bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion Species Dependence on the Interfacial Properties of Silicon Homojunctions Bonded Using an Ion Bombardment Treatment
Authors: Liao Michael Evan , Huynh Kenny , Bai Tingyu , Flötgen Christoph , Goorsky Mark S. 
Published: December 2020

Surfaces of (001) p-type silicon substrates were bombarded with either Ar or Kr ions prior to direct wafer bonding using an EVG© ComBond© high-vacuum wafer-bonding system.1 Previously, we showed that this ion bombardment treatment induces a thin ~nm amorphous region at the bonded interface.2 In this study, we extend upon this previous effort towards a fundamental understanding of this amorphous interfacial region by examining the dependence of the bonded interface’s properties with two different ion species. The ion energies used spanned from a factor of 0.5 to 2.5 times of a baseline energy E0. X-ray reflectivity measurements were performed on single unbonded wafers that were ion bombarded with either Ar or Kr to determine the thickness of the amorphous region as well as its mass density compared to bulk Si. Wafers treated with Ar showed no surface mass density dependence with ion energy, while wafers treated with Kr did show an ion energy dependence. While the Ar treatment reduces the surface density to ~80% of bulk Si density regardless of the energy used, the Kr treatment reduces the surface density to as low as ~70% of bulk Si density at 2.5⋅E0. Furthermore, for a given energy, the Ar treatment resulted in thicker layers than the Kr treatments, which is consistent with SRIM3 simulations because Kr is a heavier species than Ar. Current-voltage measurements were also used to probe the electrical properties of the bonded interfaces. Band structure modeling of the current-voltage measurements revealed that the amorphous region can be modeled with a step barrier that spans the thickness of the amorphous region.
References

Flötgen, et al., ECS Trans., 64(5), 103 (2014).

E. Liao, et al., ECS Trans., 86(5), 55 (2018).

F. Ziegler, et al., The Stopping Range of Ions in Solids vol. 1, (1985).

Figure 1
Direct Wafer Bonding Methods: A Practical Process Selection Guide
Authors: Dragoi Viorel , Rebhan Bernhard , Pabo Eric 
Published: December 2020

The development of various low temperature wafer bonding methods in early 2000’s marked an important milestone for the direct wafer bonding applications. Wafer bonding was adopted in the microelectronics fabs as the use of plasma activated wafer bonding allowed for meeting the CMOS manufacturing requirements in terms of contamination control as well as thermal budget limitations (less than 400°C).
A wafer bonding technique reported in the literature already in late 80’s – early 90’s allowed even for room temperature bonding of some materials but despite this important feature it remained mainly at the fundamental research level, with not so numerous applications in semiconductor industry. This technique is known mainly as “surface activated bonding”, “SAB” or “room temperature covalent bonding”. Over the past decade, the interest in surface activated bonding increased significantly as excellent results were reported particularly for compound semiconductors applications (e.g. solar cells manufacturing, power devices, etc.). With three types of direct wafer bonding processes, high, low and room temperature, sometimes people are facing issues in selecting the proper wafer bonding process. Our goal in this presentation is to introduce the specific features of each technique and present their benefits with applications examples. Technical as well as cost – related benefits will be emphasized.
An overview of the main metrology methods used traditionally for wafer bonding-based applications, as well as new methods adopted based on newest applications fields will be presented.
Revisiting Amorphous LixTiO2: Can x = 1 be Exceeded through Chlorine Modification?
Authors: De Taeye Louis , Vereecken Philippe M. 
Published: December 2020

LTO is a commonly used anode material for high power applications, due to its intrinsic high rate performance. LTO requires high temperature processes to crystallize the material, suffers from a low capacity of 600mAh/cm3 and high oxidation potential of 1.5V vs. Li+/Li [1]. TiO2 is a cheap alternative which exhibits high cycle life and requires less stringent high temperature processing. Amorphous TiO2 was shown to reach the theoretical capacity of 1260 mAh/cm3, twice that of LTO. The theoretical limit can only be achieved through nano-scaling of the system or through chlorine modification [2]. Hence, in both cases, all the available Ti+IV atoms are reduced to Ti+III with insertion of Li+ ion upon reductive lithiation step. Despite having twice the capacity of LTO, the energy density of batteries containing a TiO2 anode remains limited by the high oxidation potential (1.8V vs. Li+/Li), and suffer from poor rate performance.
A low temperature ALD process to deposit chlorine modified TiO2:Cl was developed, which allows high levels of chlorine impurities to be incorporated into thin-film electrodes. High level chlorine modification of TiO2 is observed to significantly enhance the Li-ion storage capability of LixTiO2, potentially exceeding x = 1, beyond the current theoretical limit of 1260 mAh/cm3 or 330 mAh/g. In addition, the chlorine modification of TiO2 leads to greatly enhanced rate performance. Finally, when going beyond x>1, the onset potential of oxidation of LixTiO2 shift to lower potentials which is beneficial for the energy density of the cell with TiO2 as anode. Indeed, the onset of oxidation shifts from 1V vs. Li+/Li down to 0.6V vs. Li+/Li, with a capacity exceeding that of LTO obtained below 1.5V vs. Li+/Li.
[1] N. Nitta, F. Wu, J. T. Lee, and G. Yushin, “Li-ion battery materials: Present and future,” Mater. Today, vol. 18, no. 5, pp. 252–264, 2015
[2] S. Moitzheim, J. E. Balder, P. Poodt, S. Unnikrishnan, S. De Gendt, and P. M. Vereecken, “Chlorine Doping of Amorphous TiO2 for Increased Capacity and Faster Li+-Ion Storage”, Chem. Mater., 29, pp. 10007−10018, 2017
Mesoscale Electrochemical-Mechanical Analyses of Solid-State Non-Planar Conversion Cathodes
Authors: Roberts Scott A. , Ferraro Mark E. , Horner Jeffrey S. , Ng Benjamin , Harrison Katharine 
Published: December 2020

In the quest for high performing battery technologies, conversion cathode materials often stand out for producing high energy densities. Combined with non-planar electrode geometries, such as 3D/2.5D battery architectures, conversion cathodes can achieve both high power and energy densities. However, electrochemical conversion processes are often mechanically abusive at the mesoscale, with significant changes in particle volumes leading to high stresses within the electrode. While previous studies have investigated mesoscale stress impacts for a variety of planar cathode materials, the added complication of non-planar electrode geometries complicates our previous understanding, particularly when the geometric features are on the same size as a mesoscale representative volume element.
In this paper, we demonstrate a coupled electrochemical-mechanical model of a 2.5D pillar conversion cathode system. The mesoscale geometry is generated using discrete element models. The electrochemical model consists of species and electrical transport coupled by Butler-Volmer interfacial reaction kinetics. A moving mesh technique is implemented to track the conversion reaction front and separate reacted from unreacted materials. The impact of the electrochemical reaction leads to the generation of mechanical stresses within the electrode structure. We demonstrate how the mechanical response differs between planar and non-planar electrode geometries and explore the role of the geometric feature sizes on stress localization.
Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
An Investigation of the Electrochemical Processes in Magnesium-Sulfur Batteries By Operando Spectroscopy Techniques
Authors: Bhaghavathi Parambath Vinayan , Zhao-Karger Zhirong , Fichtner Maximilian 
Published: December 2020

The high energy density conversion cathode material like sulfur (S) is promising in combination with Mg anode because of the high theoretical capacity (1672 mA h g-1 or 3459 mA h cm-3), as well as their wide abundance and low cost. Magnesium/sulfur (Mg/S) batteries face drawbacks like large over potential between charge/discharge cycles, rapid capacity fading, poor cycling efficiency and low kinetics. Most of these issues are strongly correlated with the electrolytes used in Mg/S cells and the polysulfide shuttling to the Mg anode side. In spite of recent achievements in Mg/S rechargeable batteries, especially in the field of electrolyte and cathode development, a fundamental understanding of the battery chemistry is still missing and needs further exploration.
In the present study, the electrochemical performances of a room-temperature Mg/S battery with a newly designed sulfur composite cathode and a non-nucleophilic magnesium electrolyte (Mg[B(hfip)4]2 in DME solvent) have been investigated [1, 2]. Operando Raman spectroscopy is employed to track the formation of polysulfide species at the cathode of Mg/S cells during the charge/discharge process, while density functional theory (DFT) calculations are used to correlate the Raman modes with a series of polysulfide species (Sx
n-, x = 1–8). Operando Raman spectroscopy proves the chemical transformation from elemental sulfur (S8) via long and short chain polysulfides to magnesium sulfide upon discharge and conversion back to elemental sulfur during charging. Furthermore, the spectral measurements indicate the formation of a nano-crystalline magnesium sulfide with a cubic zinc blende phase at the end of discharge [2].
Impedance studies of the Mg anode and sulfur cathode electrodes of Mg/S cell under static conditions prove that the total cell impedance is mainly dominated by the anode/electrolyte interface due to the formation of a highly resistive passivation layer. Indeed, upon cycling of the Mg/S cell, the amount of polysulfide species migrated to the anode side via dissolution significantly contributes to the increase of the anode overpotential and resistances. Furthermore, under dynamic conditions, the oxidation/reduction potentials applied to the electrodes dramatically influence the anode impedances due to the oxidation/reduction of chemical species present at the Mg anode interphase. The chemical composition, thickness and morphology of the Mg anode/electrolyte interphase layer is investigated by x-ray photoelectron spectroscopy (XPS) with depth profiling and focused ion beam scanning electron microscope (FIB-SEM) techniques.

Reference
s

[1] Z. Zhao-Karger et al, Journal of Materials Chemistry A, 2017, 5, 10815-10820.
[2] Vinayan, B. P. et al., Journal of Materials Chemistry A, 2019, 7, 25490-25502.

Figure 1
Limitation of Redox Mediator in Li-O2 Batteries: Indecomposable By-Products
Authors: Kim Hun , Sun Yang-Kook 
Published: December 2020

Redox mediators have been studied passionately to improve energy efficiency and cycle life of lithium-oxygen batteries by facilitating decomposition of the discharge product (lithium peroxide) and, thus, reducing the side reactions at high potential during charging. Nevertheless, the cycling performance of lithium-oxygen batteries with redox mediators is still unsatisfactory; this problem must be verified and resolved for the successful application of redox mediators. In this study, we confirmed that widely used redox mediators cannot decompose by-products on the cathode, leading to passivation of the cathode surface despite the successful decomposition of lithium peroxide. By schematizing the routes for by-products formation, we described the processes by which by-products are accumulated on the cathode in the absence and presence of a redox mediator. Based on the intuitive verification of the unproven relationship between a redox mediator and by-products, we proposed a complementary strategy to overcome the limitations of redox mediator and prevent the accumulation of by-products, which is essential for improvement of lithium-oxygen batteries.
References

W.-J. Kwak, H. Kim, Y. K. Petit, C. Leypold, T. T. Nguyen, N. Mahne, P. Redfern, L. A. Curtiss, H.-G. Jung, S. M. Borisov, S. A. Freunberger and Y.-K. Sun, Nat. Commun., 2019, 10, 1380.

W.-J. Kwak , R. Sharma , D. Sharon , C. Xia , H. Kim , L. R. Johnson , P. G. Bruce , L. F. Nazar , Y.-K. Sun , A. A. Frimer , M. Noked , S. A. Freunberger and D. Aurbach, Chem. Rev., 2020, just accepted. https://doi.org/10.1021/acs.chemrev.9b00609

M. M. Ottakam Thotiyl, S. A. Freunberger, Z. Peng and P. G. Bruce, J. Am. Chem. Soc., 2013, 135, 494.
Study on the Cycling Performance of Li-Metal Anodes Impregnated into 3D Current Collectors for Li-Metal Batteries
Authors: Eom Ji-Yong , Lee Da-Yeon , Kim Seong In , Kang Ji-Hoon 
Published: December 2020

Lithium (Li) metal is the most attractive anode material for batteries because of its high specific capacity (3861 mAh/g) and low negative potential (- 3.04 V vs. NHE). However, the Li dendrite growth during Li deposition leads to serious safety problems and poor cycling performance. With durative forming and growing of the Li dendrite during cycling, the accompanying large surface area of SEI layers induces a constant loss of both working Li metal and electrolyte, leading to a low Coulombic efficiency and a rapid capacity decay. Thus, there has been much research effort to achieve the suppression of the Li dendrite formation.
According to the previous reports, employing three-dimensional (3D) current collectors is one approach to reduce the effective current density and delay dendrite growth. In this study, we developed a strategy by impregnating Li metal into the 3D current collectors of nickel (Ni) foam and carbon (C) foam backbone to improve the cycling performance of Li-metal anodes for Li-metal batteries. As a result, Li @ Ni foam and Li @ C foam cells showed better capacity retention for 500 cycles than pure Li metal anodes.
Minerals As Electrode Materials for Ca-Based Rechargeable Batteries: Evaluation of the Pyroxene, Garnet, Melilite and Double Carbonate Groups
Authors: Torres Arturo , Luque Javier , Tortajada José , Arroyo-de Dompablo Elena 
Published: December 2020

Rechargeable lithium-ion batteries dominate the consumer electronics and electric vehicle markets. However, concerns on Li availability have prompted the development of alternative high energy density electrochemical energy storage systems. Rechargeable batteries based on a Ca metal anode can exhibit advantages in terms of energy density, safety and cost. The development of rechargeable Ca metal batteries requires the identification of suitable high specific energy cathode materials. This work focuses on Ca-bearing minerals because they represent stable and abundant compounds. Suitable minerals should contain a transition metal able of being reversibly reduced and oxidized, which points to several major classes of silicates and carbonates. A recent work [1] discusses their electrode characteristics based on crystal chemistry analysis and density functional theory (DFT) calculations. The results indicate that upon Ca deintercalation, compounds such as pyroxene, garnet and double carbonate minerals could display high theoretical energy densities (ranging from 780 to 1500 Wh/kg) with moderate structural modifications. As a downside, DFT calculations indicate a hampered Ca mobility in their crystal structures with energy barriers for Ca migration exceeding 2 eV. More recent investigations found a lower energy barrier of 1 eV in the group of melilite with formula Ca2MSi2O7, where Ca ions are in a square antiprism coordination polyhedron and M is a transition metal ion in tetrahedral coordination.
Acknowledgements: Authors are grateful for financial support from European Union H2020-FETOPEN funded project CARBAT-766617.
[1] Torres, Luque, Tortajada, Arroyo-de Dompablo, Scientific Reports 9, 9644 (2019).
(Invited) Silica Based Ionogels: Raman Study of Protic Vs. non Protic Ionic Liquids, with Lithium Salt Vs. Sodium Salt
Authors: Marie Angélique , Bayle Maxime , Galarneau Anne , Said Bilel , Balducci Andrea , Stettner Timo , Ewels Chris , Humbert Bernard , Le Bideau Jean 
Published: December 2020

Ionogels represent a route to biphasic materials, for the use of ionic liquids (ILs) for all solid devices. Confining ILs within host networks enhances their averaged dynamics, resulting in improved charge transport. Fragility, short relaxation times, low viscosity, and good ionic conductivity, all them appear to be related to the IL / host network interface. The presence of ILs at interface neighborhood leads to the lowering of cation-anion interaction, i.e. to the breakdown of aggregated and structured regions that are systematically found in bulk ILs.[1] This “destructuration”, as well as segregative interactions at interface,[2] coupled with percolation of the bicontinuous solid/liquid interface,[3] make these materials very competitive among the existing solid electrolytes.
Herein we will present an in-depth study of coordination of TFSI anion with lithium or with sodium cations, in the presence of protic or non protic pyrrolidinium cations, confined within silica with well-controlled porosities. The coordination number of TFSI-cation is shown to decrease upon confinement, making the lithium of sodium cation more diffusive. Moreover, the cation-anion layering at the interface is studied by DFT and shows striking modifications when a lithium or sodium salt is added, thus highlighting the effect of the chemistry of the host network, similarly with previous study.[4]

References

1) A. Guyomard-Lack, P.-E. Delannoy, N. Dupré, C. V. Cerclier, B. Humbert, J. Le Bideau, Phys. Chem. Chem. Phys., 16, (2014) 23639-23645
2) A. Guyomard-Lack, B. Said, N. Dupré, A. Galarneau, J. Le Bideau, New J. Chem., 40, (2016) 4269-4276
3) C. V. Cerclier, J.-M. Zanotti, J. Le Bideau, Phys. Chem. Chem. Phys., 17, (2015) 29707—29713
4) D. Aidoud, D. Guy-Buissou, D. Guyomard, B. Lestriez, J. Le Bideau, J. Electrochem. Soc., 165, (2018) A3179-A3185
(Invited) Enabling Fast Charging Li-ion Batteries through Three-dimensional Graphite Anode Design
Authors: Chen Kuan-Hung , Namkoong Min Ji , Goel Vishwas , Yang Chenglin , Mazumder Jyoti , Thornton Katsuyo , Sakamoto Jeff , Dasgupta Neil P. 
Published: December 2020

Current Li-ion battery technology is highly optimized for performance at relatively slow charging rates. However, significant challenges still present for fast-charge conditions with < 15-minute charge time.1 In state-of-the-art Li-ion batteries with high energy densities, thick electrodes (> 50 μm) are adopted, which leads to a tradeoff between energy density and high-power performance. Thicker electrodes with tortuous pathways limit Li-ion transport through the electrode thickness, resulting in large electrolyte concentration gradients during cycling. This causes large cell polarizations, which reduce the accessible capacity of the battery. In addition, the electrochemical potential of the graphite anode can become more negative than the thermodynamic potential of Li metal during fast charging, resulting in irreversible Li plating. Therefore, to simultaneously achieve fast charging and maintain energy density of Li-ion batteries, new approaches are required to address Li ionic transport limitations through the thick graphite anodes.
In this work, we demonstrate a structural modification of conventional graphite anodes to improve their fast-charge capability. This is achieved by introducing laser-patterned vertical channels into post-calendered graphite anodes.2 This 3-D electrode architecture consists of a hexagonal close-packed array of vertical channels that serve as linear pathways for rapid ionic diffusion through the electrode thickness, allowing for a more homogeneous Li-ion flux throughout the volume of the electrode and decreased ionic concentration gradients. As a result, the accessible capacity of the electrode can be significantly improved and Li plating can be minimized during fast charging. Utilizing the 3-D electrode design, we demonstrate significant improvement in capacity fade at 4C (15-minute) and 6C (10-minute) charge rate with industrial-relevant electrode material and loading (> 3 mAh/cm2 electrode loading in > 2Ah pouch cells). This work thus demonstrates the viability of realizing high energy density Li-ion batteries with fast charge capability based on thick electrodes.
Reference

Ahmed, S. et al. Enabling fast charging e A battery technology gap assessment. 367, 250–262 (2017).

Chen, K.-H; Namkoong, M.; Goel, V.; Yang, C.; Mazumder, J; Thornton, K.; Sakamoto, J; Dasgupta, N. P. Efficient Fast-Charging of Lithium-ion Batteries Enabled by Laser-Patterned Three-Dimensional Graphite Anode Architectures. J. Power Sources In Press (2020).