bluuebunny/crossref_metadata_2025_split huggingface dataset:
Porous Titania conformal Coating on Carbon Nanotubes As Energy Storage Materials
Authors: Yan Litao , Zhou Meng , Chen Gen , Luo Hongmei 
Published: February 2020

The controllable synthesis of strongly coupled inorganic materials/carbon nanotubes (CNTs) hybrids represents a long-standing challenge for developing advanced catalysts and energy-storage materials. Here we report a simple sol-gel method for facile synthesis of TiO2/CNTs hybrid. The porous anatase TiO2 nanoparticles are uniformly coated on the CNTs conducting network, which leads to remarkably improved electrochemical performances such as exceptional cycling stability, good high rate durability, and reduced resistance. This hybrid exhibits a reversible capacity as high as 200 mA∙h g-
1 at a current density of 0.1 A g-1 as an anode in lithium-ion battery (LIB). As a supercapacitor (SC), it shows a specific supercapacitance of 145 F g−
1 in 0.5 M H2SO4 electrolyte, higher than that of the previously reported TiO2 based supercapacitors. Moreover, this hybrid also exhibits excellent durability after 1000 cycles for both LIBs and SCs. Such superior performance and cycling durability demonstrate the reinforced synergistic effects between the porous TiO2 and interweaved CNTs network, indicating a great application potential for such hybrid materials in high power LIBs and SCs.
Active Material Arrangement and Its Effect on Electronic Conductivity in a Suspension Electrode
Authors: Hatzell Kelsey B. , Eller Jens , Gogotsi Yury 
Published: February 2020

Flowable or suspension electrodes are multiphase electrode systems, where an active solid material is suspended in electrolytic medium. Suspension electrodes have been demonstrated for large-scale energy storage [1], water deionization [2-4], and energy generation applications [5].
Several material chemistries have been examined in a suspension form, and all systems rely on the use of carbon-based materials to form percolation networks for efficient electron transport. Suspension electrodes based on metal oxides typically demonstrate low electrical conductivities (~10-6 mS/cm) and require the addition of conductive additives to enable efficient charge storage and rate handling. Capacitive suspension electrodes, composed of activated carbon, are significantly more conducting than those based on metal oxides (~10-1-100 mS/cm). Nevertheless, both types of suspension electrodes display electrical conductivities significantly lower than their film counterparts, because of the presence of a highly resistive solution region. One solution to this challenge is the addition of more conducting materials (carbon black or activated carbon) or controlled arrangement of the active material. The former results in high viscosity material systems which are challenging to flow.
The arrangement of the active and inactive material in a suspension electrode is expected to affect charge and ion percolation and material utilization in a suspension electrode. In this work we compare DC and AC electronic conductivity measurement techniques, and present work on visualization of the active material arrangement in a suspension electrode.

References:

[1]. K.B. Hatzell, M. Boota, E. C. Kumbur, and Y. Gogotsi. Journal of The Electrochemical Society 162, no. 5 (2015): A5007-A5012.
[2] K.B. Hatzell, M.C. Hatzell, K.M. Cook., M. Boota, G. M. Housel, A.McBride, E.Caglan Kumbur. Y. Gogotsi, Environmental science & technology, (2015) 49(5), 3040-3047.
[3] S.-I. Jeon, H.-R Park, J.-G. Yeo, S. Yang, C.H. Cho, M.H. Han, D.K. Kim, Energy & Environmental Science, 6 (2013) 1471-1475.
[4.] K.B. Hatzell, E. Iwama, A. Ferris, B. Daffos, K. Urita, T. Tzedakis, F. Chauvet, P.-L. Taberna, Y. Gogotsi, P. Simon, Electrochemistry Communications, 43 (2014) 18-21.
[5] M.C. Hatzell., K.B. Hatzell, and B.E. Logan. Environmental Science & Technology Letters 1.12 (2014): 474-478.
Supercapacitors Performance Evaluation
Authors: Zhang Sanliang 
Published: February 2020

The performance of a supercapacitor can be characterized by a series of key parameters, including for instance the cell capacitance, operating voltage, equivalent series resistance, power density, energy density, and time constant. To accurately measure these parameters, a variety of methods have been proposed and used among academia and industry. As a result, some confusion has been caused due to the inconsistencies between different evaluation methods and practices. Such confusion hinders effective communication of new research findings, and creates a hurdle in transferring novel supercapacitor technologies from research labs to commercial applications.
Based on public sources, this review article is an attempt to inventory, critique and hopefully streamline the commonly used instruments, key performance metrics, calculation methods, and major affecting factors for supercapacitor performance evaluation. Thereafter the primary sources of inconsistencies are identified and the possible solutions are suggested correspondingly, with emphasis on device performance vs. material property and the rate dependency of supercapacitors. We hope, by using reliable, intrinsic and comparable parameters produced, the existing inconsistencies and confusion can be largely eliminated so as to facilitate further progress in the field.
Low-Temperature Chemical Passivation Routes for Integration of Supercapacitors Directly into Silicon Solar Cells
Authors: Westover Andrew S , Metke Thomas , Afolabi Jeremiah , Share Keith , Carter Rachel E. , Cohn Adam P , Oakes Landon , Pint Cary L. 
Published: February 2020

Due to the intermittent nature of renewable energy sources such as solar and wind energy, systems designed to convert grid-scale power from these resources must be coupled with energy storage for off-grid operation. Traditional routes to coupling energy storage with energy conversion systems consists of an energy storage device situated external to the energy conversion system. However, direct integration of both systems offers numerous advantages, such as multipurposing of materials and storage directly at the point of generation to mitigate DC-AC inversion. Our recent efforts have demonstrated the ability to utilize the excess silicon material in a polycrystalline solar cell for supercapacitor energy storage applications. However, a key challenge that remains is to develop chemical passivation routes at low temperatures that can preserve the solar cell P-N junction and yield a passive silicon energy storage interface with a solid-state electrolyte. We address this issue by exploring multiple routes for low-temperature passivation, specifically including (i) wet chemical passivation of porous silicon using thin film metal coatings, and (ii) electrochemical passivation of porous silicon using conductive polymer networks. Our efforts demonstrate these passivation routes as being promising for the development of fully integrated energy storage and conversion systems applicable toward a range of applications ranging from grid-scale storage to remote energy transfer applications.
In-Situ Analysis of Co-Electrolysis Species Via Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS)
Authors: Tumilson Christopher , Cumming Denis J , Taylor S.F. Rebecca , Call Ann V , Hardacre Chris , Elder Rachael H 
Published: February 2020

Syngas production through co-electrolysis of steam and carbon dioxide has been shown as an effective method of CO2 utilisation, however little is known about the complex surface reaction mechanisms involved. Further understanding is needed in order to optimise SOC operation parameters and inform materials development. Currently many investigative techniques are ex-situ, some of which are even destructive: e.g. SEM imagining of the microstructure. To fully understand reaction intermediates, characterise electrochemical performance, and develop novel materials and microstructures for co-electrolysis SOCs; in-situ analysis methods are required.
The EPSRC funded research programme, 4CU aims to enhance the fundamental understanding of CO2 and its role in co-electrolysis by developing a suite of in-situ investigative methods for high temperature SOC operation. Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) we can monitor both adsorbed and gas phase species in-situ. Variation of potential and temperature conditions allow for visualization of surface mechanisms associated with single atmosphere fuel cell operation. This, along with dual atmosphere measurements, will be discussed. This work illustrates the applicability of the new technique for SOCs operated in a range of atmospheres using Au, Pt and Ag electrodes. The comparison of potential dependent DRIFTS combined with electrochemical measurements provides an important insight into the roles of oxygen ion and proton transport within the systems studied.

Figure 1
Long Term Stability Investigation of Solid Oxide Electrolysis Cell with Infiltrated Porous YSZ Air Electrode Under High Current
Authors: Veltzé Sune , Küngas Rainer , Ovtar Simona , Simonsen Søren Bredmose , Thydén Kar Tor Sune , Kiebach Wolff-Ragnar 
Published: February 2020

The increased interest in stable and low cost electrodes for solid oxide cells (SOC) has driven the research of electrode preparation to infiltration of catalyst material into porous backbone material. The infiltration method enables a reduction of amount of catalyst material and increases its activity, due to high surface area of catalyst nano particles. Advantage of infiltration is also separate production of electrolyte backbone structure with good ionic connectivity and mechanical properties.
With this study we present the results of a solid oxide cell with infiltrated porous yttria stabilised zirconia (YSZ) backbone air electrode and Ni/YSZ cermet fuel electrode. The SOC was tested at electrolysis conditions under high current (up to -1 A/cm2). The porous YSZ electrodes was infiltrated with gadolinium-doped ceria oxide (CGO), to act as a barrier layer between the catalyst and the backbone, and perovskite catalyst material. Cobalt doped lanthanum nickelate was used as the perovskite catalyst due to its excellent performance. The cell was tested in steam electrolysis for at least 2000h. This initial test indicate that a stable air electrode was formed, and that the cell performance and stability matches that of a state-of-the-art SOC.
In-Situ Surface Analysis of SOFC Cathode Degradation Using High Temperature Environmental Scanning Electron Microscopy
Authors: Niania Mathew , Podor Renaud , Skinner Stephen J. , Kilner John A. 
Published: February 2020

Solid Oxide Fuel Cell (SOFC) cathode materials rely on the catalytic processes at their surfaces to reduce and incorporate oxygen. For many common cathode materials surface passivation occurs through 'A site' segregation at common operating temperatures [1]. These processes have a negative effect upon the oxygen reduction rates and therefore overall cell performance. Quantifying the true extent these segregation effects have on the exchange properties has not been fully explored but it is clear that the properties of the surface are essential.
Many techniques have been employed to study cell properties in-situ, however, surface studies are typically restricted to post mortem or ex-situ analysis due to the necessity of a high vacuum. In this study High Temperature Environmental Scanning Electron Microscopy (HT-ESEM) has been employed to analyse the morphology changes of common SOFC cathode materials in-situ. Samples of La0.6Sr0.4Co0.2Fe0.8O3-x (LSCF) and La0.6Sr0.4CoO3-x (LSC) were annealed from room temperature to 1000oC at pressure ranges between 3 – 6mbar in atmospheres of Oxygen and Water. Using secondary electron imaging during the thermal annealing cycle morphological and compositional changes were able to be documented at temperature for the first time (Figure 1).
This technique has enabled detailed analysis of the surface degradation that occurs during SOFC fuel cell operation. Secondary phase precipitation rate and formation behaviour has been quantified over a range of temperatures and time scales furthering the understanding of SOFC cathode surfaces significantly.
[1] M. Kubicek, A. Limbeck, T. Fromling, H. Hutter, and J. Fleig, "Relationship between cation segregation and the electrochemical oxygen reduction kinetics of La0.6Sr0.4Co0.2Fe0.8O3 thin film electrodes" Journal of The Electrochemical Society, vol. 158, no. 6, pp. B727–B734, 2011.

Figure 1 - Showing in-situ growth of secondary phase particulates on a polished surface of LSCF

Figure 1
Multi Length-Scale Quantification of Hierarchical Microstructure in Designed Microtubular SOFC Electrodes
Authors: Cooper Samuel J , Li Tao , Bradley Robert S , Li Kang , Brandon Nigel P. , Kilner John A. 
Published: February 2020

Extrusion techniques can be used to produce microtubular SOFCs with a wide range of hierarchical microstructures. It is believed that by controlling the pore structure of the thicker supporting electrode, the transport properties can be optimised.
X-ray micro-tomography has been used to image the finger-like voids in a microtubular anode. These structures are on the order of 10 microns in diameter; however, smaller characteristic lengthscales can be imaged using FIB/SEM, which reveals the packing of the sintered particles, as well as the pore structure within the particles. Quantifying the tortuosity factor at each of these lengthscales offers insight into the effect of tailoring the pores.
The tortuosity factor of porous SOFC electrodes is used to account for the apparent reduction in species diffusion caused by the geometry of the network. It affects both the electrical transport in the solid phases as well as gas diffusion in the pores. The tortuosity factor is ideally calculated by solving the steady-state diffusion equation; however in systems spanning several orders of magnitude it is very computationally expensive. The figure shows the distribution of a scalar field in an interdigitated void structure, calculated using a finite element method.
This work combines the calculated tortuosity factors of each lengthscale to try and understand the significance of the hierarchical pore structure. The straight, radial pores of the microtubes imaged were found to augment the system significantly compared to an isotropic network of equivalent porosity. The importance of recasting the tortuosity factor as a function of distance from the electrolyte for hierarchical pore systems is also discussed.

Figure 1
Lanthanum Nickelate Infiltration into Porous Gd-Doped Ceria As Cathode for Solid Oxide Fuel Cells
Authors: Nicollet Clément , Flura Aurélien , Vibhu Vaibhav , Rougier Aline , Bassat Jean-Marc , Grenier Jean-Claude 
Published: February 2020

To increase Solid Oxide Fuel Cells performances, the optimization of the oxygen electrode is mandatory as its activation overpotential is higher than the one of the hydrogen electrode. One way to increase the cathode electrocatalytic properties and to decrease its polarization resistance is to increase the Triple Phase Boundaries zone, where the oxygen is reduced. A promising solution to achieve this goal is to disperse an oxygen reduction catalyst on the surface of a porous ionic conductor. The lanthanum nickelate La2NiO4+δ (LNO) has remarkable surface exchange reaction rate and oxygen diffusion coefficient. However, when the electrode is shaped by classical screen printing technique, it displays higher polarization resistance (≈ 1 Ω.cm²) than the standard lanthanum cobaltite-based materials (≈ 0.1 Ω.cm² for La0.6Sr0.4Co0.2Fe0.8O3-δ).
In this study, cathodes were prepared by infiltration of lanthanum nickelate into a Gd-doped ceria (GDC) backbone sintered on 8YSZ electrolyte pellets. The influence of the preparation parameters of the composite electrodes on their electrochemical activity will be presented. The optimization of the preparation parameters led to a large decrease of the polarization resistance, down to 0.1 Ω·cm² at 600 °C. Using the Adler-Lane-Steele model, the impedance diagrams were fitted, allowing the determination of the surface exchange rate and ionic conductivity of the electrode: the obtained values well agree with those previously reported in the literature. Using this infiltration process, single cells were made starting from commercial half cells (Ni cermet/8YSZ), the cathode being the composite LNO/GDC. Voltammetry measurements showed power density higher than 1 W.cm-2 at 800°C.
Smart Fuel Cell Demonstration Project: A Challenge to Realize SOFC-Powered Campus
Authors: Sasaki Kazunari , Taniguchi Shunsuke , Shiratori Yusuke , Hayashi Akari , Oshima Toshihiro , Nishihara Masamichi , Tachikawa Yuya , Daio Takeshi , Kawabata Tsutomu , Fujita Miki , Zaitsu Ayumi 
Published: February 2020

Based on various efforts, commercialization of fuel cell technologies has been just started in Japan. Energy Basic Plan in Japan has been revised where hydrogen is clearly stated as one of the important energy carriers. After this revision, roadmap for fuel cell and hydrogen technologies is established up to 2040. While more than 100,000 residential fuel cell units have been sold and the commercialization of fuel cell vehicles (FCV) has just been started, industrial fuel cells as distributed power systems will be commercialized probably from 2017. For such larger-scale stationary applications, SOFC is the promising technology.

In Kyushu University, “Smart Fuel Cell Demonstration Project” is going on where our University Campus will become a campus where fuel cell and hydrogen technologies are widely applied. While FCV, hydrogen fuelling station, and various residential fuel cells are in operation, installation of a few types of SOFC systems is going on, including a 250kW SOFC-MGT power generation system, 5kW SOFC cogeneration systems, and 1kW-class SOFC cogeneration units. These SOFC systems can cover ca. 5 % of the whole electricity demand of this university campus with a maximum electricity contract of 6000 kW. As shown in the Figure, the university campus will be a future energy society where SOFC is playing an important role as the efficient power generation system. The electric power generated from solar, wind, and SOFC will be displayed on the web site of our campus to improve the social acceptance of SOFC technologies. SOFC will act as a base power generator, while hydrogen refueling station will act as an energy storage station for the renewable electricity and FCV will be a zero-emission vehicle using CO2-free hydrogen. Concept for future energy society will be discussed where SOFC will take a major role, based on our demonstration experiences.

Figure 1
Thermodynamic Performance of a High Efficient Power Plant Based on Faecal Biomass Gasification, Solid Oxide Fuel Cells and Micro Steam Turbine
Authors: Recalde Mayra , Woudstra Theo , Liu Ming , Aravind P.V. 
Published: February 2020

Affordable sanitation around the world with the recovery of valuable energy and clean water from faecal biomass in an off-grid system is a challenge. An energy neutral sanitation system concept based on plasma gasification and solid oxide fuel cell (SOFC) was presented by TU Delft {Mings et al.}. The system is further optimised and novel small scale CHP toilet system concept has been developed which can generate power very efficiently and produce clean water. Pre-dryed faecal biomass, is fed to the integrated system. The system combines a dryer, a plasma gasifier, and a gas cleaning unit with an ambient pressure stack and a micro steam turbine (MST). The gasifier uses the heat supplied from the combustion of SOFC depleted fuel. With this concept syngas with high heating value can be produced, which can be efficiently converted in a SOFC system. This is reflected by the net electrical efficiency of the integrated system configuration of the order of 50%. Additional power is produced combining it with an MST and an efficiency increase of the order of 5% is achieved. Variation of the different operating conditions in the system reveals an optimum for the temperature, steam to biomass ratio and oxidant to fuel ratio in the gasifier. Furthermore, the SOFC operating temperature influences the system performance and self-sustainability. As a result, from a thermodynamic point of view it is demonstrated that a high efficiency power generation through faecal biomass can be realized.
Ming Liu, T. Woudstra, E.J.O. Promes, S.Y.G. Restrepo, P.V. Aravind. System development and self-sustainability analysis for upgrading human waste to power.
An Elementary Kinetic Model for the Electrochemical Reduction of Oxygen on LSM/YSZ Composite Cathodes
Authors: Banerjee Aayan , Deutschmann Olaf 
Published: February 2020

A detailed computational model of the oxygen reduction reaction in composite strontium-doped lanthanum manganite/yttria-stabilized zirconia (LSM/YSZ) SOFC cathodes is presented. The coupled interactions of elementary heterogeneous chemistry, elementary electrochemistry (at two separate electrochemical double layers) and transport through the porous electrode are studied. Species diffusion and convection through the porous cathode are evaluated using the Dusty Gas Model while a distributed charge transfer model is used to study the ionic and electronic transport through the cathode. Charge-transfer reactions are modeled using a spillover mechanism with no a priori assumption of rate limiting steps unlike the frequently published Butler-Volmer approach. The model is validated against overall area-specific resistance (ASR) values previously reported by Barbucci et al. [Electrochemica Acta,
47 (2002)] over a temperature range of 950-1200 K. A sensitivity analysis reveals the impact of various kinetic parameters on the ASR and subsequently leads to the identification of rate-limiting steps. Preliminary results indicate that the ASR is sensitive to the rate of dissociative adsorption of O2 on LSM and oxygen ion transfer from the YSZ surface to the YSZ bulk.
Surface Oxygen Exchange Properties of Sr Doped La2NiO4+δ as SOFC Cathode: Thin-Film Electrical Conductivity Relaxation Investigation
Authors: Guan Bo , Li Wenyuan , Zhang Xinxin , Liu Xingbo 
Published: February 2020

Roddlesden-Popper Phases, such as La2NiO4, have been proposed as promising intermediate temperature SOFC cathodes, due to their high surface oxygen exchange and bulk diffusivities. However, relatively low electrical conductivity of LNO phase is a concern for its application. It has been shown that Sr doping is an effective way to improve LNO’s electrical conductivity, but it is important to investigate the effect of such doping on other properties such as oxygen surface exchange coefficient. In this study, Sr doped lanthanum nickelates i.e., La2-xSrxNiO4+δ (0≤x≤0.4) thin and dense films on dense thick GDC (~1mm) substrate, were prepared by using spray-modified pressing method. The surface oxygen transport kinetics was investigated by electrical conductivity relaxation (ECR) technique. Since the thickness of thin films is ~15μm, much less than the characteristic length of LNO, the oxygen transport kinetics are controlled by the surface exchange steps and the oxygen ion concentration is uniform in the film at any time during the ECR process. Such situation enables a more accurate fitting results compared to the traditional fitting procedure based on thick pellets, because only k value is the unknown parameter. The fitted k for LNO is 4.02×10-5cm/s at 0.2atm 700oC, which decreases with lowered oxygen partial pressure. Sr doping harmed the surface exchange kinetics, k of Sr40 is about one order of magnitude smaller than undoped one. Interstitial oxygen and Ni oxidation state are suggested to be predominant roles in determining the surface kinetics. Both Sr doping and lowered oxygen partial pressure lead to the loss of interstitial oxygen and the oxidation of Ni2+, resulting the lowered surface exchange rate.