bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation on Phase-Induced Surface Energy Change of HfO2 Thin Films Prepared By Plasma Enhanced Atomic Layer Deposition
Authors: Lee Sangyoon , Yoon Hwi , Lee Yujin , Lee Sanghun , Kim Hyungjun 
Published: December 2020

Wettability of nanomaterials has been researched for the scientific physics based on solid/liquid interfaces. In particular, wettability of ceramic materials which is directly relevant to the surface free energy has been researched for its nature continuously in terms of thin film coatings.1 The development of such materials with finely tunable surface free energy and adequate stability under harsh conditions has been attracted enormous interests involving various applications.2,3 Among them, Hafnium oxide (HfO2), one of the representative transition metal oxides, has been recently studied for robust coating materials with investigation of its surface free energy. However, due to the complexity derived from environmental factors in a stack and differences between variety of deposition parameters, the surface free energy of HfO2 films has not been fully understood. Apart from the fact that the previously reported water contact angle (WCA) of HfO2 thin or bulk films highly vary between literatures, the interpretation of surface free energy of HfO2 and its intrinsic wettability still lacks of systematic approaches. In this study, we comprehensively investigated the surface free energy variation in HfO2 films prepared by plasma enhanced atomic layer deposition (PE-ALD). Upon precise control of film thickness with the aid of PE-ALD technique, we analyzed the surface free energy changes depending on the various properties of HfO2 films including film thickness, chemical composition, surface roughness, film crystallinity. We focused on a dependency of surface free energy of HfO2 films on film crystallinity as a determining factor for wettability changes. For in-depth studies, we performed thermal annealing treatment on PE-ALD HfO2 films and observed apparent correlation between wettability and film crystallinity. Based on the control of film crystallinity, PE-ALD HfO2 thin films show versatile wetting behaviors as to exposure of liquids with different surface energies. The experimental results from our work will contribute to the fundamental understanding of surface free energy of thin film HfO2 and its scientific backgrounds, and can also lead to feasible applications including liquid separation and purifications using HfO2 as robust coating film.
References
[1] Oh, I. K. et al. Surface Energy Change of Atomic-Scale Metal Oxide Thin Films by Phase Transformation. ACS Nano (2020). doi:10.1021/acsnano.9b07430
[2] Yang, H. C. et al. Crude-oil-repellent membranes by atomic layer deposition: Oxide interface engineering. ACS Nano (2018). doi:10.1021/acsnano.8b04632
[3] Toikkanen, O. et al. Al2O3 coating grown on Nafion membranes by atomic layer deposition. J. Memb. Sci. (2015). doi:10.1016/j.memsci.2015.08.021
(Invited) Study of Mechanical Behaviour of Si Anode upon Electrochemical Lithium Insertion
Authors: Lee Seok Woo 
Published: December 2020

A battery is one of the representative electrochemical systems studied widely for energy storage applications. In particular, Li-ion batteries are becoming an essential component in mobile electronic devices and electric vehicles, as smaller, lighter, and longer energy storage is required. Silicon is considered as one of the most promising anode materials for Li-ion batteries because of its exceptional specific capacity, which is about ten times that of commercial graphite anodes. However, conventional Si anodes typically suffer from rapid capacity decay due to mechanical fracture caused by large volume changes (300%) during repeated electrochemical lithium insertion and extraction. It this talk, I will present the mechanical behaviour of various structure of single crystalline Si nanopillar upon electrochemical lithiation. Single crystalline Si nanopillar array fabricated by top-down process provides well defined dimension and crystalline orientation. The study of lithiated Si nanopillar exhibited interesting phenomena such as anisotropic expansion, size dependency of mechanical fracture, and temperature dependency [1-4]. Single crystalline Si plate various bending behaviour for the crystalline orientation and its large fracture resistance [5]. These studies will provide better understanding of mechanical behaviour of lithited Si anode for design of robust Si anode electrode.

Acknowledgement

The contents in this paper were published in references [1-5].

References

[1] S. W. Lee, et al., Nano Lett., 11, 3034 (2011).
[2] S. W. Lee, et al., PNAS, 109, 4080 (2012).
[3] S. W. Lee, et al., Nat. Comm., 6, 7533 (2015).
[4] Y. Kim, et al., in preparation.
[5] Y. Kim, et al., Energy Storage Materials, 23, 292-298 (2019).
Analysis of Scale-up Parameters in 3D Silicon-Nanowire Lithium-Battery Anodes
Authors: Schneier Dan , Harpak Nimrod , Menkin Svetlana , Davidi Guy , Goor Meital , Mados Edna , Ardel Gilat , Patolsky Fernando , Golodnitsky Diana , Peled Emanuel 
Published: December 2020

New, higher-capacity materials are required in order to address the growing need for batteries with greater energy density and longer cycle life for modern applications. We present here a study of silicon-nanowires (SiNWs) anodes, synthesized via a novel, catalysts free and scalable chemical vapor deposition (CVD) on stainless-steel mesh[1]. Our study is focused on the adaptation of the SiNWs anode in various large-scale configurations. Our research efforts have resulted in the successful scale-up of the silicon anode from Si/Li half-cells with areal capacity of 14mAh/cm2, to coin cells with commercial cathodes, industrial 1/3AAA cells and eventually multilayered pouch cells. Testing of the anodes in industrial cells demonstrated the applicability of these anodes in commercial lithium-ion batteries that can run for hundreds of cycles, withstanding fast charge and discharge and subzero temperatures. An all-solid Si/polymer electrolyte/NCA cell was also demonstrated as a proof of concept (POC). We assign the major degradation mechanism of the SiNWs anodes to the growth of the primary and secondary SEI thickness and impedance during cycling. We found that the depth of lithiation/delithiation and the voltage profile of the cell significantly affect cell's stability[2].
Figure 1- a) SiNWs anode grown on SS mesh, b) cycle life of 1Ah pouch cell with a 5.5mgSi/cm2 anode References
[1] N. Harpak, G. Davidi, D. Schneier, S. Menkin, E. Mados, D. Golodnitsky, E. Peled, F. Patolsky, Large-Scale Self-Catalyzed Spongelike Silicon Nano-Network-Based 3D Anodes for High-Capacity Lithium-Ion Batteries, Nano Lett. (2019) acs.nanolett.8b05127. doi:10.1021/acs.nanolett.8b05127.
[2] D. Schneier, N. Harpak, S. Menkin, G. Davidi, M. Goor, E. Mados, G. Ardel, F. Patolsky, D. Golodnitsky, E. Peled, Analysis of Scale-up Parameters in 3D Silicon-Nanowire Lithium-Battery Anodes Analysis of Scale-up Parameters in 3D Silicon-Nanowire Lithium- Battery Anodes, (2020). doi:10.1149/1945-7111/ab6f5a.

Figure 1
Effects of Polysulfide Solubility and Li Ion Transport on Li–S Batteries Using Sparingly Solvating Electrolytes
Authors: Ueno Kazuhide , Dokko Kaoru , Watanabe Masayoshi 
Published: December 2020

Sparingly solvating electrolytes are an emerging class of electrolytes used in Li–S batteries. In this type of electrolytes, polysulfide dissolution and shuttling can be suppressed, leading to high Coulombic efficiency and cycle life. To optimize the electrolytes for high energy density Li–S cells, effects of polysulfide solubility and Li ion transport properties on Li–S battery performance were investigated for tetraglyme (G4)- and sulfolane (SL)-based electrolytes diluted with a hydrofluoroether (HFE). The Li2S8 solubility was found to be very low (1 mM in atomic S concentration) in [Li(G4)0.8][TFSA]-4.3HFE and [Li(SL)2][TFSA]-4.0HFE. Cells with [Li(SL)2][TFSA]-4.0HFE exhibited better rate capability compared with cells with [Li(G4)0.8][TFSA]-4.3HFE despite lower ionic conductivity of [Li(SL)2][TFSA]-4.0HFE. With regard to the Li ion coordination structure in [Li(SL)2][TFSA]-4.0HFE, the two oxygen atoms of the SL sulfonyl group coordinates to two different neighboring Li ions and TFSA anions form ionic clusters with Li ions. The unique SL- and anion-bridged, chain-like Li ion coordination structure was considered to be involved in the unusual Li ion self-diffusion behavior and Li ion tranport for [Li(SL)2][TFSA]-4.0HFE. The higher Li ion transference number measured under anion-blocking condition (t
Li
+) of [Li(SL)2][TFSA]-4.0HFE was suggested to contribute to the better rate performance, rather than the polysulfide solubility and ionic conductivity. Furthermore, [Li(SL)2][TFSA]-4.0HFE demonstrated an initial discharge capacity of 1130 mAh g−1 at a low electrolyte volume to sulfur weight ratio of 4, whereas a typical organic electrolyte failed to achieve such a high capacity owing to limitations of the redox mechanism mediated by dissolved polysulfides. In addition to the low solubility of polysulfides, the high t
Li
+ is crucial for achieving high energy density Li–S batteries by reducing the electrolyte amount. The SL-based electrolytes were found to manifest a significant improvement in Li ion mass transfer as a sparingly solvating electrolyte, enabling the solid-state sulfur redox reactions in high-performance Li-S batteries.

Acknowledgement

This study was supported by the Advanced Low Carbon Technology Research and Development Program (ALCA) of the Japan Science and Technology Agency (JST).

References

1) A. Nakanishi. et al, J. Phys. Chem. C,
2019, 123, 14229.
2) M. Yanagi et al, J. Electrochem. Soc., 2020, 167, 070531.

Figure 1
Silicon Monoxide As Anode Material for Lithium Ion Batteries
Authors: Lu Wenquan , Zhang Linghong , Kirner Joel , Yang Zhenzhen , Qin Yan , Liu Yuzi , Ren Yang , Jansen Andrew N. 
Published: December 2020

Silicon monoxide (SiO) is a very promising anode material for the next generation high energy lithium ion batteries due to its high theoretical specific capacity of 1710 mAh/g and volumetric capacity of 1547 Ah/L.[1] Compared to commercially used graphite, SiO can offer 18% cell stack level improvement in volumetric energy density and 11% in gravimetric energy density (calculated based on the same cell stack model), enabling utilization of smaller and lighter batteries. It also offers more stable cycle performance compared to Si due to less volume change (134% initial volume expansion and 117% reversible volume expansion), making it a more practical choice for lithium ion batteries in the near future.
SiO is composed of Si nanodomains in a SiO2 matrix. An interphase region of transitional stoichiometry (SiOx, 0 < x < 2) is also present between Si and SiO2 and takes up 20-25 at.% of the entire composition.[2] During the lithiation and delithiation, the Si nanodomains react reversibly with lithium, similar to amorphous silicon, to give the reversible capacity. The SiO2 matrix reacts irreversibly with lithium to form lithium silicates and lithium oxide. Therefore, the Si domain size and interphase suboxide between Si and SiO2 have effect on the electrochemical performance of SiO. In this study, we gradually changed the microstructure of SiO via annealing treatment and thoroughly studied the change of the SiO microstructure and its impact on the electrochemical performance of the SiO. Together with electrode formulation optimization, up to 99% capacity retention during 50 cycles was obtained in full cells when using pure SiO as anode and LiNi0.5Mn0.3Co0.2O2 as cathode.

Acknowledgement

We gratefully acknowledge the support from Peter Faguy at the U.S. Department of Energy’s (DOE) office of Energy Efficiency & Renewable Energy (EERE) - Vehicle Technologies Office. This work is conducted under the Cell Analysis, Modeling, and Prototyping (CAMP) Facility at Argonne National Laboratory. Argonne National Laboratory is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357.
Reference:

Obrovac, M. N.; Chevrier, V. L., Alloy Negative Electrodes for Li-Ion Batteries. Chemical Reviews 2014, 114 (23), 11444-11502.

Hirata, A.; Kohara, S.; Asada, T.; Arao, M.; Yogi, C.; Imai, H.; Tan, Y.; Fujita, T.; Chen, M., Atomic-scale disproportionation in amorphous silicon monoxide. Nature Communications 2016, 7, 11591.
Preparation of Artificial SEI Containing LiNxOy on Lithium Metal Anode By Solid-Gas Interface Reaction for Sulfolane Electrolyte
Authors: Iwahara Ryohei , Nara Hiroki , Momma Toshiyuki , Osaka Tetsuya 
Published: December 2020

Li-S battery is promising next generation energy storage device, and lithium metal anode is promising electrode due to its low electrochemical potential and high theoretical specific capacity. However, the Li metal anode in Li-S battery has problems such as short circuit by growth of dendrite and low coulombic efficiency by continuous electrolyte decomposition. In past study, it was reported that high concentration sulfolane electrolyte attributed to prevent polysulfide dissolution into electrolyte and suppressed shuttle effect.1) Also, by adding LiNO3 into electrolyte, stable passivation film formed on lithium metal anode, and lithium deposition became rounded shape and dendrite was suppressed, and long life was reported to be achieved.2)3) While LiNO3 does not dissolve much in high concentration sulfolane electrolyte, in this study, in order to achieve the effect of LiNO3 even with high concentration sulfolane electrolyte, artificial SEI including LiNxOy made by solid-gas reaction was examined. Solid-gas reaction is considered to have also the advantage for the mass production.
In order to produce artificial SEI containing LiNxOy on Li metal anode, which is LiNO3-derived component, polished Li foil was exposed to NO2 gas for 1 h. For the purpose of reacting fresh Li metal surface with NO2 gas, surface of Li foil was polished until metallic luster appeared.
Fig. 1 shows XPS spectra (N1s) of polished Li and NO2 exposed Li. Fig. 1 shows the existence of LiNxOy by an exposure to NO2.
Fig. 2 shows charge-discharge curves in Li/Li symmetrical cells. Fig. 2(a) shows charge-discharge curve using the polished Li, and Fig. 2(b) shows the one exposed to NO2. In Fig. 2(a), short circuit was recognized by only 5 cycles of charge and discharge. Contrastingly, analogous voltage profile was obtained for 16 cycles, as shown in Fig. 2(b). In addition, from Fig. 2(b), a larger overvoltage in voltage plateau was confirmed than that in Fig. 2(a). The reason is considered to be that Li electrode surface is covered with artificial SEI composed of inorganic components such as LiNxOy having relatively high ionic resistance. In addition, it was suggested that the artificial SEI improved the morphology of lithium deposition to smoother one from the SEM investigation.
With an exposure to NO2 on Li metal anode, it was confirmed that artificial SEI containing LiNxOy was prepared and contributed to a certain improvement in cycle life in Li/Li symmetrical cell.

Acknowledgement

This work was partly supported by Advanced Low Carbon Technology Research, Development Program Special Priority Research Area “Next-Generation Rechargeable Battery” (ALCA-Spring) from the Japan Science and Technology Agency (JST) (Grant Number JPMJAL1301).

Reference

1) Azusa Nakanishi et al, Phys. Chem. C, 2019, 123, 14229-14238
2) Allen Pei et al, Nano Lett. 2017, 17, 2, 1132-1139
3) Doron Aurbach et al, J. Electrochem. Soc., 2009, 156, A694

Figure 1
Fabrication of High Burn Rate Fuse Strip for Thermal Battery
Authors: Park Tae-Ryong , Kim Kiyeol , Ahn Tae-Young , Cho Jang-Hyeon 
Published: December 2020

Thermal batteries are widely used in various military applications such as missiles and torpedoes due to high power output, long shelf-life, and reliability. In order to react quickly to an enemy, quick activation time of the thermal battery is required. In the process of activation, fuse strip transfers heat energy to the heat source of each layer. Therefore, to achieve short activation time, fuse strip with high burn rate is highly needed. However, although there are lots of variables affecting burning rate of fuse strips, such as a combination of fuel and oxidizers, additives and particle size, it's not well-studied yet.
In this study, we fabricated high burn rate fuse strips by applying additives and new oxidizer. Usually, to fabricate fuse strip, Zr and BaCrO4 slurry is deposited onto supporting ceramic paper and then dried. In order to improve burn rate, we additionally applied HDC-M10, NH4HCO3 and PbO into the Zr/BaCrO4 slurry. The retention agent HDC-M10 makes the dispersion solution stable, making the structure of fuse strip uniform. And the blowing agent NH4HCO3 controls the distance between the particle that makes optimal heat transfer path between the Zr and BaCrO4 particles. Also, PbO was chose as the best additional oxidizer among other several oxidizers which has appropriate reactivity, burn rate and heat calories. The mixed slurry was placed on a sheet former and then made into hollow cylindrical shape. The burning rate was then measured by self-made burning rate measurement equipment. As a result, we observed 10 times improved burn rate than previous studies. In addition, the fuse strip was applied to the thermal battery and its test result is also presented in this study.
Patterned GeSn Strip Growth on Si By Sn Self-Catalyzed Method
Authors: Li Chuanbo , Zhao Yue , Zhang Xiaoming , Feng Shuai , Cheng Buwen 
Published: December 2020

GeSn has been attracted much attention in recent years due to its direct band characteristic. However, due to the large lattice mismatch and the low solid solubility of Sn in Ge, the growth of GeSn on Si is still a challenge. Thick-layer GeSn alloy have been grown by molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) by applying the low-temperature-grown Ge buffer layer, but there is still high the dislocation density(more than 107cm-2) and it limits its application in optoelectronics. We have reported a simple way to grow the defect-free GeSn alloy strips on Si substrates with the assistance of Sn metal. It can be lateral grown on Si(111) by Sn self-catalyzed method. The GeSn materials are grown in a MBE system with a base pressure of 5 × 10−8 Pa.
Here we will report our recent progress of the growth of GeSn wires and GeSn pattern on pattered substrate. It is found that GeSn materials can be selected grown in the patterned window. The size of wires can be down to 100 nm. We can grow 10x10 GeSn pattern with size of 2um x 2 um and 5 um x 5um. Here we will also discuss the growth mechanism and the impact factors on the growth of GeSn materials. It is found that Sn has an important impact on morphology of the GeSn wires and different depositions and annealing times of Sn will impact their morphology. GeSn alloy strips show a good quality by the TEM micrographs and the SAED patterns. It has an important application in Si based laser and photodetectors.
Impact of Contact Doping on Electrical Characteristics in WSe2 FET
Authors: Matsuzaki Takahiro , Kawanago Takamasa , Oda Shunri 
Published: December 2020

Since layered semiconductor tungsten diselenide (WSe2) has no dangling bond and a relatively large band gap, it is expected as a channel material for an application of field effect transistor (FET)[1]. On the other hand, high energy process destroys the crystal structure of the layered semiconductor. In this context, carrier doping by the low energy process is important for improving the electrical characteristics. This study reports that CYTOP (9 wt%) was applied as a doping material on the WSe2 FET for p-type operation by spin coating and the impact of contact doping on the electrical characteristics was investigated. A SiO2 gate dielectric was formed on a heavily-doped p-Si substrate (p+-Si) using thermal oxidation for back-gate structure. Next, a source / drain of Au (40 nm) / Ti (10 nm) was prepared by using photolithography and lift-off. Using a PDMS stamp and a micromanipulator, WSe2, which was mechanically peeled off using Scotch tape, was transferred between the source and drain to fabricate a back-gate WSe2 FET. After measuring the electrical characteristics without CYTOP, CYTOP was applied on the WSe2 FET surface using a spin coating. Then, the electrical characteristics with CYTOP were measured again. In this study, the annealing was performed for 30min at 200 ° C and 250 ° C. Id-Vg characteristics as a function of annealing temperature of the fabricated back gate WSe2 FET are shown in Fig. 1. From the Fig. 1, it can be confirmed that WSe2 FET shows p-type operation. Moreover, it can be confirmed that the drain current increases by applying the CYTOP, while the low drain current was observed without CYTOP. It was found that the drain current was increased with increasing the annealing temperature.
[Acknowledgments]
The authors would like to thank Professor Y. Kawano, Professor T. Hoshii, Professor I. Muneta, Professor K. Kakushima, Professor K. Tsutsui, and Professor H. Wakabayashi of Tokyo Institute of Technology for their continuous support in the experiments. This study was supported by JST CREST (Grant No. JPMJCR16F4) and a JSPS Grant-in-Aid for Scientific Research (C) (Grant No. 20K04616).
[References]
[1] In-Tak Cho et al., Applied Physics Letters 106, 023504 (2015).

Figure 1
(Invited) Printing Optical Materials
Authors: Li Xinhao , Du Huifeng , Liu Zhiguang , Fang Nicholas Xuanlai 
Published: December 2020

Will future of smart lighting and window coatings enable energy-efficient cooling in smart buildings? Can printed color converters lead to next generation micro displays with high brightness, sharp image resolution, and ultra‐low power consumption? Recently, exciting new physics of nanoscale optical materials has inspired a series of key explorations to manipulate, store and control the flow of information and energy at unprecedented dimensions. In this talk we will report our recent efforts on controlling light harvesting and conversion process using scalable micro/nanofabrication. These emerging optical materials show promise to a range of important applications, from optical networks and chip-scale photonic sensors to lasers, LEDs, and solar technology.
For example, pixelated color converters are envisioned to achieve full-color high-resolution display through down conversion of blue micro-LEDs. Quantum dots (QDs) are promising narrow-band converters of high quantum efficiency and brightness enabling saturated colors. However, challenges still remain to produce high resolution color-selective patterns compatible with the advanced blue micro-LEDs with pitch and pixel size approaching 1 µm. Here we demonstrate our preliminary study on scalable printing of high-resolution pixelated red and green color converters patterned through projection lithography. We will also discuss potential applications such as high-resolution wide-gamut microdisplay for mixed reality and high speed visible light communication.
In this talk, We will also introduce versatile 3D shape transformations of nanoscale structures by deliberate engineering of the topography-guided stress of gold nanostructures. By using the topography-guided stress equilibrium, rich 3D shape transformation such as buckling, rotation, and twisting of nanostructures is precisely achieved, which can be predicted by our mechanical modeling. Benefiting from the nanoscale 3D twisting features, giant optical chirality is achieved in an intuitively designed 3D pinwheel-like structure, in strong contrast to the achiral 2D precursor without nano-kirigami. The demonstrated nano-kirigami, as well as the exotic 3D nanostructures, could be adopted in broad nanofabrication platforms and could open up new possibilities for the exploration of functional micro-/nanophotonic and mechanical devices.