 .考察了催化剂层不同制备工艺对电池性能的影响 ,表明催化剂层数越多电池性能越好 。

直接涂膜技术用于质子交换膜燃料电池膜电极制备

A new membrane electrolyte assembly (MEA) preparation method for polymer electrolyte membrane fuel cell (PEMFC) was developed by applying the directly printing catalyst on membrane technique.This method was simple and easy to be controlled as verified by repetition experiment. When the membrane with catalyst prepared by the new technique and the electrode with diffusion layer was only sandwiched but not hot pressed, this kind of MEA was called not-hot-press MEA (NPMEA) and its fuel cell performance was better than that of MEA which was hot pressed (HPMEA).The effects of 6 different kinds of solvents in catalyst mixture ink on the performance of fuel cell were assessed.It was discovered that iso-propanol was the best solvent in catalyst mixture ink and showed the best performance of fuel cell. Finally several MEAs prepared by different ways were tested on fuel cell station and it was reported that the performance of MEA prepared by the directly printing catalyst on membrane technique was the best in the whole voltage region.

Improvement of electrochemical and electrical properties of LiFePO_4 coated with citric acid

LiFePO4 was synthesized using hydrothermal method and coated with different amounts of citric acid as carbon source. The samples were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscope （TEM）, surface area measurement--Brunauer-Emmett-Teller （BET）, dis- charge capability, cyclic voltammetry （CV）, and electrochemical impedance spectroscopy （EIS）. The results show that the quality and thickness of the carbon coating on the surface of LiFePO4 particles are very important. The optimum carbon content （about 30 wt%） can lead to a more uniform carbon distribution. Electrochemical results show that the samples containing 20 wt%, 30 wt%, 40 wt%, and 50 wt% carbon deliver a discharge capacity of 105, 167, 151, and 112 mAh.g-1, respectively, at the rate of 0.1C. The increase of carbon content leads to the decrease of discharge capacity of LiFePO4/C, owing to the fact that excess carbon delays the diffusion of Li＋ through the carbon layers during charge/discharge procedure. The LiFePO4/C with low carbon content exhibits poor electrochemical performance because of its low electrical conductivity. Therefore, the amount of carbon must be optimized in order to achieve excellent electrochemical performance of LiFePOjC for its application in a lithium ion battery.

Performance variability of Ba0.5Sr0.5Co0.8Fe0.2O3-δ cathode on proton-conducting electrolyte SOFCs with Ag and Au current collectors

Ba0.5Sr0.5Co0.8Fe0.2O3-δ （BSCF） is one of the most active cathode materials and shows significant hydration effect suggesting possible proton conductivity. In this study, the performance of BSCF cathode on a protonconducting BaZr0.1Ce0.7Y0.2O3-δ（BZCY） electrolyte with silver and gold current collectors was determined. The electrochemical characteristics of the symmetrical and anode-supported cell with diluted silver electrode, silver current collector or gold current collector on BSCF electrode were compared. The significant result is that, although the diluted silver electrode itself shows poor operation stability, the silver current collector has strong electrocatalytic contribution to the BSCF cathode performance on the proton-conducting electrolyte, leading to higher cell performance than that with the gold current collector.