Rinlee Butch Cervera

Rinlee Butch Cervera

Sex: Male

Education:

Doctor of Philosophy in Materials Engineering, University of Tokyo

Masters in Materials Engineering, University of Science Malaysia

Bachelor of Science in Materials Engineering, University of the Philippines

Field of Specialization

Electrochemical Energy

Lithium batteries

Materials Science

Researches:

Article title: Determination of Dose Distributions by High-energy Electrons in Alumina Pellets Using Monte Carlo Simulations

Authors: Frederick C. Hila, Haydee M Solomon, Andrea G Baule, Rinlee Butch M. Cervera, et al.

Publication title: Philippine Journal of Science 150(1): 201-208, 2021

Abstract:

Electron beam (E-beam) accelerators are widely used in multiple industrial and medical applications and investigations (Zhang et al. 2019; Uribe et al. 2009; Zeng et al. 2005; Marrale et al. 2015). E-beams are used in important radiotherapy research, for instance in examining the FLASH effect for efficient tumor treatment (Favaudon et al. 2014; Durante et al. 2017). E-beams are also largely used in investigating grafting and crosslinking of natural and synthetic polymers, as well as degradation and radiation damage applications

Article title: Preparation and Structural Stability of LiFePO4| Ga-LLZO Composite Cathode Material Heat-Treated at Intermediate Temperatures

Authors: Pearl Jamela Diamansil, Jessa Hablado, John Carlo Palomares, Rinlee Butch M. Cervera, et al.

Publication title: Materials Science Forum 987:70-74, 2020

Abstract:

In this study, cathode and lithium-ion conducting solid electrolyte composite pellet with 1: 1 wt.% composition of LiFePO 4 and Li 7-3X Ga x La 3 Zr 2 O 12 (x= 0.1)(LiFePO 4| Ga-LLZO) was prepared via solid-state reaction. The aim of the study is to investigate the phase stability between LiFePO 4 cathode and Ga-LLZO solid electrolyte material when heat treated at 400 to 600 C. The as-mixed LiFePO 4| Ga-LLZO composite was characterized by TG/DTA and the heat treated sample was then analyzed for its structure using XRD and compared to the just as-mixed composite. XRD patterns of the heat treated composite pellet showed that it retains its as-mixed phases of LiFePO 4 and Ga-LLZO when sintered below 500 C under Ar gas flow environment. However, upon heat treatment at 600 C, the sample already reacted and decomposed with the formation of other phases.

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Article title: Fabrication of Solid Oxide Electrolysis Single Cell Using NiO-YSZ/YSZ/LSM-YSZ via Drop-Coating Method

Authors: Jennet R. Rabo and Rinlee Butch M. Cervera

Publication title: Key Engineering Materials 847:129-134, 2020

Abstract:

Solid oxide electrolysis cell (SOEC) is a highly efficient and environmentally friendly technology for future hydrogen generation. In this study, electrolyte-supported SOEC single cell was fabricated via a simple and facile drop-coating technique. Thin film electrodes of nickel oxide/yttria stabilized zirconia (NiO-YSZ) cathode and strontium-doped lanthanum manganite/ytrria-stabilized zirconia (LSM-YSZ) anode were deposited onto yttria-stabilized zirconia (YSZ) solid electrolyte substrate. Scanning electron microscopy (SEM) with energy dispersive analysis (EDS) was used to study the microstructural properties of the heat-treated samples and revealed a successful thin film deposition of porous electrodes onto the dense YSZ substrate. XRD patterns showed the desired crystal structure of the deposited electrode thin films. Distinct phases of cubic YSZ and monoclinic LSM were observed for the LSM-YSZ anode while cubic NiO and YSZ phases were observed for the deposited cathode. Electrochemical conductivity of the cell was investigated using electrochemical impedance spectroscopy analysis (EIS) which revealed a total conductivity of about 2.0 mS/cm at 700 °C.

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Article title: XRD and SEM Analyses of Bulk Ga-Doped Li7La3Zr2O12 Li-Ion Conducting Solid Electrolyte Prepared via Hot-Pressing Method

Authors: Aimee Lorraine Blaquera, Christine Mae Macalisang, John Carlo Palomares, Rinlee Butch M. Cervera

Publication title: Materials Science Forum 998: 215-220, 2020

Abstract:

In this study, bulk lithium-ion conducting solid electrolyte of Ga-doped Li7La3Zr2O12 (Li7-3XGaxLa3Zr2O12) where x = 0.1 (Ga-LLZO) was prepared via hot pressing at 500 °C. Precursor powder for hot-pressing was prepared using conventional solid state reaction method. Planetary ball milling was employed to investigate the particle size effect on the structure and densification of hot-pressed samples. XRD patterns of the bulk hot-pressed sample revealed a crystalline phase of which the major peaks observed can be indexed to a cubic LLZO structure; however, a major impurity phase of La2Zr2O7 was observed for the ball-milled sample. Thermogravimetric and differential thermal analysis showed about 12% weight loss below 900 °C which may have affected the observed hot-pressing structure. Although lower density measurement and an impurity phase of La2Zr2O7 were observed for the ball-milled sample, ball-milling also resulted to a more homogeneous and finer particle size as shown by SEM images results.

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Article title: Experimental and Analytical Study of an Anode‐Supported Solid Oxide Electrolysis Cell

Authors: Rose Marie Mendoza, Joy Marie Mora, Rinlee Butch Cervera, Po-Ya Abel Chuang

Publication title: Chemical Engineering and Technology 43(12): 2350-2358, 2020

Abstract:

A 1‐D electrochemical model for a solid oxide electrolysis cell (SOEC) is developed and validated using published experimental data. The model combines thermodynamics, kinetic, ohmic, and concentration overpotentials to predict cell performance. For the anode‐supported SOEC, good agreement is obtained between the model and experimental data, with ohmic loss being the major contributor to the cell's total overpotential. Both kinetic and concentration losses are less significant due to high‐temperature operation. Due to the dominating performance loss, reducing the anode thickness is effective in diminishing the cell potential. Overall, this simple 1‐D model can be employed as a design tool to evaluate component design and estimate system performance for industrial applications.

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Article title: Morphology of alumina particles synthesized by sol-gel method and irradiated with high-energy electrons

Authors: Frederick Corpus Hila, Ariel Jorge F. Payot, Roland V. Rallos, Rinlee Butch M. Cervera, et. al.

Publication title: Proceedings of the Samahang Pisika ng Pilipinas, 2020

Abstract:

The morphology of aluminum oxide synthesized by sol-gel method and irradiated by high-energy electrons was investigated. Aluminum foils were dissolved in hydrochloric acid to obtain aluminum chloride which was converted to aluminum hydroxide by the addition of baking soda. The resultant powder was dried at 200 C for 4 hrs, calcined at 500 C for 2 hrs, pelletized, sintered at 1100 C for 1.5 hrs, and irradiated by high-energy electrons for an absorbed dose of 50 kGy. The results of XRD showed that γ-alumina particles were synthesized. SEM images show irregular and flake-like grains for the non-irradiated pellet, and larger rounded grains for the irradiated one.

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Article title: Investigation on Varying Aluminum Doping Concentrations and Sintering Temperatures on the Synthesis of Garnet Li7La3Zr2O12 Solid Electrolyte via Modified Pechini Method

Authors: Benjamin Jose Alfaro and Rinlee Butch M Cervera

Publication title: Materials Science Forum 950:160-164, 2019

Abstract:

Solid electrolytes such as lithium lanthanum zirconate have shown a lot of promise in an all-solid-state Lithium-based battery since the discovery of its highly conductive cubic garnet structure. In this study, different concentrations of Al-doped Lithium Lanthanum Zirconate (Al-doped LLZ) having the formula of Li7-.3xAlxLa3Zr2O12 with x = 0.1,0 .2, 0.3, were synthesized via modified Pechini method and the effect of sintering temperatures, 1150 and 1200 °C, on the resulting properties were investigated. X-ray diffraction results have shown that cubic Al-doped LLZ can be obtained at a lower temperature using Pechini method. Significant effect to the conductivity on the different sintering temperatures was observed for the 0.1 Al-doped LLZ. With the different studied compositions synthesized via modified Pechini method, it was revealed that the 0.2 Al doped LLZ sintered either at 1150 or 1200 °C showed the highest conductivity of about 1.4x10-4 S/cm.

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Article title: Screen-Printed NiO-YSZ Thin Film Electrode for Solid Oxide Electrochemical Cell and Subsequent Reduction to Ni-YSZ

Authors: Agnes L. Manalo and Rinlee Butch M. Cervera

Publication title: Materials Science Forum 950:123-127, 2019

Abstract:

Nickel and yttria-stabilized zirconia (Ni-YSZ) ceramic-metal composite electrodes are commonly used for solid oxide electrochemical cells because of their good ionic and electronic conductivity. In this study, a thin film of NiO-YSZ was prepared via screen-print method and subsequently reduced to Ni-YSZ. The precursor powder for screen-printing was prepared via glycine-nitrate combustion process. The effect of precursor particle size and of the use of PVP as binder on film uniformity and quality were investigated. For the NiO-YSZ film, scanning electron microscopy (SEM) micrographs and X-ray diffraction (XRD) patterns confirmed that size reduction and the use of binder both improved the quality and uniformity of the deposit without changing the composition of the sintered film. SEM with energy-dispersive spectroscopy (EDS) showed elemental mapping of unreduced and reduced films, revealing micro grain size faceted particles of NiO and Ni, while smooth and much larger YSZ grains were also observed. XRD of reduced Ni-YSZ film revealed that the NiO peaks had been replaced by Ni.

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Article title: Preparation and Characterization of NiO/YSZ and Ni/YSZ Porous Composite Electrodes Synthesized via Glycine-Nitrate Combustion Process

Authors: James Francis Imperial and Rinlee Butch M. Cervera

Publication title: Key Engineering Materials 801:205-210, 2019

Abstract:

Electrode materials require a good porosity and a fine microstructure in order to maximize the triple phase boundary between the electronic conductor, ionic conductor and the gases involved in the reaction. In this study, NiO/YSZ composite, one of the most desired candidates as a cathode material for solid oxide electrolysis cells, was synthesized via glycine-nitrate combustion process. The composite powder was mixed with carbon black pore former in order to increase the porosity of NiO/YSZ. The samples were sintered at 1300 °C and subsequently reduced. X-ray diffraction patterns of the as-reduced samples confirm the transformation of NiO to Ni phase. Scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) images were able to confirm the reduction of NiO to Ni. From the results of the electrochemical impedance spectroscopy analysis, the total conductivity of Ni/YSZ at 700 °C were about 1.37 × 10-1 and 1.12 × 10-1 S/cm for the unmodified and carbon black-modified samples, respectively.

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Article title: Solid State Reaction Synthesis and Characterization of Lithium Lanthanum Titanate Lithium-Ion Conducting Solid Electrolyte with Different Li to La Content

Authors: Andrew Dono and Rinlee Butch M. Cervera

Publication title: Key Engineering Materials 821:389-394, 2019

Abstract:

Lithium Lanthanum Titanate, Li3xLa(2/3)-x□(1/3)-2xTiO3, with three different compositions of (i) x = 0.097 (Li0.29La0.57TiO3), (ii) x = 0.117 (Li0.35La0.55TiO3), and (iii) x = 0.167 (Li0.50La0.50TiO3) were prepared via solid state reaction synthesis sintered at 1150 °C for 36 hours. X-ray diffraction (XRD) analysis revealed that all samples can be indexed to a cubic perovskite structure with lattice parameter a of about 3.86 Å. Morphological analysis using SEM showed that the samples are relatively dense and the calculated relative density of the LLTO samples range from about 94% to as high as 99% with increasing trend as Li content increases. Room temperature conductivity and its temperature dependence up to 120 °C were investigated. LLTO sample with x =0.117 revealed the highest total ionic conductivity at room temperature of about 1.69 x 10-03 S/cm which can be a promising solid electrolyte for an all-solid-state lithium-ion batteries.

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Article title: Morphology and Structure of Ni/Zr0.84Sc0.16O1.92 Electrode Material Synthesized via Glycine-Nitrate Combustion Method for Solid Oxide Electrochemical Cell

Authors: Marion Garcia Renz and Rinlee Butch Cervera

Publication title: Applied Sciences 9(2), 2019

Abstract: Not available

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Article title: Effects of Mechanical Activation of Precursors in The Synthesis of Ca-Doped BaTiO3 Via Conventional Solid State Reaction Method

Authors: M.B. Gili, R. Chu, R. Cervera

Publication title: Journal of Physics: Conference Series 1191, 2019

Abstract:

The synthesis of pure ceramics with high degree of crystallinity is a major challenge especially in fabricating electronic devices. In this study, Ca-doped BaTiO3 with minimal impurity was successfully synthesized using conventional solid-state reaction method. The effect of mechanical activation of the precursors in the crystallinity and porosity of the material was investigated. For samples sintered at 1000 °C, the crystallite size slightly decreased from 5.410 Å to 5.288 Å which is equivalent to 2.31% reduction upon activation of precursors. At sintering temperature of 850 °C, the porosity increased from 35.985% to 39.217% with mechanical activation of the precursor powders while at 1000 °C, it jumped from 54.803% to 57.084%.

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Article title: One-Step Co-Precipitation Synthesis of Water-Stable Poly (Ethylene Glycol)-Coated Magnetite Nanoparticles

Authors: A.E.B. Gorospe, S.C. Buenviaje, Y.D.G. Edañol, R.B.M. Cervera, L.M. Payawan

Publication title: Journal of Physics: Conference Series 1191(1): 012059, 2019

Abstract:

Magnetite is one of the important materials used in drug delivery systems, magnetic resonance imaging, and cancer therapy due to its low toxicity, durability, high biocompatibility, and low cost. Among the different methods of synthesizing magnetite, co-precipitation presents a facile route for synthesizing nanoparticles. Since rapid crystallization occurs in this method, a coating agent is essential to prevent the aggregation of the nanoparticles and increase its water-stability. In this study, PEG-coated and uncoated magnetite nanoparticles were synthesized by one-step co-precipitation. FeSO47H2O, FeCl36H2O, and PEG were used as the precursors for the magnetite nanoparticles. Addition of NH4OH while maintaining the reaction in an N2 environment at 80 ° C completed the synthesis of the nanoparticles. XRD analysis confirmed the structure of the synthesized nanoparticles is magnetite. The addition of PEG coating results in generally weaker diffraction peaks as well as the absence of some peaks, indicating a decrease in the crystallinity of the sample. AFM and SEM measurements reveal a spherical morphology for both PEG-coated and uncoated magnetite nanoparticles. DLS measurements showed that the PEG-coated magnetite nanoparticles had a lower average particle diameter (73.95 ± 0.786 nm) compared to that of the uncoated magnetite nanoparticles (143.72 ± 1.60) nm. The observed values are lower compared to the results of a previous study. DLS also showed that both the uncoated and PEG-coated magnetite nanoparticles are monodisperse. Zeta potential analysis reveals that the PEG-coated magnetite nanoparticles are more stable in water than the uncoated magnetite nanoparticles. Addition of the polymer coating reduces the particle size and enhances the water-stability of the magnetite nanoparticles, making it useful for biomedical applications.

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Article title: Influence of Carbon Black Pore Former on the Synthesis of LSM-YSZ Composite Electrode Material via Solid-State Reaction and Glycine-Nitrate Process

Authors: Ariana B. Benipayo and Rinlee Butch M. Cervera

Publication title: Materials Science Forum 950: 154-159, 2019

Abstract:

Utilizing two different synthesis methods, solid-state reaction and glycine-nitrate process, composite lanthanum strontium manganite and yttria-stabilized zirconia (LSM-YSZ) powders were prepared. The powders were then mixed with 0, 5, and 10 wt% carbon black nanosized pore former and pressed into 10mm diameter pellets then sintered at 1150 C for 5 hours. The pellet composition and microstructure were investigated using FTIR, XRD, SEM-EDX, and their density and open porosity were measured using the Archimedes principle. The resulting microstructure of the composite pellets obtained using the two fabrication methods and different pore former weight percentages were studied and compared. It was found that the addition of 5 wt% carbon black pore former yields about 40% desired open porosity, and synthesis via GNP results to finer and more evenly distributed LSM and YSZ particles.

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Article title: Water Adsorption and Dissociation on Ni3 and Ni5 Decorated Y-and Sc-stabilized Zirconia: Insights from Density Functional Theory Investigation

Authors: Darwin Barayang Putungan and Rinlee Butch Cervera

Publication title: e-Journal of Surface Science and Nanotechnology 17: 117-123, 2019

Abstract:

In this work, water adsorption and dissociation on Ni3-and Ni5-decorated Y-and Sc-stabilized zirconia (YZO and ScZO respectively), were probed using planewave, pseudopotential-based density functional theory calculations, to assess water splitting and subsequent hydrogen evolution potential of these metal-on-zirconia structures. It is found that the strength of Ni cluster binding on zirconia depends on the size of the cluster, at least for Ni3 and Ni5, and on the nature of the stabilizing atom. The Ni3 and Ni5 clusters tend to bind more favorably on the Sc site of ScZO compared to that of the Y site of YZO. Water is found to adsorb strongly on Ni3-YZO, Ni3-ScZO, and Ni5-ScZO. Water dissociation barrier for both the first and second hydrogen atoms tends to decrease for larger Ni cluster, with the Ni5-YZO system giving the lowest energy barriers. With relatively fine dissociation barriers, such systems could potentially be tapped for electrocatalytic water dissociation reactions leading to hydrogen evolution. These results are of importance and could contribute significantly in the further search and design of electrocatalytic materials for water dissociation and eventual hydrogen evolution for sustainable hydrogen production.

Article title: Morphology and structure of Ni/Zr0. 84Sc0. 16O1. 92 electrode material synthesized via glycine-nitrate combustion method for solid oxide electrochemical cell

Authors: Renz Marion Garcia and Rinlee Butch Cervera

Publication title: Applied Sciences 9(2): 264, 2019

Abstract:

Nickel oxide and Sc-doped ZrO 2 electrode material with a 1: 1 wt% composition of NiO and Zr 0.84 Sc 0.16 O 1.92 was synthesized via a single-step glycine-nitrate combustion method. Different glycine to nitrate (g/n) molar ratios of 0.27, 0.54, and 1.1 were used to investigate its effect on the structural, morphological, and electrical properties of the heat-treated samples. X-ray diffraction (XRD) patterns of the as-sintered samples for all the g/n ratios were indexed to cubic phases of NiO and ScSZ. Upon reduction at 700 C, NiO was fully reduced to Ni. In-situ XRD patterns showed that the composite Ni/Zr 0.84 Sc 0.16 O 1.92 electrode material retains its cubic structure at intermediate temperatures from 500 C to 800 C. High magnification scanning electron microscopy (SEM) images revealed that nanoparticles of Ni are also formed and situated at the surfaces of ScSZ grains, apart from agglomerated submicron particles of Ni. SEM and electron-dispersive spectroscopy mapping revealed interconnected grains of ScSZ oxide-ion conducting phase. From the calculated conductivity based on electrochemical impedance spectroscopy results, the 0.27 g/n ratio showed an order of magnitude-higher total conductivity among the other prepared samples.

Article title: Morphological and Structural Characterization of YSZ Thin Film Fabricated by Electrophoretic Deposition on LSM/YSZ Substrate

Authors: Alexis Karla Garcia and Rinlee Butch M Cervera

Publication title: Key Engineering Materials 775:224-228, 2018

Abstract:

YSZ film was fabricated by a facile electrophoretic deposition process using commercial YSZ powders. YSZ films with average thickness of around 10 µm were deposited on LSM/YSZ substrate at 20 V for 20 minutes and subsequently sintered at 1200 C, 1300 C, and 1350 C. XRD patterns of the deposited and sintered films can be attributed to mostly cubic YSZ phase. On the other hand, SEM images revealed that a sintering temperature above 1300 C was needed to obtain a denser YSZ film. The film morphology also showed that as the sintering temperature increases, the YSZ grain size also increases.

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Article title: Effect of Precursor Grain Size on the Sinterability and Conductivity of Commercial Yttria-Stabilized Zirconia as Solid Electrolyte

Authors: Anna Romina T. Mercado, Emmalin S. Mesina, Jennet . Rabo, Rinlee Butch M. Cervera

Publication title: Key Engineering Materials 775:331-335, 2018

Abstract:

Solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) have been receiving significant attention for future energy storage and hydrogen production applications. This research focuses on the electrolyte material which can be used for both SOEC and SOFC particularly on 8 mol% yttria-stabilized zirconia (8YSZ) electrolyte material. YSZ has been used because of its high stability at elevated temperature, excellent mechanical and chemical properties and its excellent oxygen ion conductivity. This study aims to determine the effect of precursor’s grain size and sintering temperature on the properties of YSZ as electrolyte material for SOEC. Solid-state sintering was done to transform the ceramic powders into solid compacts. Pure cubic fluorite structure YSZ was achieved by both micrograined and nanograined YSZ sintered at 1200°C and 1500°C. It was observed that the micrograined YSZ sample sintered at 1500°C achieved the highest relative density at 99.48%. SEM images showed a smooth and compact microstructure for micrograined YSZ while small pores were still present in the micrographs of nanograined YSZ. However, interestingly, the nanograined YSZ has higher total conductivity as compared to the micrograined YSZ.

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Article title: Effect of sintering temperature on the structure, morphology, and conductivity of LSM/YSZ composite electrode synthesized via solid state reaction

Authors: Christian C. Vaso, Arianna Benipayo, Rinlee Butch Cervera

Publication title: Philippine e-journals for Applied Research and Development 8:34-43, 2018

Abstract:

To fully achieve the advantages of hydrogen-producing solid oxide electrochemical cells (SOCs), it is necessary to synthesize electrodes that would lengthen the operating time of these SOCs. This study synthesized Lanthanum Strontium Manganite (LSM), yttria-stabilized zirconia (YSZ), and LSM/YSZ composites using the solid state reaction method. LSM/YSZ composites having 50: 50 weight percent composition were sintered at two different sintering temperatures of 1150 and 1300 C. XRD patterns showed distinct peaks of the desired phases, which can be indexed to a rhombohedral structure for LSM and to a cubic structure for YSZ. Morphological results revealed a porous composite microstructure of LSM/YSZ as compared to a more dense structure of pure LSM and pure YSZ. Upon increase in the sintering temperature, larger grain sizes and porosities were observed. The total conductivities of the samples measured at 500 C are 1.22 Scm-1, 1.02 x 10-3 Scm-1 and 8.67 x 10-1 Scm-1 at activations energies of 0.20 eV, 0.85 eV and 0.22 eV for the LSM, YSZ and composite samples, respectively. These measurements were all taken under the oxygen gas environment.

Article title: Preparation of porous LSM/YSZ composite with varying grain size of YSZ precursor using solid state reaction method

Authors: Romar Angelo M. Avila, Trina G. Tambago, Rinlee Butch M. Cervera

Publication title: Materials Science Forum 917:93-97, 2018

Abstract:

Lanthanum strontium manganite (LSM) and yttria-stabilized zirconia (YSZ) composite is a promising material as an anode for solid oxide electrolysis cell (SOEC) applications. In this study, LSM/YSZ with a 1:1 LSM to YSZ weight ratio was synthesized via solid state reaction method using oxide precursors of commercial micrograined size LSM with varying YSZ precursor grain size. For the YSZ precursor, both nanograined (nanoYSZ) and micrograined YSZ (microYSZ) precursors were studied. Graphite was added at 10% weight ratio as a pore former. Density measurements using Archimedes principle revealed that LSM/nanoYSZ had the highest relative density of 97.8%, whereas LSM/nanoYSZ with graphite had the lowest density of 89.1%. The addition of graphite to LSM/nanoYSZ reduced the density by 8.7% compared to the decrease of 5.5% for LSM/microYSZ. Scanning electron microscopy confirms that the addition of graphite has a greater effect on the microstructure of LSM/nanoYSZ as compared to LSM/microYSZ. The electrochemical impedance spectroscopy results show that the samples with nanoYSZ had a higher total conductivity than the samples with microYSZ. LSM/nanoYSZ and LSM/nanoYSZ with graphite revealed a total conductivity values of 0.0470 Scm-1 and 0.0440 Scm-1 at 700 °C with activation energies of 0.0178 eV and 0.0234 eV, respectively.

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Article title: A Multi-Physics Model of Low-Voltage Dual-Electrolyte Water Electrolyzers

Authors: Joy Marie Mora, Rinlee Butch Cervera, Joey Duran Ocon, Jan Samuel C Matuba

Publication title: ECS Meeting Abstracts 22:1161, 2017

Abstract:

Traditional water electrolyzers usually require large overvoltages for splitting water into hydrogen and oxygen due to ohmic resistances, electrode overpotentials, and thermodynamic requirements. One of the most promising concepts in electrolyzer design is the hybrid dual-electrolyte water electrolyzer. This type of system takes advantage of the pH gradient between electrodes whereby a theoretical potential of around 0.4 V vs. SHE is possible. While the traditional electrolyzer operates at 1.23 V, the hybrid electrolyzer operates at voltages as low as 0.8 V, as shown in a recent work by Chen et al. In order to fully understand the mechanisms of this type of system, it is important to perform a multi-physics model that would predict the behavior of a hybrid dual-electrolyte water system across a specified set of parameters. The modelling approach done in this study allows describing a range of dual-electrolyte water systems. The study takes into account the dependence of the electrical performance on structural parameters and operating conditions of the electrolyzer. The developed multi-physics model was solved using COMSOL MultiphysicsⓇ simulation software. The simulation tool was also used to compare the performance of a single- (both acidic and alkaline) and dual-electrolyte system. The analysis of the results showed dual-electrolyte systems having superior performance over their traditional counterparts and that improved electrolyzer operating strategies can be identified with the developed simulation study.

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Article title: Enhancing the Electrocatalytic Activity of Graphitic Carbon Nitride Towards Oxygen Reduction Reaction Via Heteroatom Doping: A DFT Approach

Authors: Wilbert James Claridad Futalan, Rinlee Butch Cervera, Joey Duran Ocon

Publication title: ECS Meeting Abstracts 12:788, 2017

Abstract:

With the continued depletion of conventional fuel sources, the search for alternative fuel becomes increasingly important. Low temperature fuel cells such as PEMFCs and AFCs have attracted significant attention as a power generation technology. However, the cost of noble metals—which are important in speeding up the sluggish oxygen reduction reaction—remains an impediment in the commercialization of this technology. Metal-free catalysts are now being seen as possible alternatives to these noble metals. Among these metal-free catalysts is the graphitic carbon nitride. Graphitic carbon nitride, g-C3N4, is a polymeric material consisting of C, N, and some impurity H, connected via tris-triazine-based patterns. Due to its unique electronic structure, g-C3N4 and other graphene analogs have garnered interest in the material science community. While previous studies have been able to show experimentally the activity of g-C3N4 towards ORR, ab initio studies to explain and generalize the findings of the experiments remain scarce. Here we explain from the standpoint of density functional theory (DFT) calculations the effect of heteroatom doping (e.g., phosphorus, boron, sulfur) in further altering the material's electronic structure in an effort to render g-C3N4 more active towards oxygen reduction reaction. The trends exhibited by graphitic carbon nitrides in our DFT computations indicate that this emerging class of material can pave the way for the rational design of fuel cell catalysts.

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Article title: Quantum chemical predictions for Alkaline Earth (AE)- Doped Graphene: A Density Functional Theory (DFT) based investigation for a novel class carbon-based two-dimensional nanomaterials toward electrochemical, catalytic and electronic applications

Authors: Ace Christian Feraren Serraon, Allan Abraham Bustria Padama, Julie Anne Dalmacio del Rosario, Rinlee Butch Cervera, et al.

Publication title: ECS Meeting Abstracts 12:813, 2017

Abstract:

Graphene doping is a known route towards increasing the reactivity of graphene, particularly for the oxygen reduction reaction in fuel cells and metal-air batteries. The most prominent dopants in graphene for ORR are non-metals near to carbon in the periodic table. While alkaline-earth elements, such as beryllium, magnesium, calcium, strontium and barium are relatively abundant in the Earth's crust, graphenes modified with these elements have not been fully explored.

Graphene systems, which were substitutionally doped with alkaline-earth elements, were investigated through density functional theory (DFT) calculations to elucidate its energetics and electronic properties. A localized ionic bonding between alkaline-earth elements and the graphene substrate was observed, with greater charge transfer as inferred by Bader analysis for Be and Mg. The localized nature of the charge transfer from the dopant to the adjoining carbon atoms in the substrate is a novel property of AE-doped graphene. Semi-metallic properties due to strongly localized states near the Fermi level have been observed for all AE-doped graphenes except for Be. For Be, p-type semiconductor properties were observed consistent with previous studies on Be doped graphene.

This will provide the groundwork for further study towards the use of alkaline-earth metal dopants in an alternative precious-metal free cathode material for metal-air battery and fuel cell applications. The basic and exploratory nature of this scientific study is also expected to open a path towards other emergent applications for the catalysis of other reactions, as well as in electronics and other domains. Observable trends between different alkaline-earth doped graphenes have also been investigated.

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Article title: Trends in Buckled and Planar Halogen-Doped Graphene for ORR Activity: A DFT Study

Authors: Reynaldo Marcelino Geronia, Ace Christian Serraon, Rinlee Butch Cervera, Joey Duran Ocon, et al.

Publication title: ECS Meeting Abstracts 12:787, 2017

Abstract:

Owing to the sluggish oxygen reduction reaction (ORR), high-performance catalysts like Pt-based alloys are widely used to render the reaction practically useful in systems like fuel cells. Nonetheless, high costs and technical complications associated with such catalysts have encouraged the exploration of alternative ORR catalysts like heteroatom-doped carbon nanomaterials. To improve the catalytic activity of carbon, earlier studies used boron, nitrogen, phosphorus, sulfur, and selenium as dopants. In this paper, we perform density functional theory (DFT) calculations to explore the potential of halogens (X = F, Cl, Br, I) substituted within the two-dimensional structure of graphene. We also validate some of the results of previous experimental and theoretical studies on halogen-doped graphene. For example, we compare halogen adsorption and band structures of the resulting halogen-doped materials, as well as the possible influence of atomic size and atomic interactions (e.g., Br2/Br interactions, polyiodide formation) on their experimentally observed properties. Based on the resulting electronic and structural information, we then identify which among the buckled and planar forms of halogen-substituted graphene show the most promise for ORR activity. Finally, we compare this method of doping with previously studied methods like adsorption and edge-halogenation to provide additional insight on halogen doping.

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Article title: CoMn2O4 Anchored on N-Doped High-Dimensional Hierarchical Porous Carbon Derived from Biomass for Bifunctional Oxygen Electrocatalysis

Authors: James Lincuna Digol, Marc Francis Maligsa Labata, Maricor Fernandez Divinagracia, Joey Duran Ocon

Publication title: ECS Transactions 77(11): 525, 2017

Abstract:

There is an emerging interest in developing bifunctional oxygen electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), being key electrochemical reactions that govern the overall performance of unitized regenerative fuel cells and rechargeable metal-air batteries. However, such undertaking has been a huge challenge due to the high cost of noble metals (e.g. Pt, Ir) and their stability when used as catalysts. Herein, we report CoMn2O4 embedded on three-dimensional (3D) hierarchical porous carbon (HPC) derived from waste corn cobs as a possible noble metal-free bifunctional electrocatalyst. The hybrid catalyst is fabricated by solvothermal reaction of as-prepared N-doped 3DHPC and CoMn2O4. The template-free approach in preparing N-3DHPC ensures ample nitrogen doping using melamine to improve electronic conductivity of carbon and formation of three-dimensional, interconnected pore network, which is favorable for CoMn2O4 crystal dispersion. The same hybrid material also presents good OER activity, rendering an active and inexpensive dual-function electrocatalyst.

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Article title: Structure and conductivity of NiO/YSZ composite prepared via modified glycine-nitrate process at varying sintering temperatures

Authors: Felix Rey Bueta, James Francis Imperial, Rinlee Butch Cervera

Publication title: Ceramics International 43(18): 16174-16177, 2017

Abstract:

Nickel oxide and Yttria-stabilized zirconia (NiO/YSZ) composite is one of the most promising mixed conducting electrode materials in both solid oxide electrolysis cell and solid oxide fuel cell applications. In this study, 50 wt% NiO and 50 wt% YSZ composite was synthesized via a modified glycine-nitrate combustion process (GNP) and the effect of sintering temperatures (1100 °C, 1300 °C and 1500 °C) on its microstructure and electrical properties were investigated. TG/DTA and in-situ high temperature XRD revealed the thermal property behavior and the structural changes of the as-combusted precursor material. For all the samples sintered at different temperatures, room temperature XRD patterns revealed a distinct cubic phases of both YSZ and NiO while SEM images showed a porous microstructure. The total conductivities at 700 °C are 9.87 × 10−3, 5.26 × 10−3, 4.02 × 10−3 S/cm for the 1100, 1300, and 1500 °C with activation energies of 0.1722, 0.3555, and 0.3768 eV, respectively. Conductivity measurements of the different sintered samples revealed that the total conductivities as well as the activation energies are greatly affected by different sintering temperatures.

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Article title: Preparation of Amorphous Nanosilica from Philippine Waste Rice Hull via Acid Precipitation Method

Authors: Rinlee Butch M. Cervera and Emie A. Salamangkit-Mirasol

Publication title: Materials Science Forum 864:112-116, 2016

Abstract:

Rice hull or rice husk (RH) is an agricultural waste obtained from milling rice grains. Since RH has no commercial value and is difficult to use in agriculture, its volume is often reduced through open field burning which is an environmental hazard. In this study, amorphous nanosilica from Philippine waste RH was prepared via acid precipitation method. The synthesized samples were fully characterized for its microstructural properties. X-ray diffraction pattern reveals that the structure of the prepared sample is amorphous in nature while Fourier transform infrared spectrum showed the different vibration bands of the synthesized sample. Scanning electron microscopy (SEM) and particle size analysis (PSA) confirmed the presence of agglomerated silica particles. On the other hand, transmission electron microscopy (TEM) revealed an amorphous sample with grain sizes of about 5 to 20 nanometer range and has about 95 % purity according to EDS analyses. The elemental mapping also suggests that leaching of rice hull ash effectively removed the metallic impurity such as potassium element in the material. Hence, amorphous nanosilica was successfully prepared via a low-cost acid precipitation method from Philippine waste rice hull.

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Article title: Microstructural and Electrochemical Investigation of Carbon Coated Nanograined LiFePO4 as Cathode Material for Li-Batteries

Authors: Rinlee Butch M. Cervera and Princess Stephanie P. Llanos

Publication title: International Journal of Chemical and Materials Engineering 11(1):19-22, 2016

Abstract:

Lithium iron phosphate (LiFePO4) is a potential cathode material for lithium-ion batteries due to its promising characteristics. In this study, pure LiFePO4 (LFP) and carbon-coated nanograined LiFePO4 (LFP-C) is synthesized and characterized for its microstructural properties. X-ray diffraction patterns of the synthesized samples can be indexed to an orthorhombic LFP structure with about 63 nm crystallite size as calculated by using Scherrer’s equation. Agglomerated particles that range from 200 nm to 300 nm are observed from scanning electron microscopy images. Transmission electron microscopy images confirm the crystalline structure of LFP and coating of amorphous carbon layer. Elemental mapping using energy dispersive spectroscopy analysis revealed the homogeneous dispersion of the compositional elements. In addition, galvanostatic charge and discharge measurements were investigated for the cathode performance of the synthesized LFP and LFP-C samples. The results showed that the carbon-coated sample demonstrated the highest capacity of about 140 mAhg-1 as compared to non-coated and micrograined sized commercial LFP.

Article title: Preparation and Conductivity Measurements of LSM/YSZ Composite Solid Oxide Electrolysis Cell Anode Materials

Authors: Christian C. Vaso and Rinlee Butch M Cervera

Publication title: International Journal of Materials and Metallurgical Engineering 11(1): 23-27, 2016

Abstract:

One of the most promising anode materials for solid oxide electrolysis cell (SOEC) application is the Sr-doped LaMnO3 (LSM) which is known to have a high electronic conductivity but low ionic conductivity. To increase the ionic conductivity or diffusion of ions through the anode, Yttria-stabilized Zirconia (YSZ), which has good ionic conductivity, is proposed to be combined with LSM to create a composite electrode and to obtain a high mixed ionic and electronic conducting anode. In this study, composite of lanthanum strontium manganite and YSZ oxide, La0.8Sr0.2MnO3/Zr0.92Y0.08O2 (LSM/YSZ), with different wt.% compositions of LSM and YSZ were synthesized using solid-state reaction. The obtained prepared composite samples of 60, 50, and 40 wt.% LSM with remaining wt.% of 40, 50, and 60, respectively for YSZ were fully characterized for its microstructure by using powder X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and Scanning electron microscope/Energy dispersive spectroscopy (SEM/EDS) analyses. Surface morphology of the samples via SEM analysis revealed a well-sintered and densified pure LSM, while a more porous composite sample of LSM/YSZ was obtained. Electrochemical impedance measurements at intermediate temperature range (500-700 °C) of the synthesized samples were also performed which revealed that the 50 wt.% LSM with 50 wt.% YSZ (L50Y50) sample showed the highest total conductivity of 8.27x10-1 S/cm at 600 oC with 0.22 eV activation energy.

Article title: Synthesis of Yttrium-doped Barium Zirconate/Barium Cerate (BZY20/BCY20) Core-shell Structured Proton-conducting Solid Electrolyte via Modified Pechini Method

Authors: Mary Jozen Balanay and Rinlee Butch M Cervera

Publication title: Advanced Materials Research 1098: 92-97, 2015

Abstract:

Intermediate temperature solid oxide fuel cells (IT-SOFCs) operating at 400-700°C utilizes proton conducting electrolytes and are now being one of the focus of many research studies with regards to efficient, clean power sources and energy conversion. Potential electrolyte materials include acceptor-doped barium zirconates and barium cerates. In this study, preparation of a core-shell structured proton-conducting solid electrolytes of 20 vol% BaZr0.8Y0.2O3-δ (20BZY20) for the core and 80 vol% BaCe0.8Y0.2O3-δ (80BCY20) for the shell is done by wet chemistry route. The synthesized core-shell structured material (20BZY20/80BCY20) is developed to possibly address the problem of high grain boundary impedance of Y-doped BaZrO3 and low chemical stability of Y-doped BaCeO3. The obtained samples were characterized for its structure, thermal stability, morphology and elemental distribution of the material. At a lower sintering temperature of 1150°C, a densified pellet was obtained as observed by SEM analysis. The diffraction pattern of 20BZY20/80BCY20 powder shows two distinct phases corresponding to BZY20 and BCY20 suggesting a successful synthesis of the core-shell solid electrolyte.

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Article title: On the formation of nanograined LiCo2O3 (OH) Spinel-type Material Synthesized via Modified Low-temperature Sol-gel Approach

Authors: Rinlee Butch M. Cervera and Shu Yamaguchi

Publication title: Advanced Materials Research 1119: 106-110, 2015

Abstract:

A new lithium cobalt oxyhydroxide compound has been successfully synthesized. This new compound has been found to be related to the low temperature LiCoO2 (LT-LiCoO2) spinel structure formed at low processing temperatures. With the use of a modified sol-gel approach, this compound with the composition of LiCo2O3(OH) can be successfully synthesized at around 150 °C. Structural analyses using powder X-ray diffraction (XRD) and selected area electron diffraction (SAED) suggest a cubic-spinel structure, which is also supported by FT-IR and TG/DTA analyses. In addition, from the TEM morphological analysis, a very fine nanograined LiCo2O3(OH) powder with an average grain size of 5 nm has been obtained. From these results, the presence of OH or water at low processing temperatures promotes a favorable formation of this structure. At higher temperatures (>400 °C), the phase transforms to a layered high-temperature LiCoO2 (HT-LiCoO2) structure with the excess cobalt precipitated as Co3O4 as suggested by the in-situ high temperature XRD analysis.

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Article title: Thermal analysis and infrared spectroscopy of acetic anhydride plasma treated chitosan films

Authors: Sidney M. Palardonio, Philippe Martin B. Tingzon, Apollo R. Agcaoili, Henry J. Ramos, Rinlee Butch M. Cervera

Publication title: Proceedings of the Samahang Pisika ng Pilipinas, 2015

Abstract:

This study investigates the effects of acetic anhydride plasma treatment of chitosan films. Chitosan films were prepared by solvent casting method and then exposed to acetic anhydride plasma for 1, 3, and 5 mins. ATR-FTIR revealed that–-NH 2 groups were oxidized to-C≡ N. Non-hydrogen bonded–OH groups appeared as hydrogen bonding with water was diminished. Entrapment of the CO 2 gas was not observed. Reacetylation was unsuccessful as no C= O group was introduced. DSC studies suggested that the thermal stability of the acetic anhydride plasma treated films were found to be higher than unmodified films.

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Article title: Production of Amorphous and Crystalline Silica from Philippine Waste Rice Hull

Authors: Emie Salamangkit Mirasol and Rinlee Butch M Cervera

Publication title: Advanced Materials Research 1098: 80-85, 2015

Abstract:

Rice husk is the covering of rice seeds and a by-product of milling rice grain. This study is conducted to investigate the production of silica (SiO2) formed from waste rice hull (RH) at different processing temperatures and study its structure, morphology, and thermal properties. Thermal analysis by thermogravimetric analysis (TGA) of the dried RH showed two mass-loss steps associated to the moisture desorption and thermal decomposition. Powder X-ray diffraction patterns of the rice hull calcined at 550 oC showed a purely amorphous SiO2 structure while those calcined for 900 oC for 1 hour and for 3 hours showed a glass-ceramics and crystalline SiO2 structure, respectively. This structural result is supported by the results obtained from the FTIR and Raman analyses of the samples. On the other hand, the Scanning electron microscopy (SEM) images showed the morphology of the samples revealing an increasing particle and grain size of the samples calcined at higher temperatures and longer heat treatment duration. In addition, Energy dispersive X-ray (EDX) spectra of both amorphous and crystalline SiO2 samples confirm that the sample contains mostly silicon and oxygen. Thus, in this study, the desired form of either amorphous or crystalline SiO2 from waste rice hull can be successfully obtained by controlled heat treatment.

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Article title: Preparation of Y-Doped BaZrO3 Proton Conducting Solid Electrolyte via Modified Low Temperature Pechini Method

Authors: Gandy Nuñez, Mary Jozen Balanay, Rinlee Butch M Cervera

Publication title: Advanced Materials Research 1098: 86-91,2015

Abstract:

One of the promising material for proton-conducting solid electrolyte operating at intermediate temperature range (400-600 °C) is the Yttrium-doped BaZrO3 (BZY) due to its high conductivity and chemical stability. In this study, a modified citrate-nitrate combustion method (Pechini method) has been employed for BZY powder preparation. A stoichiometric amounts of starting nitrates and oxide raw materials with nitric acid, citric acid and ethylene glycol for the synthesis of 20 mol% Y-doped BaZrO3 (BZY20) were prepared, then calcined and sintered at 1000 °C for two heat treatment durations of 24 hours and 48 hours. The obtained BZY20 powder samples have been fully characterized for its structure, morphology, and thermal properties. From the X-ray diffraction (XRD) results, the sample sintered for 48 hours showed a cubic phase of BZY20 which can be indexed to a Pm3m cubic structure which is also supported by Raman analysis. The calculated lattice parameter is 4.2067 Å which is higher than the reported lattice parameter of a pure BaZrO3 (BZ) of 4.1930 Å which indicates a successful doping due to higher ionic radius of Y3+ dopant as compared to Zr4+ in the B-site ABO3 perovskite sub-lattice. In addition, SEM-EDX analyses of the sintered pellet revealed a uniform distribution of Yttrium dopant in the BZY20 prepared solid electrolyte.

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Article title: Anode Properties of Si–FeS Films Prepared By Pulsed Laser Deposition in Solid-State Lithium Batteries

Authors: Rinlee Butch Cervera, Naoki Suzuki, Tsuyoshi Ohnishi, Minoru Osada, et al.

Publication title: ECS Meeting Abstracts 2:227, 2014

Abstract:

Lithium–silicon alloys are one of the most attracting anode materials for next-generation lithium-ion batteries due to the high theoretical capacity, low electrode potential, and the second largest Clark number. However, they have exerted their high performance only in nano-sized form. This study reveals that Si-based anodes fabricated into films exhibit excellent performance even in a bulky state, when they are in a solid electrolyte.

The Si-based films were deposited on stainless steel plates used as current collectors by pulsed laser deposition. Because it is impossible to ablate pure Si by the KrF excimer laser used in this study, 10wt% of FeS, which was reported to be effective in enhancing electrode activity in solid electrolytes [1], was added to Si powder before pressed into a target in order to allow the ablation. Film thickness was varied from 30 nm to 1 µm. Electrode properties of the films were investigated in a solid electrolyte, 70Li2S–30P2S5 glass ceramics, with an In–Li alloy as a counter electrode. The films were galvanostatically lithiated (charged) down to 0.01 V vs. Li+/Li and then delithiated (discharged) up to 2.62 V vs. Li+/Li at various discharge rates.

The Si–FeS films exhibit excellent performance in the solid electrolyte, as shown in the figure. The rate dependence of the discharge capacity clearly indicates that a film with thickness of 30 nm delivers a high capacity approaching the theoretical value at 0.1 C-rate discharge and maintains a high capacity of 2300 mAh g−1 at 100 C. Although such high rate capability may have been reported only for nano-sized Si materials, the film keeps it against increasing thickness. Even a 1-µm-thick film anode delivers a capacity of 3100 mAh g−1 at a discharge rate of 0.1 C, and 2500 mAh g−1is kept at a high rate discharge of 10 C.

It should be emphasized that such high performance is realized in a solid-state cell, which will be free from safety issues. In addition, the use of solid electrolytes is effective in improving cycling performance, which is a great drawback of Si anodes, by preventing detachment of the active material from current collectors. Capacity retention observed for a 400 nm-thick film over 120 cycles exceeds 80% in the solid electrolyte, while it decreases to 38% in an organic liquid electrolyte.

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Article title: Nanograined Sc-doped BaZrO3 as a proton conducting solid electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs)

Authors: Rinlee Butch Cervera, Yukiko Oyama, Shogo Miyoshi, Itaru Oikawa, et al.

Publication title: Solid State Ionics 264:1-6, 2014

Abstract:

Nanograined 25 mol% Sc-doped BaZrO3, BaZr0.75Sc0.25O3 − δ, well-known as a proton conductor, has been successfully synthesized at low processing temperature with average grain sizes of 8.9 nm, 15.9 nm, and 68.5 nm, and the effect of grain size on the conductivity has been examined. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns for these samples suggest a simple cubic perovskite type structure. The total DC conductivity, bulk and grain boundary contributions, of BaZr0.75Sc0.25O3 − δ as-pressed at room temperature (non-sintered) is 5.53 × 10− 6 S/cm (8.9 nm grains) at 500 °C, while values of 2.68 × 10− 5 S/cm and 1.27 × 10− 3 S/cm are observed at 500 °C for those samples post-annealed at 800 °C and 1250 °C with average grain sizes of 15.9 and 68.5 nm, respectively. The observed total DC conductivity for 68.5 nm grain size is almost comparable to that reported for benchmark Y-doped BaZrO3 with nanometer and micrometer grains.

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Article title: High performance silicon-based anodes in solid-state lithium batteries

Authors: Rinlee B Cervera, Naoki Suzuki, Tsuyoshi Ohnishi, Minoru Osada, et al.

Publication title: Energy & Environmental Science 7(2): 662-66, 2014

Abstract:

Silicon–lithium alloys are one of the most attractive anode materials for next-generation lithium-ion batteries; however, they have demonstrated high performance, only when they are fabricated into nano-sized materials. Here we show that even bulky alloys exhibit high potential that has never been shown in conventional liquid electrolytes, when they are in solid electrolytes.

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Article title: N-doped and Al-doped ZnO thin films as thermoelectric energy harvesters

Authors: Evan Angelo Mondarte, Jefferson Abrenica, Miguel Heinritz Majella Miguel, Rinlee Butch Cervera, Arnel Salvador, et al.

Publication title: Proceedings of the Samahang Pisika ng Pilipinas, 2013

Abstract:

Nitrogen-doped ZnO (P-type) and aluminum-doped ZnO (N-type) thin films were investigated for their thermoelectric properties. Under a temperature difference of 33.7 K, N-doped ZnO was found to have higher ZT value of 0.697 and conversion

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Article title: Perovskite-Structured BaScO2(OH) as a Novel Proton Conductor: Heavily Hydrated Phase Obtained via Low-Temperature Synthesis

Authors: Rinlee B Cervera, Shogo Miyoshi, Yukiko Oyama, Youssef E Elammari,, et al.

Publication title: Chemistry of Materials 25(9): 1483-1489, 2013

Abstract:

A novel proton-conducting material, BaScO2(OH) has been successfully fabricated. The known high-temperature proton conductors are typically perovskite-type oxides, in which the proton concentration is determined by hydration reaction of oxygen vacancies introduced by a small amount of acceptor dopant. On the other hand, the novel material BaScO2(OH) is still associated with the A2+B4+O3 perovskite structure but with the B-site cation fully consisting of an acceptor cation Sc3+, which facilitates to retain an appreciable amount of protonic defects. While it is difficult to obtain the material by simply hydrating the unhydrated form (Ba2Sc2O5), a combination of a new low-temperature sol–gel synthesis and ultrahigh-pressure (4 GPa) compaction at room-temperature enables us to obtain the heavily hydrated phase BaScO2(OH) due to on-synthesis hydration. The BaScO2(OH) synthesized has been proved to be a pseudocubic perovskite phase with XRD and Raman analyses. The thermal dehydration analyses have verified the composition BaScO2(OH) in terms of proton concentration, and their mobile nature has been observed with in situ FT-IR analysis. The protonic conductivity of the material is as high as 1.7 × 10–2 S·cm–1 at 500 °C, which is well higher than the total conductivity of the best proton-conducting perovskite oxides at intermediate temperature range.

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Article title: Silicon nitride thin film electrode for lithium-ion batteries

Authors: Naoki Suzuki, Rinlee Butch Cervera, Tsuyoshi Ohnishi, Kazunori Takada

Publication title: Journal of power sources 231: 186-189, 2013

Abstract:

This paper presents electrode properties of silicon nitride (SiN0.92) as a negative electrode in a lithium battery investigated in a solid electrolyte. SiN0.92 thin films formed by using pulsed laser deposition technique show redox reactions below 0.5 V vs. Li+/Li. A 200 nm thick film delivers a high capacity of 1800 mAh g−1 at the first reduction process and retains 1300 mAh g−1 after 100 cycles. Although increasing the film thickness to 500 nm decreases the capacity to some extent, the capacities in the 1st and 100th are 1200 and 700 mAh g−1, respectively, which are quite higher than that of the current carbon negative electrode.

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Article title: Epitaxial Growth of LiCoO2 Thin Film on Single Crystal Substrate by Sol-Gel Method

Authors: Taeri Kwon, Tsuyoshi Ohnishi, Kosho Akatsuka, Rinlee B Cervera, et al.

Publication title: ECS Meeting Abstracts 8:628, 2012

Abstract:

No available

Article title: Silicon nitride thin film electrode for lithium-ion batteries

Authors: Naoki Suzuki, Rinlee B Cervera, Tsuyoshi Ohnishi, Kazunori Takada

Publication title: ECS Meeting Abstracts 10:855

Abstract:

Article title: Phase relation in the BaO–ZrO2–YO1. 5 system: Presence of separate BaZrO3 phases and complexity in phase formation

Authors: Yukiko Oyama, Akira Kojima, Xinyu Li, Rinlee Butch Cervera, et al.

Publication title: Solid State Ionics 197(1):1-12. 2011

Abstract:

In order to estimate the phase stability and homogeneous range of BaZrO3, which is expected as a candidate electrolyte material for intermediate temperature solid oxide fuel cell, the phase relation in the BaO–ZrO2–YO1.5 systems has been examined at a typical processing temperature of 1600 °C. The stable existence of two cubic phases of BaZrO3, termed as BZ(I) and BZ(II), with different dopant concentration is observed above 1400 °C in the present study. The latter is of long-range ordered supercell with a wide range of solid solution between Ba3Zr2YO8.5 and Ba9Zr4Y8O29. Also observed is the presence of liquid phase at higher BaO concentration region above the ternary eutectic temperature that is estimated to be around 1300 °C, giving enormous effects to sintering process when Y3+ is overdoped beyond the solubility limit. From the present results, the pseudo-ternary phase diagram of BaO–ZrO2–YO1.5 of the isothermal section at 1600 °C is proposed.

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Article title: Bulk-Nanograined BaScO2 (OH) as a New Class of Oxide Protonics Materials

Authors: Rinlee Butch Cervera, Yukiko Oyama, Shogo Miyoshi, Kiyoshi Kobayashi, et al.

Publication title: ECS Meeting Abstracts 13: 1396, 2008

Abstract:

Solid electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFC) applications are usually multicomponent metal oxides. The typically studied are those of acceptor-doped ABO3 type perovskite structures [1-3]. In principle, protonic defects can be incorporated in the ABO3 lattice structure in the form of hydroxyl anions as replacement for oxygen vacancies (Vö) created by the acceptor dopant on the B-site sublattice according to equation (1) in Kröger-Vink notation.

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Article title: Protonic Conduction in Nano-Grained Fluorite Oxides of Y-doped ZrO2 and Yb-doped CeO2

Authors: Yasuaki Akao, Tetsuo Fukuda, Rinlee Butch Cervera, Shogo Miyoshi, et al.

Publication title: ECS Meeting Abstracts 13:1398, 2008

Abstract:

No available

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Article title: Structural study and proton transport of bulk nanograined Y-doped BaZrO3 oxide protonics materials

Authors: Rinlee Butch Cervera, Yukiko Oyama, Shogo Miyoshi, Kiyoshi Kobayashi, et. al.

Publication title: Solid State Ionics 179:7-8, 2008

Abstract:

Nanograin size of about 3-5nm of 20mol% Y-doped BaZrO3 (BZY20) proton conducting solid electrolyte has been prepared at low processing temperature (< 200°C) and a bulk nanograined sample has been obtained at room temperature using cubic anvil pressing at 4GPa. The grain morphology and structural changes of the as-pressed and annealed BZY20 samples have been studied using powder X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM) equipped with energy dispersive X-ray (EDX), and electron diffraction analyses. Due to the presence of inhomogeneity such as trace formations of hydroxide phases of the as-pressed sample as observed from thermogravimetric and differential thermal analysis (TG/DTA), Fourier transform infrared (FTIR) results, and from the thermodynamics phase equilibria viewpoint, the conductivity is immeasurable. On the other hand, the sample annealed at 800°C with ∼ 10nm grain size shows a rather low protonic conductivity possibly due to poor interfacial grain boundary contacts and structurally disordered interface. However, as the grain grows to a well-crystallized structure with better interfacial and refined grain boundary and better yttrium distribution from grain interior to the grain boundaries, the total protonic conductivity increases and shows a good agreement with the results obtained using proton and deuteron isotope exchange reaction. The total protonic conductivities, bulk and grain boundary contributions, at 500°C for samples annealed at 800°C, 1250°C, and 1500°C are 8.7 × 10− 6Scm− 1, 2 × 10− 3Scm− 1, and 4 × 10− 3Scm− 1 with grain sizes of about 10nm, 50nm, and 200nm, respectively.

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Article title: Low temperature synthesis of nanocrystalline proton conducting BaZr0. 8Y0. 2O3− δ by sol–gel method

Authors: Rinlee Butch Cervera and Yukiko Oyama, Shu Yamaguchi

Publication title: Solid State Ionics 178(7-10): 569-574, 2007

Abstract:

Nanoceramic powders of proton conducting BaZr0.8Y0.2O3 − δ (BZY20) have been prepared at low crystallization temperature (below 130 °C) by sol–gel synthesis using all-alkoxide route. Due to a very low crystallization temperature, hydroxyl defects in the lattice crystal are incorporated in-situ during the synthesis process as confirmed by the gradual decrease in the lattice constant from 4.227 to 4.200 Ǻ on annealing from X-ray diffraction (XRD) analysis, OH vibrations observed in the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis, and weight loss and heat exchange reaction observed by TG/DTA analysis. The results of XRD have revealed well-crystallized BZY20 peaks of this advanced ceramic material even at low processing temperature. Analysis of FT–Raman spectrum taken at room temperature for the nanocrystalline BZY20 samples prepared at 130 °C using sol–gel processing has revealed an ideal Pm3m cubic crystal symmetry. However, a very slight distortion due to the difference in the B-site sublattice is also observed in the FT–Raman spectrum of the samples upon annealing at higher temperatures. SEM images show the microstructural evolution of the powders from agglomerated nanoscaled crystallites to the nanosized pseudospherical morphology with diameter less than 50 nm. The present low temperature synthesis can be successfully applied to other oxide protonics materials highly doped with protonic defects.

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