Sulfonated polybenzimidazole/amine functionalized titanium dioxide(s PBI/AFT) composite electrolyte membranes for high temperature proton exchange membrane fuel cells usage

The novel sulfonated polybenzimidazole(sPBI)/amine functionalized titanium dioxide(AFT) composite membrane is devised and studied for its capability of the application of high temperature proton exchange membrane fuel cells(HT-PEMFCs),unlike the prior low temperature AFT endeavors.The high temperature compatibility was actualized because of the filling of free volumes in the rigid aromatic matrix of the composite with AFT nanoparticles which inhibited segmental motions of the chains and improved its thermal stability.Besides,amine functionalization of TiO2 enhanced their dispersion character in the sPBI matrix and shortened the interparticle separation gap which finally improved the proton transfer after establishing interconnected pathways and breeding more phosphoric acid(PA) doping.In addition,the appeared assembled clusters of AFT flourished a superior mechanical stability.Thus,the optimized sPBI/AFT(10 wt%) showed 65.3 MPa tensile strength;0.084 S·cm^-1 proton conductivity(at 160℃;in anhydrous conditions),28.6% water uptake and PA doping level of 23 mol per sPBI repeat unit.The maximum power density peak for sPBI/AFT-10 met the figure of0.42 W·cm^-2 at 160℃(in dry conditions) under atmospheric pressure with 1.5 and 2.5 stoichiometric flow rates of H2/air.These results affirmed the probable fitting of sPBI/AFT composite for HT-PEMFC applications.

Effect of temperature on the efficiency of organometallic perovskite solar cells

In recent years perovskite solar cells have attracted an increasing scientific and technological interest in the scientific community. It is important to know that the temperature is one of the factors which have a strong effect on the efficiency of perovskite solar cell. This study communicates a temperature analysis on the pho- tovoltaic parameters of CH3NH3Pbl3-based perovskite solar cell in a broad interval from 80 to 360 K. Strong temperature-dependent photovoltaic effects have been observed in the type of solar cell, which could be mainly attributed to CH3NH3PbI3, showing a ferroelectric-paraelectric phase transition at low temperature （T 〈 160 K）. An increase in temperature over the room temperature decreased the perovskite solar cell performance and reduced its efficiency from 16Z to 9%. The investigation with electronic impedance spectroscopy reveals that at low temperature （T 〈 120 K） the charge transport layer limits the device performance, while at high temperature （T 〉 200 K）, the interfacial charge recombination becomes the dominant factor.

Status and prospects of intermediate temperature solid oxide fuel cells

Compared with conventional electric power generation systems, the solid oxide fuel cell （SOFC） has many advantages because of its unique features. High temperature SOFC has been successfully developed to its commercial applications, but it still faces many problems which hamper large-scale commercial applications of SOFC. To reduce the cost of SOFC, intermediate temperature solid oxide fuel cell （IT-SOFC） is presently under rapid development. The status of IT-SOFC was reviewed with emphasis on discussion of their component materials. 2008 University of Science and Technology Beijing. All rights reserved.

Preparation and Characterization of Component Materials for Intermediate Temperature Solid Oxide Fuel Cell by Glycine-Nitrate Process

La1-xSrxGa1-y MgyO3-δ(LSGM) electrolyte, La1-xSrxCr1-y MnyO3-δ( LSCM ) anode and La1-xSrxFe1-y MnyO3-aaaaaaa(LSFM) cathode materials were all synthesized by glycine-nitrate process (GNP). The microstructure and characteristics of LSGM, LSCM and LSFM were tested via X-ray diffraction(XRD), scanning electron microcopy (SEM), A C impedance and four-probe direct current techniques. XRD shows that pure perovskite phase LSGM electrolyte and electrode (LSCM anode and LSFM cathode) materials were prepared after being sintered at 1400℃for 20 h and at 1000℃for 5 h, respectively. The max conductivities of LSGM (ionic conductivity), LSCM (total conductivity) and LSFM (total conductivity) materials are 0.02, 10, 16 S·cm-1 in the air below 850℃, respectively. The conductivity of LSCM becomes smaller when the atmosphere changes from air to pure hydrogen at the same temperature and it decreases with the temperature like metal. The porous and LSGM-based LSCM anode and LSFM cathode films were prepared by screen printing method, and the sintering temperatures for them were 1300 and 1250℃, respectively. LSGM and electrode (LSCM and LSFM) materials have good thermal and chemical compatibility.

The Temperature Variation of a Solar Cell in Relation to Its Performance

The temperature of a solar cell subjected to the incident global solar radiation as a function of the local day time is determined. A heat balance equation is solved considering the heat losses due to convection and thermal radiation. The cell efficiency is estimated as a measure of its performance. The results reveal that the temperature within the cell attains significant values. Nevertheless, the temperature dependence of its efficiency along the day time is not pronouncing. It slightly decreases with temperature.

Development of nickel based cermet anode materials in solid oxide fuel cells–Now and future

High temperature solid oxide fuel cell(SOFC)is the most efficient and clean energy conversion technology to electrochemically convert the chemical energy of fuels such as hydrogen,natural gas and hydrocarbons to electricity,and also the most viable alternative to the traditional thermal power plants.However,the power output of a SOFC critically depends on the characteristics and performance of its key components:anode,electrolyte and cathode.Due to the highly reducing environment and strict requirements in electrical conductivity and catalytic activity,there are limited choices in the anode materials of SOFCs,particularly for operation in the intermediate temperature range of 500–800C.Among them,Ni-based cermets are the most common and popular anode materials of SOFCs.The objective of this paper is to review the development of Ni-based anode materials in SOFC from the viewpoints of materials microstructure,performance and industrial scalability associated with the fabrication and optimization processes.The latest advancement in nano-structure architecture,contaminant tolerance and interface optimization of Ni-based cermet anodes is presented.And at the end of this paper,we propose and appeal for the collaborative work of scientists from different disciplines that enable the inter-fusion research of fabrication,microanalysis and modelling,aiming at the challenges in the development of Ni-based cermet anodes for commercially viable intermediate temperature SOFC or IT-SOFC technologies.

Suppression of the vapor cell temperature error in a spin-exchange relaxation-free comagnetometer

The fluctuation of the vapor cell temperature leads to the variations of the density of the alkali metal atoms,which seriously damages the long-term stability of the spin-exchange relaxation-free(SERF)comagnetometer.To address this problem,we propose a novel method for suppressing the cell temperature error by manipulating the probe laser frequency.A temperature coefficient model of the SERF comagnetometer is established based on the steady-state response,which indicates that the comagnetometer can be tuned to a working point where the output signal is insensitive to the cell temperature fluctuation,and the working point is determined by the relaxation rate of the alkali metal atoms.The method is verified in a K-Rb-^(21)Ne comagnetometer,and the experimental results are consistent with the theory.The theory and method presented here lay a foundation for the practical applications of the SERF comagnetometer.

Phosphorus induced activity-enhancement of Fe-N-C catalysts for high temperature polymer electrolyte membrane fuel cells

Fe-N-C materials with atomically dispersed Fe–N_(4) sites could tolerate the poisoning of phosphate,is regarded as the most promising alternative to costly Pt-based catalysts for the oxygen reduction in high temperature polymer electrolyte membrane fuel cells(HT-PEMFCs).However,they still face the critical issue of insufficient activity in phosphoric acid.Herein,we demonstrate a P-doping strategy to increase the activity of Fe-N-C catalyst via a feasible one-pot method.X-ray absorption spectroscopy and electron microscopy with atomic resolution indicated that the P atom is bonded with the N in Fe–N_(4) site through C atoms.The as prepared Fe-NCP catalyst shows a half-wave potential of 0.75 V(vs.reversible hydrogen electrode(RHE),0.1 M H_(3)PO_(4)),which is 60 and 40 mV higher than that of Fe-NC and commercial Pt/C catalysts,respectively.More importantly,the Fe-NCP catalyst could deliver a peak power density of 357 mW·cm^(−2)in a high temperature fuel cell(160℃),exceeding the non-noble-metal catalysts ever reported.The enhancement of activity is attributed to the increasing charge density and poisoning tolerance of Fe–N_(4) caused by neighboring P.This work not only promotes the practical application of Fe-N-C materials in HT-PEMFCs,but also provides a feasible P-doping method for regulating the structure of single atom site.

Preparation and Characterization of Cathode Materials La_(0.7)Sr_(0.3-x)Ca_xCo_(0.9)Fe_(0.1)O_(3-δ) by Reverse Titration Co-Precipitation Method for ITSOFC

The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitation method with metal-nitrates as starting materials and mixed alkali (NaOH and Na2CO3) as a precipitating agent. The formation process of LSCCF from the precursors was monitored by TG-DSC, and the crystal structure and particles morphology of the precursors which were calcined at 600, 800, 1000 ℃ for 3 h were characterized using XRD, SEM technologies. Compared with the solid state reaction of constituent oxides, when the pH value of the precipitating solution was in the range of 9.1～9.5, the LSCCF powders from the precursors caclined at 800 ℃ for 3 h had high purity, homogeneous and single perovskite phase. The electrical conductivity of the LSCCF samples sintered at 1200 ℃ for 3 h, which was measured as a function of temperatures from 100 to 800 ℃ by DC four-probe method in air, decreased with x from 0.05 to 0.20. The value of electrical conductivity was almost equal because of Ca2+, Sr2+ co-dopant resulting in the 'mix effect' while x=0.10 or 0.15. The electrical conductivity of all doped samples was higher than 100 S·cm-1 at intermediate temperatures from 500 to 800 ℃, and there was good compatibility between the LSCCF cathode and Ce0.8Sm0.2O2 electrolyte.

The influence of environment temperatures on single crystalline and polycrystalline silicon solar cell performance

The influence of the cell temperature (named interior environment temperature) and ambient air temperature (named exterior environment temperature) on the open-circuit voltage,short-circuit current,and output power has been carefully studied for the Si solar cells.The results show that one of the environment temperatures plays the major role,and the temperature dependence of device performance parameters is different for single crystalline and polycrystalline Si solar cells.Furthermore,the ambient air temperature builds a bridge for the comparison of the effect between the cell temperature and the illumination intensity on solar cell performance.Based on the experimental results,the reasons which cause the difference of the environment temperatures dependence are analyzed.

Ln_2MO_4 cathode materials for solid oxide fuel cells

One of the major challenges to develop "intermediate temperature" solid oxide fuel cells is finding a novel cathode material, which can meet the following requirements: (1) high electronic conductivity; (2) chemical compatibility with the electrolyte; (3) a matched thermal expansion coefficient (TEC); (4) stability in a wide range of oxygen partial pressure; and (5) high catalytic activity for the oxygen reduction reaction (ORR). In this short review, a survey of these requirements for K2NiF4-type material with the formula Ln2MO4, Ln = La, Pr, Nd, Sm; M = Ni, Cu, Fe, Co, Mn, is presented. The composition-dependent TEC, electrical conductivity and oxygen transport property are considered. The Ln2MO4 materials exhibit improved chemical stability and compatibility with most of the traditional electrolytes. The complete fuel cells integrated with Ln2MO4 materials as cathodes show promising results. Furthermore, these materials are considered as cathodes of protonic ceramic fuel cell (PCFC), and/or anodes of high temperature steam electrolysis (HTSE). First results show excellent performances. The versatility of these Ln2MO4 materials is explained on the basis of structural features and the ability to accommodate oxygen non-stoichiometry.

Effect of thermal load on performance parameters of solar concentrating photovoltaic:High-efficiency solar cells

The triple-junction solar cell is designed to exploit a wide range of the solar spectrum photons.These triple-layers consisting of GaInP/GaInAs/Ge,it is monolithically stacked,leading to high conversion efficiency.To describe and understand it’s operating behaviour,this paper presents a performance analysis of a triple-junction solar cell,based on estimation modelling.A model was developed to determine the performance characteristic of the solar cell.Hence,the J-V curve is characterising the performance of solar cells,which used to optimise and improve the design of the cells.It has been discussed the effects of thermal load related to cell temperature increases on the cell’s operating performance parameters.Cell temperature increases from 25 to 125℃ have resulted variances,which causes a significant decrease in efficiency to approximately−17%,open circuit voltage by−15%and fill factor by−4.5%.On the other hand,the current density slightly increased by+5.5%.Finally,ought to consider the thermal management while designing and developing solar CPV technology;therefore,it’s significant to improve cell efficiency and to maintain cell integrity from thermal damage.

Internal Short Circuit Detection for Parallel-Connected Battery Cells Using Convolutional Neural Network

Reliable and timely detection of an internal short circuit(ISC)in lithium-ion batteries is important to ensure safe and efficient operation.This paper investigates ISC detection of parallel-connected battery cells by considering cell non-uniformity and sensor limitation(i.e.,no independent current sensors for individual cells in a parallel string).To characterize ISC-related signatures in battery string responses,an electro-thermal model of parallel-connected battery cells is first established that explicitly captures ISC.By analyzing the data generated from the electro-thermal model,the distribution of surface tem-perature among individual cells within the battery string is identified as an indicator for ISC detection under the constraints of sensor limitations.A convolutional neural network(CNN)is then designed to estimate the ISC resistance by using the cell surface temperature and the total capacity of the string as inputs.Based on the estimated ISC resistance from CNN,the strings are classified as faulty or non-faulty to guide the examination or replacement of the battery.The algorithm is evaluated in the presence of signal noises in terms of accuracy,false alarm rate,and missed detection rate,verifying the effectiveness and robustness of the proposed approach.

Bulk flow properties of fly ashes at ambient and high temperature

The bulk flow properties of four different fly ashes were assessed at ambient temperature and at 500 ~C, using a high temperature annular shear cell. These powders all resulted from industrial processes and had similar chemical compositions but different particle size distributions. Applying a high temperature was found to increase the powder cohesion, with this effect being more significant in the case of the sample with the highest proportion of fines. To better understand the effect of temperature on the bulk flow properties of these materials, a model previously proposed by some of the authors was used to correlate the powder isostatic tensile strength with the interparticle forces and microscale particle contact struc- ture. This model combines the continuum approach with description of particle-to-particle interactions. A comparison with experimental data indicated that the effects of consolidation and temperature on the tensile strength of the fly ashes were correctly described by the model. This theoretical approach also elucidates the mechanism by which the temperature affects the bulk flow properties of fly ashes through modifications of the microscale intemarticle contacts.

Modeling of Packed Bed Methanol Steam Reformer Integrated with Tubular High Temperature Proton Exchange Membrane Fuel Cell

This work proposes a novel tubular structure of high-temperature proton exchange membrane fuel cell(PEMFC)integrated with a built-in packed-bed methanol steam reformer to provide hydrogen for power output.A two-dimensional axisymmetric non-isothermal model was developed in COMSOL Multiphysics 5.4 to simulate the performance of a tubular high temperature proton membrane fuel cell and a packed bed methanol reformer.The model considers the coupling multi-physical processes,including methanol reforming reaction,water gas shift reaction,methanol cracking reaction as well as the heat,mass and momentum transport processes.The sub-model of the tubular packed-bed methanol reformer is validated between 433 K and 493 K with the experimental data reported in the literature.The sub-model of the high temperature proton exchange fuel cell is validated between 393 K and 433 K with the published literature.Our results show that power output and temperature distribution of the integrated unit depend on methanol flow rates and working voltages.It was suggested that stable power generation performance of 0.14 W/cm_(2)and temperature drop in methanol steam reformer of≤10 K could be achieved by controlling the methanol space-time ratio of≥250 kg·s/mol with working voltage at 0.6 V,even in the absence of an external heat source.

An Experimental Study on a Microclimatic Layer of a Bionic Facade Inspired by Vertical Greenery

A microclimatic layer of the green facade is proven to have specific temperature and flow conditions on the building en- velope. Lower temperatures and wind velocities, and higher relative humidity in the microclimatic layer are the characteristics of vertical greenery systems, which cause lower energy consumption for the cooling and heating of buildings. Despite innova- tive architectural solutions, there are some drawbacks to applying vertical greenery on building envelopes. In this study, a bionic facade that mimics the positive effects and eliminates the disadvantages of green facades is presented. The bionic fagade consists of bionic leaves, which are made ofphotovoltaic cells and evaporative matrices. A real scale experiment was carried out in the summer to evaluate the potential of the cooling efficiency of the microclimatic layer and a new photovoltaic cooling technique. The results show a good agreement of the thermal performance between the bionic and the green facade and up to 20.8 K lower surface temperatures of photovoltaic cells, which increase the daily electricity yield by 6.6%.

A novel porous channel to optimize the cooling performance of PV modules

This paper dealt with a series of numerical investigations on a new porous cooling channel applied to PV/T systems in order to improve the insufficient heat transfer in the conventional channel.The proposed porous cooling channel based on field synergy theory had a higher overall heat transfer coefficient,which enhanced the total efficiency of the PV/T system.The numerical model was validated with experimental data.The results showed that holes distributed non-uniformly near the outlet of the cooling water led to a better cooling effect,and a hole diameter of 0.005 m led to an optimal performance.The total efficiency of the PV module with the new cooling channel was 4.17%higher than the conventional one at a solar irradiance of 1000 W/m^(2)and an inlet mass flow rate of 0.006 kg/s.In addition,as the solar irradiance increased from 300 to 1200 W/m^(2),the total efficiency of the new PV/T system dropped by 5.07%,which included reductions in both the electrical and thermal efficiency.The total efficiency was improved by 18.04%as the inlet mass flow rate of cooling water increased from 0.002 to 0.02 kg/s.

Synthesis and characterization of Y and Dy co-doped ceria solid electrolytes for IT-SOFCs:a microwave sintering

In this communication,the electrical conductivities and thermal expansion studies of microwave sintered co-doped ceria Ce_(0.8)Y_(0.2-x)Dy_(x)O_(2-δ)(x=0,0.05,0.10,0.15 and 0.20) solid electrolyte materials for intermediate temperature solid oxide fuel cells(IT-SOFCs)synthesized by sol-gel auto-combustion method were discussed.Microwave sintering at 1300℃ for 30 min was used for making dense powder compacts.The relative densities of all the samples are noticed above 95%.Raman spectrum was characterized by the presence of a very strong band near 460 cm^(-1),which along with X-ray diffraction(XRD) analysis ascertain the sample formation with a single-phase cubic fluorite structure.The lattice parameter values were calculated from XRD patterns.SEM images show nearly uniform grains with distinct grain boundaries.The thermal expansion coefficients(TECs) are found to vary linearly with temperature and were measured in the range from 14.15 to 13.20×10^(-6)℃^(-1).The investigation on total ionic conductivity(TIC) was executed with variation in dopant concentration and relative oxygen vacancies.The impedance analysis reveals that the sample Ce_(0.80)Y_(0.10)Dy_(0.10)O_(2-δ) displays the highest TIC,i.e.,7.5×10^(-3) S·cm^(-1) at 500℃ and minimum activation energy 0.90 eV compared to others.With the highest TIC and minimum activation energy,the Ce_(0.80)Y_(0.10)Dy_(0.10)O_(2-δ)might be the possible material as the solid electrolyte in intermediate temperature SOFCs.