bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nano-Rod Gradient Li[Ni0.81Co0.06Mn0.13]O2: Preserving Cathode Structure for Long-Term Cycling (1000 Cycles) Li-Ion Batteries
Authors: Sun HoHyun , Yoon Chong seung , Heller Adam , Mullins Charles Buddie 
Published: February 2020

To address the growing demand for both energy density and cycling stability, a layered nanorod gradient (NRG) Li[Ni0.81Co0.06Mn.0.13]O2 cathode was synthesized with a high Ni-content bulk and a radially columnar nano-rod comprised surface and benchmarked against the widely used constant concentration (CC) Li[Ni0.82Co0.14Al0.04]O2. The NRG cathode delivered a discharge capacity of 225 mAh g-1, equivalent to ~ 830 Wh kg-1 at the cathode level, with 91%
capacity retention in half-cells after 100 cycles (210 mAh g-1 and 79 % for CC cathode) and 88% capacity retention in full-cells after 1000 cycles (56 % for CC cathode). Through a combination of in-situ and time-resolved X-ray diffraction (XRD), cross-section scanning electron microscopy imaging (SEM), and high-resolution transmission electron microscopy (HR-TEM), we confirm that the exceptional electrochemical performance of the NRG material, both in energy density and cycling performance, is attributed to its radially columnar concentration graded nano-rods at the surface. These nano-rods function as a buffer to diminish abrupt stress from the high Ni-content bulk during the H2 → H3 phase transition by suppressing crack propagation to preserve particle coherency, enabling reversibility of the cathode particle. This is important because electrolyte infiltration into the reactive Ni-rich bulk and subsequent formation of the electrically insulating rocksalt nano-structure (NiO) along the cracks are prevented, thereby minimizing impedance increase during long-term cycling. Furthermore, the nano-rods also enhance the thermal stability by delaying the layered to rocksalt phase transition on the surface through an increased concentration of Mn on the exterior.
A New Formulation of the Pseudo2D Battery Model Coupling Macroscopic and Microscopic Deformations
Authors: Mai Weijie , Smith Kandler , Colclasure Andrew M. 
Published: February 2020

High-capacity electrode materials such as silicon are promising in improving the capacity and energy densities of lithium ion battery (LIB). However, the broad application of such material is hindered by their large volume change during lithiation/delithiation, which not only causes active particle pulverization, but also leads to macroscale deformation that changes the dimension and porosity distribution of the cell. The objective of this work is to consistently reformulate the Pseudo2D battery model to incorporate the effect of large deformation during battery cycling, at both the particle and electrode levels.
In this work, the finite strain theory is used to approximate deformations in electrode by coupling it with the distribution of intercalation fraction within the cell. The porosity variation is approximated assuming conservation of the volume of the solid phase, which is then combined with the electrode deformation to consistently yield the magnitude of particle deformation at each position. The specific particle surface area is also consistently updated, which is ignored in most existing models. All transport equations are also reformulated in the reference frame but with the effect of large deformation incorporated.
Preliminary simulation results for a LIB with Si anode and NMC532 cathode show that porosities in both electrodes are notably reduced and become nonuniform when charged at a relatively high C rate. The increase of transport resistances and the gradual build-up of compressive stress due to active material volume change contribute to additional overpotentials that adversely affect the electrochemical performances of the cell, such as its accessible capacity/energy. In the future, this model will be used for cell design optimization in terms of electrode loadings, compromise between cell stress and strain, optimal range of Si SOC and possibly the optimal composition of a composite electrode, etc.
(Invited) Fully-Coupled 3D Electrochemical-Thermal Modeling of Cylindrical Lithium-Ion Batteries
Authors: Gomadam Parthasarathy M. 
Published: February 2020

A rigorous three-dimensional electrochemical-thermal model is developed without having to make dimension-reduction approximations to the electrochemical model. The fully-coupled model is developed for the spiral battery in the unwound form taking advantage of the coordinate-transformation technique published in Ref. 1. Key thermal model parameters such as heat capacity, entropy coefficient and hysteresis heating are obtained by direct measurements or by fitting simplified versions of the model to a host of experimental data. The thermodynamics software package – Advanced Electrolyte Model (AEM) – is used to obtain electrolyte transport parameters as functions of concentration and temperature. Exothermic chemical reactions that are triggered under high temperatures are included following Ref. 2-3. The chief safety feature of separator shutdown is modeled and its effects studied under a range of conditions. Model predictions for normal operations as well as under abuse such as internal and external shorts are presented. Comparisons between predictions and data are shown for some external short conditions, demonstrating the accuracy of the model.
References

M. Gomadam, R.E. White, and J.W. Weidner, J. Electrochem. Soc., 150, A1339 (2003).

G-H.Kim, A.Pesaran, and R.Spotnitz, Power Sources, 170, 476 (2007).

F.Lopez, J.A.Jeevarajan, and P.P.Mukherjee, J. Electrochem. Soc.,
162, A2163 (2015).

Fig. 1. Predicted temperature profile along before separator shutdown during an external short condition.

Figure 1
Improved Output Power Behavior of Ultraviolet GaN-Based Light-Emitting Diode By Using Agpdcu Reflector
Authors: Sim Kee-Baek , Yoon Su-Jung , Seong Tae-Yeon 
Published: February 2020

GaN-based ultraviolet UVLEDs have attracted a great deal of interest because of their applications in water and air purification and solid-state lighting. These applications have stimulated the technological development of high-efficiency UVLEDs. On the one hand, UVLEDs exhibit relatively lower external quantum efficiencies (EQEs) than visible LEDs. In particular, high-power UVLEDs should have high light extraction and heat dissipation efficiencies. For the flip-chip (FC) LEDs, the fabrication of high-performance p-type reflector with low contact resistance and high reflectivity is reqyired. Silver (Ag) is a commonly adopted p-type reflector for near UV LEDs but suffers from thermal instability, namely, agglomerated when annealed in air above 300 °C. In addition, electromigration (EM) is one of the major failure mechanisms of electronic interconnect under high current density (> ~105 A/cm2) stressing in microelectronics devices.
In this talk, we investigated the opto-electrical properties, and electromigration reliability of a Ag-Pd-Cu alloy (APC) reflector for near UV (385 nm)-LEDs as a function of temperature and compared with those of Ag only reflector. SEM results revealed that the Ag samples were less stable than the APC samples upon annealing. The contact resistivities of the Ag and APC contacts annealed at 500 °C were measured to be 2.59 × 10–
4 and 1.85 × 10–4 Wcm2, respectively. The Ga 2p core level for the APC sample shifted towards the lower binding-energies by 0.67 eV as compared to that of the as-deposited sample. The forward I-V properties of near UV LEDs fabricated with the Ag and APC reflectors were observe to be similar each other. Notably, the UV LEDs with the APC reflector produced 9.04% higher output at 100 mA than those with the Ag reflector. To investigate the device reliability, the EM behaviour of Ag and APC films were also characterised. The APC samples exhibited better EM resistance than the Ag samples. The APC samples yielded higher activation energies of the EM failures than the Ag sample. The better EM behaviour of the APC samples will be described and discussed on the basis of XRD pole figure and electron back scatter diffraction, phi scan, and inverse pole figures (IPFs) examination results.
Development of the Drying Process of Antibody-Immobilized FET Sensors for Long Term Storage
Authors: Wu Chang-Run , Chen Po-Hsuan , Sarangadharan Indu , Wang Yu-Lin 
Published: February 2020

The biomarker cardiac troponin I (cTnI) is a clinical marker used to diagnose acute myocardial infarction. In our work, we have developed an extended gate FET biosensor with high sensitivity, a wide dynamic range and high selectivity to detect cTnI from clinical samples. The biosensor allows a user to detect cTnI in 5 min from one drop of blood, without any prior training or knowledge of the assay.
However, antibody functionalized biomedical sensors face problems in practical implementations such as device preservation for long term and in transportation. Drying the antibody on the sensor can be a solution which avoids liquid handling. In this study, firstly, the activity of cTnI antibody that has been dried with different drying reagents (in-house recipes) and in different concentrations was analyzed using ELISA. We can get optimized reagent concentration from the ELISA results. Then, cTnI antibodies immobilized on the gold surface of extended gate FET biosensor were dried using different reagents. After drying, the antibodies were reactivated in 1X PBS. Following this, the electrical sensor measurement reveals that the antibody activity is maintained and calibration curve can be obtained. These results suggest that drying the sensor chip with these reagents maintains antibody activity and allows our sensor system to function as well as before drying. This is significant for practical implementation of our sensor as a homecare diagnostic device.

Figure 1
(Invited) Self-Powered Medical Electronics
Authors: Li Zhou 
Published: February 2020

Recently, piezoelectric nanogenerator（PENG） and triboelectric nanogenerator (TENG) have attracted much attention and been considered as another potential solution for harvesting mechanical energy. With its high output performance, outstanding biocompatibility and low cost, nanogenerator（NG） has been studied for powering implantable and wearable electronic medical devices.
Here, we demonstrated a biomechanical-energy harvesting using a NG as a power source or an active sensor. The NGs can convert the mechanical energy from human motion into electricity and drive the implanted long-term self-powered medical devices or biosensors. An implantable triboelectric nanogenerator (iTENG) in a living animal has been developed to harvest energy from its periodic breathing. The energy generated from breathing and body moving was used to power a prototype pacemaker and a low-level laser cure (SPLC) system, respectively. Meanwhile, it was found that the self-powered system could regulate the heart rate of a rat and significantly accelerated the mouse embryonic osteoblasts' proliferation and differentiation. Real-time acquisition and wireless transmission of self-powered cardiac monitoring data was also demonstrated for the first time. Another NG based self-powered pulse sensor have been applied for antidiastole of coronary heart disease, atrial septal defect and atrial fibrillation from health. These works are concentrated on live-powered medical devices. It showed broad clinical applications of self-powered medical systems for disease detection and health care.
(Invited) Biomimetic Approaches for the Practical Utilization of Discrete Liquid-Solid Contact Electrification
Authors: Kim Dong Sung 
Published: February 2020

The concept of “discrete liquid-solid contact electrification”, which is result of sequential process of the liquid contact on the solid surface and successive detachment of contact liquid from the solid surface, was reported. After the first report on discrete liquid-solid contact electrification inside the conventional pipet tip surface, the phenomenon is deeply investigated and explored with the help of utilization on a hydrophobic surfaces, which enables easy detachment of liquid from its surface. As a result, the phenomenon can be intentionally enhanced.
Recently, discrete liquid-solid contact electrification has been utilized as a fundamental operation mechanism of the energy harvester, called triboelectric nanogenerator (TENG), which utilizes the contact electrification phenomenon with electrical induction to efficiently convert ambient mechanical energy to electrical energy.
In this presentation, the history from the discovery of discrete liquid-solid contact electrification to its application as a TENG is introduced. Especially, the biomimetic approaches (mimicking natural lotus leaf and moth's eye) in the fabrication the TENG are introduced not only to enhance the electrical output as an energy harvester, but also to give an additional function for practical utilization. The present study would broaden the applications of discrete liquid-solid contact electrification, which is ubiquitous but previously inconspicuous in our daily life.
(Invited) Ultraflexible Organic Photonic Devices
Authors: Yokota Tomoyuki , Someya Takao 
Published: February 2020

Recently, flexible electronics has much attracted to realize bio medical application for their flexibility and conformability [1-3]. To improve these characteristics, reducing the thickness of the device is very effective [4]. We have developed ultra-flexible and lightweight organic electronics and photonics devices with few micron substrates. We fabricated the 2-V operational organic transistor and circuits which has very thin gate dielectric layers. The gate dielectrics were composed of thin aluminum oxide layer and self-assembled monolayers (SAMs). Due to the very thin substrate and neutral position, our device shows the highly flexibility and conformability. The device doesn’t be broken after crumpling.
And also we fabricated highly efficient, ultra-flexible, air-stable, three-color, polymer light-emitting diodes (PLEDs) have been manufactured on one-micrometer-thick parylene substrates. The total thickness of the devices, including the substrate and encapsulation layer, is only three micrometers, which is one order of magnitude thinner than the epidermal layer of the human skin. The PLEDs are directly laminated on the surface of skin and are used as indicators/displays owing to their amazing conformability as their superthin characteristics. Three-color PLEDs exhibit a high external quantum efficiency (EQE) (12, 14, and 6% for red, green and blue, respectively) and large luminescence (over 10,000 candelas per square meter at 10 V). The PLEDs are integrated with organic photodetectors and are used as pulse oximeter.
References
[1] D. Khodagholy et al., Nature Commun. 4 1575 (2013).
[2] G. Schwartz et al., Nature Commun. 4, 1859 (2013).
[3] L. Xu et al., Nature Commun. 5 3329 (2014).
[4] D. H. Kim et al., Nat. Mater., 9, 511 (2011).
Tuning and Mechanistic Insights of Metal Chalcogenide Molecular Catalysts for the Hydrogen-Evolution Reaction
Authors: McAllister James , Miras Haralampos , Bandeira Nuno , Bo Carles , McGlynn Jessica C , Ganin Alexey Y , Song Yu-Fei 
Published: February 2020

The production of hydrogen through water splitting using earth-abundant metal catalysts is a promising pathway for converting solar energy into chemical fuels. However, existing approaches for fine stoichiometric control, structural and catalytic modification of materials by appropriate choice of earth abundant elements are either limited or challenging. One promising strategy is the design of molybdenum sulfide nanoclusters which mimic the catalytically active sites found in MoS2. These molecules have the unique property of exposing a high degree of active edge sites leading to improved catalytic activity. Here, we explore the implementation of new design principles for the development of efficient molecular HER catalysts.
In this work, we prepared [Mo2O2(µ-S)2(S2)2]2–
(1)
, [Mo2O2(µ-S)2(S2)(S4)]2–
(2) and [W2O2(µ-S)2(S2)(S4)]2–
(3) by wet-chemical methods and investigated their HER electroactivity. Specifically, we aim to investigate the effects of stoichiometric and structural control resulting from the appropriate choice of the chalcogen elements and their ratio (e.g. O2-/S2
2-, O2-/S2
2-/S4
2-) within the coordination sphere of earth abundant transition metals (e.g. Mo or W). We evaluate the performance of these molecular catalysts for the hydrogen evolution reaction while we propose potential mechanistic pathways in relation to the interaction between catalysts and substrate.
The employed design principles offer the opportunity to bridge the gap between molecular and solid-state heterogeneous catalysts when immobilized on a carbon electrode surface. These molecular species represent an exciting class of low-cost earth-abundant materials and display great promise as HER electrocatalysts. Both molybdenum-based catalysts were shown to be exceptionally active towards the HER, with a reported overpotential of just –114 3 mV (at j = 10 mA cm–2) and no catalyst degradation over 1000 cycles. Density functional calculations reveal the effect of the electronic and structural features and confer plausibility to the existence of a unimolecular mechanism in the HER process based on the tested hypotheses. We anticipate these findings to be a starting point for further exploration of molecular catalytic systems.

Figure 1
(Invited) Development of Standards and Best Practices for Materials Testing in Low Temperature Electrolysis
Authors: Ayers Katherine E. , Capuano Christopher B , Motz Andrew R , Mani Prasanna 
Published: February 2020

As part of any overall strategy for environmental sustainability, a source of renewable hydrogen is needed, as a chemical feedstock as well as part of the portfolio of energy storage solutions. Currently over 95% of hydrogen is made from fossil fuels through natural gas reforming or coal gasification. However, water electrolysis has decreased significantly in capital cost and increased in scale. At the same time, renewable electricity costs have also dropped, especially in periods of high capacity, providing a potential pathway for competitively priced “green” hydrogen from water splitting. Still, continued materials and manufacturing research is essential to achieve cost parity with fossil fuels and produce renewable hydrogen at scale.
As new materials are developed, it is important to make accurate comparisons to a common baseline, to understand the potential for improvement over existing technology and to compare different pathways. Currently, research on electrolysis materials published in the scientific literature tends to be scattered across a range of test conditions and configurations, making these comparisons difficult. For example, catalysts may be tested with a range of membranes, at different temperatures, with different counter electrodes, and different electrolytes. In addition, test configurations can impact performance and cause variation in results even for the same materials. Having a standard baseline set of conditions can ground the results, even if additional tests are also performed to look at benefits of specific conditions for specific materials.
There are currently efforts in both Europe and the United States to select common standards and define test parameters and configurations for low temperature electrolysis. The U.S. Department of Energy is funding a team to coordinate similar work across all of the major water splitting pathways: low temperature electrolysis (primarily ion exchange membrane-based), high temperature electrolysis (primarily solid oxide), solar thermochemical water splitting (STCH), and direct photoelectrochemical water splitting (PEC). This talk will describe status of this project, including a workshop held in October 2018 and follow up work for specific materials tests.
Theoretical and Experimental Investigations in Metal−N−C Composites for Oxygen Reduction Reaction and Hydrogen Evolution Reaction at Universal Phs
Authors: Qin Xueping , Zhang Lulu , Shao Minhua 
Published: February 2020

During the development of platinum group metal (PGM)-free electrocatalysts for both polymer electrolyte membrane fuel cells and electrolyzers, non-precious metal and nitrogen co-doped carbon (denoted as Me-N-C) has been widely investigated as a promising catalyst for oxygen reduction reactions (ORR)1-3 and hydrogen evolution reactions (HER)4. However, these studies were conducted by different groups under various experimental conditions and most of the experiments were focused on a certain kind of reaction (ORR or HER) in either acid or alkaline media. In addition, current understanding can not explain well the activity discrepancy between Fe-N-C and Co-N-C. For instance, the former is much active than the latter for ORR, while the trend is reversed for HER4. This study aims to solve this dilemma by a first-principles density functional theory (DFT) approach.
In the theoretical simulations, the catalytic activities on Fe-N-C and Co-N-C were studied for ORR and HER in both acid and alkaline solutions by constructing the free energy diagrams. Meanwhile, the effect of applied potential on the activity was also included. Figure 1 shows the free energy diagrams of ORR for Fe-N-C and Co-N-C at low pH at 0 V (Fig. 1a) and 0.80 V (Fig. 1b), respectively. At 0 V, all elementary reaction steps are downhill for Fe-N-C (blue line) and Co-N-C (red line), indicating that both catalysts have good ORR activity in acid media; however, when the potential increases to 0.80 V, the OOH* and O* formation steps become uphill for Co-N-C while the Fe-N-C still possesses the downhill trend, illustrating the latter one has a better activity at low overpotentials. Similarly, the free energy diagrams based on the elementary reaction steps were constructed for ORR in alkaline media as well as the HER, from which the comparison between the Fe-N-C and Co-N-C regarding the ORR and HER activities at universal pHs could be obtained.
Our DFT calculation results demonstrateed that Fe-N-C had the better ORR activity than Co-N-C in both acid and alkaline media but a completely different trend was found for HER. These theoretical findings were also verified by our experimental results.

References

(1) Wu, G.; More, K. L.; Johnston, C. M.; Zelenay, P. Science
2011, 332, 443.
(2) Shao, M.; Chang, Q.; Dodelet, J.-P.; Chenitz, R. Chemical reviews
2016, 116, 3594.
(3) Lefèvre, M.; Proietti, E.; Jaouen, F.; Dodelet, J.-P. science
2009, 324, 71.
(4) Zhang, L.; Liu, W.; Dou, Y.; Du, Z.; Shao, M. The Journal of Physical Chemistry C
2016, 120, 29047.

Figure 1. Gibbs free energy diagrams for ORR in acid media for Fe-N-C (blue) and Co-N-C (red) at 0 V (a) and 0.80 V (b).

Figure 1