bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural Antioxidants for Activated Carbon-Based Electrochemical Capacitors with Enhanced Energy and Cycle Life
Authors: Fic Krzysztof , Menzel Jakub , Bujewska Paulina
Published: February 2020

Several forms of activated carbons have already been implemented and widely investigated as electrodes for electrochemical capacitors. Aqueous solutions based on inorganic salts demonstrated effective operating voltages around 1.6 V, and several interesting strategies have been furthermore implemented to improve these systems, including the redox activity of the electrolyte.

This work is focused on the electrochemical performance of the activated carbon electrodes operating in various electrolytes containing redox couple based on the ascorbic acid and sodium ascorbate. Since sulphate (SO4
2-) and nitrate (NO3
-) -based aqueous solutions have already been widely investigated, this study will discuss these electrolytes modified by the redox-active additive and their interaction with a carbon electrode. The results obtained clearly indicated that redox mediators play an important role in the charge accumulation process and has an excellent redox chemistry. Dependently on the electrolyte pH, the ionic specimen might be easily reduced or oxidized and perfectly preserves the activated carbon surface against oxidation.

A variety of electrochemical methods used in the study confirmed that a specific formulation of the electrolyte with ascorbate-based redox shuttle might remarkably enhance the electrode capacitance (up to 260 F g-1) and the operating voltage (up to 1.8 V). Moreover, operando Raman spectroscopy proved that several bonds are reversibly created while the charge transfer occurs. Furthermore, high specific energy (ca. 14 Wh kg-1) maintained at excellent power rates (1 kW kg-1) has been preserved during 8 000 charge/discharge cycles with reversibility of 94%.

Acknowledgements

European Research Council is acknowledged for financial support within the Starting Grant project (GA 759603) under European Unions’ Horizon 2020 research and innovation programme.
Bio-Derived Nanocarbons in Electrochemical Applications
Authors: Acznik Ilona , Lota Katarzyna
Published: February 2020

Carbonaceous materials are well known and readily used in a broad range of applications. Owing to the well-developed porous structure and the presence of certain surface functional groups, these materials are commonly used as adsorbents for a wide range of contaminants from gaseous or liquids media. Currently, activated carbons are also widely used as the electrodes for electric double-layer capacitors because of their high surface area, chemical stability and acceptable price.

This work is focused on the carbon materials obtained from biopolymers such as lignin, cellulose and chitosan as precursors. The carbonisation in nitrogen atmosphere followed by chemical activation in KOH was chosen as a synthesis method. The resulting carbon materials were characterised by well-developed surface area and microporous structure, beneficial for electric double-layer capacitors (EDLC) electrodes. In parallel, graphene-like materials obtained from graphite oxidation followed by thermal reduction were also synthesised.

The main goal of performed research tasks was to compare the electrochemical properties of carbon materials applied as electrode materials in different energy storage systems - electrochemical capacitors and in hydrogen storage systems. The special example taken into the consideration were hybrid capacitors composed of a battery-type electrode and a high surface area carbon electrode. This kind of configuration allows merging the advantages and reduces the drawback of redox and capacitive based systems. Since the same electrode material can give different electrochemical response depending on the type of device in which they are employed, this work will report on the influence of the physicochemical properties of carbon-based electrodes of various origin on their electrochemical response in various energy storage systems.
Solution Processed Alternating Organic/Inorganic Multilayer for OLED Encapsulation
Authors: Sun Lina , Kurosawa Yuu , Yoshida Tsukasa , Suzuri Yoshiyuki
Published: February 2020

Organic light-emitting diodes (OLEDs) are promised to replace the existing displays and lightings in terms of the quality of light. One of the most exciting features of organic electronics is that they can be made flexible. However, flexible OLED encapsulation is actually one of the major challenges because they are very sensitive to oxygen and moisture. Thin-film encapsulation (TFE) prepared by vacuum-deposition processes (ALD, CVD) have high barrier properties, but low throughput and high cost. For the significant cost reduction, all solution-processed roll to roll (R2R) production of OLEDs need to be established. Among the technologies needed, that for the thin-film encapsulation (TFE) imposes the highest challenge, because thin films with a very high level of barrier performance needs to be fabricated onto a complete organic device, so that solvents to attack the materials and high temperature treatments need to be strictly avoided.

In this work, organic/inorganic multilayer encapsulation structures based on one step solution-processed alternating polysiloxane and silica layer are presented in Fig. 1(A), in which organic layers are spin-coated, followed by polymer crosslinking reaction, and finally subjected to photochemical conversion of the surface into dense silica barrier layers under exposure to vacuum ultraviolet（VUV) light. The whole process is very simple and fast to perform at room temperature, and the coating solution is successfully developed not to destroy the pre-formed organic emitting layer.

Transmission electron microscopic (TEM) image shows successful fabrication of multi-stacks of organic/SiOx hybrid alternating layers (Fig. 1(B)). The thickness of ~ 100 nm was achieved per coating. The performance of such multilayer as thin-film encapsulation (TFE) of an OLED device has also been investigated as shown in Fig. 1 (C). The preliminary life time to reach 90% of the initial luminance (5000 cd/m2) was 73 hours for the OLED encapsulated with 450 nm TFE, about 6 times extended compared to that of the bare device.

Figure 1
(Invited) Control of Silicon Doping Level By Self Limited Reactions
Authors: Laus Michele , Perego Michele
Published: February 2020

Precise control over dopant dose and distribution at the nanoscale is required to support further evolution in microelectronics, photovoltaics, solar fuel conversion, sensors, and quantum computation.

In this contribution, an effective bottom-up technology is proposed as a promising solution to overcome the limitations of conventional doping approaches.

Precise control of the amount of dopant atoms tethered on silicon substrates is presented, based on polystyrene and poly(methyl methacrylate) polymers, with controlled molar mass and featuring a narrow molar mass distribution, end-terminated with a P-containing moiety. These polymers are spin coated and subsequently end-grafted onto nondeglazed silicon substrates. P atoms were bonded to the surface during the grafting reaction, and their surface density is set by the polymer molar mass, according to the self-limiting nature of the “ grafting to” reaction. Polymeric material was removed by O2 plasma hashing without affecting the tethered P-containing moieties on the surface.

Repeated cycles of polymer grafting followed by plasma hashing led to a cumulative increase, at constant steps, in the dose of atoms grafted to the silicon surface. P injection in the silicon substrate was promoted and precisely controlled by high temperature thermal treatments. Sheet resistance measurements demonstrated effective doping of silicon substrate.

Although the method is demonstrated for P-containing molecules on planar deglazed and nondeglazed Si substrates, but the it can be readily implemented to other types of dopants and semiconductor substrates by using suitable combination of dopant-containing moieties and surface chemistry.
Orientational Distribution of Reinforcing Fibers of Thermoplastic Composites Produced By Compression Molding – Heat & Cool vs Cold Pressing
Authors: Yamamoto Tetsuya , Masubuchi Yuichi
Published: February 2020

We theoretically predict the orientational dynamics of the reinforcing fibers of thermoplastic composites during the compression molding for cases in which the composites are molded by using the heat & cool (H&C) technique and by using the cold pressing technique [1]. For simplicity, we treat cases in which a cylindrical material, in which fibers are randomly oriented in a melt thermoplastic, is compressed by parallel plates. The compression is stopped when the material becomes the prescribed thickness for cases in which the H&C is used and it is stopped when the entire region of the material is solidified for cases in which the cold pressing is used. We derive the local orientational order parameter, which characterizes the extent of the orientational ordering of the fibers towards the flowing direction, after the molding process as a function of position [2].

Our theory predicts that the orientational order parameter is determined by the total shear strain applied to the fibers during the molding process. For cases in which the composite is molded by H&C, the orientational order parameter decreases as a function of the distance from the molds because the shear rate decreases with separating from the molds. The orientational order parameter does not depend on the compression speed because the orientations depend on the total shear strain applied to the fibers. In contrast, for cases in which the composite is molded by cold pressing, the orientational order parameter is a non-monotonic function of the distance from the molds, with a maximum at a half-way between the mold and the middle plane. This is because the reorientation of the fibers stops when the background thermoplastic material is solidified and the shear rate decreases with separating from the solidification front. The orientational order parameter depends on the compression speed and the speed of solidification. We thus conclude that the orientational distribution of the reinforcing fibers of thermoplastic composites is sensitive to the solidification dynamics of the background thermoplastic material.

[1] T. Ishikawa et al., Compos. Sci. and Technol., 155, 221 (2018).

[2] M. Doi and S. F. Edwards, The Theory of Polymer Dynamics, Oxford Univ. Press, 1986
Cold Atmospheric Plasma Annealing of Plasmonic Silver Nanoparticles
Authors: Sonawane Apurva , Mujawar Mubarak A , Bhansali Shekhar
Published: February 2020

Silver nanoparticles deposited on quartz substrate are annealed by cold atmospheric plasma jet to tailor the surface plasmon resonance (SPR) of silver nanoparticles. SPR is the unique optical property which arises due to the interaction of electromagnetic waves with the conduction electrons on the metal nanoparticle surface. The collective oscillations of these conduction electrons at specific EM wavelengths leads to strong scattering and absorption. For silver nanoparticles (AgNPs), the SPR occurs in UV-visible region and therefore AgNPs are used in various applications including solar energy harvesting, light emitting diodes, printed optoelectronic devices, and surface enhanced Raman scattering(SERS). The SPR absorbance peak strongly depends on the size, shape and assembly of the metal nanoparticles. The SPR absorbance peak can be tailored by thermal annealing of AgNPs. The annealing or sintering leads to change in mean diameter of nanoparticle due to agglomeration or reduction in the outside oxide layer of nanoparticles and therefore either red or blue shift in SPR is observed. However, thermal annealing is not always desirable, especially for the flexible polymer substrates. In the present work, we demonstrate the efficacy of cold atmospheric plasma annealing to achieve desired thermal annealing effects at room temperature. Silver nanoparticle films were deposited on the quartz substrate by injecting NP aerosol in the flowing argon gas. As deposited AgNP films were annealed by low temperature atmospheric plasma jet for 5 mins, 10 mins and 15 mins. Fig 1(a) shows the optical absorption spectra for un-annealed as well as annealed AgNP films. For un-annealed sample we observed the SPR absorbance peak at 426 nm. This peak was blue shifted by 14 nm, 36 nm and 62 nm for plasma annealed films for 5 min, 10 min and 15 min respectively. The AgNP films were also annealed using rapid thermal processing (RTP) at 100°C, 250°C, and 400°C for 5 min, 10 min and 15min. For all the temperatures, SPR peaks were blue shifted and for 400°C (corresponding the thermal energy of 58 meV) the blue shift values coincided with the values observed for plasma annealed AgNP films at room temperature. The plasma treated AgNP films were used as SERS substrates for Raman scattering studies of cortisol biomolecule. The Raman scattering signal from plasma annealed AgNP film was two times higher than that of bare quartz substrate.

Figure 1
(Invited) On the NaMeO2 (Me = 3d metal) for Na-Ion Batteries
Authors: Komaba Shinichi , Kubota Kei
Published: February 2020

Since the first report of NaMeO2 electrode about 40 years ago, the oxides have attracted much attention in battery researchers’ community particularly after 2010 because of their new chemistries different from LiMeO2 as well as abundant material-resources in the Earth [1-4]. Table 1 shows the variety of directly crystalizable oxides of A
x
MeO2s (A = Li, Na, and K) on 3d transition metal species. Clearly, Na
x
MeO2 crystalizes with a wider variety of 3d transition metals without Na/Me cation-mixing unlike Li/Me due to proper difference in ionic radii between Na+ and Me3+ ions [5-7]. The wide variety of 3d metals and crystal structures such as O3, P3, and P2 types including the distorted ones are found only in the Na system [5-7], unlike Li and K cases. Such structural variety gives us so wide selection of Na
x
MeO2 materials, which is highly attractive to develop high-performance positive electrode and to fine new electrochemical properties. Even if the same 3d transition metal is adopted in Li and Na systems, the electrochemical properties are often different from Na one in the batteries. For examples, O3-type LiCrO2 is electrochemically inactive in a Li cell, while O3-NaCrO2 delivers a reversible capacity of ca. 120 mAh g-1 with anomalously high thermal-stability in Na cell [8,9], which is also found in between O3-LiFeO2 and O3-NaFeO2 [10-12]. Our group has studied layered Na
x
MeO2 since 2005, and our achievements and recent progress on the layered oxides will be presented.

Reference
s
:

[1] N. Yabuuchi, K. Kubota, M. Dahbi and S. Komaba, Chem.
Rev., 114, 11636 (2014).

[2] M. Dahbi, K. Kubota, S. Komaba et al., Phys.
Chem. Chem. Phys., 16, 15007 (2014).

[3] K. Kubota and S. Komaba, J. Electrochem. Soc., 162, A2538 (2015).

[4] K. Kubota, S. Komaba et al., Chem. Rec., 18, 459 (2018).

[5] C. Delmas, C. Fouassier, and P. Hagenmuller, Mater. Res. Bull., 11, 1483 (1976).

[6] K. Kubota, S. Komaba et al., MRS Bull., 39, 416 (2014).

[7] K. Kubota, S. Komaba et al., Adv. Energy Mater., 8, 1703415 (2018).

[8] S. Komaba et al., Electrochem. Commun., 12, 355 (2010), and J. Phys. Chem. C,
119, 166–175 (2015).

[9] N. Yabuuchi, S. Komaba, et al., ACS Appl. Mater. Interfaces,
8, 32292−32299 (2016).

[10] K. Ado, et al., J. Electrochem.
Soc., 144, L177 (1997).

[11] S. Okada, the 210th ECS Meet., Cancun, Mexico (2006).

[12] N. Yabuuchi, S. Komaba et al., Electrochemistry, 80, 716 (2012).

Figure 1
(Invited) Hybridizing Fullerenes and Two-Dimensional Nanomaterials
Authors: Yang Shangfeng
Published: February 2020

Fullerene has a definite zero-dimensional (0D) closed-cage molecular structure composed of sp2-hybridized carbon atoms merely, enabling it as important building blocks useful for constructing supramolecular assemblies and micro/nano functional materials.[1] Upon hybridization 2D nanomaterials with fullerenes noncovalently or covalently, the physical/chemical properties of 2D nanomaterials can be tailored and in most cases improved, significantly extending their functionalities and applications.[2] Recently, we succeeded in synthesizing several novel fullerene-2D nanomaterial hybrids via both covalent and noncovalently approaches, including graphene,[3] g-C3N4,[4] black phosphorus,[5] and MoS2,[6] and achieved enhanced photo/electrocatalytic activities.

References:

S. F. Yang, T. Wei, F. Jin, Chem. Soc. Rev.
2017, 46, 5005-5058.

M. Q. Chen, R. N. Guan, S. F. Yang, Adv. Sci.
2018, 10, DOI: 10.1002/advs.201800941.

J. Guan, X. Chen, T. Wei, F. P. Liu, S. Wang, Q. Yang, Y. L. Lu, S. F. Yang, J. Mater. Chem. A
2015, 3, 4139.

X. Chen, H. L. Chen, J. Guan, J. M. Zhen, Z. J. Sun, P. W. Du, Y. L. Lu, S. F. Yang. Nanoscale
2017, 9, 5615.

X. J. Zhu, T. Zhang, D. Jiang, H. Duan, Z. Sun, M. Zhang, H. Jin, R. Guan, Y. Liu, M. Chen, H. Ji, P. Du, W. Yan, S. Wei, Y. L. Lu, S. F. Yang,
Nature Commun.
2018, 9, 4177.

J. Guan, J. H. Wu, D. C. Jiang, X. J. Zhu, R. N. Guan, X. Y. Lei, P. W. Du, H. L. Zeng, S. F. Yang, Int. J. Hydrogen Energy
2018, 43, 8698.
(Invited) 2D Materials for Cryptography
Authors: Das Saptarshi
Published: February 2020

In recent year, there has been unprecedented advances in 2D materials based devices that provide low cost, energy efficient, and high performance solutions for emerging technologies such as the Internet of Things (IoT). The IoT technology is estimated to connect more than 200 million smart digital devices by the year 2020 that will be involved in the generation, acquisition, storage and communication of an unfathomable amount of digital information pertaining to individual, institutional, governmental and military activities. Unfortunately, this digital information continues to be vulnerable to theft, manipulation, and misuse through hacking, cyber-attacks and internet crimes. Therefore, it is apparent that the IoT technology will benefit from smart devices with powerful, robust and in-built information security system in order to ensure data integrity, and confidentiality. In this invited talk, I will introduce, for the first time, a robust, reliable, high entropy, low cost, low power, area efficient, reconfigurable, non-volatile, and on-chip security for 2D material based multifunctional devices by exploiting inherent disorders associated with carrier transport in grain boundary dominated 2D field effect transistors (FETs).
(Invited) Single Nanoelectrode Photodissolution Mechanisms
Authors: Landes Christy F
Published: February 2020

The nanoscale stability of metal and metal oxide surfaces is crucial to the performance and degradation of catalysis supports and battery electrodes. Our lab is developing single particle spectroelectrochemical methods to untangle the complex dynamics of dissolution of plasmonic metal nanoparticles. We are particularly interested in plasmon enhanced electrochemical processes. I will discuss our recent results in which we vary the electrolyte anion chemistry, ground state carrier energy levels, and excited state carrier levels in order to study the photodissolution of nanorods into more complex shapes. We also identify the role of hot carriers in the photo-electrochemical dissolution process.
(Invited) Enhanced Water Splitting Under Modal Strong Coupling Conditions
Authors: Misawa Hiroaki
Published: February 2020

Metallic nanoparticles such as gold (Au) and silver (Ag) shows light absorption and scattering at the arbitrary wavelength of visible and near-infrared regions based on localized surface plasmon resonances (LSPRs). LSPRs which are collective oscillations of conductive electrons give rise to the enhancement of near-field and are expected as a light harvesting optical antenna for light energy conversion devices due to their spectrum tunability. We have successfully developed the plasmon-induced artificial photosynthesis systems such as water splitting and ammonia synthesis systems as well as solid-state plasmonic solar cells based on the principle of plasmon-induced charge separation between gold nanoparticles (Au-NPs) and the semiconductor photoelectrode.[1]-[6] Recently, the plasmon-induced charge separation has received considerable attention as a novel strategy for the solar energy conversion.[7],[8] However, for the monolayer of Au-NPs on the semiconductor in the regular Au-NPs loaded semiconductor photoelectrode, the insufficient absorption limited its solar energy conversion efficiency. Aiming at the enhancement of light absorption, in the present study, we apply the principle of modal strong coupling to plasmonic water splitting using Au-NPs/titanium dioxide (TiO2) thin-film/Au-film photoelectrode. [9]

References

Nishijima, K. Ueno, H. Misawa et al. J. Phys. Chem. Lett.
1, (2010)2031.

Zhong, K. Ueno, Y. Mori, X. Shi, T. Oshikiri, K. Murakoshi, H. Inoue, H. Misawa, Angew. Chem. Int. Ed., 53 (2014)10350.

Oshikiri, K. Ueno, H. Misawa, Angew. Chem. Int. Ed., 53, (2014)9802.

Oshikiri, K. Ueno, H. Misawa, Angew. Chem. Int. Ed., 55, (2016) 3942.

Nakamura, T. Oshikiri, K. Ueno, H. Misawa et al. J. Phys. Chem. Lett., 7, (2016) 1004.

V. Hoang, K. Hayashi, K. Ueno, H. Misawa et al. Nat. Commun., 8, (2017)771.

Ueno, T. Oshikiri, H. Misawa, ChemPhysChem, 17, (2016)199.

Ueno, T. Oshikiri, Q. Sun, X. Shi, H. Misawa, Chem. Rev., 118, (2018) 2955.

Shi, K. Ueno, T. Oshikiri, Q. Sun, K. Sasaki, H. Misawa, Nature Nanotech., 13, (2018) 953-958.
(Invited) Cobalt Interconnects at 36nm Beol Pitch and Beyond: Material Challenges & Circuit-Level Performance Impact
Authors: Lanzillo Nicholas , Yogendra Karthik , Yang Chih-Chao , Vega Reinaldo , Bolam Ron , Choi Kisik , Robison Russ , Clevenger Larry
Published: February 2020

Cobalt metallization in the back-end-of-line (BEOL) presents several interesting opportunities and challenges1-5. In this work, we evaluate the performance of Co interconnects at narrow BEOL pitch using chemical vapor deposition (CVD) for Co and a Ta-based barrier layer. In-line electrical measurements demonstrate a higher RC-delay for Co interconnects relative to Cu interconnects. Various challenges associated with Co metallization at narrow-pitch are identified. Simulations based on temperature-coefficient of resistivity (TCR) measurements are used to identify various cross-over points in which Co line resistance becomes lower than Cu line resistance depending on width, aspect ratio and barrier material/thickness.

In addition to in-line characterization of damascene Co interconnects, we employ a state-of-the-art multi-scale modeling approach to evaluate overall BEOL-loaded device performance for both Co and Cu conductors. We consider a single-driver reference circuit6,7 to evaluate the delay penalty for Co v. Cu metallization at several representative pitches. Ab initio simulations are employed to determine lower-limits of Co via resistance and surface scattering for a variety of possible barrier materials and thicknesses. These results are fed into a field solver to calculate stage delay for several representative logic gates, including a 3-input NAND and a 2-input multiplexer (MUX). Results indicate that despite having a higher line resistance, a net improvement in stage delay can be achieved for a suitably-tuned Co via resistance. Critical dimension (CD) sensitivity is also characterized for both Co and Cu metallization schemes.

These results highlight some of the challenges and potential advantages of using Co-based conductors in advanced interconnects beyond the 7nm technology node. This work was performed by the Research and Development Alliance Teams at various IBM Research and Development Facilities.

Figure 1
Flexible and Self-Supported Sulfur Cathode for High-Energy-Density Lithium-Sulfur Batteries
Authors: Liu Jun
Published: February 2020

For developing lithium-sulfur (Li-S) batteries, it is critical to design and synthesis advanced cathode materials with high sulfur loading, utilization ratios and strong binding interactions with sulfur species to prevent the ‘shuttle effect’ of electrolyte soluble intermediate polysulfides. Self-supported nanoarrays with hierarchical void and rich reaction sites are promising for advanced electrodes high-performance Li-S batteries. Here we report an effective sulfur host material prepared by integrating sulfur, carbon cloth, and CoP covered metal organic framework-derived N-doped carbon nanoarrays. These polar covered nanoarrays with a unique structure possess not only offer the enough void for volume expansion to maintain the structural stability during the electrochemical process, but also promote the physical encapsulation and chemical entrapment for all sulfur species. As a result, the CC@CoP/C electrodes with a high sulfur loading and display a high specific capacity at different current densities and long-term cycling performance (e.g. 600 cycles at 2C with an ultra-low capacity decay of 0.016% per cycle).
Effects of N-Doped Graphene and Carbon Black As Conductive Additives on Sulfur Cathodes in Lithium-Sulfur Batteries
Authors: Han Xiaoxiao , Cai Jiyu , Meng Xiangbo
Published: February 2020

Lithium-sulfur (Li-S) batteries hold great promise to meet the pursuit on transportation electrification, given their theoretic energy density of 2600 Wh/kg, low cost, and S abundance[1, 2]. However, Li-S batteries are currently being retarded from commercialization due to several severe issues. On the S cathode side, S is highly insulating electrically and ionically. In addition, intermediate products of lithium polysulfides are prone to dissolve in liquid electrolytes and shuttle between the S cathode and Li anode. In this case, conductive materials are essential to maintain S cathodes accessible to electrons and ions. Carbon black is the most widely used conductive materials in various battery systems. In addition, other carbon materials such as carbon nanotubes and graphene have also been used as alternatives in previous studies. However, there lacks a comparative study on identifying their effects. Thus, we recently conducted a systematic study on the effects of a carbon black (Super P) and a nitrogen-doped graphene nanosheets (NGS) on S cathodes. Experimental results showed that the S cathode with Super P (see Figure 1a) achieves higher initial capacity but fade rapidly. In contrast, the S cathode with NGS (see Figure 1b) exhibits more stable cycling performance. In addition, there also are some differences in their discharge/charge profiles of the two S cathodes, indicating different effects of Super P and NGS on S cathodes. Based on the experimental results and other characterizations, fundamental mechanisms as well as the prospects of these two conductive materials are discussed.

Manthiram, A., et al., Rechargeable lithium–sulfur batteries. Chemical Reviews, 2014: p. 11751-11787.

Sun, Q., et al., Atomic and Molecular Layer Deposition for Superior Lithium-Sulfur Batteries: Strategies, Performance, and Mechanisms. Batteries & Supercaps, 2018. 1(2): p. 41-68.

Figure 1
Centrifugally Spun Carbon Composite Fibers and Their use as Anode Materials in Lithium-ion Batteries
Authors: Elizondo Antonio , Gonzalez Ramiro , Lopez Jorge , Alcoutlabi Mataz
Published: February 2020

We present results on the centrifugal spinning of Metal-oxides (MOx)/PAN and Metal-Sulfides (MS)/PAN precursors for the mass production of MOx /C and MS/C composite fibers as anode materials for Lithium-ion batteries. MOx and MS such as NiO, TiO2, and SnO2, SnS2 and MoS2 were chosen with carbon as the active materials for the composite-fibers anodes. The microfiber preparation process involved the centrifugal spinning of MOx/MS/PAN precursors into microfibers and subsequent stabilization in air at 280ºC and calcination at 700ºC under Argon atmosphere. The MOx/C and MS/C composite-fibers anodes exhibited a specific capacity between 300 and 1200 mAhg-1 at the first cycle with a high irreversible capacity. The initial high irreversible capacity was attributed to the formation of the SEI layer and the high surface area of the centrifugally spun composite microfibers. In the subsequent cycles, the MOx/C and MS/C composite-fibers anodes exhibited a much stable cycling performance, i.e. 150-600 mAhg-1 was maintained after 100 cycles. The effect of pre-lithiation of the electrode after the first discharge cycle and coating the composite fibers-anode with active materials, prior to cycling, was systematically investigated. The pre-lithiation of carbon composite-fibers anodes after the first cycle exhibited higher charge/discharge capacities and higher coulombic efficiency up to 98% than the pristine carbon composite fibers.
Nanoengineered Separators for a High Energy Density, Long Cycle Life Li-S Battery
Authors: Xing Weibing
Published: February 2020

Rechargeable lithium-sulfur (Li-S) batteries are widely considered the most promising “Beyond Li-ion” candidates, notably for their high theoretical energy density. The low and moderate atomic weight of Li and S, respectively, translates to a battery chemistry pairing that is lightweight. Since each S atom can ultimately host two lithium ions (Li+), compared with 0.5–0.7 Li+ per host atom in Li-ion batteries [1], the Li-S battery chemistry offers a much higher Li storage capacity potential. Assuming a complete redox couple reaction, S8 + 16Li+ + 16e- ↔ 8Li2S, the S cathode can have a high theoretical specific capacity of 1672 mAh/g with an average discharge voltage of ~2.1V (vs. Li/Li+), which leads to a theoretical specific energy of ~2500 Wh/kg based on the active material weight of a Li-S cell [2]. Other compelling attributes of Li-S batteries include high S natural abundance, low cost of S materials and safety characteristics owing to an intrinsic tolerance to overcharge [3]. In addition, the primary constituents of Li-S batteries are non-toxic and environmentally friendly [4].

However, currently no commercial Li-S battery exists due to some significant technical challenges that have thus far prevented the realization of the tremendous energy density and performance potentials of Li-S batteries. These technical challenges include: low practical specific energy or energy density yield, significant capacity loss with cycling, high self-discharge rates, low Coulombic efficiency and safety concerns due to the use of Li metal anode [5].

We will present our efforts in the development of a high energy density and long cycle life Li-S battery technology via nanoengineered battery separators. We will show that our atomic and/or molecular level, functional material coated separators exhibit much improved physical properties including tensile strength, thermal shrinkage, and electrolyte wettability (Figure 1). When used in Li-S cells, the nanoengineered separators (coated) afforded a significant increase in specific capacity compared with the control (uncoated) separator, as illustrated in Figure 2. The enhanced Li-S cell performance suggests polysulfide blockage from the nanoscale functional material coated separators used in the resultant Li-S cells.

Our study demonstrates that the nanoengineered separator approach represents a very promising strategy to develop a high energy density, long cycle life, safe and economically scalable Li-S battery technology.

References

Bullis, “Revisiting Lithium-Sulfur Batteries” MIT Review, May 22, 2009.

Arumugam Manthiram, Yongzhu Fu, and Yu-Sheng Su, Acc. Chem. Res., 46 (5), pp 1125–1134 (2013)

James R. Akridge, “Lithium Sulfur Rechargeable Battery Safety”, Battery Power Products & Technology, October 2001.

Yongguang Zhang, Yan Zhao, Kyung Eun Sun and P. Chen, The Open Materials Science Journal, 5, 215-221 (2011).

Monica Marinescu, Laura O’Neill, Teng Zhang, Sylwia Walus, Timothy E. Wilson, and Gregory J. Offer, J. Electrochem. Soc, 165 (1) A6107-A6118 (2018).

Figure 1
A Fast-Charging Long-Life Li–S Battery Incorporating a MoO3 nanobelt/Polypropylene Functional Separator
Authors: Chu Chih-Wei , Kaisar Nahid , Jou Shyankay , Abbas Syed Ali , Fang Jason
Published: February 2020

Dissolution of lithium polysulfide (LiPS) into the electrolyte during discharging, causing shuttling of LiPS from the cathode to the lithium (Li) metal, is mainly responsible for the capacity decays and short battery lives of lithium–sulfur batteries (LSBs). Herein, we designed a separator—comprising polypropylene (PP) coated with MoO3 nanobelts (MNBs), prepared through facile grinding of commercial MoO3 powder. Formation of Li2Sn–MoO3 during discharging inhibited the polysulfide shuttling; during charging, Li passivated LixMoO3, facilitating ionic transfer during the redox reaction by decreasing the charge transfer resistance. This dual-interaction mechanism of LiPS—with both Mo and LixMoO3—resulted in a substantially high initial discharge capacity at a very high current density of 5C, with 29.4% of the capacity retained after 5000 cycles. The simple fabrication approach and extraordinary cycle life observed when using this MNBs-coated separator suggests a scalable solution for future commercialization of LSBs.
Tunable Syntheses of Advanced Silicon Anodes Using Cyclohexasilane
Authors: Elgammal Ramez Ahmed
Published: February 2020

The ability to develop fast charging lithium-ion batteries with high-energy density is being pursued intensively due to increasing demands of portable electronics and electric vehicles. Replacing the conventional graphite anode with a silicon-based one offers several advantages, namely the roughly 10 times higher gravimetric capacity and the safer lithium alloying potential. However, full scale realization of replacing graphite with silicon has been hampered due to the large volumetric expansion silicon typically suffers which causes mechanical degradation, low electrical conductivity, and multiple-step syntheses from a traditional silicon precursor which leads to higher cost. Here we present a silicon precursor, cyclohexasilane, that can offer solutions to all three of those limitations. Cyclohexasilane (CHS) exists as a liquid at room temperature and is relatively low boiling (~ 200 °C) relatively facile synthesis of nanostructured silicon materials, significantly reducing the volumetric expansion typically observed. Cyclohexasilane can be readily used to manufacture silicon/carbon composite materials and is readily chemically functionalized allowing the development of tailored materials with improved electrical conductivity. CHS may also be tailored to deliver structures with engineered artificial SEIs during the device fabrication step, offering an efficient and direct route to electrode structures. Moreover, cyclohexasilane is relatively inexpensive and its physical properties allow for roll-to-roll manufacturing with significantly reduced capital costs. Relevant comparisons of this technology compared to incumbent technologies will be given.
Atomic Layer Deposition of Nanocomposite Fluoride Coatings for Li-Ion Batteries
Authors: Mane Anil U. , Choudhury Devika , Gutierrez Arturo , Croy Jason R. , Elam Jeffrey W.
Published: February 2020

The energy storage market is projected to reach >$50 billion in the next five years. Major segments of this market consist of rechargeable lithium-ion batteries for consumer electronics, electric vehicles (automobiles, drones, aviation and space applications) and stationary storage for smart grids. For all these applications, high energies and capacities are required to meet the needs of consumer demands and economic viability. However, in order to meet these demands, lithium-ion materials must operate successfully at relatively high voltages (i.e. ≥ ~4.4V vs. Li/Li+) in practical cells. In particular, the cathode/electrolyte interfaces must be stabilized to prevent deleterious electrochemical reactions which can cause transition metal dissolution, capacity fade, and cell failure.

The conventional approach to stabilize cathode surfaces is to use protective coatings consisting mostly of metal oxides such as TiO2, ZrO2, HfO2, and Al2O3. However, despite nearly two decades of research and development, these metal oxide coatings are still susceptible to chemical attack by hydrogen fluoride (HF) that forms in the liquid electrolyte during battery cycling. The HF dissolves the metal oxide coatings exposing the underlying cathode material. To resolve the issues related to HF and improve electrode-surface stability, we have developed atomic layer deposition (ALD) based, nanocomposite fluoride coatings that resist dissolution by HF. We have added ultrathin nanocomposite fluoride coatings on various cathode materials such as conventional LiCoO2, various NMCs-(e.g., LiMO2, M=Mn, Ni, Co), and Li/Mn-rich, layered-layered-spinel (LLS) composite cathodes. These coatings are found to significantly improve the stability and performance of the cathodes in lithium-ion cells. Here we will present ALD growth of nanocomposite fluorides for Li-ion batteries and some of the latest electrochemical results.
(Invited) Model-Based Battery Management System of Lithium-Ion Batteries
Authors: Pathak Manan , Kolluri Suryanarayana , Jang Taejin , Pathak Chintan , Santhanagopalan Shriram , Subramanian Venkat R.
Published: February 2020

The advances in the automotive sector for plug-in hybrid electric vehicles (PHEV) and battery electric vehicles (BEV) along with penetration of renewables for power generation, cell phones and electric-flights have increased the use of batteries, as energy storage devices to a great deal. Some limitations of existing lithium-ion battery technology include underutilization, stress-induced material damage, capacity fade, and the potential for thermal runaway.1-3

Model-based control approaches (Model predictive control) can be used to design a smarter Battery Management System (BMS) that guarantees safety, efficiency, lifetime and performance of lithium-ion batteries at the stack and module level.4-7 This talk will present approaches for determining model-based optimal charging profiles for batteries, and experimental validation of the same. Optimal profiles that increase the cycle life of the cells were implemented on 16 Ah cells. An improvement of more than 100% in cycle life is observed experimentally, for our test conditions on this cell design.8 To test across multiple chemistries and form factors, optimal profiles were also implemented on a 1.5 Ah cylindrical cell, leading to an improved cycle life for these cells.

The interplay between the fundamental depth in modeling, choice of numerical algorithms, and application-driven problem formulation will be presented.

Acknowledgements

The work presented herein was funded in part by the Advanced Research Projects Agency – Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000275 along with the Clean Energy Institute (CEI) at the University of Washington (UW) and the Washington Research Foundation.

References

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V. Ramadesigan, P.W.C. Northrop, S. De, S. Santhanagopalan, R.D. Braatz, and V.R. Subramanian, Journal of the Electrochemical Society, 159, R31 (2012).

S. Santhanagopalan, Q. Guo, P. Ramadass and R.E. White, Journal of Power Sources, 156, 620 (2006).

B. Suthar, P.W.C. Northrop, R.D. Braatz,and V.R. Subramanian Journal of the Electrochemical Society, 161, F3144 (2014).

B. Suthar, V. Ramadesigan, P.W.C. Northrop, B. Gopaluni, S. Santhanagopalan, R.D. Braatz, and V.R. Subramanian, in American Control Conference (ACC), p. 5350, Seattle, WA, USA (2013).

M. Torchio, L. Magni, R.D. Braatz, and D.M. Raimondo, in 11th IFAC Symposium on Dynamics and Control of Process Systems, including Biosystems, p. 827, Trondheim, Norway (2016).

M. Torchio, N.A. Wolff, D.M. Raimondo, L. Magni, U. Krewer, R.B. Gopaluni, J.A. Paulson, and R.D. Braatz, in American Control Conference (ACC), p. 4536, Chicago, IL, USA (2015).

M. Pathak, D. Sonawane, M. Powell, S. Santhanagopalan, R.D. Braatz, and V.R. Subramanian, ECS Transactions, 75, 51 (2017).
Water Oxidation and Surface Protonation of Small IrOx Clusters
Authors: Juhasz Gergely
Published: February 2020

Electrochemical water oxidation on the anode is a common bottleneck of electrocatalytic processes. For their efficiency and relative stability, IrOx-type anodes are among the best ones in acidic environment. In spite of all the efforts, however, it is still a complicated system from theoretical point of view. The small band gap and complicated band structure around Fermi level, strong electron correlation makes Ir(IV) oxides challenging itself, and the amorphous structure or nanoparticle structure of the electrodes just adds to the complications.

We focused on these later aspects and studied the behavior of small cluster models of IrOx (Ir3 and up), instead of regular slab models. Crystalline IrO2 has a rutile lattice where Ir atoms are forming Ir-O-Ir chains along the x/y and Ir-O2-Ir chains z direction. In amorphous oxides and nanoclusters those chains are terminated by –OH or –OH2 groups, to compensate the missing positive charges. In our cluster models we mostly kept the local environment around most Ir similar to bulk, but studied the effect of terminating –OH and –OH2 groups, i.e. the H isomerism on the cluster surface.

For the calculation we used DFT (DMol3) with the PBE (GGG) functional and DNP (4.4) basis set. The convergence criteria of for geometry optimization was 1.0-5 Ha and 1.0-6 for the SCF. Due to the large number of states around the HOMO-LUMO gap, we applied thermal smearing. The accuracy of the calculations was assessed compared to calculations with B3LYP hybrid functional, however the geometry and charges remained essentially the same. We found that surface protonation can significantly stabilize the lower valence states of Ir, therefore mobile H on the surface can reduce the energy required for each step of the water oxidation cycle.
(Invited) Laser Thermal Annealing for Low Thermal Budget Applications: From Contact Formation to Material Modification
Authors: Huet Karim , Tabata Toshiyuki , Aubin Joris , Curvers Benoit , Mazzamuto Fulvio , Mori Yoshihiro
Published: February 2020

Pulsed Laser thermal annealing at the nanosecond timescale was successfully introduced into semiconductor device manufacturing in the late 2000s for high volume manufacturing of sensitive 3D architectures such as vertical Si-based Insulated Gate Bipolar Transistors, SiC-based vertical power diodes and backside illuminated CMOS imaging sensors. It is now on the verge of being successfully integrated as process of record for key annealing process steps in next generation CMOS and memory devices manufacturing. This invited paper presents recent experimental and simulation work involving sub-µs Laser annealing for a wide range of applications, from contact formation to material modification and 3D sequential integration.
Thermal Resistance in ALD Grown Dielectric Thin Films
Authors: Scott Ethan Adam , King Sean W. , Smith Sean , Gaskins John , Ihlefeld Jon , Hopkins Patrick
Published: February 2020

The need for increased control of layer thickness and uniformity as device dimensions shrink has spurred increased use of atomic layer deposition (ALD) for thin film growth. The ability to deposit high dielectric constant (high-k) films via ALD has allowed for their widespread use in a swath of optical, optoelectronic, and electronic devices, including integration into CMOS compatible platforms. As the thickness of these films is reduced, the interfacial thermal resistance can dictate the overall thermal resistance of the material stack compared to the resistance due to the finite dielectric layer thickness. In this study, time domain thermoreflectance is used to interrogate the thermal conductivity and the thermal boundary resistance of routinely used high-k dielectrics, aluminum oxide, hafnium oxide, and titanium oxide films ALD grown on silicon, as well as films of hafnium zirconium oxide, which has demonstrated potential for applications in energy storage devices as well as electronic memory devices and architectures.
(Invited) Two-Dimensional Materials for Electronic Devices: Transition-Metal Dichalcogenides and Topological Insulators
Authors: Vandenberghe William , Laturia Akash , Tiwari Sabyasachi , Sorée Bart , Van de Put Maarten
Published: February 2020

As scaling of electronic devices has reduced dimensions into the nanoscale regime, investigations towards intrinsically two-dimensional (2D) materials are being pursued. Examples of 2D materials under investigation are monolayers of graphite, transition-metal dichalocogenides (TMDs), tellurium, and 2D topological insulators (TIs). To enable practical applications however, 2D materials must outperform currently employed three-dimensional materials. Properties of interest are mobilities, device drive current, and dielectric response but these properties are not yet fully known and understood in 2D materials.

We present a theoretical investigation of the dielectric response in transition-metal dichalcogenides. We determine a method to define and extract, from first principles, the dielectric constant of a two-dimensional material. We apply this method to calculate the low-frequency and high-frequency dielectric constant of semiconducting TMDs, both those in the hexagonal phase, e.g. MoS2, WSe2, as well as those in the tetragonal phase, e.g. ZrS2 and HfSe2. We find that the in-plane static dielectric constant for the TMDs in the tetragonal phase is very large, which will give rise to large polar-optical phonon scattering and low mobilities in tetragonal TMDs. [1]

We also present a new strategy to deal with both the high concentration of defects found in 2D materials as well as the difficulty of making perfectly straight edges. The strategy proposes to make transistors out of 2D TIs since 2D TI materials host topologically protected edge states that are robust against perturbations. In fact, we show how 2D TI field-effect transistor performance is actually improved in the presence of defects. The high on-current, related to the high electron velocity in these devices gives 2D field-effect transistors a predicted performance that exceeds that of conventional field-effect transistors. [2, 3]

[1] A. Laturia, M. L. Van de Put, and W. G. Vandenberghe, "Dielectric properties of hexagonal boron nitride and transition metal dichalcogenides: from monolayer to bulk," npj 2D Materials and Applications, vol. 2, no. 1, p. 6, 2018/03/08 2018.

[2] W. G. Vandenberghe and M. V. Fischetti, "Imperfect two-dimensional topological insulator field-effect transistors," Nature Communications, vol. 8, 2017.

[3] S. Tiwari, M. L. Van de Put, B. Sorée, and W. G. Vandenberghe, "Carrier Transport in a Two-Dimensional Topological Insulator Nanoribbon in the Presence of Vacancy Defects," in 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD), 2018, pp. 92-96: IEEE.