bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polycarbonate and Poly(ethylene oxide) Blending As a Solid Polymer Electrolyte for All Solid State Li-Ion Batteries
Authors: Sung Bong-Joon , Didwal Pravin N. , Park Chan-Jin 
Published: February 2020

Lithium-ion batteries (LIBs) have been used as a power source for electric vehicles and portable electronic devices. However, conventional LIBs which include organic liquid electrolyte have safety problems such as flammability, leakage of electrolyte, poor thermal stability, and internal short circuit. These safety issues can be addressed using a strategy by switching from organic liquid electrolyte to solid polymer electrolyte (SPE). Among the numerous polymer materials, the poly(ethylene oxide) (PEO) has been extensively studied. Even though PEO possesses some advantages such as high solubility of lithium salt and high ionic conductivity at high temperature, PEO has some drawbacks such as poor mechanical strength, inferior electrical stability window, and poor lithium ion transference number. Recently, polycarbonate which is composed of carbonate group and ethylene oxide, has attracted attentions as polymer electrolyte. This polymer has the higher lithium transfer number and ionic conductivity compared with pristine PEO at room temperature. However, since the strength of polymer was not sufficient for free-standing, the cellulose non-woven was used as framework.
In this work, we studied the effect of blending of polycarbonate and PEO for the use as solid electrolyte. The morphology of blended polymer was investigated by using SEM. The XRD and DSC were used to investigate the crystallinity and glass transition temperature of the blended polymer, and the ionic conductivity of the polymer was investigated. Electrochemical impedance spectroscopy analysis of the polymer showed an increase in ionic conductivity compared with that of pure PEO. In addition, the blended polymer enabled free-standing. The all-solid-state cell composed of Li/polymer/NCM622 was fabricated and its electrochemical performance was evaluated.
Increasing Surface Charge Density By Intrinsic Charge Layer Inclusion for High Performance Efficient Triboelectric Nanogenerators
Authors: Ravichandran Aravind , Ramuz Marc , Blayac Sylvain 
Published: February 2020

In recent years, mechanical transducers for energy harvesting, particularly triboelectric nanogenerators (TENGs) have been conceived as a practical power source due to its simple, compact and high efficiency for energy harvesters. Charge injection and retention in thin film dielectric layers remain critical issues in realizing TENGs as a sustainable power source.
In this work, we have presented a novel technique to boost the output electrical performance of triboelectric nanogenerators by the inclusion of charge accumulation layer. This thin film layer allows to store and accumulate the charges generated by triboelectrification and refill the charges on every triboelectrification process of the vertical contact separation TENG mechanism. This increase in the stored charges has an effect of inducing many free charges on the electrodes of the device in a much larger quantity and gives rise to a much higher electrical output power.
A proof of concept TENG structure is devised to validate the electrical output performance. Experimental results show that, the devised structure reaches an open circuit voltage of 600 V demonstrating 25 times enhancement than the conventional triboelectric devices in ambient conditions. The in–situ surface characterization implemented using atomic force microscopy (AFM) reveals the charge retention characteristic due to the presence of the charge accumulation layer.
This technical outcome will significantly facilitate the future research in increasing the charge density to efficiently provide higher output power attractive to charging applications for portable electronics/ wearables and large-scale harvesting without massive volume. By this technique, numerous friction-based operation challenges including lack of uniform contact, material loss through wear, high sensitivity to humidity, and output power storage have been resolved.
Ethylene Carbonate-Free Electrolytes for High-Nickel Layered Oxide Cathodes
Authors: Li Wangda , Dolocan Andrei , Li Jianyu , Xie Qiang , Manthiram Arumugam 
Published: February 2020

Layered lithium nickel oxide (LiNiO2), with a specific charge-storage capacity of almost 250 mA h g-1, an operating voltage of 3.8 V vs. Li+/Li, and a high packing density of above 3.4 g cm-3, offers a very high energy density approaching the limits of layered oxide cathode materials for lithium-ion batteries. However, despite early interests in the community, practical application of LiNiO2 was soon dismissed for a multitude of problems. This includes (i) poor thermal-abuse tolerance triggering battery thermal runaway at high states of charge, and (ii) severely restricted reversible capacity of < 200 mA h g-1 for desired cycle/calendar life owing to a high surface reactivity with conventional ethylene carbonate (EC)-based electrolytes and not fully reversible rhombohedral H2/H3 phase transition at > 4.2 V vs. Li+/Li. In spite of recent efforts on stabilizing ultrahigh-nickel layered oxides (Ni > 0.9) during battery operation through compositional tuning, the poor thermal stability and cyclability over a broad Li content range remain challenges of LiNiO2-based cathodes.
Here we design nonaqueous electrolytes with exclusively aprotic acyclic carbonate solvents (such as ethyl methyl carbonate, EMC) tailored to an ultrahigh-nickel layered oxide cathode (LiNi0.94Co0.06O2). Common lithium-conducting salts (e.g., lithium hexafluorophosphate, LiPF6) and interphase-forming additives (e.g., vinylene carbonate, VC) are adopted in two model electrolyte systems. Assembled graphite|LiNi0.94Co0.06O2 pouch-type full cells in the two EC-free electrolyte systems show excellent long-term cycling performance of ~ 80% capacity retention after 1,000 charge-discharge cycles at 25 oC (1C, 2.5 – 4.2 V), notably superior to the same cells in the baseline EC-containing electrolyte (1.0 M LiPF6/EC-EMC(3:7)+2%VC). Through time-of-flight secondary-ion mass spectrometry coupled with lithium isotopic labelling and in situ X-ray diffraction, we demonstrate suppressed unwanted electrode-electrolyte reactions and irreversible structural degradation of LiNi0.94Co0.06O2 at highly delithiated states in the EC-free electrolytes during battery operation. In addition, through differential scanning calorimetry, we also show significantly inhibited self-heating of the ultrahigh-Ni layered oxide cathode at full charge in the EC-free electrolytes, outperforming charged LiNi0.8Co0.15Al0.05O2 in the EC-containing electrolyte. In summary, we present a facile approach of nonaqueous EC-free electrolytes to address the long-standing challenges of LiNiO2-based cathode materials for safer and long-life high-energy-density lithium-ion batteries.
Redox Chemistry in Conventional Layered Lithium Metal Oxide Cathodes
Authors: Tong Wei , Li Ning , Yang Wanli , Sallis Shawn , McCloskey Bryan D. , Papp Joseph K 
Published: February 2020

Li-ion battery technology is one of the best performing energy storage devices and holds the best promise to power the upcoming electrical vehicles (EV). Extensive efforts have been devoted to further advancing conventional layered oxide cathodes, such as LiNixMnyCozO2 and LiNixCoyAlzO2 (0 < x, y, z <1), for Li-ion batteries of even better performance and lower cost ($/Wh). Strategies that are largely pursued include increasing Ni content to achieve a higher practical capacity at a given charge cutoff voltage and/or increasing charge cutoff voltage for a given composition. Alongside with these research efforts, questions regarding the stability of electrode, especially at highly delithiated states, electrolyte and electrode/electrolyte interface arise.
In this work, of particular interest is the redox chemistry upon electrochemical (de)lithiation of LiNiO2, the parent compound of Ni-rich layered oxides, with a key focus on highly delithiated states in the high voltage region. Electrochemistry of LiNiO2 seems straightforward, in principle, Ni3+/Ni4+ redox can perfectly accommodate 1 Li+ transport during (de)lithiation process. However, the precise state at full oxidation of Ni3+ to Ni4+ and/or full removal of 1 Li+ are difficult to achieve because of the possible side reactions between highly charged electrode and electrolyte, for example, surface Ni reduction and gas evolution upon charge often occur at high voltages. Here, the electronic states of Ni and O are probed at different states of charge through combined soft X-ray absorption (XAS), resonant inelastic X-ray spectroscopy (RIXS) and in situ differential electrochemical mass spectrometry (DEMS) in the high voltage region to elucidate the explicit redox chemistry in LiNiO2. This work is anticipated to provide additional insights into the redox chemistry of conventional Ni-rich layered oxides, especially its utilization in the high voltage region.
Dandelion-like Mesoporous SiOx@C Nanoparticles for High-Capacity and Ultralong Lifespan Lithium-Ion Battery Anode
Authors: Li Zhaolin , Zhao Hailei , Wang Jie 
Published: February 2020

Silicon suboxide (SiOx, 0˂x˂2) is one of the promising anode materials for lithium-ion batteries (LIBs) due to its high specific capacity, low operating voltage (˂0.4 V) and rich natural resource [1]. SiOx converts to Si nanoparticles and inert components (lithium oxide and lithium silicate) during initial lithiation process, where the Si nanoparticles can reversibly store lithium ions and the inert components act as buffer matrix to accommodate the large volume variation of nano-sized Si. Compared to pure Si, SiOx electrode shows relatively good cycling stability while maintaining high specific capacity, thus is a promising anode material for high energy density Li-ion batteries. Nevertheless, bulk SiOx electrode cannot withstand long-term cycling due to the inevitable volume variation upon lithium uptake and removal. In addition, the poor intrinsic electrical conductivity of SiOx often limits the capacity utilization [2].
In this work, we prepared mesoporous SiOx@C nanoparticles with unique “dandelion flower” structure by a facile microemulsion method combined with a subsequent carbon coating process. The SiOx particles display a dandelion flower like porous structure with large void space and specific surface area. A uniform carbon layer wholly encapsulates the SiOx backbone, forming a 3D mono-dispersed SiOx@C particle with particle size of ~70 nm. The abundant mesopores inside particle can accommodate the volume expansion of SiOx during lithiation and lower the diffusion-induced stresses, which prevent from the electrode pulverization and thus maintain the structural integrity of SiOx@C electrode during repeated cycles. The 3D carbon network not only effectively facilitates the fast electron transport throughout the whole SiOx particle and thereby improving the electrode reaction kinetics, but also homogenizes the local current density of active particles and hence decreases the mechanical stress induced by volume change of SiOx. Benefiting from these advantages, the prepared SiOx@C anode exhibits ultrahigh reversible capacity (1261 mAh g-1 at 0.1 A g-1), ultralong lifespan (635 mAh g-1 at 2 A g-1 after 1000 cycles with retention of 88.6%), as well as superior rate capability (293 mAh g-1 at 10 A g-1).
[1] Journal of Power Sources, 2017, 363: 126-144.
[2] J. Mater. Chem. A, 2014, 2, 3521-3527.
Development of Carbon Fiber-Based Electrodes for Lithium-Ion Battery
Authors: Liu Yi-Hung , Lin Heng-Han , Hsu Chun-Han 
Published: February 2020

Introduction

To meet the increasing requirement on high energy density, power density and long cycle life of large-scale lithium ion batteries (LIBs), advanced electrodes which can afford more active material loading while reducing extra use of additives are desired. In light of this purpose, carbon fibers (CFs) are regarded as a potential material because they can be used as current collectors where more active materials can be loaded on their 3-dimensional (3D) electrically conductive network. In addition, CF-based current collectors enable a binder-free electrode design for lithium ion batteries and sodium ion batteries (SIBs). [1,2] In this work, we develop several CF-based electrodes for use in not only positive electrode but negative electrode of LIBs, demonstrating their characteristics in terms of electrode fabrication methods and electrode performances.

Experimental

For the fabrication of CF-based electrodes, two approaches, namely hydrothermal and sol-gel reaction routes, are applied. In the hydrothermal process, an electrodeposition of precursor was first carried out, followed by the hydrothermal reaction and post-calcination treatment to synthesize the target active material. For the sol-gel route, active materials were primarily synthesized in the sol-gel reaction step. After a calcination treatment of the gel, powder-type active materials can be obtained. Then, a slurry was prepared by mixing the powders with solvents and specific additives. After coating the slurry on CFs and drying, fabrication the CF-based electrodes were completed. SEM and XRD are generally used for the material analysis. With respect to the electrochemical evaluation, a coin cell (CR2032) was used to accommodate the CF-based working electrode and lithium metal foil as a counter/reference electrode.

Results and Discussion

According to the electrode performances, it is convinced that both hydrothermal and sol-gel routes are appropriate for the fabrication of CF-based electrodes. The physical properties, including morphology, chemical composition and crystallinity, vary depending on the fabrication methods and conditions. While the hydrothermal route is capable of binder-free electrode design, the sol-gel route offer the benefit to the formation of active materials with purer crystal phase and better crystallinity. Moreover, CF-based electrodes exhibit satisfactory electrode performances due to their 3D conductive structure, facilitating ion transport and electron conduction during the cell operation.

References

1. Y. H. Liu, H. H. Lin, Y. J. Tai, J. Alloy. Compd., 735, 580–587 (2018).
2. Y. H. Liu, T. Takasaki, K. Nishimura, S. Katsura, M. Yanagida, and T. Sakai, J. Electrochem. Soc., 161, A1194–A1199 (2014).
(Invited) Differential Reference Concentration Cell Method for Determination of Thermodynamic Factors in Concentrated Binary Electrolytes
Authors: Wang Andrew , Hou Tianhong , Monroe Charles W 
Published: February 2020

Accurate models of ion transport in isothermal binary solutions require measurements of various properties, including ionic conductivity, salt diffusivity, cation transference number (t0
+), and the thermodynamic Darken factor (χ). In this work a novel method is proposed to quantify composition-dependent values of χ(1-t0
+).
Recent studies of highly concentrated “solvent-in-salt” electrolytes suggest a strong variation of transference number with respect to composition. In fact t0
+ for electrolyte systems may double in magnitude in the highly concentrated regimes.1

Previous studies have quantified the Darken factor by assuming that t0
+ is relatively constant across the concentration range of interest. Furthermore, concentration-cell experiments typically fix arbitrary reference concentrations that may be far from the test concentration across the liquid junction. Such methods employ integral values of t0
+; the accuracy of thermodynamic properties, and thereby numerical models, may be compromised if there are substantial concentration differences and concomitant local changes in t0
+.2 An alternative approach to concentration-cell experiments would apply differential forms of the equations relating potential difference, composition, thermodynamic factor, and cation transference number.3

We propose a novel approach to concentration-cell experiments in which a matrix of liquid-junction potentials banded about a variable reference concentration is employed. Coupled with independent t0
+ measurements, this 3-dimensional surface for potential difference can be numerically fitted to reliably and accurately determine differential values of the thermodynamic factor χ across the solubility range of an electrolyte. The feasibility of the method is demonstrated with the electrolyte lithium hexafluorophosphate in propylene carbonate (LiPF6:PC) to determine concentration-cell liquid-junction potential (U) across a wide concentration range (0M-3M). Transference-number measurements via Hittorf-cell experiments are then used to isolate χ from differential measurements of χ(1-t0
+) as a function of electrolyte particle fraction (y).

Suo, L., Hu, Y. S., Li, H., Armand, M. & Chen, L. A new class of Solvent-in-Salt electrolyte for high-energy rechargeable metallic lithium batteries. Nat. Commun.
4, 1–9 (2013).

Lundgren, H., Scheers, J., Behm, M. & Lindbergh, G. Characterization of the Mass-Transport Phenomena in a Superconcentrated LiTFSI:Acetonitrile Electrolyte. J. Electrochem. Soc.
162, A1334–A1340 (2015).

Newman, J. & Thomas-Alyea, K. E. Electrochemical Systems. (John Wiley & Sons, 2004).

Figure 1
(Dielectric Science and Technology Division Thomas D. Callinan Award Address) Colorful Adventures in the Field of Dielectrics Science: Some Highs and Lows with a Touch of a Chilly Forecast
Authors: King Sean W. 
Published: February 2020

Dielectric materials are utilized throughout semiconductor microelectronic devices for a variety of applications ranging from passive electrical isolation and charge storage to more functional etch stopping and diffusion barriers and more active layers such as humidity sensing and solid state electrolyte materials. Just in the past two decades alone, the semiconductor industry has researched and adopted a vast array of new dielectric materials with exceptionally high or low values of dielectric permittivity (k). While scaling of these so called high-k and low-k dielectrics may have reached their limits, numerous additional applications for dielectric materials continue to emerge as the industry seeks to adopt new methods for patterning nanoscale features and considers a dizzying array of beyond CMOS devices.
In this talk, I will discuss my colorful adventures over these past two decades as a dielectric materials scientist starting with molecular beam and atomic layer epitaxy of III-N nitrides to plasma enhanced chemical vapor deposition of low-k dielectrics and back to atomic layer deposition of high-k dielectrics (various misadventures in between will also not be neglected!). It has been an exciting journey and I will use it to highlight the multi-disciplinary nature of dielectric science as well as illustrate how something that was once old can be reimagined to fulfill the needs of future beyond CMOS devices. I will further address some of the future challenges and opportunities presented for dielectric materials that have been created by the new patterning methods and beyond CMOS devices now under consideration. We will conclude by reviewing the unique obstacles that dielectric materials present for the realization of advanced cryogenic quantum computing architectures and the necessary associated research vectors to prevent dielectrics from becoming quantum computing’s Achilles heel.
(Invited) 2D Materials for Nanoelectronics: Prospects and Materials Integration Challenges
Authors: Wallace Robert M 
Published: February 2020

The size reduction and economics of integrated circuits, captured since the 1960’s in the form of Moore’s Law, is under serious challenge. Current industry roadmaps reveal that physical limitations include reaching aspects associated with truly atomic dimensions, and the cost of manufacturing is increasing such that only 2 or 3 companies can afford leading edge capabilities. To address some of the “conventions;” material’s physical limitations, “2D materials” such as graphene, phosphorene, h-BN, and transition metal dichalcogenides have captured the imagination of the research community for advanced applications in nanoelectronics, optoelectronics, and other applications. [1,2] Among 2D materials “beyond graphene,” some exhibit semiconducting behavior, such as transition-metal dichalcogenides (TMDs), and present useful bandgap properties for applications even at the single atomic layer level. Examples include “MX2”, where M = Mo, W, Sn, Hf, Zr and X = S, Se and Te.
In addition to the potentially useful bandgaps at the monolayer thickness scale, the atomically thin layers should enable thorough electric field penetration through the channel, thus enabling superior electrostatic control. Further, with such thin layers, the integration with suitable gate dielectrics can result in a mobility enhancement. Applications “beyond CMOS” are also under exploration. From an interface perspective, the ideal TMD material may ne expected to have a dearth of dangling bonds on the surface/interface, resulting in low interface state densities which are essential for efficient carrier transport. The ideal TMD materials have much appeal, but the reality of significant densities of defects and impurities will surely compromise the intrinsic performance of such device technologies. This presentation will examine the state-of-the-art of these materials in view of our research on semiconductor device applications, and the challenges and opportunities they present for electronic and optoelectronic applications. [3,4]
This research was supported in part by the Semiconductor Research Corporation (SRC) NEWLIMITS Center and NIST through award number 70NANB17H041 and the Erik Jonsson Distinguished Chair at the University of Texas at Dallas.

References

[1] Z. Lin, et al., APL Materials, 6, 080701 (2018)
[2] N. Briggs, et al., 2D Materials, in press (2019)
[2] S. J. McDonnell and R.M. Wallace, JOM
. in press (2018).DOI: 10.1007/s11837-018-3156-x
[2] S. J. McDonnell and R.M. Wallace, Thin Solid Films, 616, 482-501 (2016); and references therein.
(Invited) Nanoporous Titaninum Nitride Electrodes for Neural Probes
Authors: Cheng Mark Ming-Cheng 
Published: February 2020

We report corrosion-resistant and high-capacity implantable nanoporous titanium nitride (TiN) electrodes for neural probes applications Traditionally, the TiN electrodes are prepared using reactive sputtering techniques and have limited surface areas. To research smaller electrodes to minimize tissue damage, high aspect ratio TiN nanotube structures were fabricated using electrochemical anodization of Ti wires followed by high-temperature nitration. The specific charge capacity of nanoporous TiN correlates proportional with the surface area and pore size.
According to Shannon criteria, an empirical rule in neural engineering for possibility of tissue damage from electrical stimulation, the recommended limit density of a stimulation pulse is 30 μCcm-2 for a geometric surface area of 0.06 cm2. Nevertheless, the charge injection capacity of chronically implanted electrodes has shown degraded over the time (within one month to a year), including sputtered iridium oxide (SIROF), porous platinum and tungsten. One of the challenges for these implantable electrodes involves irreversible reduction and oxidation reactions occurring at the electrode surface through faradic or pseudocapacitive charge transfer. On the other hand, TiN has different mechanism of charge injection (through capacitive double layers). TiN has been shown promising electrode material in neural implants thanks to its super electrical conductivity, biocompatibility and chemical stability. TiN is also known for physiologically inert and corrosion resistant. To increase the spatial resolution of neural stimulation, small electrodes with high surface areas are more desirable. To the best of our knowledge, TiN nanotubes electrodes have not been studied in the literature for neural implants. Compared to tungsten electrode, the impedance and morphology of nanoporous TiN was found stable over a long-term in stress tests (at an elevated temperatures in phosphorous buffered solution).