bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Phase Change Material to Increase Solar Panel Efficiency
Authors: Rose Kyle Duane , Aggarwal Mohan 
Published: February 2020

Research has shown that heat is the number one deterrent to power production and efficiency of solar panels. To remedy this problem we used special techniques to apply a phase change material (PCM), non-intrusively to the back of our test panels. This process provided the ability to extract heat utilizing conduction mechanism with a diathermic material.
The method used for this research was quantitative data collection. This methodology involves use of existing historical documents such as climate, temperature, and insolation data along with currently measured data for analysis.
The results showed with the PCM applied to our test panels remained cooler than the controlled panels until the PCM absorbed its capacity of heat energy. The test panel’s temperature was cooler than the control panel. Power production, and efficiency showed a noticeable increase. Future research will utilize passive thermoelectric devices to convert the waste heat to useful energy. Furthermore working fluids such as glycol, and antifreeze of various concentrations to remove heat energy from the saturated PCM once the heat capacity has been reached. The application of PCM applied to the backside of a standard solar panel lowers the temperature and improves the panel’s energy conversion and efficiency. Author acknowledges some work which was accomplished with the partial support of NSF APEX project DRL 1238192.
17.6%-Efficient Radial Junction Solar Cells Using Silicon Nano/Micro Hybrid Structure
Authors: Hwang Inchan , Lee Kangmin , Seo Kwanyong 
Published: February 2020

We develop a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with areas of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA·cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells.
High Resolution TEM Study on Phase Transformations in Redox Active Silver Nanoparticles
Authors: Singh Poonam , Carpenter Ray , Buttry Daniel A 
Published: February 2020

In the last two decades, nanoparticles (NPs) have been intensively studied because of the wide range of applications in catalysis, sensor, energy storage, electronics etc. The recent interest in fabricating core-shell nanoparticles is very fascinating and the substantial development of these nanoparticles for a variety of applications has only been enabled because of various characterization efforts. In spite of this, it is still very challenging to understand the growth mechanism that governs the formation of core-shell nanoparticles. A previous contribution from our group focused on electrochemical studies confirming the phase transformation of chemically synthesized capped silver nanoparticles to Ag2O or AgCl NPs. However, it is also important to understand the nucleation and growth mechanism of these nanoparticles, especially forming core shell or the complete recrystallization of NPs. In the current work, we are focused on microscopic studies in correlation with electrochemical results to understand the nucleation mechanism of silver nanoparticles.
Silver nanoparticles (Ag NPs) capped with adenosine triphosphate (ATP), synthesized via wet chemical method and assembled in single layer-by-layer (LbL) film have been characterized using voltammetry and high resolution transmission electron microscopy (HRTEM). The ex-situ voltammetry and HRTEM analysis confirms the phase transformation of AgNPs to Ag2O or AgCl NPs. Atomic resolution image by high-angle annual dark field scanning transmission electron microscopy (HAADF STEM) confirms the partial or complete oxidation of NPs which is consistent with the electrochemical results. The growth mechanism/pathways focused on core-shell nucleation and point nucleation for phase transformation of Ag NPs embedded in LbL film has been discussed.

Acknowledgement

We acknowledge the support from National Science Foundation (NSF) for this work.

References

1. P. Singh, K.L.Parent and D.A.Buttry, J. Am. Chem. Soc., 134

(12), 5610–5617 (2012).
2. M. Tang, W.C.Carter, J.F.Belak and Y.Chiang, Electrochim. Acta,
56, 969–976 (2010).
3. A.H.Latham, M.J.Wilson, P.Schiffer and M.E.Williams, J. Am. Chem. Soc.,
128, 12632-12633
(2006).
4. J. Ghilane, F. Fan, A.J.Bard and N. Dunwoody, Nano Lett., 7(5), 1406-1412 (2007).
5. E.V. Shevchenko, M.I.Bodnarchuk, M.V. Kovalenko, D.V.Talapin, R.K.Smith, S.Aloni,
W.Heiss and A.P.Alivisatos, Adv. Mater.
20, 4323–4329 (2008).
Synthesis of Ferromagnetic Cobalt Nanofibers By Electrospinning
Authors: Kessler Joseph Edward , Rugge Christopher Paul , Rosales Espitia Nataly , Myung Nosang Vincent 
Published: February 2020

The increase in coercivity of materials composed of fine powders (10 nm to 100 nm) of important ferromagnetic materials, such as cobalt or iron, is well understood where the flux-closure configuration is energetically unfavorable[3].[4]. Thus, it is not too surprising that 1-D nanofiber structures of cobalt synthesized by electrospinning display enhanced coercivity over current bulk methods[1]. The exclusively high surface area-to-volume ratio of nanostructures and the rotation being opposed by the shape anisotropy of the demagnetization energy play a key role in achieving high coercivity[3]. Likewise, the synthesis method using electrospinning offers many advantages: ease of control over nanofiber dimensions, repeatability, scalability, and ease of assembly[2]. Electrospinning was used to fabricate nanofibrous cobalt structures by electrospinning a cobalt acetate (CoAc2)/poly (vinyl pyrrolidone) (PVP) composite solution followed by reduction in hydrogen environment. Two separate 2-level, full-factorial, design of experiments (DOEs) were conducted to control and optimize the process to minimize fiber diameter and eliminate beading defects. A 3-factor DOE was run on solution properties (viscosity, surface tension, electrical conductivity) and a 2-factor DOE was run on electrospinning parameters (voltage, flow rate). Solution viscosity was found to be the main factor in controlling fiber diameter. The high and low values in viscosity were achieved by changing both the molecular weight of PVP and the weight percentage of PVP in the solution. In the second DOE, the applied potential had a larger effect on fiber diameter than the flow rate. However, both were found to be significant factors and a balance between these two parameters is needed to prevent clogging of the needle as a function of evaporation rate. The as-spun nanofiber mats were subsequently annealed in pure H2 gas to produce pure cobalt nanofibers. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and X-ray powder diffraction (XRD) were all used to characterize fiber diameter, morphology, and crystal structure. The smallest, average, as-spun fiber diameter achieved was 126 nm with minimal beading. We will be investigating the magnetic properties of these cobalt nanofibers as a function of fiber size using a vibrating sample magnetometer.
References:
[1] - H. Wu et al., Chem. Mater. 19, 3506 (2007)
[2] - Ramakrishna S., Kazutoshi, F., Teo, W., Lim, T., Ma, Z., 2005, An Introduction to Electrospinning and Nanofibers, World Scientific Publishing Co., Singapore.
[3] Charles Kittel, Introduction to solid state physics, third edition, p. 495- 496
[4] L.Neel, Compt. Rend. 224, 1488(1947), C.Kittel, phys. Rev. 70, 965 (1946).
Hybrid Film Deposition for High-Aspect-Ratio Structures with Functional Surfaces
Authors: Kim Jeong Hwan , Lee Seong Woong , Yoon Jae-Sung , Yoo Yeong-Eun 
Published: February 2020

Thin film deposition is one of the most significant issues in the fabrication of nano structures. Especially it is difficult to achieve conformal films on high-aspect ratio nanostructures, such as nanoholes and nanochannels. Though there are various thin film deposition processes, atomic layer deposition (ALD) has attracted due to its extreme surface conformality and excellent thickness controllability. Because ALD is a chemical gas phase thin film deposition method based on sequential and self-saturating surface reactions, it can be used for coating of nano structures with high-aspect ratio.
Sputtering process is one of the popular film deposition techniques due to its relative simplicity of process and fast deposition speed. However, film depositions by sputtering technique are less conformal compared to those by ALD, because of ions directionality sputtered by plasma. Therefore it is difficult to form films on the surfaces perpendicular to substrate by sputtering process.
However, if ALD and sputtering processes are combined, hybrid thin films deposition which different films are deposited on selectively different surfaces (eg. surfaces perpendicular and parallel to substrate).
In this poster, I will present the results of hybrid films deposition on nano holes/channels structures with high-aspect ratio. For different functionalities (hydrophilicity and hydrophobicity) of surfaces, Al2O3 and Pt films were grown on nanochannel structures. Al2O3 films deposition on the vertical surfaces (inner surfaces of nanochannels) was controlled precisely in nanometer scale by using ALD process. Pt films were formed on horizontal surfaces (outer surfaces of nanochannels) by using DC magnetron sputtering.
Carbon Materials Converted from PIM-1
Authors: Kim Byoung Gak , Jeon Jun Woo , Yoo Young Jae , Kim Yong Seok 
Published: February 2020

As an effort to prepare carbon nanosheet and carbon film through catalyst- and transfer free process, several research groups have reported carbonization of polymers and small molecules such as polyacrylonitrile (PAN) and a small molecular pitch extracted from petroleum. Carbon nanosheets converted from PAN or pitch were obtained through two steps: cyclization and carbonization. Because the quality of the carbon materials sensitively depends on the cyclization conditions such as temperature, ramping rate, and oxygen contents, there is a great need for a cyclization-free process.
Recently, we developed a cyclization-free carbonization process (one-step process) using PIM-1 (polymer of intrinsic microporosity). Various nano-structured PIM-1s were formed by using different methods such as electrospray, ultrasonic spray pyrolysis(USP), electrospining and spin coating methods, which were carbonized at 800~1200 oC without any catalyst. All carbonized PIM-1 maintained their original shape and their Raman spectra showed G graphitic carbon peak at 1590 cm-1 and D disordered carbon peak at 1330 cm-1. Especially, it is confirmed that carbonized PIM-1 prepared by spin coating had properties similar to graphene and could be used as the electrodes of ITO-free OSCs. Carbon nanosheets converted from PIM-1 showed a high efficiency of 1.922 % and electrical conductivity of 500 S/cm.
In this presentation, shape and dimension control of carbon materials and direct use as electrodes of organic solar cells and supercapacitors will be discussed more in detail.
H2TiO3 Composite Nanofibers for Lithium Recovery from Spent Lithium-Ion Secondary Batteries
Authors: Chung Wook-Jin , Nisola Grace Masbate , Lawagon Chosel Pepito , Gebreegziabher Hana , Albarico Jed , Lee Seong Poong 
Published: February 2020

Lithium recovery attempts from spent lithium-ion batteries (LIBs) often employed complex methods utilizing toxic chemicals. In this study, a relatively facile and environmentally benign lithium recovery process was developed using H2TiO3 (HTO) as a highly selective lithium-ion adsorbent. This lithium ion sieve (LIS) has a chemically stable structure and remarkably higher theoretical Li+ capacity (126.47 mg/g) than manganese-based LIS. The low titanium dissolution of HTO upon acid pickling makes it an ideal LIS for lithium recovery. However, in its powder form, HTO application in actual systems is limited due to difficulty in its handling. The HTO particles must be incorporated in a suitable support for its feasible utilization. Herein, electrospun nanofibers with unique dimensional properties were utilized to serve as three-dimensional frameworks for HTO.
Different types of polymeric (PAN, PSf, PVC, and PVDF) nanofibers with varied HTO loading were prepared by electrospinning method. The composite nanofibers were characterized by SEM, UTM mechanical test and applied for lithium adsorption. It was determined that PAN composite nanofibers with 100 wt.% HTO loading showed the highest adsorption capacity (31.4 mg g-1) and superior mechanical property. It retained up to 93.6% of the adsorption capacity of the pure H2TiO3 powder (33.6 mg g-1). The PAN-HTO nanofiber was then employed to recover Li+ from spent LIBs. The spent batteries were dismantled and sonicated in deionized water to elute Li+ from the waste. The resulting solution was then filtered through the PAN-HTO nanofiber membrane to capture the Li+. The captured Li+ were easily retrieved by mild acid treatment of the spent PAN-HTO nanofiber, which was also regenerated for reuse. Overall, the results of the study showed the feasibility of using PAN-HTO nanofiber for continuous and efficient recovery of lithium ions from spent LIBs. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2009-0093816) and Ministry of Science, ICT and future Planning (2015R1A2A1A15055407).
Characteristics of SrxY1-XTiyNi1-YO3-d anode in Humidified Methane Fuel for Intermediate-Temperature Solid Oxide Fuel Cells
Authors: Yun Jeong Woo , Park Eun Kyung 
Published: February 2020

Solid oxide fuel cells (SOFCs) are a promising alternative energy conversion device because of high energy efficiency and fuel flexibility. Nickel/yttria-stabilized zirconia (Ni/YSZ) cermet has been widely used as an anode material in SOFCs. The Ni/YSZ anode, however, may not be appropriated for direct use of commercial hydrocarbon fuels because of carbon deposition and sulfur poisoning on the Ni phase.
In this study, yttrium and nickel co-doped strontium titanium oxide SrxY1-xTiyNi1-yO3-δ (SYTN) was investigated as an alternative anode material for SOFCs. To improve the ionic conductivity of the Sr0.92Y0.08TiO3-δ (SYT) anode, Ti4+ at the B-site was substituted to Ni2+, leading to introduction of oxygen vacancies in the SYT. The stability of the SYTN anode at high temperatures and reducing atmospheric conditions was as good as the SYT anode. The SYTN exhibits excellent phase stability during the cell fabrication processes, SOFC operation, and good electrical conductivity at 700~900 oC in methane. The SYTN anode was compatible with YSZ at the SOFC operating condition. The electrochemical reactions of the SYT anode in both hydrogen and methane were limited by relatively slow reactions, such as non-charged processes including oxygen surface exchange and solid surface diffusion. To improve such poor electrochemical activities, the surface of the SYTN anode was modified by the SDC coating. The polarization resistance and the cell performance in hydrogen and methane were significantly improved by the SDC modification. The SDC-coated SYT anode cell was successfully operated with methane for more than 300 hours without any degradation of the cell performance.
The Effect of the Amount of Intercalated Li-Ions on the Electrochemical Performances and the Color Changes in the Electrochromic Layer
Authors: Han Taeyeong , Lee Hoogil , Kim Seokwoo , Ryou Myung-Hyun , Lee Yong Min 
Published: February 2020

Global warming and the energy crisis have been accelerated the necessity to develop the energy saving system and to increase energy efficiency are for many researchers. For instance, smart window consisting of glass, electrochromic layer, and electrolyte is one of the promising candidates to fulfill this goal. The color change of this smart window should be delicately controlled responding to the capriciousexternal environment condition. Although many researchers have been mainly focused on the physical properties of active materials such as crystalline and morphological structures to modulate optical density of the smart window[1,2], the color difference of smart window according to amount of intercalated Li-ions in electrochromic layer has never been considered thus far.
Hence, we investigated the effects of the color changes of electrochromic layer corresponding to the different amount of intercalated Li-ions. We employed three-electrode type unit cells consisting of working electrode (WO3/ITO), reference electrode (Ag/AgCl with 3M KCl), counter electrode (Pt) and electrolyte (1M LiClO4 in PC) throughout this study. We monitored the correlation between the voltage changes and the transmittance of electrochromic devices as applying a constant current as a function of the amount of the intercalated Li-ion. Furthermore, the crystalline structure of active materials was also investigated using an X-ray diffraction (XRD) technique.

Acknowledgements

This work was supported by the *Energy Technology Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20142010102980)

References

[1] Christopher S. Blackman and Ivan P. Parkin, Chem. Mater. 2005, 17, 1583-1590
[2] By Se-Hee Lee, Rohit Deshpande, Phil A. Parilla, Kim M. Jones, Bobby To, A. Harv Mahan,
and Anne C. Dillon, Adv. Mater. 2006, 18, 763–766
Crystalline Cd3As2
Authors: Kouklin Nikolai , Hosseini Tahereh , Yavarishad Niloufar 
Published: February 2020

Thermo-electric generators (TEGs) directly convert thermal into electrical energy and are the prime candidates for application in low-grade thermal energy/heat waste recovery. TEGs possess several critical advantages as they remain silent, highly reliable and lightweight, which make them uniquely suited for niche deployments in transportation, space satellites, electronics cooling and thermo-voltaic cells. With the efficiency in a few percent range, the efficiency-to-cost ratio remains poor, with the bottleneck traced back to the thermo-electric (TE) materials. PbTe and Bi2Te3, two key TE materials that are in commercial operation, have room temperature ZT of less than 1, whereas ZT exceeding 3 is required for a TEG to be economically viable.
Until recently, the enhancement of ZT was mainly attained by introducing phonon scattering interfaces and rattling centers to slow heat transport. With thermal conductivity already approaching the fundamental limit of amorphous materials, further gain in ZT can be only realized by improving the thermo-electric power factor, S2, typically via costly band structure engineering or by means of quantum confinement.

In this work, we instead focus on Cd3As2, a high performance 3D Dirac semimetal. Compared to other semimetals, Cd3As2 possess Dirac fermions that disperse linearly in k3-space and in turn, one of the largest electron mobilities known for crystalline materials, i.e. ~104-105cm2V-1s-1. The carrier back-scattering remains suppressed and the electrical transport is dominated by high-energy carriers that favorably affect the thermopower of Cd3As2. Since the power factor scales with the carrier mobility, μ, and weighted density-of-states effective mass, i.e. S2 ~ μ, and the lattice thermal conductivity is within amorphous limit for this material, Cd3As2 shows a strong potential for demonstrating high, device-favorable S and in turn ZT.
A reduced temperature vapor-based crystallization pathway was developed to produce free standing, stochiometric 2D cm-size crystals in Cd3As2. In contrast to previous findings, the Seebeck coefficient is seen to initially rise linearly with T to reach a peak within ~ 300-400 K range which is followed by a decline with the shift in the trend attributed to the increase in the role of the ambipolar heat transfer as temperature increases.The primary mechanism of the minority carrier generation in our samples is attributed to phonon-assisted interband electronic transitions involving E and A1 bands. Possessing a very high room-temperature thermopowers of ~613 uV/K and amorphous limit thermal conductivity, bulk Cd3As2 is identified as another high promise phonon-glass electron-crystal TE material for development of next generation a high efficiency thermo-electric generators and refrigerators operating under normal conditions.

Figure 1
Battery Reliability, Safety, and Failure Modes and Effects Analysis
Authors: Liaw Bor Yann 
Published: February 2020

On the subject of battery safety, current ability in the industry to deal with safety hazards in any incidents is based on empirical experiences patched up with specific solutions. Such a solution is not systematic (i.e. case-by-case), thus often costly and conflicting with the desire for better battery performance due to the restrictive nature of the solution (i.e. trade-offs between safety constraints and performance limits). Even worse, these solutions do not provide a systematic approach and accumulative engineering expertise to allow a more sustainable pathway to solve any future encountered issues efficiently and effectively. There is little emphasis on the inter-relationships among battery variability, durability, reliability, and safety. A more resilient approach such as failure modes and effects analysis (FMEA) to address these issues is not often discussed in such a broad basis of interrelationships. Most of the literature does not consider these issues in a coherent and consistent framework to find a common solution. Such a lack of recognition of these interrelationships may be the largest technical barrier to prevent the advent of battery technology to provide a reliable battery system for electrification of transportation and modernization of infrastructure in a modern electrical grid. Finding better materials and battery cell designs is not sufficient to make the battery products viable in the market place. We might not have realized that FMEA is the prevailing approach to make battery durable, reliable, and safe, just like it has helped the aviation and other industry to succeed in providing the services to our daily life.
In this presentation, emphasis on this thought process will be discussed and explained and the usefulness of failure modes and effects analyses and a feasible approach will be proposed with a few preliminary illustrations demonstrated. The author would like to bring the research community to pay attention to this need and using this symposium as a platform to pave the way for future consensus on how to address battery safety issues with increasing ability from the research capability to enhance battery durability, reliability and ability to address abuse tolerance in battery systems.