bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) In Situ Investigation of Interface Evolution and Chemo-Mechanics in Batteries
Authors: McDowell Matthew T
Published: December 2020

It is critical to understand how energy storage materials transform and degrade within devices to enable the development of next-generation batteries. In my research group, multi-scale in situ techniques are used to reveal reaction mechanisms and interfacial transformations in battery materials. In this talk, I will first present our recent work on understanding and controlling transformations at interfaces between solid-state electrolytes and lithium electrodes within solid-state batteries, where we use interlinked in situ investigations to investigate how these interfacial transformations control chemo-mechanical degradation. In situ X-ray tomography experiments of operating NASICON-based cells reveal that the growth of the interphase causes fracture of the SSE, and quantification of the crack network shows that the extent of fracture with time is directly correlated to impedance increases within the cell. In situ transmission electron microscopy (TEM) shows that the reaction of LAGP with lithium is similar to a conversion reaction, in which lithium insertion causes amorphization and volume expansion of ~130%. The use of structured alloy anodes is shown to be effective for controlling degradation and improving cycle life. Finally, I will discuss results on understanding how chemo-mechanics controls the transformation process of nanocrystal-based battery anodes. Specifically, sufficiently small antimony nanocrystals with native oxide are found to undergo spontaneous and reversible hollowing during delithiation, and this process is found to be driven by the energetic balance between void formation and oxide shell buckling. Together, these findings show the importance of controlling chemo-mechanics in next-generation battery materials, with in situ experiments being critical for understanding these processes.
Ambient Na-S Discharge Mechanisms in Glyme Electrolytes Identified with in-Situ Optical Microscopy
Authors: Carter Rachel E. , NewRingeisen Addison , Reed Daniel , Sassin Megan B. , Mukherjee Partha P. , Love Corey T.
Published: December 2020

Ambient Na-S systems have regained attention as global abundance of materials becomes a concern for Li-ion batteries.1 The fundamental Na-S system consists of a sulfur cathode, liquid electrolyte and a sodium anode, and it can be informed by discoveries in Li-S and Li metal battery research. Early Li-S research identified the propensity for various Li-S discharge products to solubilize in the electrolyte. This behavior proved crucial to performance. Because the analogous solubilized Na-S discharge products have distinct colors in the visible spectrum, we employ a specially designed in-situ electrochemical cell, developed at the Naval Research Laboratory,2 to track electrolyte color during discharge. This optical tracking allows the identification of the chronology of solubilized discharge products and assess the efficacy of promising electrolytes. The discharge products (Na2Sn, 8<n<1) and relative quantities are determined via their distinct colors, and UV-vis calibration, respectively. Since these behaviors prove strongly dependent on electrolyte solvent and salt concentration, the study is valuable to selection of the optimal composition for anode stability and cathode performance.

1.Carter, R.; Oakes, L.; Douglas, A.; Muralidharan, N.; Cohn, A. P.; Pint, C. L., A Sugar-DerivedRoom-Temperature Sodium Sulfur Battery with Long Term Cycling Stability. Nano Letters 2017, 17 (3),1863-1869.

2.Love, C. T.; Baturina, O. A.; Swider-Lyons, K. E., Observation of Lithium Dendrites at AmbientTemperature and Below. Ecs Electrochem Lett 2015, 4 (2), A24-A27.
(Invited) Heterogeneous Integration of GaN and Ga2O3 with High Thermal Conductivity Substrates Via Surface Activated Bonding
Authors: Mu Fengwen , Suga Tadatomo
Published: December 2020

The high-power high-frequency devices of both GaN and Ga2O3 needs careful thermal management to migrate the self-heating effect during operation. One promising strategy is to integrate GaN and Ga2O3 with a high thermal conductivity substrate such as SiC and diamond. Epitaxial growth, usually at high temperature, met many challenges because of the lattice mismatch and thermal expansion mismatch. Recently, we realized room-temperature bonding of GaN and Ga2O3 with high thermal conductivity substrates via surface activated bonding methods, which can avoid the transition layer necessary for growth method and make the GaN or Ga2O3 device close to the high thermal conductivity substrates as much as possible.
Phase Transformation in Germanium-on-Insulator (GeOI) Films Using Raman Spectroscopy and Nanoindentation
Authors: Mohammed Yousuf , Zhang Kai , Heissler Stefan , Baumgart Helmut - , Elmustafa Abdelmageed
Published: December 2020

Germanium-on-insulator (GeOI) films fabricated using the SMART CUT wafer bonding and film exfoliation technology were investigated for the mechanical properties and induced phase transformations by using nanoindentation and Raman spectroscopy experiments. The hardness and modulus results of the GeOI films are significantly different from the published SOI literature and bulk germanium results obtained by Liu et al., 2020 [1] and SOI films results obtained by Miller et al., 2007 [2]. From our measured hardness results of 8 to 10 GPa for very thin single crystal Ge(100) films compared to 13.1 GPa for Bulk Ge (100), one can conclude that the thinning of crystalline Ge films leads to a considerable softening of the crystalline Ge resulting in less brittle robust films. Similarly, our measured modulus of 130 to 140 GPa for thin Ge (100) films compared to the reported bulk Ge (100) value of 157 GPa corroborates these research findings. The GeOI films are softer and more flexible as compared to bulk Ge hardness and stiffness properties. The Raman spectroscopy of the spherical indents indicate bands of metastable Ge phases @ 220 cm-1, 195 cm-1 and 184 cm-1 wavenumbers. Our results demonstrate that a spherical indenter impacted a wider area of contact and produced GeOI indented surfaces free of cracks and fracture. The spherical indenter tip kept the Ge top layer intact when compared to the Berkovich indenter tip during penetration. In contrast, the Berkovich indenter tip developed excessive fracture that resulted in displacing the Ge top layer sideways and exposed the Si substrate underneath revealing Raman spectra bands of metastable Si phases @ 350 cm-1, 399 cm-1 and 430 cm-1.

Apart from the well documented electrical advantages of GeOI, the reported research on the nanomechanical properties reveals considerable softening and flexibility of the very thin exfoliated single crystal Ge films that promise added benefits and further implications for enhancing potential device application of GeOI wafers for process integration.

1.] N. Liu, X-J Yang, Z. Yu, and L. Zhao, Trans. Nonferrous Met. Soc. China, 30, 181 (2020).

2.] N. Miller, K. Tapily, H. Baumgart, G.K. Celler, F. Brunier, and A.A. Elmustafa, Mater. Res. Soc. Symp. Proc. Vol. 1021 © 2007 Materials Research Society, 1021-HH05-24. Boston, Massachusetts. (2007).
(Invited) Copper Surface Passivation for Low Temperature Cu-to-Cu Bonding Applications
Authors: Park Hae-Sung , Seo Han Kyeol , Kim Gahui , Park Young-Bae , Kim Sarah Eunkyung
Published: December 2020

As the IC devices are rapidly scaled down, IC integration has faced several technical bottlenecks: further miniaturization, power delivery and distribution, signal/power integrity, and heat dissipation. In this regard, chip or wafer stacking processes have attracted attention to improve an interconnect delay and an inter-die bandwidth, reduce a form factor, and decrease manufacturing costs. Vertically stacking technology not only enhances device performance, but also can realize heterogeneous packaging systems for the next generation heterogeneous integration. Of the three unit processes in the vertical stacking system, Cu-to-Cu bonding has emerged as a core technology for efficient power density, high bandwidth, and fine-pitch connecton.

Various Cu-to-Cu bonding studies have been reported, such as thin metal passivation on Cu surface, self-assembled monolayer that passivates Cu surface with alkane-thiol, surface activated bonding that removes surface oxide layers and contaminants by plasma treatment, and direct bonding interconnect that enables Cu/SiO2 hybrid bonding. Despite many studies, Cu surface oxidation and high bonding temperature are still major issues to be resolved in high volume manufacturing. Sustainable, oxidization-free copper surface prior to Cu-to-Cu bonding is critical, especially since chip-to-chip bonding must still be performed in the air. Therefore, in this study, the copper surface passivation using the two-step plasma treatment has been investigated.

The Cu-to-Cu bonding process of less than 300℃ was investigated using the copper nitride passivation. The copper nitride passivation layer was formed on 8-inch Si/SiO2/50nm Ti/1μm Cu using the two-step Ar-N2 plasma treatment process. The purpose of two step plasma treatment is first to remove copper oxides and any contaminants through Ar plasma, activate the Cu surface, and then form a copper nitride layer through N2 plasma. This metastable passivation of couple nanometer thickness prevents further oxidation and reduces surface roughness. In addition, since a copper nitride tends to decompose at 300oC or lower it does not adversely affect Cu bonding interface. The two-step plasma treatment was optimized to improve Cu bonding quality, and optimization was systematically carried out by the response surface methodology (RSM) based on a central composite design (CCD) in design of experiment (DOE). It has been found that copper nitride passivation lasts at lasts for 1 week.. The two-step plasma treatment showed the Cu2O removal and Cu4N formation on the Cu surface. Under the optimized two step Ar-N2 plasma treatment at 300℃, Cu-to-Cu bonding quality has significantly improved compared to the Cu-to-Cu bonding without any surface treatment. The interfacial strength measured by 4-point bending test and shear test and electrical measurements will be discussed.
Nanostructural Investigation on GaAs//Indium Tin Oxide/Si Junctions for III-V-on-Si Hybrid Multijunction Cells
Authors: Hara Tomoya , Liang Jianbo , Araki Kenji , Kamioka Takefumi , Sodabanlu Hassanet , Watanabe Kentaroh , Sugiyama Masakazu , Shigekawa Naoteru
Published: December 2020

Hard X-ray photoemission spectroscopy (HAXPES) measurements and transmission electron microscopy (TEM) observations are performed on GaAs thin film//Indium tin oxide (ITO)/Si junctions fabricated by surface-activated bonding and selective wet etching. Both of the Ga-O/Ga-As ratio in the Ga 2p3/2 HAPES core spectrum (Fig. 1(a)) and As-O/As-Ga ratio in the As 2p3/2 HAXPES core spectrum (Fig. 1(b)) demonstrate that the GaAs layers are oxidized after annealing at 400 °C. This observation is consistent with the formations of a ~1-nm-thick intermediate layer in the cross-sectional TEM image of the junctions after the 400 °C annealing, as is shown in Figs. 2(a) and 2(b). It is found by using in-house X-ray photoelectron spectroscopy in combination with Ar+ bombardment that the oxide layers are formed at GaAs//ITO bonding interfaces after annealing at 200 °C or higher temperatures. The observation of the oxide layers corresponds with the onset of resistivity increase in GaAs//ITO/Si junctions due to the annealing [1]. These results suggest that annealing brings about the reaction between GaAs and ITO layers and hence the oxidation of GaAs layers, which causes the degradation of the electrical properties of GaAs//ITO/Si junctions. A fabrication process at lower temperatures is likely to be required so as to fully exploit the advantage of ITO as intermediate layers in III-V//Si hybrid tandem solar cells with lower series resistance.

[1] Tomoya Hara, Tomoki Ogawa, Jianbo Liang, Kenji Araki, Takefumi Kamioka, and Naoteru Shigekawa, "Electrical properties of GaAs//indium tin oxide/Si junctions for III-V-on-Si hybrid multijunction cells", Jpn. J. Appl. Phys. 57, 08RD05 (2018). DOI: 10.7567/JJAP.57.08RD05

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Modeling and Understanding Variations in Redoxmer Cyclability
Authors: Silcox Benjamin , Zhang Jingjing , Zhang Lu , Thompson Levi
Published: December 2020

Non-aqueous redox flow batteries (RFBs) offer several benefits over aqueous RFBs including higher cell voltages and energy densities. Among candidate active materials for nonaqueous RFBs, redox active organics, or redoxmers, offer several advantages including low cost and high solubility in non-aqueous solvents. However, they currently lack the stability and cyclability to be used beyond laboratory scale. One challenge complicating redoxmer performance characterization is dependence on electrolyte choice and experimental conditions. We performed bulk electrolysis on three common catholyte materials while varying concentration, cycling rate, and electrolyte to identify trends in cyclability and recovery. In this talk, we report the results of these comprehensive cycling experiments, the ensuing trends, and preliminary modeling to help identify ideal conditions for cycling these redoxmers.
First-Principles Study of Layered Transition Metal Oxides As a Cathode Material for Ca-Ion Intercalating Batteries
Authors: Park Haesun , Zapol Peter
Published: December 2020

The Ca-based rechargeable batteries are a promising direction in multivalent energy storage that requires development of the intercalating cathode materials capable of high voltage and capacity. Given that monovalent alkaline metals (e.g. K, Na) with similar ionic radius of Ca can be reversely stored in layered transition metal (TM) oxides, we infer that divalent Ca-ion can be as well. Here, we demonstrate on the basis of first-principles calculations that layered TM oxides exhibit favorable thermodynamic and kinetic properties that enable topotactic Ca intercalating reactions. From the calculated phase diagram, the layered CaXCo2O4with space groups of P1 and P21/m are stable at multiple Ca concentrations x ranging from 0 to 1 and show a smooth voltage plateau higher than 3V up to x=0.5. The Ca migration barriers calculated by nudged elastic band method can be as low as 0.36 eV and 0.27 eV at the dilute and high vacancy concentration limits, respectively. At the intermediate vacancy concentration, the calculated migration barriers depend on the local vacancy environments of diffusing atom, and stochastic analysis of Ca hopping events performed by ab initio molecular dynamics (AIMD) simulation has shown that the migration barriers are still lower than 0.32 eV. Therefore, the Ca diffusivity at room temperature extrapolated from the AIMD results is comparable to Li diffusivity, suggesting feasibility of use of layered CaxCo2O4 as multivalent cathode materials. We will also discuss the trends in thermodynamic and kinetic properties as the TM in the layered structure is substituted with other TM species.
(Invited) C-14 Powered Dye-Sensitized Betavoltaic Cells: Next Generation Battery
Authors: In Suil
Published: December 2020

A dye sensitized betavoltaic cell has been developed for the first time, which utilizes radioisotopic carbon, composed of nano-sized quantum dots, and ruthenium-based dye sensitized TiO2 as electrodes. The dye-sensitized betavoltaic cell (DSBC) is an energy generating device with a MLCT-based ruthenium ligand complex dye and a C-14 as a beta radiation source and a counter electrode. This combination allows for relatively efficient electron harvesting for improved performance in a betavoltaic device. The DSBC system using the Ru-N719 dye had an energy efficiency of 0.48%. If some problems are improved, DSBC can be used as a semi-permanent battery.We opened the new horizon that is explored first time in the field of betavoltaic. We believe it has potential to show higher efficiency through modifications such as optimization of TiO2 thickness, dye loading and energy control of beta radiation. The use of dye-sensitized semiconductor anodes in modified betavoltaic cells will create new opportunities in the field of nuclear batteries. The figure below shows an illustrated mechanism for dye-sensitized betavoltaic cell.

Figure 1
Promoting Lithium Electrodeposition Towards the Bottom of 3-D Copper Meshes in Lithium-Based Batteries
Authors: Kim Sujung , Kim Yena , Nguyen Chi Thang , Jang Taegyu , Lee Han-Bo-Ram , Byon Hye Ryung
Published: December 2020

Lithium (Li) has been considered as the promising negative electrode in rechargeable batteries, owing to the negative redox potential (-3.04 V vs. SHE), low density (0.534 g/cm3), and high theoretical specific capacity (3,860 mAh/g). However, the non-uniform stripping/plating process of the metallic Li is still challenging.[1] As one of the solutions, three-dimensional (3-D) metallic scaffolds were introduced to the negative electrode. The uniform electric field applied in the porous scaffolds could suppress the dendritic growth of the Li during the plating process. In addition, a decrease in the effective current density prolonged Sand’s time.[2] However, such a Li deposition mainly proceeded on the top surface and led to rapid surface clogging due to the strong surface electric field. In this presentation, we show the preferred Li deposition inside the 3-D copper (Cu) scaffold using gold nanoparticles (Au NPs). The lower Li nucleation energy barrier on the Au surface than that on the typical Cu current collector was investigated intensively.[3] However, the role of Au for spatially promoting Li deposition was not studied in depth. We added the Au NPs with an average particle size of ~7.5 nm to the bottom of 3-D Cu. The Au NPs with a total ~28 nmol reduced the charge-transfer resistance, which suggested the fast Li nucleation on the Au. In addition, we coated aluminum oxide (Al2O3) layer with ~ 26 nm of thickness on the top surface of 3-D Cu scaffold through the atomic layer deposition (ALD) process. This insulating layer further suppressed the Li deposition on the surface. As a result, apparent Li deposition towards the bottom of 3-D Cu was clearly demonstrated. During Li plating/stripping cycles, the surface clogging of the 3-D Cu/Au by an accumulation of solid electrolyte interphase (SEI) was also dramatically alleviated even in the absence of Al2O3 layer. It demonstrated the continuous Li deposition towards the bottom of the 3-D Cu/Au scaffold. Besides, symmetric 3-D Cu/Au cells exhibited over 95 % of Coulombic efficiency (CE) for ~120 cycles. The full cells comprised of the 3-D Cu/Au and LiFePO4 (LFP) electrodes delivered stable 300 cycles with a capacity of ~140 mAh/g at 1 C-rate. I will discuss the detailed role of the Au NPs and the Al2O3 layer, and comparative cell performances in the presentation.

References

[1] D. Lin, Y. Liu, and Y. Cui, Nat. Nanotechnol.
12 (3), 194-206 (2017).

[2] P. Bai, J. Li, F. R. Brushett, and M. Z. Bazant, Energy Environ. Sci.,
9 (10), 3221-3229 (2016).

[3] K. Yan, Z. Lu, H.-W. Lee, F. Xiong, P.-C. Hsu, Y. Li, J. Zhao, S. Chu, and Y. Cui, Nat. Energy,
1 (3), 16010-16017 (2016).

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Flower-petal Grain Layered Li[Ni89Co0.10Sb0.01]O2 as Next-generation Cathode Material
Authors: Sun HoHyun , Weeks Jason A. , Dolocan Andrei , Heller Adam , Mullins Charles Buddie
Published: December 2020

In layered oxide cathodes for lithium-ion batteries, nickel provides high capacity but compromises stability. Although much progress has been made in upsetting this trade-off, the stability of Ni-rich cathodes is not yet adequate to satisfy the expectations of commercial batteries. Here, a layered Li[Ni0.89Co0.10Sb0.01]O2 cathode material, which overcomes the instabilities associated with highly Ni-rich cathodes to deliver excellent capacity retention, is reported. This cathode shows a significantly enhanced resistance to performance deterioration and microcrack propagation compared to the more conventional Li[Ni0.885Co0.10Al0.015]O2 material. Furthermore, it delivers more capacity than its counterpart despite the same nickel content. The robustness of the material arises from the ordering of the grains into a dense flower-petal arrangement, which collectively preserves the coherency of the particle. Through extensive cross-sectional imaging and chemical mapping, a correlation between microcracks and electrolyte infiltration into the particle is demonstrated.

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Parametric study of lithium-ion battery using electrochemical model in conjunction with machine learning techniques
Authors: Pathak Anil Daliprasad , Gogineni Ajay K , Pati Soobhankar , Sahu Kisor Kumar
Published: December 2020

Lithium-ion batteries (LIBs) are widely used in consumer electronics because of its high energy density, superior rate capability, and long cycling life. Lately, the demand for LIBs in other sectors such as automobiles and grid level storage has been growing because of emphasis on renewable energy. However, performance such as rate of charging, energy density, and cost of storing energy ($/kWh) of LIBs does not meet the US-DOE targets for battery electric vehicles. Since, the LIB consists of several components like cathode, anode, electrolyte and separator, its performance is limited by the performance of individual components in the assembled LIB. Further, the performance represents the full LIB and it is difficult to isolate the performance of individual components in the assembled battery. Electrochemical modelling can be extensively used to identify the limitation and improve the performance of individual components since it is an efficient, and cost effective tool. In this work, an isothermal electrochemical model is developed for LIBs with LiC6 anode; LiPF6 based electrolyte, and LiMnO4 cathode. A porous electrode theory is used to describe the insertion and de-insertion of Li+ ions into electrode. A concentrated solution theory is used to describe the transport mechanism in the electrolyte. The Butler-Volmer kinetics is used to model reactions at the electrode/ electrolyte interface.

The electrochemical model developed is solved using COMSOL Multiphysics® 5.1a finite element modelling software. The modeling results are verified with the experimental results available in the literature. The model is used to evaluate the influence of various design parameters that influence the performance of LIB such as the electrode dimensions, structure, conductivity, etc. Furthermore, the electrochemical model data was used to develop machine learning techniques such as random forests (RF), support vector machine (SVM) and gradient boosting (GB) for feature-analysis of the LIB parameters. Feature analysis, an extremely important metric for estimating relative importance of a particular parameter, were studied towards understanding the relative importance of other parameters for maximizing energy and power density of a battery. Random forest techniques performed well for predicting the energy density which is depend on thickness (after current) but gradient boosting failed to predict it (as shown in Fig.1). However, gradient boosting techniques performed well for forecasting power density which depend on conductivity (after current), here random forest failed to predict this. Without such feature-analysis by machine learning techniques, it would have been very difficult to have a quantitative estimation of their ranking towards understanding the relative importance of other battery parameters for maximizing energy and power density of LIBs.

Figure 1
Synchronized Lithium and Lithium-Ion Battery Enabled to in-Situ Replenishment for Enhancing Battery Life
Authors: Palanisamy Manikandan , Parekh Mihit H. , Pol Vilas G.
Published: December 2020

In-situ replenishment of formation cycle lithium-ion loss is considered for the development of longer-lasting rechargeable batteries that uses lithium-electrode, which acts as a reservoir and booster-electrode to mitigate the formation cycle capacity loss in mesocarbon microbeads (MCMB) anode vs LiFePO4 cathode and C-Si anode vs LiNi1/3Mn1/3Co1/3O2 cathode in standard electrolyte. For the synchronized lithium and lithium-ion battery (SLLIB) – full-cell specific charge- discharge capacities were 146/ 144 mAh g–1 for MCMB vs LiFePO4 and 187/ 171 mAh g–1 for C-Si vs LiNi1/3Mn1/3Co1/3O2 configurations at 0.2 C rate. The irreversible capacity loss compensation from the reservoir-electrode, offered to a renewed voltage profiles and recovered electrodes specific capacities by reservoir replenishment and replenished cycling. The energy reduced cell due to SEI formation of MCMB and C-Si anodes was replenished and achieved increased energy density of 455 Wh kg–1 with retained flat-voltage profile for SLLIB – MCMB vs LiFePO4 and 576 Wh kg–1 for SLLIB – C-Si vs LiNi1/3Mn1/3Co1/3O2 through Li+ ion in-situ reservoir replenishment from the reservoir-electrode to MCMB/ C-Si anode. Furthermore, reservoir reserve mode cycling of SLLIB configurations were delivered the charge-discharge capacities of 126/ 124 mAh g–1 for SLLIB – Li vs LiFePO4 and 137/ 136 mAh g–1 for SLLIB – Li vs LiNi1/3Mn1/3Co1/3O2 at 0.2 C, associated with the Li+ ion transportation between reservoir-electrode and LiFePO4/ LiNi1/3Mn1/3Co1/3O2 cathode, confirmed by Li+ ion diffusion path through MCMB and C-Si electrodes, using EIS analysis. Ultimately, the in-situ reservoir replenishment, replenished cycling and reserve mode cycling processes of synchronized lithium and lithium-ion battery leads to enhanced battery life.

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Development of Non-Deteriorating Lithium-Sulfur Battery
Authors: Machida Kazuki , Ushioda Yusuke , Inaba Kohei , Miyauchi Hibiki , Takahashi Keitaro , Seki Shiro
Published: December 2020

To resolve energy issues, the demand of large-scaled capacity storage batteries are increasing. Therefore, the realization of lithium-sulfur (Li-S) battery, which is one candidate of the next-generation high-performance innovative battery systems, is strongly desired. In general, lithium metal is used as the negative electrode for Li-S batteries. On the other hand, elemental sulfur (S8) is also used as the positive electrode, and it has high theoretical reversible capacity of 1,672 mAhg-1. However, effect of Li metal negative electrode is unclear due to their chemical properties with charge/discharge process. In this study, we applied Li-doped negative electrode for suppressing the Li-dendrite formation. Therefore, we obtained Li4Ti5O12 (LTO) electrode as stable negative electrode, which is strain-free intercalation material, and high reversible characteristics of battery system are expected.

To applying LTO for Li-S batteries, electrochemical doping of Li into LTO is required owing to their lack of carrier ion into LTO. Therefore, at first [Li| electrolyte |LTO] cells were assembled by using disassemble cell, which can be easily taken out cell materials without short circuit into inert atmosphere (e.g., glove box). After takeoff of Li-doping LTO (Li-LTO), lithium (Li-doped) -sulfur battery was fabricated by using SPAN as sulfur positive electrode ([Li-LTO|1M-LiFSI EC/DEC=3/7|SPAN] cell). (SPAN:developed non-degraded S positive electrode). Charge / discharge performance of prepared cells were evaluated.

Fig. 1 (a) and (b) shows the charge and discharge profiles and the cycle number dependences of coulombic efficiency for prepared cell at 303K. Although operating voltage and capacity are relatively low, charge and discharge over 2000 cycles were observed. Therefore, this cell has suitable constitution in battery materials. Within 200 cycles, high coulombic efficiencies (about 99.9%) were always observed. Therefore, it suggests the possibility of realizing a non-degraded battery, which has high reversible characteristics by using Li-LTO electrode and SPAN electrode.

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Modifying Carbon Felt Electrodes Using High-Temperature Ammonia Treatment to Improve the Performance of All-Vanadium Redox Flow Batteries
Authors: Gass Kaycee , Bera Bapi , Aaron Douglas , Mench Matthew M
Published: December 2020

High temperature ammonia treatments were performed on carbon felt electrodes in this study. Their physical and electrochemical properties were investigated.

Carbon felt electrodes are often used in vanadium redox flow batteries (VRFBs). Without intervention, carbon felt has poor wettability which frustrates electrochemical activity. This material must be modified to make it more effective, which has been historically accomplished with thermal treatments to promote oxygen functional groups. [1] Many attempts have been made to improve performance of carbon felt in VRFBs, but some of the more successful modifications have resulted in an increase in the specific surface area. [2-4] Preliminary experiments on carbon felt performed by this lab with ammonia at high temperatures have shown promising results. [5]

For our experiments, commercially available carbon felts (SIGRACELL® GFD3 by SGL Carbon, Meitingen, Germany) were modified by exposure to flowing ammonia gas through a furnace at 900°C for varying lengths of time. The samples were tested in a single-cell flow battery using cyclic voltammetry (CV), polarization curves, and electrochemical impedance spectroscopy (EIS). This treatment results in a significant increase in electrochemical surface area and performance.

The physical properties were characterized using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and Raman spectroscopy. A pitting effect was observed in SEM images, preceded by surface blistering at shorter lengths of exposure.

Greatly increased active surface area, along with a substantial increase in cell performance, was achieved with the ammonia-modified carbon felts described in this work.

Sun, B. and M. Skyllas-Kazacos, Modification of graphite electrode materials for vanadium redox flow battery application—I. Thermal treatment. Electrochimica Acta, 1992. 37(7): p. 1253-1260.

Lu, W., et al., High-performance porous uncharged membranes for vanadium flow battery applications created by tuning cohesive and swelling forces. Energy & Environmental Science, 2016. 9(7): p. 2319-2325.

Zhou, X.L., et al., A high-performance dual-scale porous electrode for vanadium redox flow batteries. Journal of Power Sources, 2016. 325: p. 329-336.

Wei, L., et al., Highly catalytic hollow Ti3C2Tx MXene spheres decorated graphite felt electrode for vanadium redox flow batteries. Energy Storage Materials, 2020. 25: p. 885-892.

Pezeshki, A.M., "Impedance-Resolved Performance and Durability in Redox Flow Batteries. " PhD diss., University of Tennessee, 2016.

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(Invited) Spatial ALD Challenges and Opportunities in Advanced Integrated Circuit Manufacturing
Authors: O'Meara David , Dip Anthony , Igeta Masanobu , Clark Robert D. , Higuchi HIsashi , Liu Eric , Raley Angelique , Smith Jeffrey , Tapily Kandabarra , Triyoso Dina , Leusink Gert J.
Published: December 2020

Miniaturization in Integrated Circuit fabrication has scaled to atomic dimensions in recent times. With critical device dimensions moving into the range of ~10nm, atomic layer processing control is becoming essential. Atomic Layer Deposition (ALD) uses separated film components at (or near) self-limiting conditions for atomic level uniformity and thickness control. The unique nature of ALD processing has opened the opportunity for a deposition technique that presents deposition components in a spatially separated method compared to sequential component exposure of traditional systems. Spatial ALD has differentiating characteristics that can benefit IC Fabrication at current fabrication dimensions.

Historically, deposition systems for IC fabrication use batch furnace or single wafer configurations. The economic benefit of batch furnace processing has been challenged by the enhanced capabilities of single wafer processing as IC scaling emphasized critical film properties and uniformity. ALD processing has rejuvenated batch furnace benefits since separate exposures of deposition components provides excellent uniformity from self-limiting deposition layers, and lower particle defectivity since the components don’t mix. However, the sequential processing of individual components has strained the efficiencies of batch furnace and single wafer ALD processing.

Spatial ALD moves substrates (wafers) through each deposition component separately in space, compared to the time sequential processing of batch furnaces and single wafer processing. There are several advantages to Spatial ALD processing, and several unique capabilities that can apply to IC fabrication. By depositing through movement, the deposition components can be maintained through a steady state, which is advantageous for plasma processing and for limiting peripheral equipment film accumulation. By its nature, the deposition rate of Spatial ALD is controlled by the speed of substrates passing through the deposition zones, which can provide unique controls for deposition. Deposition chemistry and process conditions can be designed to take advantage of Spatial ALD properties for unique benefits in IC fabrication. The presentation will explore some fundamental aspects of Spatial ALD processing, the dependency and opportunities of relevant chemistries, and potential applications for the unique capabilities of Spatial ALD, including unsaturated process conditions.
(Invited) Atomic Layer Deposition of Functional Films for Organic Optoelectronic Devices
Authors: Duan Yu , Li Huiying
Published: December 2020

Among the advanced electronic devices, transparent flexible organic electronic devices with rapid development are the most promising technologies to customers and industries. However, thin film encapsulation (TFE) and transparent oxide conductive (TOC) of organic devices still remain a big challenge, because of the difficulty in low temperature and low plasma power fabricating process. Atomic layer deposition (ALD) is increasingly used in the field of organic electronics. However, the deposition of ALD outside the temperature window still cannot be stably implemented. In this study, transient steric hindrance caused by gas-phase molecules at low-temperature (80℃) was investigated. In order to mitigate the effect of this transient hindrance, a process of consecutive short-pulses was adopted in fabricating TFE and TOC. Overall, the proposed idea would help low temperature ALD for organic electronics become mature and be widely promoted.
Atomic Layer Deposition for Surface Area Characterization of Porous Solid Oxide Fuel Cell Electrodes and Beyond
Authors: Schmauss Travis Anthony , Barnett Scott A
Published: December 2020

Conventional surface area determination techniques are inadequate for calculating the surface areas of porous solids with absolute totals less than ~1 m2, but with nm-scale feature sizes, such as state-of-the-art, lab-scale solid oxide fuel cell electrodes. Meaningful contextualization of their electrochemical performance requires knowing system surface area, but the two predominant classes of techniques, tomography and gas adsorption theory, either lack the resolution or require prohibitive amounts of material. Presented here is a new method for the accurate determination of absolute surface areas on the order of 1-1000 cm2 with precision ±0.3 cm2 utilizing atomic layer deposition (ALD) of commonly available trimethylaluminum (TMA) and water vapor to conformally deposit alumina over internal features. The area of alumina can then be quantified using plasma spectroscopy and the known nm-scale thickness of the layer. As a model system, scaffolds of La0.8Sr0.2MnO3-δ/Ce0.9Gd0.1O2-δ (LSM/GDC) of 2.6 m2/g were measured under the new technique and compared against the B.E.T. method, with remarkably similar results obtained, but with ~1000 times less mass needed for the experiment. Under the modest ALD reactor soak times used (~10 s), and with conservative precursor pulse durations, the penetration depth of the coating was found to be ~50 µm, exceeding the requirement for the electrodes under study. To demonstrate the technique’s capabilities further, the LSM/GDC scaffolds were infiltrated with PrOx nanoparticles of ~50 nm, and the increase in surface area (+ ~25%) and enhanced electrochemical performance were measured. After annealing for 1000 hours at 700°C, both were again measured, and the surface area was found to have reverted to non-infiltrated levels, despite the infiltrated cells maintaining their higher performance. The technique, due to its ease versus other surface area determination methods and its pairing with an established analytical chemistry method, enables a useful combined chemical/morphological approach to the characterization of next-generation solid oxide cell electrodes, and may find other uses among nanostructured yet low absolute surface area systems in the broad field of heterogeneous catalysis.

Figure 1. Measured specific surface areas for La0.8Sr0.2MnO3-δ/Ce0.9Gd0.1O2-δ (LSM/GDC) scaffolds and the ALD Al2O3-based technique, in lab-scale mg quantities, versus the B.E.T. method result for gram-scale LSM/GDC flakes. Shown is ALD-derived surface area quantified both via inductively coupled plasma-optical emission spectroscopy (ICP-OES) (Blue) and gravimetrically (Green), with the ICP-OES offering comparable accuracy and precision to the B.E.T. (Purple). Error bars reflect repetition of the same sample (intra-cell) and among different samples (inter-cell).

Figure 1
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) High Energy and Power Density Dense and Deterministically Mesostructured Electrodeposited Electrodes for Lithium and Sodium-Ion Batteries
Authors: Braun Paul V
Published: December 2020

Electrodeposition of electrode materials has the potential to grow anode and cathode materials with unprecedented energy and power densities for both Li-ion and Na-ion rechargeable batteries and to broaden the scope of available electrode form factors. I will present our work on the electrodeposition of high performance silicon and tin-based Na and Li-ion anodes and LiCoO2, NaCoO2, LiMn2O4, and Al-doped LiCoO2-based Na and Li-ion cathodes. The electrolytically active materials were formed either as solid films, or where significant volume changes upon cycling are present, as a 3D mesostructured film. The capacities are near-theoretical, and in the case of the electroplated oxides, the crystallinities and electrochemical capacities are comparable, or in some cases, even better than powders synthesized at much higher temperatures. Time permitting, I will also discuss some of our recent work on the fundamentals of energy transport in redox-active materials for flow batteries.
(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
High Sulfur Loading Layered Cathode and Gel Electrolyte
Authors: Zamani Somayeh , Yi Caspar , Gao Xiaosi , Joo Yong Lak
Published: December 2020

Lithium sulfur (Li-S) batteries are promising candidates for next-generation energy storage devices as they are capable of providing higher energy density and lower cost in comparison to the state of the art Li-ion batteries. To gain these characteristics, there are challenges such as polysulfide crossover, large volume changes during cycling, and deposition of insulating lithium sulfide that need to be alleviated. A popular approach to address these issues is to control the structure and properties of the carbon cathode in order to influence the transport of polysulfides, surface area for reaction, and lithium sulfide deposition. Using gel electrolyte is another approach that can reduce the shuttle effect and also safety concerns regarding the flammable liquid electrolyte can be reduced by deploying gel electrolyte. Towards this direction, we developed a layer-on-layer cathode structure with sulfur-impregnated activated carbon alternating with graphene layer, which was fabricated by Air-assisted electrospray. A much higher sulfur loading compared to slurry cast cathodes can be provided in this method. Combining the new cathode with gel electrolyte can offer higher safety of the battery and capacity retention.
(Invited) Nano-Engineering of Low-Dimensional Materials for High-Energy-Density Sulfur Cathode and Lithium Metal Anode
Authors: Kim Do-Kyung
Published: December 2020

High energy density is mainstay of future battery technology, which is vital for large-scale energy storage system. Lithium-sulfur (Li-S) batteries using lithium metal anode are in the spotlight due to its high theoretical capacity (1,675 mAh g-1) and energy density (2,500 Wh kg-1). However, the ever-present obstacles hinder the practical use of Li-S; low areal capacity (<3 mAh cm-2) of cathode emanated from the insulating property of elemental sulfur, polysulfide dissolution devastating both cathode and anode, and dendritic growth of lithium metal anode. Of significant, herein, we introduce the nano-engineering of electrode materials to cope with those issues on both cathode and anode. The architecture of functional skeleton using zero-, one-, and two-dimensional materials for the host of sulfur cathode and lithium metal anode enhances areal capacity and cycling stability. The strategies discussed in this talk open new avenues for the design of high-performance sulfur cathode and lithium metal anode to develop the practical high-energy-density lithium rechargeable batteries.