bluuebunny/crossref_metadata_2025 huggingface dataset:
Taxonomic Dynamics of Nitrate Reducing Microbial Fuel Cell Communities
Authors: Salvacion Michael , Ishii Shunichi , Ishii Shino , Bussey Lauren , Carpenter Kayla , Babanova Sofia , Bretschger Orianna
Published: February 2020

The presence of nitrogen encourages the growth of organic matter and algae, which leads to eutrophication of marine and freshwater ecosystems. In conventional wastewater treatment facilities the removal of nitrogen is achieved through simultaneous nitrification and denitrification of the wastewater. Microbial fuel cells (MFC) present an alternative technology to conventional methods for nitrate removal. The MFC is a bioelectrochemical device capable of harvesting electrons from organic sources. Bacteria in the anode compartment oxidize organic compounds, and the electrons are transferred across an external load to a terminal electron acceptor at the cathode. A typical MFC has an abiotic cathode and biotic anode. Recently more attention has been given toward the utilization of biological cathodes for the reduction of sulfate, nitrate, carbon dioxide, fumarate, and other electron acceptors. Previous studies have demonstrated an MFC’s capacity for biological denitrification at the cathode1 where bacteria can reduce nitrate to nitrite to nitrogen gas. In this study we monitored the performance and taxonomic dynamics of two denitrifying MFCs with different cathode materials.

            A two-chamber reactor configuration (600mL total volume) was used with alternative cathode catalysts. Acetate was provided at the anode as the electron donor and sodium nitrate was introduced at the cathode as the electron acceptor. Denitrification efficiency of the MFC was evaluated as a function of the different cathode materials and the taxonomic communities. One of the reactors had carbon cloth cathode with activated carbon/carbon black mixture (AC-MFC); the other reactor had carbon cloth cathode with carbon black layer (CB-MFC). Nitrate was periodically added to cathode chamber and the concentration of nitrate and nitrite was periodically monitored. Initial results show a removal rate of 2.02 mg/L/d and 5.31 mg/d [NO3
-] for the AC-MFC and CB-MFC after 230 days of operation. Biofilm and planktonic samples were periodically extracted from the anode, cathode, solution, and membranes of each system and were used to estimate the phylogenetic composition of each community based on 16S rRNA gene sequences. The presence of Geobacteraceae at the anode supports the observed acetate consumption and current production of both systems. Additionally, denitrifying and nitrifying bacteria were identified in the cathode compartment and support the simultaneous nitrification and denitrification observed in the cathode chamber. Further studies will be conducted to evaluate functional roles of dominant species in the community.

Figure 1
Membrane-Less Microbial Fuel Cell Powering a Smart Phone: A Self-Stratifying Urine Column
Authors: Walter Xavier Alexis , Gajda Iwona , Forbes Samuel , Stinchcombe Andrew , Greenman John , Ieropoulos Ioannis
Published: February 2020

The microbial fuel cell (MFC) is a technology in which microorganisms employ an electrode (anode) as a solid electron acceptor for anaerobic respiration. This result in direct transformation of chemical energy into electrical energy, which in turn means that organic wastewater can be used as fuel. Amongst the various organic wastes that are employed as fuel for MFCs, urine is of interest since it represents 75% of the nitrogen present in domestic wastewaters and yet only 1% of the total volume. However, here is a persistent problem for the scaling up of MFCs. The smaller the surface of electrode to volume ratio of an MFC is, the higher its power density is. Hence, to reach usable power levels, a plurality of units needs to be assembled in stack, which implies configuring both the hydraulic circuitry and the serial/parallel electrical connection patterns. Because of this plurality, the units need to have a simple design for the whole system to be cost-effective. The goal of this work is to address how to build these multiple MFCs in stack.

We report a novel membrane-less stack design using manifold ceramic plates semi-submerged with anodes and cathodes sharing urine solution. The top half of each plate were semi-submerged were covered in cathodes while the anodes, on the lower half of each plate, were fully submerged. The MFCs in each box were connected in parallel and multiple modules were configured in series and placed. This allowed  self-stratification of the collective environment (urine column) under the natural activity of the microbial consortia thriving in the system. For size comparisons, the module footprints were enlarged from 900 mL to 5000 mL and, importantly, this scaling-up did not negatively affect power density (» 19 W/m^3), a factor that has proven an obstacle in previous studies. However, we should note that this observation is limited for the dimensions we tested. This was achieved by maintaining a plurality of microenvironments within the collective system and resulted in a simple, robust system fuelled by urine. The developed system was then used to treat urine of single individual (» 2.5L per 24h), in order to serve as the energy source charging mobile phones. Six boxes, each comprising 20 MFCs connected in parallel, were hydraulically cascaded and connected in series. Best performances were obtained in pulse-feed batch mode. At equilibrium, the stack of six boxes was feed with 600 mL every 6h at a flow rate of 2 L/min and was producing between 110 and 125 mW. Under these conditions, a smart phone (Samsung Galaxy S, battery of 1600 mAh) was fully charged in 68 h and 80 h, when turned off or on respectively. It has to be noted that these performances were stable for a period of 8 months. We concluded that our scaling-up approach within the tested range was successful to convert chemical energy in urine to electricity and this was demonstrated by charging cell phones.
(Invited) Ionic Liquids for Rechargeable Metal Batteries
Authors: Kar Mega , Howlett Patrick C , Forsyth Maria , MacFarlane Douglas R
Published: February 2020

The emergence of global warming driven by greenhouse gases has put tremendous emphasis on the need to develop improved large scale energy storage systems including low-cost, and high energy density batteries such as rechargeable metal batteries. Batteries in which metals such as lithium (Li), magnesium (Mg), sodium (Na) and zinc (Zn) act as the electroactive species offer great potential in these applications. Room temperature ionic liquids (RTILs) that are, generally, non-volatile, non-flammable and thermally stable have recently been shown to enhance the electrochemical characteristics and long-term cycling of some of these metals[
1
]. For example, Figure 1 below compares the charging behaviour of a Li|LiCoO2 cell in conventional organic electrolyte (solid bold line) to that of RTIL (dashed line)[
2
]. The high rate charging behaviour is substantially improved in the latter electrolyte due to the high solubility of Li ions in the RTIL.  The thermal stability of RTILs is also becoming very significant in offering improved safety with these large-scale batteries.

Recent work has demonstrated the importance of functional groups in the RTIL cations and anions [
3
] and the role of additives[
4
] in influencing speciation and electrochemical behaviour.  These functionalised ILs are providing a pathway towards cheaper, rechargeable batteries such as those based on zinc[
5
] and magnesium[
6
]. 

This talk will discuss recent work from our group, and others, in these areas.

Figure 1:  1 C to 5 C charging profiles of organic liquid electrolyte [1M LiPF6, EC:DMC = 50:50 vol.%] (Solid bold line) and 3.2 mol.kg-1 LiFSI in C3mpyrFSI (Dashed line). (Reproduced from ref [
2
]).

[1]          a) M. Kar, T. J. Simons, M. Forsyth, D. MacFarlane, Phys. Chem. Chem. Phys.
2014, 16, 18658-18674; b) D. R. MacFarlane, M. Forsyth, P. Howlett, M. Kar, S. Passerini, J. Pringle, H. Ohno, M. Watanabe, F. Yan, W. Zheng, S. Zhang, J. Zhang, Nature Review Materials
2016 - in press.

[2]          H. Yoon, P. C. Howlett, A. S. Best, M. Forsyth, D. R. MacFarlane, J. Electrochem. Soc.
2013, 160, A1629-A1637.

[3]          M. Kar, B. Winther-Jensen, M. Forsyth, D. R. MacFarlane, Phys. Chem. Chem. Phys.
2013, 15, 7191-7197.

[4]          T. J. Simons, A. A. J. Torriero, P. C. Howlett, D. R. MacFarlane, M. Forsyth, Electrochem. Commun.
2012, 18, 119-122.

[5]          a) M. Kar, T. J. Simons, B. Winther-Jensen, M. Forsyth, M. Armand, D. MacFarlane, Electrochim. Acta
2014; b) T. J. Simons, M. Salsamendi, P. C. Howlett, M. Forsyth, D. R. Macfarlane, C. Pozo-Gonzalo, ChemElectroChem
2015.

[6]          M. Kar, Ma, Z., Chen, K, Azofra, L. M,  Forysth, M, MacFarlane, D.R., Chem Comm - submmitted
2015.

Figure 1
Development and Testing of an Electrochemical Methane Sensor
Authors: Sekhar Praveen K. , Brosha Eric L. , Kreller Cortney R , Kysar Jesse
Published: February 2020

In this paper, the development of an electrochemical methane sensor is presented. The mixed potential based sensor is based on tin doped indium oxide (ITO) and platinum electrodes and yttria-stabilized zirconia (YSZ) electrolyte. The sensor was fabricated using the inexpensive tape-cast method. The sensor responded to methane with a response time of 15 s. The staircase response to methane indicated a 44 mV sensor response to 100 ppm of methane. The sensor response indicated a log-linear relationship with the methane concentration. Upon 500 hrs of sensor testing, a 5% reduction in methane sensitivity was observed. The cross-sensitivity study on the sensor indicated minimal interference to NO, NO2, and CO2. To improve the sensitivity to methane, a signal conditioning method referred to as the pulsed discharge technique (PDT) was applied. A fourfold increase in methane sensitivity was observed when the sensor was subjected to PDT. Future studies include the miniaturization of the sensor with integrated heater design.
(Keynote) Wearable Electrochemical Sensors
Authors: Wang Joseph
Published: February 2020

The presentation will discuss the status and potential of textile- and tattoo-based flexible screen-printed electrochemical sensors. The portable nature and low power demands of electrochemical system satisfy many of the requirements for on-body sensing. Miniaturized electrochemical systems offer tremendous potential for obtaining the desired analytical information in a faster, simpler (“user-friendly”), and cheaper manner compared to traditional laboratory-based assays. Thick-film (screen-printing) microfabrication has been widely used for mass production of highly reproducible electrochemical sensors (e.g., glucose strips for diabetics). This process has recently been applied for printing flexible electrochemical sensors but not in connection to common textiles and garments. The integration of printable sensors directly onto fabrics and garments, such as those described in this presentation, would provide the wearers with the ability to continuously assess their health and condition. Since the performance of textile- and tattoo-based electrochemical sensors is directly related to the printing quality, it is imperative that the printing protocol and ink formulation be tailored for the specific substrate material.

         The presentation will review recent advances in developing flexible printable textile- and tattoo-based electrochemical sensors. We will describe the preparation and characterization of various textile-based and skin-worn electrochemical sensors, will illustrate their favorable electrochemical behavior and examine the influence of the clothing stretching and folding upon their sensing performance. Such mechanical stress studies indicate that textile-based printed electrochemical sensors survive large deformations. Technical challenges and prospects for using textile- and tattoo-based electrochemical sensors for monitoring the wearer’s health, fitness, or surrounding environment will be discussed, along with several demonstrations and prospects for future healthcare and sport applications.
A Versatile Bioanode with Improved Current Density and the Coulombic Efficiency through a Cascade Reaction
Authors: Zafar Muhammad Nadeem , Aslam Iqra , Murtaza Shahzad , Gorton Lo
Published: February 2020

To improve communications between enzymes and electrodes, many different methods were developed including the use of diffusional electron mediators, the “wiring” of enzymes through immobilization in redox polymers, the functionalization of enzymes with electron relays, and the use of nanomaterials. Recently a new promising strategy was reported, in which the glycoprotein glucose oxidase (GOx) was directly electrically contacted with the electrodes after removal of the glycosylating layer. Although a lot of advances in the electrical communication between enzymes and electrodes has made it possible to fabricate new biosensors and biofuel cells, the technologies still face challenging issues, such as development of long-term stable miniaturized implantable amperometric biosensors and biofuel cells.

Our approach to the development of a glucose biofuel cell anode is based on the combination of different redox enzymes with complementary oxidation positions thus forming a reaction cascade to oxidize the substrate at more than one position. Improvements in current density and coulombic efficiency of a glucose oxidizing electrode were realized by a combination of pyranose dehydrogenase from Agaricus meleagris (AmPDH) with either glucose dehydrogenase from Glomerella cingulata (GcGDH) or cellobiose dehydrogenase from Myriococcum thermophilum (MtCDH). The mixed enzyme electrode oxidizes glucose in several combinations at the C-1, C-2 and C-3 positions of the pyranose ring. This concerted action of enzymes increases (i) the coulombic efficiency by extracting more than 2 e- per substrate molecule and (ii) the current density of the electrode when the mass-transfer of substrates becomes rate limiting. The electrodes were investigated with flow injection analysis (FIA) using different substrates under physiological conditions (pH 7.4). These investigations showed that the product of one enzyme can be used as substrate for the other enzyme and maximally 6 e- can be gained from the oxidation of one glucose molecule using mixed enzyme electrodes like AmPDHb/GcGDH/Os-polymer 2 or the AmPDHa/MtCDH/Os-polymer 1. We propose a bioanode for use in biofuel cells with an increased current density and coulombic efficiency obtained by a cascade reaction catalyzed by redox enzymes with a different site-specificity for glucose.
Smart Patch Systems: Iontophoretic Microheater Assemblies for Controlled Transdermal Delivery
Authors: McConville Aaron , Davis James
Published: February 2020

The majority of currently approved transdermal drug delivery systems utilise low doses of low molecular weight lipophilic drugs, falling within the category of first generation approaches. Systems incorporating improvements such as chemical enhancers, heat, iontophoresis and non-cavitational ultrasound to reversibly disrupt the structure of the stratum corneum, fall under second generation approaches. Although heat is a somewhat uncommon and perhaps understudied enhancement technique, there is considerable evidence to suggest that it can significantly increase epidermal penetration. Given the tolerable nature of these temperatures, there is a clear opportunity for heat assisted absorption to be incorporated into future transdermal drug delivery systems. The use of heat has been shown to increase the rate of transdermal drug delivery in a number of applications, such as administration of fentanyl and lidocaine. The aim of the present project has been to investigate the development of a hybrid smart patch system, which involves the integration of transdermal heat transfer with iontophoresis. This would enable enhanced drug delivery to be achieved in a controlled manner without significant disruption to the skin’s structure.

Iontophoresis provides a mechanism through which delivery rate may be controlled to a high degree of specificity. It is therefore possible to regulate or inhibit delivery rate over a period of time, due to the direct relationship between the applied current and transdermal flux. Rate control may be the responsibility of the patient, or more commonly, controlled by incorporation of a microprocessor, enabling complex and bespoke delivery profiles to be enacted. The addition of the transdermal heater, in this instance, brings a new dimension to the delivery process, but there remains a considerable challenge to the design and implementation of the proposed smart patch.

The basic approach is outlined in Figure 1. In order to address the issue of controlled release and subsequent flux, the design incorporates a temperature sensitive hydrogel as a drug entrapment matrix or reservoir. Hydrogels have traditionally been employed as a barrier mechanism or encapsulation medium in a number of drug delivery studies, where their manipulation and/or degradation may be controlled by environmental influences, hydrolysis and enzyme interaction. In this prototype, thermal control (typically 45oC) facilities the release of drug from the gel, and its subsequent transfer across the stratum corneum is induced through the combination of heat and iontophoresis.

The design of the microheater / iontophoretic electrode assembly is described and its operation characterised. The drug delivery profiles from prototype smart patches employing a range of model drugs are critically assessed. The extent to which precise control and augmentation of both the release and transdermal delivery rate, for a range of drug species and therapeutic agents has been assessed.

Figure 1
(Invited) Elucidation of Lithiation Process As a Function of Structural and Chemical Transformations in Li2MnO3
Authors: Persson Kristin A , Shin Yongwoo
Published: February 2020

The layered Li2MnO3 is a key component in the Li/Mn-rich cathode materials, and provides a representative end-member for the spectrum of compositions reported in the literature. While exhibiting excellent initial capacity, the Li excess materials suffer from voltage fade, high impedance, and poor rate capability, particularly in the Mn-rich, high Li excess concentration regime.  In this talk we present insights about the Li electrochemical reactivity of Li2MnO3, from first-principles calculations. In particular, we elucidate the bulk lithiation/delithiation mechanism in pristine bulk LixMnO3 for 1< x < 2, involving coherent Li migration from the two Li-containing layers. Surprisingly, and contrary to expectations from available experimental results, we find that the pristine material exhibits excellent Li mobility enabling a Li rate capability on par with the well-known layered LiCoO2. For lower Li contents (x < 1), we have previously shown that Li2MnO3 becomes increasingly unstable towards manganese migration into the Li layer as well as oxygen loss at the surface. We systematically investigate the influence of these factors on the lithiation/delithiation process, which provides a hypothesis for the experimentally observed slow, and increasingly poor, electrochemical response of this material.
Graphite Phase Behavior during Lithium (de)Intercalation
Authors: Smith Raymond B. , Guo Yinsheng , Yu Zhonghua , Efetov Dmitri , Wang Jungpu , Kim Philip , Brus Louis , Bazant Martin Z.
Published: February 2020

One of the processes limiting the rate of charging of lithium ion batteries is the possibility that lithium will plate onto the graphite anode at high charging currents, leading to safety hazards. Lithium can plate when the filling fraction of lithium within the graphite approaches unity near the particle surface, which occurs when transport into the particles is not fast enough compared to the intercalation current. Thus, models must correctly describe the transport of lithium within the graphite, a phenomenon complicated by the fact that graphite particles tend to phase separate, both by forming staged structures in which lithium is only located between every n'th layer of graphene, and also by forming high and low concentration domains within individual layers. The different stages correspond to plateaus in the open circuit voltage and are characterized by a distinct visual color change, allowing optical characterization of local state of charge of graphite electrodes and particles. We propose here a simple free energy model to explain the intralayer phase separation as well as the high filling fraction staging structures. Then, we apply this free energy to a phase field transport model which allows us to capture single-crystal experimental intercalation results and makes distinct predictions from Fickian diffusion models, which we describe here.
Real-Time Dynamic Simulation of Electrochemical Battery Models for Grid Applications
Authors: Lee Seong Beom , Pathak Manan , Gao Wenzhong , Viswanathan Vilayanur , Subramanian Venkat R.
Published: February 2020

Lithium-ion batteries are important energy storage systems implemented in a microgrid and they are the most expensive single component, accounting for about 60% of overall capital expenditure1. As of today, however, the microgrid significantly underutilizes the battery’s performance, which causes high cost and low energy efficiency in the grid operation. For example, the microgrid involves large battery modules. In order to perform the most accurate simulation and control of these systems the model must include multiple cells in parallel series. For large modules charge balancing becomes problematic2. Not all the cells will be at the same state of charge and health. However, current technology considers battery packs as just one big battery/a black box having the same state of charge and health.

This talk will present progress in real-time simulation of physics based models for batteries in the microgrid framework including batteries, power electronics, energy generators and controls.

Acknowledgements

The authors acknowledge financial support from the University of Washington’s Clean Energy Institute and Washington Research Foundation.

References

1. Ivanova, N. Lithium-ion costs to fall by up to 50% within five years. http://analysis.energystorageupdate.com/lithium-ion-costs-fall-50-within-five-years.

2. Moore, S. W.; Schneider, P. J. A review of cell equalization methods for lithium ion and lithium polymer battery systems; SAE Technical Paper: 2001.
Smoothed Boundary Method Simulations of Electrochemical Impedance Spectroscopy for Energy Materials with Complex Microstructures
Authors: Yu Hui-Chia , Choe Min-Ju , Chiang Yet-Ming , Amatucci Glenn G , Thornton Katsuyo
Published: February 2020

Electrochemical impedance spectroscopy (EIS) is commonly utilized to measure ionic and electronic conductivities in energy materials (e.g., battery and solid oxide fuel cell electrodes), which are often represented as equivalent circuits that contain capacitors and resistors. Although effective capacitance and resistance can be calculated with the simplified representation as circuits, such representation cannot incorporate microstructural characteristics (e.g., porosity, tortuosity, grain boundary density, etc.) that strongly influence the performance of these energy materials. For example, the grain boundary network can enhance or hinder the overall transport of ions and electrons, which in turn influence polarization. Such a microstructural effect cannot be captured with the simplified representation as circuits. As such, a comprehensive model of EIS should take into account the microstructural characteristics that play a crucial role in determining material properties and device performance.

In this work, we develop an innovative approach based on the smoothed boundary method, which allows us to simulate EIS behavior of materials with complex microstructures. Using a continuous domain parameter to define the geometry of a porous electrode, different physical mechanisms, such as surface transport along irregular particle surfaces, electrochemical reaction at the particle surfaces, and diffusion through the tortuous complex bulk of the electrode, are coupled and taken into account in the simulation of the ion concentration responding to oscillating loadings. In addition, using multiple domain parameters, each of which defines a primary cathode particle, transport through complex grain boundary networks in secondary particles is simulated and accounted for in the simulation of the EIS response. From the simulation results, the effects of microstructures and the impact of interface/boundary transport on EIS behavior are elucidated.

This work is supported by the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award Numbers DE-SC0012583.
Parameter Characterization for a Li-Ion Cell with Blended Cathode
Authors: Guo Meng , Carlson Eric , Chamberlain Rick
Published: February 2020

In this work, in-depth numerical studies for Li-ion cells with blended cathode were conducted using Newman’s pseudo-2D model. A spontaneous material-potential balance in the blended electrode was quantified at different open-circuit states. Using the matrix exponential approach, Newman’s model can be efficiently solved in the high-frequency discretized time space. This numerical method enables fast simulation and accurate parameter estimation of a practical drive cycle.
(Invited) High-Throughput DFT Thermochemistry Applied to the Design of Cathode Coatings Forlithium-Ion Batteries
Authors: Wolverton Chris
Published: February 2020

We present a high-throughput (HT) density functional theory (DFT) based framework to identify new functional coatings that can suppress cathode degradation in Li-ion batteries. This HT framework is based on reaction models that describe the thermodynamic and electrochemical stabilities and acid-scavenging capabilities of oxide materials. Using the framework, we search for coatings with different functionalities including physical barriers, hydrofluoric acid (HF) barriers and HF scavengers, by screening more than 130,000 candidate oxide materials. Employing two alternative material selection methods, namely, weighted-sum and rank aggregation multi-objective optimization, we predict new promising physical and HF-barrier coating materials such as WO3, LiAl5O8, ZrP2O7, Hf2P2O9, TaPO5, CaSn4(PO4)6, and new or under-explored HF-scavengers such as Sc2O3, Li2CaGeO4, Li3NbO4, TaBO4, LiBO2, Mg3(BO3)2, Ca5(BO3)3F, Ca2Ta2O7 and Li2MgSiO4. Using principal component analysis, we show that the the likelihood of discovery of effective HF-scavenger coatings is highest in silicates and borates among all oxides. We further present a new HT design strategy where thermodynamically optimal HF-scavenger coatings for a given cathode material can be found by (i) incorporating the cathode material itself in the chemical space, (ii) evaluating the cathode-coating reactivity, and (iii) monitoring cathode reactivity in electrochemical (charge and discharge) and HF-attack reactions. Examples of such optimal coatings we found include Li2SrSiO4, Li2CaSiO4 and CaIn2O4 coatings for the layered LiCoO2 and Li2GeO3, Li2TiSiO5, Li4NiTeO6, Ca2Mn3O8, and Li2MnO3 for the spinel LiMn2O4 cathodes. These candidate coating materials have the potential to prolong the cycle-life of lithium-ion batteries and surpass the performance of common coating technologies based on conventional materials such as Al2O3, ZnO, MgO or ZrO2. This work was performed in collaboration with Muratahan Aykol, Soo Kim, Vinay I. Hegde, David Snydacker, Zhi Lu, Shiqiang Hao, Scott Kirklin, and Dane Morgan.
Experimental Validation of Surface Coverage Model for Li-Air Battery
Authors: Yuan Hao , Wang Yun
Published: February 2020

The Lithium-air battery has captured so much interest and been considered as a promising candidate for the future renewable energy sources because of its high specific energy density comparable to gasoline. But unfortunately, the maximum amount of the lithium metal utilized is limited because of the tunnel blockage and surface coverage inside cathode, which are caused by insoluble lithium composite generated at cathode. In other words, the total energy capacity is restricted by the cathode under adequate lithium. So if we can fully understand how the deposits work on the cathode, we are supposed to develop a better cathode, which can hold more products per unit volume, with immensely higher energy capacity per unit cathode volume. This paper describes a surface coverage model and two relative dominating effects, electrode passivation and transport resistance. By using the electron conservation combined with experimental formula from previous works, we could investigate how much the insoluble there is and the coverage coefficient used to evaluate what degree deposits damage the effectivity of cathode to. We could use the coverage coefficient to describe the effective surface area under different stage of precipitation. We may go further to obtain the oxygen profile by taking the oxygen transport equation into account. Then we have a chance to use the above model to formulate the loss of effective voltage and total energy capacity. We could eventually split the voltage loss into 2 pieces, one caused by electrode passivation and another caused by oxygen transport resistance. We can compare them to find out which one is the prime force to kill the battery, or that they cooperate together. We can also know how much deposits the cathode can be filled with before exhausted. Then the total energy capacity is ready to come out by integrating the voltage along the time under constant current. By looking into the integral, there are actually three parts, which are the capacity without considering voltage loss effect, and two capacity losses solely considering the voltage loss from the electrode passivation or oxygen transport resistance respectively. If we compare these different part, we could have a knowledge of whether the capacity loss is immense enough to be cared about, or which kind of loss costs more. To validate our model, we will also perform the experiments by using our sandwich cell to get the discharging curve, which will be used to validate our model by comparing the voltage loss and energy capacity loss. The sandwich cell structure from bottom to top is: bottom frame, aluminum foil, lithium metal, separator, rubble sealing ring, top frame with air window and electrolyte pool on top, and cathode. The whole cell is assembled by using screws. We could get open circuit voltage and discharging curves under different current. The data will be used to validate and improve our model mentioned above.
Development of Peptide Functionalized Smart Bandages for Real-Time Wound Diagnostics
Authors: McLister Anna , Cundell Jill , Finlay Dewar , Davis James
Published: February 2020

The treatment of chronic wounds, particularly those associated with diabetic complications, is a perennial problem for modern healthcare services, affecting an ever-increasing portion of society.This is particularly worrisome given that the diabetic population and associated costs are set to at least double in size in the next 25 years. In the US alone, approximately 6.5 million people suffer from slow healing wounds, with healthcare costs in the region of $25 billion annually. A critical factor that needs to be considered when dealing with chronic wounds is infection. This can have a huge impact on healing time and could inevitably lead to further discomfort of the patient and complications that could ultimately be life threatening. Most chronic wounds (>74%) are treated within the community and as such there can be a delay in the patient seeking medical attention resulting in a deterioration of the wound condition. It is estimated that 12% of individuals with a chronic foot ulcer, will require amputation due to infection.

A new approach to the design of disposable pH sensors that can be directly integrated within conventional wound dressings and which can communicate to an app on a smart phone (Figure 1) is described. The system is based on an aminoacid / peptide functionalized electrode interface through which the pH can be rapidly determine through either potentiometric or voltammetric means. It has been shown that wound pH can be a versatile marker of wound condition and can be used to track the stage of healing. Importantly, sustained changes in pH from a given regime could provide an early warning signal for the early onset of infection.  A range of bioactive groups have been assessed in terms of their ability to facilitate the long term/periodic monitoring of pH with a matrix which can express significant amounts of exudate that would otherwise irreversibly contaminate conventional electrode substrates.

This presentation details characterization of the fabrication processes, the electrode response and the clinical utility of the measurement. The integration of the sensing substrate within the dressing and its communication with the smart phone/tablet via an Arduino system is described and critically assessed. Ultimately, the aim would be for the development of a prototype that would be able to alert the patient to the onset of infection.

Figure 1
The Effect of Alloying of Transition Metals (M = Fe, Co and Ni) to Palladium Catalyst on Durability of Electrocatalytic Activity of Oxygen Reduction Reaction in Alkaline Media
Authors: Gunji Takao , Wakabayashi Ryo , Abruña Héctor D. , DiSalvo Francis , Matsumoto Futoshi
Published: February 2020

Polymer electrolyte membrane (PEMs) fuel cells have attracted a great deal of attention as next-generation electrical portable device due to the high energy efficiencies and carbon-free emission. However, the cost of electrocatalyts in PEMs is very high because platinum (Pt) is used as electrocatalyst for both the oxidation of hydrogen in the anode and oxygen reduction reaction (ORR) in the cathode. Palladium (Pd) is an attractive candidate as an alternative electrocatalyst towards the ORR in alkaline media because Pd is more abundant, much less expensive than Pt, and has a higher activity towards ORR than pure Pt in alkaline media [1]. Stable and long-term electrocatalytic performance towards the ORR was achieved by Pd-shell Pd3
M-core (M = Fe, Co, Ni and Cu) structures on carbon supports. Herein, we report on the synthesis of Pd-based bimetallic compounds using 3d transition metals, such as Fe, Co, and Ni, as secondary materials and demonstrate enhanced electrocatalytic activity towards the ORR in alkaline media as well as improved durability. The catalytic activity of these nanoparticles has been compared to that of pure Pd nanoparticles. We have also dealloyed the catalysts using electrochemical treatment by potential cycles in alkaline media and examined their activities towards the ORR.

   The various bimetallic Pd-M (M = Fe, Co and Ni) nanoparticles (NPs) were prepared by an impregnation method followed by an annealing treatment. In order to enhance the electrocatalytic activity towards the ORR, bimetallic Pd-M nanoparticles were electrochemically deallyoed. Dealloyed Pd-M NPs exhibit a core-shell structure, Pd3
M-Core and Pd-shell, and showed enhanced catalytic activity towards the ORR as well as better durability than pure Pd.

 [1] Sun, W.; Hsu, A.; Chen, R.; J. Power Sources, 2011, 196, 4491.
Effect of Guest Binding on a Redox Active Three Hydrogen Bond Array
Authors: He Ran , Smith Diane K.
Published: February 2020

Proton-coupled electron transfer (PCET) reactions are essential to many of the fundamental chemical processes of life. In the Smith group we are investigating the role of H-bonding intermediates in PCET by studying the voltammetry of compounds capable of multiple, strong H-bond interactions.  In particular we have studied a p-phenylenediamine-based urea, U(H)H, which contains two H donor sites making a DD array. In this study, the phenyl group in U(H)H is replaced by an imidazole group to form a three hydrogen bond array, UImH. In this array, the two major conformers both present a DDA H-bond motif (1 and 2 in Fig 1). Therefore, AAD arrays, such as APy, are needed as guest compounds to form three intermolecular non-covalent contacts.

The cyclic voltammetry of UImH has been examined in methylene chloride and acetonitrile with platinum (Pt) and glassy carbon (GC) electrodes. On both electrodes, CV’s show two, closely-spaced, reversible waves of similar height. We initially hypothesized that the first electron oxidation happens on the phenylenediamine unit, followed by rapid intramolecular proton transfer in conformer 2, Fig. 1. The second electron is removed at a slightly more positive potential due to the positive charge remaining on the array after the first oxidation. However, the voltammetry is observed to have a strong concentration dependence and this cannot be explained by this mechanism.  Based on the CVs we now propose the first wave is due to loss of 2e- from UImH with an intramolecular PT to form UImH2+. Then UImH2+ undergoes an intermolecular PT with unreacted UImH to produce UIm+ and HUImH+.  The second wave is due to 2e- oxidation HUImH+ to form HUImH3+ at a more positive potential. Lastly, an intermolecular PT between HUImH3+and UIm+ gives the final product UImH2+.

Addition of the guest, APy, results in is a slight increase in the current of the CV waves of UImH. This could be due to preferential binding and stabilization of UImH which prevents decomposition and adsorption. Surprisingly, very little change in the potential of the CV wave is observed upon addition of the guest, indicating that oxidation does not change binding strength. Even though the H-donors in UImH2+ should be stronger than in UImH, the H-acceptor in UImH2+ is weaker than in UImH. So the two effects cancel each other.

Figure 1
Nano Sized Defect Free Al2O
3
Thin Film for High Performance Gas Barrier
Authors: Jang YunSung , Hong MunPyo
Published: February 2020

Recently, our interests in flexible display for next generation have been increased. Plastic substrate is used for flexible display. However it has less chemical resistance, heat resistance, gas transmittance resistance characteristics than glass substrate. By these reasons, plastic substrate requires functional coatings. Because the OLED is degraded by moisture and oxygen, it requires intensely ultralow Water Vapor Transition Rate (WVTR) as 1ⅹ10-6gm-2day-1. To achieve the ultralow WVTR, defects must be prevented.

Defects generated by particles can be prevented carefully controlling the process, but defects generated in grain boundary have to be annealed to get rid of them. Organic materials have weakness for heat so annealing process has to be avoid. In this study, we developed Al2O3 nano-structure single gas barrier layer using Neutral Beam Assisted Sputtering (NBAS) process. The NBAS process can be continuously changing crystalline structure from amorphous phase to nano-crystal phase of various grain sizes within single inorganic thin film. These NBAS process effect can lead to formation of nano-structure barrier layer which effectively passivate and healing gas diffusion pathways between grain boundaries. As a result, we confirmed nano-structure of NBAS processed Al2O3 single gas barrier layer through the dielectric constant measurement, Ellipsometry, AFM, and TEM analysis. Finally, WVTR property of Al2O3 nano-structure single gas barrier layer is measured under 1ⅹ10-6gm-2day-1. The Al2O3 nano- structure single gas barrier layer is very suitable in the OLED application.
Probing the Role of Organic Additives on the Film Formation Mechanism Relevant to Metal CMP
Authors: Mlynarski Amy , Janes Lisa M. , Keleher Jason J
Published: February 2020

With the increasing demand of high performance technology, the necessity to improve the mechanics of electronic devices is becoming of great importance. This requires atomic level planarization to avoid defects on the surface of integrated circuits (IC) and hard disk drive (HDD) media through CMP by removing the metal complex film formed. Traditional CMP systems incorporate a synergistic interaction between slurry chemistry and various mechanical parameters to achieve high surface quality while ensuring surface planarity. In order to understand this relationship, it is necessary to probe the film forming capabilities of oxidizers, complexing agents, and corrosion inhibitors on the substrate surface. The changes and dissolution of the film formed on the surface will be analyzed through the comparison of activation energy and Open Circuit Potential (OCP).  More specifically, the separate molecular interaction of Benzotriazole (BTA) and Salicylhydroxamic Acid (SHA), and the substrate will be studied through the quantization of activation energy.  The difference in the surface quality of the substrate, dependent on the film formation mechanism, will be understood through Atomic Force Microscopy (AFM). This work aims to show how the use of electrochemical techniques and surface spectroscopy can be useful in understanding the underlying mechanism of film formation on Cu and NiP substrates. Previous studies have shown promise that the use of various additives plays an intricate role on the films formed, relying heavily on the metal substrate used.
Deposition and Electrical Characterization of CaCu3Ti4O12 Thin Films
Authors: Skaria Giji , Sundaram Kalpathy B
Published: February 2020

There is an increased interest in very high dielectric constant (high-k) material studies due to their potential applications in energy storage elements. In this aspect, the perovskite materials seem to achieve very high-k values [1]. In this study, the focus has been to deposit thin films of CaCu3Ti4O12. These films are deposited by RF magnetron sputtering process using CaCu3Ti4O12target. The films are deposited under varies deposition conditions that include argon gas flow ratios, process pressures and RF power. Metal–insulator–metal (MIM) structures have been fabricated using aluminum film as the electrodes. The electrical properties of the films have been characterized and reported as a function of deposition parameters for the above MIM structures.

REFERENCE:

[1] M.A. Subramanian, Dong Li, N. Duan, B.A. Reisner, A.W. Sleight, High Dielectric Constant in ACu3 Ti4 O12 and ACu3 Ti3 FeO12 Phases
(Invited) Silicon Nanocrystals: Size Control, Basic Understanding and High Quantum Yields
Authors: Gutsch Sebastian , Laube Jan , Zelenina Anastasia , Hiller Daniel , Zacharias Margit
Published: February 2020

Controlled fabrication of Si nanocrystals via the SiOx/SiO2 superlattice approach enables size control as well as density control [1]. The resulting layer arranged Si nanocrystals represent a model system to systematically study photonic and electronic properties of indirect gap quantum dots. Hence a deeper understanding can be developed for absorption, recombination, carrier kinetics and transport. As example, the temperature dependence of confined excitons in Si quantum dots and their respective temperature depending band gap will be analyzed for different sizes and will be compared with theory prediction. [2] The interplay of radiative and non-radiative recombination will be studied using recombination kinetics based on detailed time resolved measurements. [3] In addition, the origin of the luminescence in Si2N3embedded Si NCs are discussed. [4] Transport properties will be evaluated as a function of NCs size and distance. [5] Finally, systematic doping experiments with P will be analyzed for doping efficiency, in-cooperation into the Si NCs and self-purification, and electronic transport. [6, 7]

[1] M. Zacharias et al. Appl. Phys. Lett. 80 (2002) 661.

[2] A. M. Hartel et al. Phys. Rev. B 85, 165306 (2012).

[3] A.M. Hartel et al. Rev. B 87 (2013) 035428.

[4] A. Zelinina et al. J. Appl. Phys. 114 (2013) 184311.

[5] S. Gutsch et al. J. Appl. Phys. 113 (2013) 133703.

[6] H. Gnaser et al. J. Appl. Phys.113 (2013) 034304

[7] S. Gutsch et al. Appl. Phys. Lett. 106 (2015) 113103.
Synthesis of Nano-Phosphor By Water Assisted Room Temperature Solid State Reaction (WASSR) Method
Authors: Toda Kenji , Hasegawa Takuya , Kaneko Tatsuro , Toda Ayano , Kim Sun Woog , Uematsu Kazuyoshi , Ishigaki Tadashi , Koide Junko , Toda Masako , Kudo Yoshiaki
Published: February 2020

A solid-state reaction method has been usually used as a basis synthesis processing technique to obtain the ceramic materials, including phosphor materials, because of its very simple and easy. However, ceramic materials are generally synthesized at high temperature when the solid state reaction method used as synthesis method. Because ionic-diffusion in ionic crystal is very slow at room temperature, high temperature is essential for solid state reaction. The high temperature synthesis leads to increase in the processing cost and irregular particle morphology of the obtained powder. In contrast, we have proposed the two novel solid phase synthesis technique to synthesize the ceramic materials at low temperature below 100 °C without after any chemical or physical treatment. We refer to these synthesis techniques as water assisted room temperature solid state reaction (WASSR) method and solid hydratethermal reaction (SHR) method.1-3 We successfully synthesized the functional ceramic materials including phosphors. Furthermore, we demonstrated that the reaction mechanism of novel low temperature synthesis methods is different from the conventional solid state reaction and solution reaction. In this study, we present the practicability of our original novel solid state reaction methods on an industrial application in the ceramic oxide materials synthesis processing.

References

K. Toda, M. Sato, K. Uematsu, and T. Ishigaki, Japanese Unexamined Patent Application Publication No. 2011-16670 (2009).

S.W. Kim, T. Kaneko, K. Toda, K. Uematsu, M. Sato, J. Koide, M. Toda, and Y. Kudo, IDW'2014, PH1-3 (2014).

T. Kaneko, S.W. Kim, A. Toda, K. Uematsu, T. Ishigaki, K. Toda, M. Sato, J. Koide, M. Toda, Y. Kudo, T. Masaki, and D.H. Yoon, Sci. Adv. Mater., (2015) in press. doi:10.1166/sam.2015.2364.
Epitaxial Thin-Film Approach to Fundamental Studies and Modeling of Cathodes and Solid Electrolytes of Li-Ion and Other Batteries
Authors: Bendersky Leonid A.
Published: February 2020

Thin film electrodes and electrolytes, especially grown epitaxially and approximating a single crystal, can be utilized as model systems to correlate electrochemical processes with structural changes on an atomic scale. In addition, studying the thin film components can be of importance for understanding and improving technology of the all-solid-state batteries. In our research program the focus is on making epitaxial intercalation cathodes by pulse laser deposition (PLD) on single-crystal SrTiO3 (STO) substrates of different orientations. Placing an epitaxial conductive SrRuO3 (SRO) layer on STO, that is acting as a current collector, allows performing electrochemical testing with either liquid or solid electrolytes. By inducing different charge/discharge states, the pseudo-single-crystal cathodes can be studied by high-resolution transmission electron microscopy (HRTEM) in great details. In this presentation we will discuss successes and difficulties related to the thin-film synthesis, in particular of such cathode materials as LiCoO2, Li2MnO3, commercial Li-rich HE5050 (Li1.2Mn0.55Ni0.15Co0.1O2) and Na(Fe,Mn)O2. We will also present HRTEM results on the structural changes occurring at different stages (voltage and number of cycles) of electrochemical testing; some of the results, e.g. formation of Co3O4 spinel on the {104} facets, could be obtained only with the thin-film approach.