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Porous and antioxidative gC3N4–Gd2Zr2O7 facilitates a highly conductive Nafion composite membrane, leading to efficient and durable performance in high-temperature polymer electrolyte fuel cells.

A proton exchange membrane fuel cell uses perfluorosulfonic acid polymers as a proton exchange membrane but exhibits poor performance and durability under dry operating condition. Herein, we develo...

Sulfonated silica, synthesized by using tetraethyl orthosilicate and chlorosulfuric acid through calcination, was used as a filler to create Nafion-SSA composite membranes for applying proton exchange membrane fuel cells under low relative humidity (RH) condition. High water uptake and ion exchange capacity values were observed, and the Nafion-SSA composite membrane showed improved proton conductivity than that of the recast Nafion. The fuel cell operating at 80 °C under 20% RH with Nafion-SSA composite membrane showed 2.8 times higher maximum power density (454 mW cm−2) and current density (2062 mA cm−2) in comparison with the recast Nafion (159 mW cm−2, 734 mA cm−2). The thermal stability and mechanical properties of recast Nafion and Nafion-SSA composite membranes were evaluated by TGA and Tensile test.

A block copolymer composite membrane of sulfonated poly(arylene ether sulfone ketone) (SPESK) decorated with porous hygroscopic titanium oxide nanotubes (TNT) is designed and fabricated for low relative humidity (RH) operating polymer electrolyte fuel cells (PEFCs). The SPESK-TNT composite membrane in a PEFC operated at 100% RH, and 80 °C resulted in about 1.3 and 1.1-folds higher power density in comparison with the benchmark Nafion (NRE-212) and pristine SPESK membranes at 0.6 V. Further, operating under 30% RH and 80 °C, the SPESK-TNT composite membrane generates 3.8 and 2.8-folds improved power density in comparison with the pristine SPESK and commercial NRE-212 membranes, respectively, at 0.6 V. An outstanding improvement of PEFC performance using SPESK-TNT composite membrane also maintains relative to a SPESK-TiO2 nanoparticles composite membrane, operating under 100 and 30% RH. Moreover, the SPESK-TNT composite membrane shows a stable operating potential of more than 200 h at 30% RH and 80 °C, confirming the durable PEFC operation. The enhanced PEFC performance under dry conditions is mainly the result of improving water management by the TNT filler in the membrane and cathode catalyst utilization, yielding significantly suppressing both ohmic and mass transport overpotentials.

Understanding the ionic channel network of proton exchange membranes that dictate fuel cell performance is crucial when developing proton exchange membrane fuel cells. However, it is difficult to characterize this network because of the complicated nanostructure and structure changes that depend on water uptake. Electrostatic force microscopy (EFM) can map surface charge distribution with nano-spatial resolution by measuring the electrostatic force between a vibrating conductive tip and a charged surface under an applied voltage. Herein, the ionic channel network of a proton exchange membrane is analyzed using EFM. A mathematical approximation model of the ionic channel network is derived from the principle of EFM. This model focusses on free charge movement on the membrane based on the force gradient variation between the tip and the membrane surface. To verify the numerical approximation model, the phase lag of dry and wet Nafion is measured with stepwise changes to the bias voltage. Based on the model, the variations in the ionic channel network of Nafion with different amounts of water uptake are analyzed numerically. The mean surface charge density of both membranes, which is related to the ionic channel network, is calculated using the model. The difference between the mean surface charge of the dry and wet membranes is consistent with the variation in their proton conductivity.

The design of high performance oxygen reduction reaction (ORR) electrocatalysts play an important role in the commercialization of polymer electrolyte membrane fuel cells. The morphology, structure, and composition of the support material significantly affect the catalytic activity of the fuel cell catalyst. In this work, we report a systematic and comparative study of the effects of the support morphology for Pt–Ni nanoparticles for the ORR. The effect of the support morphology on the electrocatalytic oxygen reduction reaction was investigated. Pt–Ni alloy catalysts were characterized using various physico-chemical techniques, such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Pt–Ni alloy nanoparticles were deposited uniformly on a graphene support and their oxygen reduction activities were evaluated in an acid electrolyte. The ORR activity of Pt–Ni supported on graphene was also compared with Pt–Ni supported on Vulcan carbon XC-72 and carbon nanotubes. The electrocatalytic activity and stability of Pt–Ni alloy catalysts were studied using cyclic voltammetry, linear sweep voltammetry, rotating disk electrode, and rotating ring disk electrode techniques. The results demonstrate that the graphene supported Pt–Ni catalyst showed the highest ORR activity among the three evaluated catalysts.

Herein, NiCo2S4 supported on sulfur-doped carbon with multi-porous nanostructures are developed to achieve excellent bifunctional catalytic activities. We present a comprehensive study on the composite effect between NiCo2S4 and sulfur-doped carbon as a bifunctional catalyst for oxygen reduction reaction and oxygen evolution reactions. Further, the high catalytic activities of NiCo2S4 modified sulfur-doped carbon composite are explored as an air cathode for rechargeable Li-O2 batteries. The sulfur-doped carbon surface modification with NiCo2S4 improves the reversibility and capacity due to its high specific surface area, exposing of large active sites, and the formation of smaller sized toroidal Li2O2 discharge product on cathode, which can be decomposed at a lower potential compared to a pristine carbon electrode. The Li-O2 battery constructed with the rationally designed composite air cathode delivers ultra-high discharge capacity of 14,173 mA hg−1 at 150 mAg−1 and superior cyclability for over 1704 h without capacity fade due to the excellent surface properties.

Unmanned Aerial Vehicles (UAVs) have gained significant attention in recent times due to their suitability to a wide variety of civil, military and societal missions. Development of an unmanned amphibious vehicle integrating the features of a multi-rotor UAV and a hovercraft is focus of the present study. Components and subsystems of the amphibious vehicle are developed with due consideration on aerodynamic, structural and environmental aspects. Finite element analysis (FEA) on static thrust conditions and skirt pressure are performed to evaluate the strength of structure. For diverse wind conditions and angles of attack (AOA), computational fluid dynamic (CFD) analysis is carried out to assess the effect of drag and suitable design modification is suggested. A prototype is built with a 7 kg payload capacity and successfully tested for stable operations in flight and water-borne modes. Internet of Things (IoT) based water quality measurement is performed in a typical lake and water quality is measured using pH, dissolved oxygen (DO), turbidity and electrical conductivity (EC) sensors. The developed vehicle is expected to meet functional requirements of disaster missions catering to the water quality monitoring of large water bodies.

Proton exchange membrane fuel cells are a promising energy conversion device which can help to solve urgent environmental and economic problems. Among the various types of fuel cells, the air breathing proton exchange membrane fuel cell, which minimizes the balance of plant, has drawn a lot of attention due to its superior energy density. In this study a compact, air breathing, proton exchange membrane fuel cell based on Nafion and a Pt/C membrane electrode assembly was designed. The fuel cell was tested using a Scribner Associates 850e fuel cell test station. Specifically, the hydrogen fuel and oxygen starvation of the fuel cell were accurately and systematically tested and analyzed using a frequency analysis method which can analyze the input and output frequency. The analysis of the frequency variation under a fuel starvation condition was done using RMSF (root mean square frequency) and ACSD (autocorrelation standard deviation). The study reveals two significant results: first, the fuel starvations show entirely different phenomenon in both RMSF and ACSD and second, the results of the Autocorrelation show clearer results for fuel starvation detection than the results with RMSF.

We report a high performance and durable electrolyte membrane operated in polymer electrolyte membrane fuel cells under low relative humidity (RH). This was accomplished by incorporating water retaining mesoporous zirconium oxide (ZrO 1.95 ) nanotubes (ZrNT) in a perfluorosulfonic acid (Nafion) membrane. Porous ZrNT with average diameters of 90 nm was synthesized by pyrolysing electrospun zirconium precursor embedded polymer fibers at 600 °C under an air atmosphere. The superior water retention ability and the tubular morphology of the ZrNT fillers resulted in facile water diffusion through the membrane, leading to a significant improvement in membrane proton conductivity under both fully humid and dry conditions. Compared to a commercial membrane (Nafion, NRE-212) operated under 50% and 100% RH at 80 °C, the Nafion–ZrNT membrane exhibited 2.7 and 1.2 times higher power density at 0.6 V, respectively. Under dry conditions (18% RH at 80 °C), the Nafion–ZrNT membrane exhibited 3.1 times higher maximum power density than the NRE-212 membrane. In addition, the Nafion–ZrNT membrane also exhibited durable operation for 200 h under 18% RH at 80 o C. The remarkably high performance of the Nafion–ZrNT composite membrane was mainly attributed to the reduction of ohmic resistance by incorporating the mesoporous hygroscopic ZrO 1.95 nanotubes.

This paper analyzes the behavior and studies the thermal degradation phenomena of a novel sodium rich Prussian blue cathode with a sodium deficient and sodium rich anode system viz. amorphous TiO2, crystalline (pristine), and heat treated TiO2 and Na2Ti3O7, respectively. The primary aim of the research was to demonstrate the superiority of the Na2Ti3O7 anode, which in principle can be considered “pre-stressed” by Na atoms when converted from TiO2 to Na2Ti3O7. Another motive of the research was to analyze exhaustively the layered anode structure and its degradation phenomena using the unique technique of thermal imaging to correlate it with post cycled X-ray diffraction (XRD) and an AC impedance study. The Na2Ti3O7 system was seen as more stable than the other tested TiO2 based anodes and produced an open circuit voltage (OCV) of 3.59 V and a maximum specific capacity of 92.18 mAh g−1 when the electrolyte used was dissolved in an organic solvent. Under the same conditions, the TiO2 sample showed an OCV of 3.41 V and a maximum specific capacity of 71.93 mAh g−1. Thermal imaging studies show that the maximum electrochemical degradation occurs at the anode of the samples with the TiO2 sample being more susceptible to corrosion.

Summary The goal of the work presented here was to develop a simulation approach for studying the effects of materials and geometry on the performance of Li-ion Solid State Batteries (SSB). Simulation provides the opportunity to explore, with ease, different material properties and cell geometries to optimize a Li-ion SSB's performance. Simulations shown in this paper are time-dependent and consider electrochemical reaction, heat transfer, the diffusion of Li-ions and electrons in the electrolyte, and solid Li diffusion in the positive electrode. A 2D model was simulated and the results shown. The simulations were able to show discharge curves, heat flux, the concentration of Li-ions, electrons, and solid Li at any time in the discharge cycle. Copyright © 2015 John Wiley & Sons, Ltd.

Conventional lithium-ion liquid-electrolyte batteries are widely used in portable electronic equipment such as laptop computers, cell phones, and electric vehicles; however, they have several drawbacks, including expensive sealing agents and inherent hazards of fire and leakages. All solid state batteries utilize solid state electrolytes to overcome the safety issues of liquid electrolytes. Drawbacks for all-solid state lithium-ion batteries include high resistance at ambient temperatures and design intricacies. This paper is a comprehensive review of all aspects of solid state batteries: their design, the materials used, and a detailed literature review of various important advances made in research. The paper exhaustively studies lithium based solid state batteries, as they are the most prevalent, but also considers non-lithium based systems. Non-lithium based solid state batteries are attaining widespread commercial applications, as are also lithium based polymeric solid state electrolytes. Tabular representations and schematic diagrams are provided to underscore the unique characteristics of solid state batteries and their capacity to occupy a niche in the alternative energy sector.

Korean society has seen a surge in the inflow of information, accompanied by colors and lights, with the emergence and technological advancement of devices such as TVs and smart phones. Human beings receive a significant proportion of their information visually. Among the five senses (visual, auditory, olfactory, gustatory, and tactile). Thus, human beings have a high reliance on the visual sense, which undoubtedly plays a crucial role in their lives. For that reason, research has been conducted in various fields to develop applications involving the visual sense. Particularly, it has been vigorously aiming to induce direct changes in physical conditions, such as the visual stimulus-induced physiological changes in the human body, emotional enrichment, concentration, attention, etc. However, the applications have yet to be developed, or have made very slow progress. This study presents the analysis of the changes in cerebral activation induced by visual stimuli delivered through a combination of colors, and has derived significant results associated with the changes in relation to indices of concentration, psychology, etc., based on the variation of stimulation.

In the recent research technical solutions have been studied to integrate renewable energy into unmanned aerial vehicles to use it as the main power source. As the weight of the aerial vehicle body is essential for its performance, we consider to use light-weight solar cell technology. Furthermore fuel cells are also integrated create a highly energy-efficient aerial robot. In this paper, construction concept and software design of the tilt-rotor aerial vehicle GAORI is introduced which uses solar cells and fuel cells as power source. The future work direction and prognosis are discussed.

Highly single-crystalline ruthenium dioxide (RuO2) nanoneedles were successfully grown on polycrystalline electrospun titanium dioxide (TiO2) nanofibers for the first time by a combination of thermal annealing and electrospinning from RuO2 and TiO2 precursors. Single-crystalline RuO2 nanoneedles with relatively small dimensions and a high density on electrospun TiO2 nanofibers are the key feature. The general electrochemical activities of RuO2 nanoneedles-TiO2 nanofibers and Ru(OH)3-TiO2 nanofibers toward the reduction of [Fe(CN)6](3-) were carefully examined by cyclic voltammetry carried out at various scan rates; the results indicated favorable charge-transfer kinetics of [Fe(CN)6](3-) reduction via a diffusion-controlled process. Additionally, a test of the analytical performance of the RuO2 nanoneedles-TiO2 nanofibers for the detection of a biologically important molecule, hydrogen peroxide (H2O2), indicated a high sensitivity (390.1 ± 14.9 μA mM(-1) cm(-2) for H2O2 oxidation and 53.8 ± 1.07 μA mM(-1) cm(-2) for the reduction), a low detection limit (1 μM), and a wide linear range (1-1000 μM), indicating H2O2 detection performance better than or comparable to that of other sensing systems.

We present a facile synthetic route to ruthenium dioxide (RuO2)-rhenium oxide (ReO3) electrospun composite nanofibers and their electrocatalytic responses for capacitance and H2O2 sensing. The contents of rhenium oxide of electrospun ruthenium dioxide (RuO2) were carefully controlled by an electrospinning process with the preparation of the precursor solutions followed by the thermal annealing process in air. The electrochemical applications of RuO2-ReO3 electrospun composite nanofibers were then investigated by modifying these materials on the surface of glassy carbon (GC) electrodes, RuO2-ReO3(n)/GC (n = 0.0, 0.07, 0.11, and 0.13), where n denotes the relative atomic ratio of Re to the sum of Ru and Re. Specific capacitance and H2O2 reduction sensitivity were remarkably enhanced depending on the amount of ReO3 increased. Among the four compositions of RuO2-ReO3(n), RuO2-ReO3(0.11)/GC showed the highest performances, i.e., a 20.9-fold higher specific capacitance (205 F g(-1) at a potential scan rate (v) of 10 mV s(-1); a capacity loss of 19% from v = 10 to 2000 mV s(-1)) and a 7.6-fold higher H2O2 reduction sensitivity (668 μA mM(-1) cm(-2), normalized by GC disk area), respectively, compared to only RuO2/GC.

This paper proposes a novel method that enables location sensing for a mobile object by utilizing deployed passive UHF Radio Frequency Identification (RFID) tags and a stationary RFID reader. In order to estimate the mobile object location, the proposed method utilizes the second order under damped system based tag to tag interference model. The empirical study using RFID systems and a mobile robot verifies the effectiveness and performance of the proposed method.

In recent, the diet is one of a trend of the world for making a wellness life. However, the diet management depending on the characteristics of each person has a limitation. Thus, in this paper, we propose a smart dietary management not only patients but also regular users for supporting a wellness service. And then, we develop a smart phone application for providing a wellness service to each person. According to the experiment results, we can improve the utility of common smart refrigerator.

This study presents the analysis of the changes in cerebral activation state induced by the visual stimuli delivered through the combination of colors, and derived significant results associated with the changes in cerebral activation state in relation to concentration index, psychological index, etc., based on the variation of stimulation. The results of this study may provide basis for building the efficient visual stimulating interfaces necessary for achieving the goals in various application in medical, educational fields, robotics, functional game sectors, and many more.

1. Introduction – Secondary Li ion batteries, regarded as the current benchmark for new battery technologies, are under extensive development throughout the world [1]. However, their requirement that organic electrolytes be used limits the rate capacity and specific power the cell can achieve and present several safety hazards and cost limitations that limit their application in large-scale storage systems [1, 2]. Here, aqueous Li ion cells utilizing LiMn2O4 spinel compound anodes is investigated, due to its ample capacity, cycling stability and high rate capability [3]. 2. Fabrication procedures – LiMn2O4 (LMO) anode is fabricated by solid state reaction of 5 mmol Li2CO3 and 10 mmol Mn2O3 at 750 °C for 20 hrs. Li2Mn4O9 cathode is fabricated by solid state reaction of 10 mmol LiOH·H2O and 20 mmol MnCO3 at 380 °C for 24 hrs. LiMn2O4 solid microspheres were prepared by calcination of LiOH·H2O and MnCO3 microspheres at 650 °C for 3 hrs in air. MnCO3 solid microspheres were prepared as follows: 1 mmol MnSO4·H2O and 1 mmol NaHCO3 were dissolved separately in 70 ml of distilled water. 7 ml of ethanol was added to the MnSO4 solution under stirring. Direct mixing of the NaHCO3 and MnSO4 solutions is done, and precipitate is allowed to form overnight. MnCO3 microspheres were obtained from multiple centrifugation and washing cycles. Obtained product was allowed to dry overnight at 100 °C in air. Activated carbon (AC, Kureha BAC) is utilized as received. 3. Experimental setup and results – XRD spectra of the solid state LiMn2O4 anode (LMO¬_SS) and LiMn2O4 solid microspheres (LMO_Sμ) are shown in Figure 1(a). SEM image of the LMO solid microspheres is shown in Figure 1(b). Cycling performance of LMO_SS vs. Li2Mn4O9 in 6M LiCl (pH 12, 0.01 M LiOH) is shown in Figure 2. 1st discharge capacities and charge voltage plateaus of cells utilizing LMO_SS vs. AC in 6M LiCl with varying pH is shown in Figure 3. Charge currents of 1.5 mA cm-2 and discharge currents of 0.25 mA cm-2 are used for all cell tests. 4. Conclusions – An initial decrease in discharge capacity of the LiMn2O4 and Li2Mn4O9 cell is observed from the 1st to 20th discharge cycle. The discharge capacity of the cell is observed to asymptotically approach 60 mAh/g by the 100th cycle. Discharge voltage and capacity of the LMO and AC cell is observed to be greatly dependent on electrolyte pH. A voltage plateau during is observed during charging that did not contribute to cell discharge capacity. Future work aims to investigate the processes occurring at the anode during the observed charge voltage plateau as well as the change in charge transfer kinetics and cell capacity when employing both solid and hollow LiMn2O4 microspheres as the active anode. Due to the dissolution tendencies of Mn in aqueous electrolyte, methods of increasing cell cycling stability are also of interest. 5. References – [1] G.X. Wang, S. Zhong, D.H. Bradhurst, S.X. Dou, H.K. Liu, Journal of Power Sources, 74 (1998) 198-201. [2] X. Zeng, Q. Liu, M. Chen, L. Leng, T. Shu, L. Du, H. Song, S. Liao, Electrochimica Acta, 177 (2015) 277-282. [3] W. Tang, S. Tian, L.L. Liu, L. Li, H.P. Zhang, Y.B. Yue, Y. Bai, Y.P. Wu, K. Zhu, Electrochemistry Communications, 13 (2011) 205-208. Figure 1

1. Introduction – Transition metal oxides are considered to be promising as anode materials for sodium ion batteries (SIB) [1, 2]. Among them tin oxide has attracted attention because of its high theoretical capacity, however the capacity drops steadily in the subsequent cycles due to large volume change [3]. A novel solvoplasma technique to produce SnO2 NWs as anode for SIBs is studied. 2. Fabrication procedures – A novel solvoplasma based technique is used to produce the SnO2 NWs. The precursor materials are a 1:1 ratio of micro-sized SnO2 particles and KOH pellets thoroughly ground together. The paste is held for about 2 minutes in a plasma arc which is operates at a power of 1000 W – 2000 W and an a.c. frequency of 2.5 GHz. SnO2 NWs such obtained are impure (containing K2SnO3) and need to be further purified. The purification is done by repeated centrifugation with DI water, thoroughly ground and finally treated with 50 ml of 0.1 M HCl for an hour. Once this is done, the NWs are retrieved and calcined in an oven at 550 ᵒC for 12 hours. The SnO2 NWs are tested against a Na metal foil and NaClO4 electrolyte mixed with ethylene carbonate and propylene carbonate (EC and PC ratio being 1:1). 3. Results – XRD spectra of the impure SNO2 and pristine SnO2 are shown in Figure 1 below. As can be seen, the impure or as-made SnO2 sample contains some K2SnO3 peaks as well. However, the purification process is effective and the pure sample contains no K2SnO3 impurity. The SEM image of the impure and the pristine SnO2 samples are shown in Figure 2(a) and (b) respectively. As can be seen from the images, very well defined nanowires are obtained by the solvoplasma process. Figure 2(b) shows the NWs to be slightly bulged in morphology, this can be attributed to the cleaning process. The first discharge cycle for the two electrodes are shown in Figure 3 below. As can be seen the pristine SnO2 performs much better than the impure SnO2 sample, providing a specific capacity of 280.48 mAh/g as against 160.29 mAh/g of the impure sample. The cleaning process helps to remove the K+ ions and free up the pores for Na intercalation to take place. 4. Conclusions – A novel scalable technique is described to produce pristine and highly crystalline SnO2 NWs starting from rather inexpensive and easily available precursors. However the SnO2 NWs produced are impure and have K2SnO3 which are removed via an HCl based cleaning process which frees up the interstices of the SnO2 NWs from the K+ ions and improves Na+ intercalation. The manifestation of this is seen in the galvanometric discharge cycles where the pristine SnO2 shows a much higher capacity. The goal of the work remains to show that these NWs will provide a great degree of stability and not suffer from considerable capacity fading due to their crystallinity and purity. 5. References – [1] L. Wang, K. Zhang, Z. Hu, W. Duan, F. Cheng, J. Chen, Nano Research, 7 (2014) 199-208. [2] D. Su, G. Wang, ACS Nano, 7 (20133) 11218-11226. [3] Y. Wang, D. Su, C. Wang, G. Wang, Electrochemistry Communications, 29 (2013) 8-11. Figure 1

In this research, we studied several factors which impact the performance of passive UHF far-field RFID based localization systems with KNN and LDTI algorithms. According to the empirical results, the localization system can be significantly interfered by distance relative factors such as the true positive reference identification rate and interrogation rates. Moreover, passive UHF RFID based localization systems need to analysis a required localization accuracy and interrogation duration to support RTLS.

This paper introduces a bio-inspired GAORI robot with renewable energy source and presents its command and data acquisition system for remote commanding as well as data forwarding/backup/relay. The hardware architecture design and software implementation of GAORI command and data acquisition system are presented in this paper.

In this paper, we propose a novel indoor localization technique of Unmanned Aerial Vehicle (UAV) using passive UHF far-field RFID systems. First, this paper presents impact of existence of UAV to RFID system. According to our empirical results, the existence of UAV, in a monitoring area, induces RF shadowing and Received Signal Strength Indicator (RSSI) interference from deployed tags. Second, we propose a localization method using observation of RF shadowing and RSSI interference under indoor environments.

In intelligent environments, detecting possible errors and completing missing values then deciding about the quality and validity of the sensed data are roles of context reasoning in order to improve the reliability of information. Particularly, learning to associate operations and roles with dynamic contexts is necessary for adapting user needs and making optimal classification to context-aware computing. However, a top-down based inference has difficulty to deal with various kinds of uncertainty such as unknown, ambiguous, imprecise, and erroneous related problems. Since misclassification by high-level classification to choice for learning the role acceptance may lead to wrong decision. Thus, we propose Evidential Fusion Network (EFN) that uses a belief or confidence level of information as a bottom-up based inference. In order to analyze advantage and disadvantage of the proposed EFN, we compare our approach (bottom-up) with decision tree approach (top-down). Finally, we suggest the combination of top-down based analysis and bottom-up based inference as a context reasoning method for obtaining reliable information.

Passive air breathing proton exchange membranes fuel cells (AB-PEMFC) have a unique advantage such as remarkably reducing stack weight by minimizing balance of plant (BOP). However, the performance of the AB-PEMFC is worse than general PEMFC because it is difficult to controlling humidification and stack temperature. Thus, the proton exchange membranes (PEMs) which are used to AB-PEMFC have to stably work under various humidification and temperature. A lot of research groups are reported that inorganic fillers (SiO2, TiO2, ZrO2) and Nafion composite membrane show high performance under low relative humidity by increasing water retention on the membrane. In this study, we synthesize SiO2/Nafion composite membrane for compensating the weakness of AB-PEMFC. The performance of membrane electrode assembly (MEA) with SiO2/Nafion composite membrane is tested under different hydration and temperature conditions. For more detailed characterization, morphological variations of the composite membrane under hydration conditions are studied by using dynamic mode atomic force microscopy (DMAFM). DMAFM can map amplitude and phase distribution on the specimen surface. The phase lag, which is mechanical vibration changing of a cantilever, is resulting of tip-sample interaction, which is induced by microscopic mechanical property of sample. Thus, the DMAFM is best tool for characterizing heterogeneous materials such as composite membrane. The morphological structure variation on the composite membrane by water retention elevation is systematically studied by using phase lag changing under different humidification condition. References C. A. Hayden, and G. R. Goward, Proton Dynamics of Nafion and Nafion/SiO2 Composites by Solid tate NMR and Pulse Field Gradient NMR Macromolecules 40, (2007), 1529-1537 Bella Nicotera, Apostolos Enotiadis, Kristina Angjeli, Luigi Coppola, Giuseppe A. Ranieri, and imitrios Gournis, Effective Improvement of Water-Retention in Nanocomposite embranes Using Novel Organo-Modified Clays as Fillers or High Temperature PEMFCs, Journal of Physical Chemistry B 115, (2011), 9087–9097 Figure 1

Among many technical barriers for the commercialization of proton exchange membrane fuel cells (PEMFC), low working temperature and carbon monoxide poisoning to catalyst have to be solved; however, they are not easy problems because they are related intrinsic properties of per-fluorinated Sulfonic Acid (PFSA) electrolytes such as Nafion. Recently, many groups report that TiO2/Nafion composite membrane shows the high proton conductivity under insufficient hydration on the membrane and high temperature operating condition. They conclude that the performance enhancement under low relative humidity and high temperature of the composite membrane is due to water retention increasing on the membrane. [1-2] DMAFM, which is called tapping mode or non contact mode AFM measures amplitude and phase shift of specimen surface by amplitude modulation. The amplitude and phase shift are induced from the attraction force variation between tip and sample. The phase shift on the membrane is corresponding mechanical properties on the specimen such as viscosity, elasticity, and viscoelasticity. We are synthesize the TiO2/Nafion composite membrane for high temperature PEMFC and characterize water retention on the membrane at variation conditions by using dynamic at mode atomic force microscopy (DMAFM). Characterization has done by two steps. Firstly, we simultaneously map topography and phase images of TiO2/Nafion composite membrane and pristine Naion under different humidity and temperature. The phase distributions on the composite membrane under different conditions are characterized. Secondly, the histograms from each image are extracted and statistically analyzed. References O. Savadogo, Emerging membranes for electrochemical systems Part II. High temperature composite membranes for polymer electrolyte fuel cell (PEFC) applications, Journal of Power Sources 127 (2004) 135–161 E. I. Santiago, R. A. Isidoro, M. A. Dresch, B. R. Matos, M. Linardi, and F.C. Fonseca, Nafion–TiO2 hybrid electrolytes for stable operation of PEM fuel cells at high temperature, Electrochimica Acta 54, (2009), 4111–4117 Figure 1

1. Introduction – Sodium batteries are being studied to overcome the drawbacks of Li ion based batteries viz. cost, poor cycle life of Li etc. [1]. Layered compounds are finding applications as anodes and cathodes as these are able to intercalate the large sized Na+ ion better [2]. Prussian blue and layered transition metal oxides are the compounds of choice to facilitate easy intercalation, increase cell performance and provide higher specific capacities [3, 4]. The TiO2 based anodic system is analyzed from different aspects to obtain the optimum system in this case. 2. Fabrication procedures – Fabrication process for the prussian blue cathode involves dissolution of 3 m mol of Na4Fe(CN)6.10H2O in 40 ml of 0.1 M conc. HCl solution followed by vigorous stirring at 500 rpm for 5 minutes. Once this is done, the resulting solution is dried at 80 °C for 20 hours. For the anode, the crystalline TiO2 anatase and the amorphous TiO2 rutile powder are used as obtained. Na2Ti3O7 is obtained by heating 1g of TiO2 and 0.36 g of NaOH at 750 °C for 20 hours, after they were mechanically milled for 4 hours. 3. Experimental steps and results – The various characterization procedures are as follows: (i) Analysis of the phase of the TiO2 and Na2Ti3O7 anode. Figure 1 shows the XRD data of TiO2 (blue, bottom) and Na2Ti3O7 anodes (orange, top). The main peaks are seen and no impurities peaks are noticed, especially in the Na2Ti3O7 sample which indicate phase formation is complete. (ii) Analysis of the Prussian blue cathode before and after the cell cycling to show the degradation of the cathode. The graph in figure 2 represents the XRD data of the pristine Na-PB cathode (bottom, in blue) and the cathode after 10 cycles of operation (top, in orange). The post cycling XRD graph shows the presence of the peaks in the same position indicating very little structural damage. (iii) Cell cycling is performed in a 2 electrode set-up within in an aqueous electrolyte in a voltage range 0 V to 0.7 V. Figure 3 gives the specific capacity with respect to the voltage for the 1st, 2nd, 5th and 10th cycles respectively. The open circuit voltages can be seen to be approximately around slightly higher than 0.55 V and a maximum specific capacity of 76.52 mAh/g. It is also seen that the graphs are very close to one another which indicate very little capacity fading. (vii) Comparison of the stability behavior of different TiO2 anodes. Figure 4 shows the stability characteristic of the different TiO2 based anode systems. As can be seen, the Na2Ti3O7 system is the most stable whereas the amorphous system demonstrates the least stability. 4. Conclusion & future work – Sodium rich prussian blue system has been tried out as a positive electrode versus a transition metal oxide e.g. TiO2 as the negative electrode. The TiO2 system has been tried from different aspects (crystalline, amorphous, heat treated and heat treated) and the imporrtant structural aspects and cell performances have been discussed. Future work would involve analysis if the corrosion mechanism at the electrode-electrolyte interface and study of the Prussian blue cathode in greater detail. References: [1] M.S. Islam, C.A.J. Fisher, Chemical Society Reviews, 43 (2014) 185-204. [2] D. Kim, E. Lee, M. Slater, W. Lu, S. Rood, C.S. Johnson, Electrochemistry Communications, 18 (2012) 66-69. [3] A.A. Karyakin, Electroanalysis, 13 (2001) 813-819. [4] Y. Yue, A.J. Binder, B. Guo, Z. Zhang, Z.-A. Qiao, C. Tian, S. Dai, Angewandte Communications, 53 (2014) 3134-3137. Figure 1

1. Introduction – Lithium-ion batteries are regarded as the current benchmark for new battery designs. While lithium-ion batteries offer both high energy densities and large cell potentials, they also possess many inherent disadvantages such as flammability and high material costs [1, 2]. Potassium-ion (K+) batteries can be of great environmental and economic importance. Potassium possesses an oxidation/ reduction potential closest to lithium among all alkali metals, only 0.12 V lower than that of lithium [3]. Furthermore, nanoscale coatings of transition metal oxides are known to behave as inhibitors to cell capacity degradation [4]. 2. Fabrication procedures – Prussian blue (Fe4[Fe(CN)6]3) cathode is fabricated by dissolution of 4 mmol K4Fe(CN)6•3H2O in 50 ml of 0.1 M HCl solution followed by vigorous mixing at 500 rpm at 80 °C overnight until dry. Resulting powder is ground, washed and separated by centrifugation and at 80 °C overnight. α MoO3 anode is fabricated by titration of 0.7 mmol (NH4)6Mo7O24•4H2O in 10 ml of 5 M (NH4)2CO3 with Nitric acid until a white precipitate is formed. Solution is aged overnight, dried at 80 °C, washed with HCl solution and separated by centrifugation, and then annealed at 500 °C for 20 hrs. Electrolyte of 0.5 M aqueous KPF6 is used. Atomic Layer Deposition technique is used to deposit thin TiO2 films of 5 and 10 nm on the Prussian blue cathode surface. 3. Experimental setup and results –XRD and SEM is done to study the crystallinity and morphology of both pristine and TiO2 coated cathodes. XRD spectrum of Prussian blue cathode and α-MoO3 anode is shown in Figure 1. Cycling performance is studied using a charge/discharge current of 2 mA and 0.5 mA respectively and voltage range of 0 to 1 V. Discharge capacity and capacity retention performance of aqueous cells of pristine, 5 nm and 10 nm TiO2 coated Prussian blue cathodes and α MoO3 anode is shown in Figures 2 and 3 respectively. 4. Conclusions and future work – A decrease in initial discharge capacity and increase in capacity retention is observed for cells utilizing a TiO2 coated cathode. Initial discharge capacities of the 5 nm and 10 nm TiO2 coated cathodes are observed to be less than that of the pristine cathode. After 10 cycles all three cell configurations are observed to approach approximately the same discharge capacity. Both TiO2 coated cathode materials show considerable increase in capacity retention with respect to the pristine cathode. Future work aims to increase cell capacity by post-fabrication modification of anode and cathode. Post-cycling changes in electrode structure and morphology are also of interest. 5. References – [1] D. Lisbona, T. Snee, Process Safety and Environmental Protection, 89 (2011) 434-442. [2] M.D. Slater, D. Kim, E. Lee, C.S. Johnson, Advanced Functional Materials, 23 (2013) 947-958. [3] A. Eftekhari, Journal of Power Sources, 126 (2004) 221-228. [4] X. Li, J. Liu, X. Meng, Y. Tang, M.N. Banis, J. Yang, Y. Hu, R. Li, M. Cai, X. Sun, Journal of Power Sources, 247 (2014) 57-69. Figure 1

1. Introduction – Solid state batteries overcome many of the essential drawbacks of liquid electrolyte batteries, such as liquid electrolyte and leakage issues [1]. Another major issue is the degradation of the Li based cathode from continuous cycling due to a change in its microstructure [2]. Nanoscale coatings are thought to prevent the degradation of the cathode by acting as a protective layer on its surface [3, 4]. This paper studies the performance of lithium cobalt oxide (LCO) based cathodes with and without protective coatings of Al2O3 and TiO2. 2. Fabrication procedures – Fabrication procedures entail the following stages: (i) Making the liquid lithium lanthanum tantalite (LLTO) electrolyte by a sol gel technique from its precursors and then vaporizing the liquid by exposing it to elevated temperature. The paste left behind is thoroughly dried and finely ground and is included as the solid state electrolyte. (ii) The cathode is made by thoroughly grinding lithium cobalt oxide (LCO) powders and then making slurry by mixing them thoroughly with PTFE binder, carbon powder, and alcohol. Pasted on to a stainless steel foil, this whole system acts as the cathode. (iii) The Atomic Layer Deposition (ALD) technique is used to deposit thin films (~6 nm) on the surface of the LCO cathodes to compare them with the pristine cathodes. (iv) The anode includes Li metal foil. Once this is complete, the three separate components are assembled into a coin cell. 3. Experimental steps and results – The characterization procedures are as follows: (i) XRD and SEM study to check the phase of the solid state LLTO electrolyte, pristine LCO cathode, and cathodes with Al2O3 and TiO2 coatings and the surface morphology. Figure 1 shows the XRD data of the LCO cathode with TiO2 deposition. The main Al2O3 peaks are seen and no TiO2 peaks are obtained, indicating the amorphous nature of the deposition. (ii) TEM and XPS analysis to study the nature and actual thickness of the coating. This will give an idea about the actual depth of the deposition as well as the nature of electronic bonding at the surface. From Figure 3 it may be seen that reduction potential shifts more to the right for the TiO2 coated cathode. The greater ΔV value exhibited by the coated cathode indicates greater energy needed for the reduction reaction owing to the deposition, and TiO2 has the highest ΔV value. Figure 2 represents the XPS data of the LCO cathode coated with Al2O3, showing clearly the Al 2s and 2p and the O 1s peaks. (iii) Cyclic voltammetry is performed within a voltage range of 3 V to 4.5 V and the applied current is 5 mA/s. (iv) Cyclical performance of the cell. Figure 4 shows that open circuit voltages are obtained of slightly less than 3 V for a current density of 10 mA/cm2, compared with 3.259 V and 3.312 V, respectively, for i = 30 mA/cm2 and 40 mA/cm2 for the LCO pristine cathode. 4. Conclusion – Amorphous transition metal oxide coatings have been tried out. XPS data have shown the formation of the thin film. A rightward shift in the reduction potential demonstrated by the CV data indicates greater energy necessary which is a measure of the protective nature of the coating. Future work includes studies of the cycling performance of the cell with the coated cathodes. References: [1] M.V. Tyufekchiev, S. Hur, Developing a Low-Cost Methodology for Fabricating All-Solid-State Lithium-Ion Battery, in: Chemical Engineering, Worcester Polytechnic Institute, 2013. [2] M. Ogawa, K. Yoshida, K. Harada, Environment, Energy and Resources, 88-90. [3] X. Li, J. Liu, X. Meng, Y. Tang, M.N. Banis, J. Yang, Y. Hu, R. Li, M. Cai, X. Sun, Journal of Power Sources, 247 (2014) 57-69. [4] H. Zhao, L. Gao, W. Qiu, X. Zhang, Journal of Power Sources, 132 (2004) 195-200.

The high temperature proton exchange membrane fuel cell (HT-PEMFC) is a key of solving corrosion problem in catalyst layer from CO Poisonning. The key issue of HT-PEMFC is developing novel proton exchange membrane which has good proton conductivity under dry condition and thermal properties compare with Nafion. Sulfonated graphene (S-graphene) and Nafion hybrid membrane is developed in our previous work. The proton conductivity of S-graphene and Nafion hybrid membrane is five times larger than pristine Nafion at 20 % RH. In addition, the morphological variation due to hybridization of Nafion and S-graphene is observed by using non-contact mode AFM. The morphological variation might induce the ionic channel network variation on the membrane. We measured and analyzed ionic channel network evolution in the membrane by hybridization. Nafion is perm selective membrane due to its heterogeneous structure such as hydrophobic backbone and hydrophilic side chain. The side chain can create ionic channel network which is source of proton conductivity when the membrane is hydrated and the structure of ionic channel network can vary with water faction on the membrane. Thus, in-situ and accurate observation for ionic channel network evolution is required. For in-situ and accurate measurement, we designed PEMFC mimicking method by using current sensing atomic force microscopy (CS-AFM). The pt-coated tip/membrane/catalyst layer can created nano-sized PEMFC. Extremely small tip can act as single Pt catalyst and it simultaneously can detect proton conductivity variation in the ionic channels. In this study, the proton conductivity distribution of S-graphene and Nafion hybrid membrane can measure and compared with the proton conductivity distribution of pristine Nafion. Then the result is analyzed by using statistical method.