High-power-density catalyst induced hydrino transition (CIHT) electrochemical cell

CIHT cells, each comprising a Mo, MoCu (50–50 at%), or MoNi (50–50 at%) hydrogen permeable membrane anode or tape cast CoCu, clad onto a hydrogen permeable Ni membrane, NiO cathode, a LiOH–LiBr eutectic mixture as the electrolyte, and MgO matrix in some cases, exploit hydrino formation as a half-cell reaction to serve as a new electrical energy source. The cells were operated under intermittent H₂O electrolysis to generate H at the anode and then discharged to form hydrinos wherein H₂O vapor as well as some O₂ was supplied from the atmosphere in open cells. Net electrical production over the electrolysis input and hydrogen supplied to the anode was measured to be multiples of the electrical input at about 10 mW/cm² anode area. The predicted molecular hydrino H₂(1/4) was identified as a product of CIHT cells by MAS ¹H NMR, electron-beam excitation emission spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence emission spectroscopy.     

Catalyst development for viability of electrochemical hydrogen purifier and compressor (EHPC) technology

Considering the disadvantages of conventional compressors, which are widely used in the world, it is thought that the electrochemical hydrogen purifier and compressor system (EHPC) to be developed will provide great advantages in hydrogen technologies. The electrocatalyst, which is one of the main components of the EHPC system, is critical for both the performance and applicability of the system. In this study, commercial carbon black supported Pt and Pd containing catalysts were prepared for the EHPC system by using microwave heating method. The synthesized catalysts were mono and bimetallic and were named as Pt/C, Pd/C and PtPd/C, respectively. By characterizing the prepared catalysts with ICP-MS, SEM-EDS, TEM, XRD and XPS, information about the distribution, amount, morphology and composition of metal nanoparticles on the support material was obtained. In addition, electrochemical properties of the catalysts were determined by CV analysis. The physical characterization results revealed that the catalysts were successfully synthesized by microwave method and that different ratios of metals and bimetallic could be loaded on the support material. It was also seen that the electrochemical activity of the PtPd/C bimetallic catalyst was better than the others.     

隔膜特性对氢气电化学压缩能耗的影响

文章选取Nafion 211和Nafion 117膜作为电化学压缩隔膜,通过仿真建模方法研究了隔膜特性对电化学压缩机压缩性能的影响。研究结果表明:隔膜欧姆阻抗对电压效率影响显著,隔膜气密性对电流效率影响显著;与Nafion 117膜相比,将Nafion 211膜应用于电化学压缩机时,电化学压缩机能够获得更高的能量效率,当工作电流为0.5 A/cm^2,压缩比为3时,等温压缩效率最高可达到50%。将以Nafion 211膜为隔膜,工作电流为2 A/cm^2的电化学压缩机用于制氢厂的管束车充装,当气源压力为2 MPa,管束车压力由5 MPa充装至20 MPa时,平均能量效率为35%,综合平均电耗为2 kW·h/kg,比目前常用的机械往复式压缩机的电耗降低了30%以上。     

Flavin mononucleotide (FMN)-ethylenediaminetetraacetic acid (EDTA) photogalvanic cell

The photovoltages and photocurrent in a photogalvanic cell containing flavin mononucleotide (FMN) and a reducing agent, ethylenediaminetetraacetic acid (EDTA) have been determined and found to be appreciable. The efficiency of the cell has been estimated to be ～ 0-048 percent. The electrochemical behaviour of FMN in the presence of EDTA has been examined by cyclic voltametry.     

Effect of tungsten doping on strontium ferrite electrode for symmetrical solid oxide electrochemical cell

Tungsten-doped strontium ferrite (SrFe_1-xW_xO_3-δ, SFW) is prepared and characterized as the electrode materials for symmetrical solid oxide electrochemical cell. X-ray diffraction refinement reveals the symmetrical structure transform from cubic $\left(pm\overline{3}m\right)$ for x = 0.1 to tetragonal (I4/m) when x = 0.2. According to the analysis including electrical conductivity, Hydrogen temperature-programmed reduction (H₂-TPR), thermal expansion and X-ray photoelectron spectra (XPS), it suggests that the decrease in conductivity, content of Fe²⁺ and oxygen vacancy concentration with the increase of W content is attributed to the stronger lattice framework. The oxygen vacancy can be dramatically activated around 600 °C. Using SrFe_0.8W_0.2O_3-δ as the electrodes, symmetrical single cells supported on doped ceria electrolytes can achieve acceptable power density (0.19 W cm⁻² at 750 °C) and considerable stability. Meanwhile symmetrical cells with La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-δ (LSGM) electrolyte substrates can achieve 0.75 A cm⁻² at 800 °C under the voltage of OCV (open circuit voltage) +0.5 V when it is operated in electrolysis mode. SrFe_0.8W_0.2O_3-δ can gain a considerable stability and electrochemical activity under both oxide and reductive atmospheres. Oxygen vacancy formation energy (E_vac) and electron density distribution are computed to verify the enhancement on crystal structure stability by doping W. The E_vac critically depends on the distance from the W atom.     

Regenerative energy control system for plug-in hydrogen fuel cell scooter

An intelligent control system was developed using simple control methodologies for an H₂-powered fuel cell scooter with the aid of a built-in microprocessor. This system increases the power input to drive a hydrogen fuel cell scooter, particularly during uphill conditions by running both the batteries and the fuel cell source in parallel. This system also improves the energy management of the scooter by recharging the battery using the fuel cell as well as automatic switching to the battery source when the hydrogen fuel cell is running low on hydrogen. This system was tested on a bench set simulating a 254 W hydrogen fuel cell stack equipped on a 200 W scooter. The test rig set-up depicts a practical scooter running on various load conditions. These results reflect the efficiencies of actual running conditions. The entire operation was embedded in a PICAXE-18 microcontroller for automatic switching between the batteries and the fuel cell source. An increase in the DC motor efficiency by 6 % has been shown. The uphill angle of the scooter has been increased by 19.3 %, which means the scooter would be able to travel on steeper hills. Copyright © 2007 John Wiley & Sons, Ltd.     

Semiconductor septum electrochemical photovoltaic cell with electrodeposited CdSe thin films

The performance of a semiconductor septum electrochemical photovoltaic (SC-SEP) cell based on electrodeposited CdSe thin films is reported. Photovoltages and photocurrent densities of 1.06 V and 15 mA/cm², respectively, were obtained. The proper selection of the electrolyte/electrode combination in the back compartment is a key factor better performance. A low fill factor causes a relatively low conversion efficiency of about 3.5%.     

Treatment of low concentration hydrogen by electrochemical pump or proton exchange membrane fuel cell

Proton exchange membrane fuel cell (PEMFC) can produce electricity through electrochemical reaction of hydrogen with oxygen with the use of a membrane and electrode assembly (MEA). In other words, the hydrogen pressure difference between the anode and cathode can produce electricity via an electrochemical process. Conversely, when we supply electricity to MEA from an external power source, we can pump up or separate hydrogen from the low-pressure anode to the high-pressure cathode, according to the principle of “concentration cell”. By the way, PEMFC cannot use the fuel completely, because a cell potential decreases and electrode material may corrode when most of the fuel is consumed. Therefore the fuel released from PEMFC should be treated safely. The depleted hydrogen from PEMFC can be recovered by the electrochemical hydrogen pump, or further can be used as a fuel for the power generation by PEMFC, even though the cell voltage might be low. In this study we preliminarily measured the voltage–current characteristics of hydrogen pump and PEMFC changing the hydrogen concentration from 99.99% to 1%, as another option to platinum catalytic combustion of low concentration hydrogen. Moreover we could successfully treat the low concentration hydrogen by electrochemical pump or PEMFC, for the widely changing hydrogen concentration and mixture flow rate. The gas chromatography confirmed the hydrogen concentration of the treated gas to be 1000 ppm at most.     

Characteristics of hydrogen generation from water splitting by polymer electrolyte electrochemical cell directly connected with concentrated photovoltaic cell

Energy storage is a key technology for establishing a stand-alone renewable energy system. Current energy-storage technologies are, however, not suitable for such an energy system because the technologies are cost ineffective and achieve low energy-conversion efficiency. The most realistic and expected technology is hydrogen generation from water splitting by an electrochemical cell directly connected with photovoltaic cell. In this study, a simple concept is proposed for generating hydrogen from water splitting by using a direct-electrically-connected polymer electrolyte electrochemical cell and a separately-located concentrated photovoltaic cell, named a “concentrated photovoltaic electrochemical cell (CPEC)”. The CPEC operates stably and achieves relatively high-energy conversion efficiency from light to hydrogen of over 12%. The conditions are comparison with those of the electrochemical cell connected with a polycrystalline Si solar cell.     

基于电化学阻抗法的质子交换膜燃料电池“三步活化法”机理研究

活化能够有效地发挥质子交换膜燃料电池膜电极的性能,"三步活化法"是其中一种比较理想的方法。为了研究"三步活化法"活化质子交换膜燃料电池的机理,利用电化学阻抗谱测试"三步活化法"过程中的膜电极阻抗,并建立等效电路模型拟合所得实验数据。结果表明,"三步活化法"可以有效降低欧姆阻抗、阳极法拉第阻抗、阴极法拉第阻抗以及阴极传质阻抗,这表明"三步活化法"有利于电子、质子、气体与水的传输通道的形成。     

Portable direct hydrogen fed PEM fuel cell model and experimental verification

This paper focuses on the experimental verification of an electrochemical model of 100 W portable direct hydrogen fed proton exchange membrane (PEM) fuel cell (FC). The model is built based on the relationship between the FC terminal voltage and the partial pressures of hydrogen and oxygen. The model is then used to predict the output voltage and study the transient response of a PEMFC when subjected to rapid changes in the load. To validate the model, the measurements obtained from a commercially available 100 W FC are compared against the model results. Three different scenarios are considered for testing the model and the actual FC. In the first two scenarios, a step change in the load is used. In the third scenario, the load is replaced by a laptop computer. Results show a close agreement between the voltage and the power responses of the proposed model and the actual PEM FC. Copyright © 2009 John Wiley & Sons, Ltd.     

Decay of material properties of degraded MEA caused by repeated cold starts under subzero conditions in polymer electrolyte fuel cells

This study investigated the characteristics of cell performance degradation, decline of component performance, and changes in the properties of membrane electrode assembly materials caused by repeated cold starts under a subzero condition of ?30 °C. It was made clear that functional decay appeared mainly at the cathode due to increased proton conductive impedance and reduction of reactivity of the electrode catalyst. Among the cathode components, an increase in proton conductive impedance in the cathode electrolyte was dominant. Furthermore, the application of ion chromatography and a newly developed proton‐induced gamma‐ray emission method to measure fluorine in the off‐gas drain revealed that decomposition of the electrolyte was dominant in the cathode catalyst layer. A decrease in fluorine in the cathode electrolyte measured by fluorine‐19 nuclear magnetic resonance confirmed this decomposition. A hypothesis is also presented concerning the cause of the performance degradation. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20394     

Nanocrystalline doped lanthanum cobalt ferrite and lanthanum iron cobaltite-based composite cathode for significant augmentation of electrochemical performance in solid oxide fuel cell

Sr-doped lanthanum cobalt ferrite (La_0.54Sr_0.40Co_0.20Fe_0.80O_3−δ) and lanthanum iron cobaltite (La_0.54Sr_0.40Fe_0.20Co_0.80O_3−δ)-based mixed ionic and electronic conducting solid oxide fuel cell cathodes are synthesized by autocombustion technique. In order to examine the electrochemical activity including thermal matching with the adjacent cell components, a composite cathode comprising of both the ferritic and cobaltite system is prepared using mechanical mixing. Powder characterizations for cobaltite and ferritic-based perovskite revealed nanocrystallinity (15–30 nm) with particulate size ranging 50–100 nm. Anode-supported half cell with suitable doped ceria based interlayer on the top of the electrolyte and developed composite cathode augments the current density to 3.98 Acm⁻² at 0.7 V at 800 °C. The oxygen reduction reaction kinetics of such composite cathode shows high exchange current density of 1.16 Acm⁻² with relatively low electrode polarization of 0.02 Ωcm² at 800 °C. The electrochemical performance is clinically correlated with the cell microstructure exhibiting minimum SrO diffusion at the electrode-electrolyte interface.     

Impedance of a tubular electrochemical cell with BZCY electrolyte and Ni-BZCY cermet electrodes for proton ceramic membrane reactors

In this work, impedance spectroscopy has been employed to explore the electrochemical behaviour of a 15 cm² complete tubular cell with BaZr_0.8Ce_0.1Y_0.1O_3-δ (BZCY) electrolyte and two asymmetric Ni-BCZY cermet electrodes for hydrogen separation. Analyses of impedance spectra at different temperatures and gas compositions reveal that the thick inner electrode contributes most to the total polarisation resistance (R_p). For R_p there are four contributions with well-separated time constants of which gas phase hydrogen diffusion within the porous Ni-BZCY anode is predominant. The other three can be ascribed to proton migration through the space charge layer of the BZCY electrolyte adjacent to the Ni electrode, hydrogen redox charge transfer reactions, and hydrogen diffusion within Ni bulk. The present study guides the way to parameterise and, on this basis, optimise electrodes for scalable proton ceramic electrochemical cells.     

Single‐chamber microbial electrochemical cell for CH4 production from CO2 utilizing a microbial consortium

We report the first single‐chamber microbial electrochemical cell for conversion of CO₂ to CH₄, with an average CH₄ production rate of 0.47 ± 0.05 mL day^?1 cm^?2 at an applied potential of 600 mV, utilizing a methanogenic microbial community collected from the formation water in the San Juan coal basin (Colorado, USA). CH₄ production was only observed at the graphite rod cathode after an electrochemical pre‐treatment that facilitates biofilm formation. The carbon contained within the CH₄ arose predominantly from the CO₂ source, as verified by experiments during which the CO₂ source was repeatedly turned off and on. Modest quantities of acetic acid and ethanol were also produced. DNA extraction and sequencing from the microbial community showed that from the Archaea kingdom, only 2 species survived prolonged exposure to CO₂ and CH₄ production, methanobacterium sp. (81.4%), and methanoculleus sp. (18.6%), while in the bacterial kingdom, anaerobaculum thermoterrnum (67.1%) was the predominant surviving species.     

Progress reports and prospect of stretchable electrochemical energy storage devices

随着人类社会的进步,人们对可穿戴电子设备的需求日益增强,其中电子皮肤、可植入传感器等新型便携式器件也对储能单元的可拉伸性提出了越来越高的要求。本综述介绍了制备可拉伸式锂离子电池或超级电容器的策略,并对其进行了简单评述;在此基础上概括地介绍了可拉伸式电化学储能器件中常用的电解质及其优缺点,以及可拉伸式储能器件的集成方案。最后,针对性地总结可拉伸储能器件制备过程中仍面临的挑战与未来可能的发展方向。     

Application of electrochemistry (Ⅱ)--Development and application of electrochemical capacitor

电化学电容器是一种新型储能元件,具有功率密度大,充放电速度快,工作温度宽,循环寿命长,安全环保等优点,受到各国研究者的广泛关注.自1957年第一份专利申请以来,电化学电容器历经了数代的发展,在电极材料,电解质等方面都取得了长足的进步.同时,电化学电容器的应用范围不断扩展,在储能,电动汽车,自动控制等领域有重要作用.本文简要介绍了电化学电容器的发展历程,基本原理及其主要应用,展望了电化学电容器的发展前景及研究方向.     

Three‐dimensional nonisothermal modeling of solid oxide fuel cell coupling electrochemical kinetics and species transport

A three‐dimensional (3D) nonisothermal model is developed and applied for anode‐supported planar solid oxide fuel cell (SOFC). The mass and momentum, species, ion, electric, and heat transport equations are solved simultaneously by implementing the electrochemical kinetics and electrochemical reaction as volumetric source terms. The interconnect land limits the O₂ transport under the land and lowers the local current density under the land. The effects of interconnect land width and cathode substrate thickness on SOFC cell performance are quantified in this study. Cathode stoichiometry is found to have a large effect on the SOFC cell temperature distribution. Under low‐cathode stoichiometry, significant temperature gradients are seen in the SOFC cell. Higher‐cathode stoichiometry is beneficial for lower temperature and more uniform current density distribution in SOFC cell. Co‐flow and counter‐flow arrangements are investigated and discussed with the model. Counter‐flow arrangement is found to induce a high temperature and high current density region near the H₂ inlet. On the other hand, co‐flow arrangement leads high temperature and high current density to occur relatively downstream, a slightly lower maximum temperature on cell and considerably more uniform current density distribution. A 67.2‐cm² SOFC cell is simulated considering the side cooling effect. The side cooling effectively lowers the cell temperature, at the same time, causes temperature, current density, and fuel utilization nonuniformity in the across multichannel direction. Because of the strong coupling of the in‐plane current density distribution and temperature distribution, limiting the locally high temperature and temperature gradient is critical for achieving a more uniform current density distribution in anode‐supported planar SOFC.