硼氢化钠制氢技术在质子交换膜燃料电池中的研究进展

硼氢化钠储氢量高达10.6%,安全、无爆炸危险,携带和运输方便;供氢系统设备简单,启动速度快,产氢速度可调,因此是一个非常良好的氢载体,是为质子交换膜燃料电池供氢的理想储氢介质。硼氢化钠供氢系统也已逐步应用于质子交换膜燃料电池电源中。介绍了这种制氢方式的几项关键技术：硼氢化钠水解制氢催化剂、硼氢化钠制氢反应器、氢气净化系统等在质子交换膜燃料电池中的研究进展,并指出了今后的研究发展方向。     

硼氢化钠水解制氢用铂基催化剂的研究

选用2种高比表面的碳载体,采用浸渍法制备了担载量为20%的铂基催化剂.经表征20%Pt/乙炔黑的孔径主要分布在2.5～5nm之间,孔径小并且分布集中;而20%Pt/珍珠碳的孔径除少量分布在2.5～5 nm之间外,大部分孔径分布在20～60nm,分布范围较宽.在20min内,20% Pt/珍珠碳和20%Pt/乙炔黑的平均制氢速率分别为1.9 L/min和2.3 L/min,当氢的利用率为100%时,可分别为功率为308W和373 W的质子交换膜燃烧电池持续供氢.     

负载动态变化时直接甲醇燃料电池的响应特性

直接甲醇燃料电池动态特性的研究对于实际应用来说非常重要.实验研究了直接甲醇单体燃料电池电流动态变化时电压的响应. 基于计算机控制的负载变化,得到了各种电流变化波形及不同的加载电流、放电/开路时间、加载斜率下的电池电压动态响应.结果表明电池电压对电流动态变换变化时的响应很迅速,动态运行时电池的开路电压要比稳态时的高,加载斜率对电池动态响应特性有重要影响. 电池内部电化学反应和传热传质瞬态变化的相互作用是电池动态响应的关键.     

直接甲醇燃料电池质子交换膜的发展现状

直接甲醇燃料电池(DMFC)是20世纪90年代兴起的第六代燃料电池,以其诸多的优点引起人们的广泛关注和研究。其中聚合物电解质膜是DMFC的关键技术,起着隔离阴阳极、质子传输、绝缘电子的作用。它的作用决定着DMFC的输出功率、电池效率、成本及应用前景。本文介绍了已商品化的全氟磺酸膜(Nafion膜)的结构及性能、以及替代膜的国内外发展现状,指出DMFC用膜的研究是21世纪能源研究的重点。     

基于离子传导增强的多孔催化剂及其直接硼氢化钠燃料电池的研究

多孔碳材料具有比传统碳载体更大的比表面积,具备担载更多电催化活性位点的能力。但多孔催化剂的孔内传质阻力较大,特别是孔内离子难以有效传导,导致电极反应的活性位利用率低下,电极过电位增大。直接硼氢化钠燃料电池(DBFC)是一种电动势高,无需贵金属作为催化剂的高能量密度碱性燃料电池,但较大的阴极极化导致电池能量密度难以提高。强化阴极催化剂的离子传导能力是降低阴极极化的有效手段之一。将阳离子交换树脂(Nafion)真空灌注于多孔催化剂孔道内可强化阳离子传导,以此提高催化位点利用率。得到的产物通过球磨粉碎得到外表面无树脂覆盖的催化剂粒子,以此避免树脂对粒子外表面覆盖对电子导电性的影响,从而降低电极极化提高催化性能。研究表明,以葡萄糖为碳源、吡咯为氮源、硝酸钴为过渡金属源制备的阴极催化剂,通过电子、离子传导强化处理,催化性能显著提高。使用了强化处理的催化剂的DBFC,室温下最大功率密度达到了280m W×cm~(-2),其性能超过了铂的质量分数为28.6%的碳载铂催化剂。     

放电条件对电晕放电等离子体脱除羰基硫的影响研究

采用了负电晕放电方法转化脱除羰基硫(COS),对不同电极形状、电极间距、温度、输入能量比(specific inputenergy,SIE)、转化效率、总能量产率进行考察。实验结果表明,圆钢型电极比锯齿型和狼牙棒型电极对COS的转化效果更好,从能量利用的角度考虑,圆钢型电极也比锯齿型和狼牙棒型更适合转化COS;极间距越小,COS的转化效率越高,总能量产率也越高;温度升高时,较低电压下就获得一定的转化效率,并且负载电压升高,COS的转化效率升高;相同SIE时,COS的转化效率随着温度的升高而降低。     

被动式直接甲醇燃料电池的性能影响因素研究

研究了制约被动式直接甲醇燃料电池(被动式DMFC)性能的因素。通过测定电池的极化曲线、功率密度曲线、长时间放电曲线等手段研究了被动式甲醇燃料电池在不同阴极供料方式、不同阳极供料方式、不同催化剂载量、不同电池温度等条件下的放电特性。测试结果表明:阴极氧气扩散速率较慢是导致被动式电池性能较低的一个主要因素,阴极采用主动进料时电池的性能相比被动式DMFC提高了23.5%,最大功率密度达到8.4mW?cm?2。而且阴极的水淹问题也制约了被动式DMFC的长时间放电性能。提高阴阳极的催化剂载量能显著提高电池的性能,阴阳极催化剂载量为4.0mg?cm?2时,最大功率密度达到11.4mW?cm?2。但是催化剂载量的提高会影响电池的长时间放电性能,特别是,提高阴极催化剂载量能显著提高电池的温度,所以能较大提升电池的性能。     

直接甲醇燃料电池阳极催化剂的制备

直接甲醇燃料电池（DMFC）阳极催化剂是DMFC的关键材料之一,其电化学活性的大小对燃料电池的输出性能及成本起着关键作用。不同催化剂的制备技术决定了催化剂电化学活性的高低。介绍了DMFC阳极催化剂的几种制备方法,并对这些方法进行了评述,对制备DMFC阳极催化剂具有很好的参考价值。     

石墨烯基直接甲醇燃料电池催化剂的制备

通过浸渍还原法以乙二醇为还原剂制备了石墨烯及石墨烯负载的铂催化剂(Pt/Graphene),通过XRD、SEM、Raman对材料进行了分析,通过电化学测试与Pt黑催化剂对比,试验数据表明:Pt/Graphene比Pt黑催化剂电化学活性面积提高了28%,对甲醇电催化氧化峰电流提高了52%,电化学活性面积和甲醇氧化反应的稳定性均有所提高。     

直接乙醇燃料电池中阳极催化剂的研究进展

直接乙醇燃料电池（DEFCs）中的阳极催化剂,在电池反应中起着至关重要的作用,但也存在成本高、乙醇的氧化效率低、耐久性差、易中毒等问题,严重阻碍了DEFCs的商业化。本文综述了提高电催化剂性能的有效策略,以期为进一步探索DEFCs提供参考。     

Material Aspects of the Design and Operation of Direct Borohydride Fuel Cells

The direct borohydride fuel cell (DBFC) has attracted increasing interest as a potential high power source for mobile and portable applications. Engineering design plays an important role in the development of the DBFC. This paper reports data for the selection of anode, cathode, and membrane materials for the DBFC. The best DBFC performance is achieved with a Au anode, a Pt cathode, and a 3541P ion exchange membrane. The use of non‐precious catalysts, e.g., Ag, leads to promising results.     

硼氢化物催化水解制氢作为燃料电池氢源(英文)

Borohydrides present interesting options for the electrochemical power generation acting either as hydrogen source or anodic fuel for direct borohydride fuel cells(DBFC).In this work,Mg-Ni composite synthesized by mechanically alloying method,used as the catalyst for the hydrolysis of borohydride,has been investigated.Co-doping treatment has been carried out for the purpose of improving the hydrolysis rate further.The as-prepared and Co-doped Mg-Ni composites with low cost showed high catalytic activity to the hydrolysis of borohydride for hydrogen generation.After Co-doping,the hydrogen generation rate was around 280 ml·g-1·min-1.Borohydride would be a promising hydrogen source for fuel cells.     

直接甲醇燃料电池用Nafion膜及其改性研究进展

讨论了 Nafion膜在直接甲醇燃料电池中的应用 ,综述了国内外对直接甲醇燃料电池用 Nafion膜改性的最新进展。     

Investigation of Ni Foam Effect for Direct Borohydride Fuel Cell

Ni foam has been used as a substrate for the anode electrocatalyst in our previous works. In this study, the effect of nickel foam as an anode electrode in direct borohydride cells has been investigated under steady state/steady‐flow and uniform state/uniform‐flow systems, since nickel has catalytic property. Cathode catalyst used has been 0.3 mg cm^–2 on PTFE‐treated Toray carbon paper. The results have showed that power densities have increased by increasing the temperature. Peak power densities of 5.01 and 9.55 mW cm^–2 have been achieved at 25 and 60 °C, respectively, for 1.5 mol dm^–3 NaBH₄. On the other hand, the electrochemical performance has not been significantly different by the sodium borohydride concentration; only a small increase of power density has been observed in steady state/steady‐flow system, and only a small decrease of fuel utilization ratio has been obtained in uniform state/uniform‐flow systems.     

Porous Carbon as Anode Catalyst Support to Improve Borohydride Utilization in a Direct Borohydride Fuel Cell

Our study explores the use of porous carbon as anode catalyst support to improve borohydride utilization in a direct borohydride fuel cell. Pt catalysts supported by carbon aerogel (CA) and macroporous carbon (MPC) are synthesized by template method. The pores in porous carbon materials catch hydrogen bubbles to regulate the contact of anolyte with catalytic sites, and this leads to the depression of hydrogen evolution during BH₄⁻ electrooxidation. However, the hydrogen bubbles in the pores simultaneously deteriorate charge carrier transport and thus increase anode polarization. The CA‐supported Pt catalyst improves the coulombic efficiency of BH₄⁻ electrooxidation. However, the MPC‐supported Pt catalyst performed better than the CA‐supported Pt catalyst. MPC also has a good pore distribution, which improves the coulombic efficiency of BH₄⁻ electrooxidation without decreasing anode performance.     

Performance Study of Direct Borohydride Fuel Cells Employing Polyvinyl Alcohol Hydrogel Membrane and Nickel‐Based Anode

A direct borohydride fuel cell (DBFC) employing a polyvinyl alcohol (PVA) hydrogel membrane and a nickel‐based composite anode is reported. Carbon‐supported platinum and sputtered gold have been employed as cathode catalysts. Oxygen, air and acidified hydrogen peroxide have been used as oxidants in the DBFC. Performance of the PVA hydrogel membrane‐based DBFC was tested at different temperatures and compared with similar DBFCs employing Nafion® membrane electrolytes under identical conditions. The borohydride–oxygen fuel cell employing PVA hydrogel membrane yielded a maximum peak power density of 242 mW cm^–2 at 60 °C. The peak power densities of the PVA hydrogel membrane‐based DBFCs were comparable or a little higher than those using Nafion® 212 membranes at 60 °C. The fuel efficiency of borohydride–oxygen fuel cell based on PVA hydrogel membrane and Ni‐based composite anode was found to be between 32 and 41%. The cell was operated for more than 100 h and its performance stability was recorded.     

Effects of Nafion® Dehydration in PEM Fuel Cells

The current dependence of the ohmic resistance of Nafion membranes was examined with different types of humidification: cathodic (ChAd), anodic (CdAh), anodic and cathodic (ChAh) and no humidification at all (CdAd). Data show that for stacks with humidified cathodes (ChAd and ChAh), the resistance is small and relatively insensitive to the presence of the anodic humidification. On the contrary, for stacks with non-humidified cathodes (CdAh and CdAd), the membrane resistance is high and strongly dependent on current and anodic humidification. The kinetics of membrane dehydration was examined by recording the galvanostatic transients of the stack voltage and resistance, after removing the humidification. It was found that the changes in the ohmic resistance ΔR _Ω(t), although significant, cannot explain entirely the observed decay of the stack voltage. To account for the difference, an additional resistive term is introduced ΔR _p(t). Explicit equations were found for the time and current dependence of the two resistive terms ΔR _Ω(t) and ΔR _p(t) after humidification removal. A tentative explanation for the new resistive term was provided using electrochemical impedance spectroscopy (EIS). EIS data obtained at low overpotential show that dehydration of the Nafion present in the cathode catalytic layer results in an increase of the polarization resistance; the apparent deactivation of the cathode electrocatalyst appears to be due to a decrease of the electrochemically active surface area.     

直接碳燃料电池研究进展

碳燃料电池直接采用固态碳作阳极,不存在气体燃料面临的存储与运输问题.碳燃料电池的热效率远高于氢燃料电池,产物二氧化碳不须进一步纯化就可工业应用或隔离存放.另外,碳燃料来源广泛,生产纯碳的过程往往比生产纯氢的过程有效能保持率高.近几年来,因固体碳燃料电池的已有的技术在集中或分散式供电方面展示出良好的应用前景,受到广泛关注.故对固体碳燃料电池的原理、碳材料结构对阳极放电性能的影响和其它组成部件及单电池原型化设计的相关内容进行了论述.     

Catalysts for Direct Methanol Fuel Cells

The activity of in house prepared carbon-supported Pt-Ru catalysts for methanol oxidation and carbon-supported RuSe for the oxygen reduction reaction in direct methanol fuel cells (DMFCs) was investigated. The composition of Pt-Ru/C was varied both in terms of weight loading (ratio of total metal content to carbon) as well as the ratio of Pt to Ru. The measurements were carried out in a half cell arrangement in sulphuric acid at various temperatures. The weight loading and ratio of Pt to Ru were varied in order to find out the optimum weight loading of precious metal and the temperature dependence of Pt to Ru ratio on methanol oxidation reaction. It has been found that there exists an optimum in the weight loading at 60 wt.% for carbon-supported Pt-Ru catalyst towards its maximum mass activity. While 1:1 Pt to Ru ratio exhibits a higher activity than 3:2 Pt:Ru above 60 °C, 3:2 ratio exhibits a higher activity at lower temperature. It has been observed that RuSe is inactive towards methanol and it is realised that RuSe is a potential candidate as methanol tolerant oxygen reduction catalyst. The activity of carbon supported RuSe for oxygen reduction reaction (ORR) was tested in sulphuric acid in the presence of methanol. Even though the mass specific activity of the RuSe catalyst is somewhat lower than that of Pt/C, the surface activity of carbon-supported RuSe is superior than that of carbon supported Pt which indicate the unfavourable size distribution of RuSe/C catalyst.     

Investigation of Carbon Supported Nanostructured PtAu Alloy as Electrocatalyst for Direct Borohydride Fuel Cell

Carbon supported bimetallic PtAu electrocatalysts for sodium borohydride electrooxidation are prepared by a modified citrate stabilized NaBH₄ reduction process at different pH and temperature values. The physical properties of the materials are characterized by X‐ray diffraction spectroscopy, energy dispersive spectrometry, X‐ray photoelectron spectroscopy and transmission electron microscopy. Nano sized electrocatalysts have narrow size distributions and are uniformly dispersed on the surface of carbon support. Electrochemical performances of catalysts for sodium borohydride electrooxidation are tested with 25 cm² single fuel cell. The highest performance is obtained at a peak power density of 161 mW cm⁻² with 20 wt. % PtAu/C catalyst of 7.03 nm. Impact of the fuel cell operation parameters including concentration of NaBH₄, flow rates of oxidant and fuel, and fuel cell operation temperature are investigated. The best operation parameters are obtained at 1 M NaBH₄ concentration, 3 cm³ min⁻¹ NaBH₄ flow rate, 0.2 dm³ min⁻¹ oxygen flow rate and 65 °C fuel cell temperature.