bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Impact of Polarization Variation on Ferroelectric Field-Effect Transistor and Compute-in-Memory
Authors: Choe Gihun , Yu Shimeng
Published: November 2022

The discovery of Hafnia-based ferroelectric materials made ferroelectric field-effect transistor (FeFET) a more promising nonvolatile memory device than ever. Compared to the perovskite-based ferroelectrics, it could have a larger coercive field, better compatibility with CMOS fabrication, and good scalability. The importance of shrinking down FeFET cannot be overemphasized in the same manner as the CMOS. However, scaling down devices results in device-to-device variation. In the case of FeFET, the deposited ferroelectric layer possesses polarization variation (PV) induced by its crystallinity, whereby FeFET suffers from performance variation. Hence, it is critical to assess its influence quantitatively to utilize the FeFET for storage or compute-in-memory applications. In this review, recent trend and progress of the performance variation on the FeFET are surveyed. First, we present the impact of PV on three-dimensional (3D) NAND FeFET and 3D AND FeFET. In addition, to show its capability for compute-in-memory application, the inference accuracy is discussed under the structure. Second, the Voronoi diagram is introduced to model the different sizes and shapes of ferroelectric grains. Third, a comparative study of the device variability by different sources is investigated under the 28 nm to 7 nm technology node. Last, a machine learning-aided methodology to analyze the variability of FeFET based on the metrology results is proposed.
Observing Second Harmonic Generation and Enhancing Second-Order Nonlinearity from Germanium-on-Insulator
Authors: Tan James Zi Jing , Shi Xuncheng , Wang Yadong , Burt Daniel , Lu Kunze , Nam Donguk
Published: November 2022

Second-order nonlinear χ2 processes hold the key to realizing various promising classical and quantum applications. Only conventional non-centrosymmetric materials like aluminium nitride (AlN) and lithium niobate (LN) exhibit a strong second-order nonlinearity. While germanium (Ge) has the advantage of mature foundry processing due to its complementary metal-oxide-semiconductor (CMOS) compatibility compared to conventional χ2 materials, it has a weak second-order nonlinearity owning to its inversion symmetry. It is predicted that exploiting micro-scale strain gradients induced by silicon nitride (SiN) stressors can break the inversion symmetry of Ge and enable more efficient second harmonic generation (SHG) in mid-infrared (MIR). We herein demonstrate SHG in visible and telecom S-band ranges by pumping our germanium-on-insulator (GOI) sample with a tunable femtosecond pulse laser. The signature quadratic power dependence curve of SHG has also been experimentally observed. In this report, we also propose a novel approach to breaking the inversion symmetry of Ge, which can amplify its weak second-order nonlinearity. We designed a Ge micro-bridge with a periodically changing nano-scale strain gradient that is orders of magnitude higher than the previously proposed structures utilizing SiN stressors. This results in a 3-orders of magnitude enhancement in χ2 according to both a classic anharmonic model and density potential theory. Our work paves the way toward a CMOS compatible and high χ2 nonlinear material for integrated photonic applications.
(Battery Division Student Research Award Sponsored by Mercedes-Benz Research & Development) The Role of Ion Solvation in Reduced Temperature Li Metal Batteries
Authors: Holoubek John , Liu Haodong , Yin Yijie , Wu Zhaohui , Cai Guorui , Kim Kangwoon , Li Mingqian , Baskin Artem , Pascal Tod A. , Chen Zheng , Liu Ping
Published: November 2022

The advent of Li metal batteries is considered to be crucial for to ensure the ubiquity of electric transport due to their improved energy densities relative to Li-ion cells. Additionally, the electrochemical kinetics of current batteries are insufficient to provide charging times comparable to standard refueling periods, and to deliver power at reduced operating temperatures. Operating the Li metal anode under such conditions adds another layer of complexity due to the poorly understood dynamics of Li plating and stripping under kinetic stress. Though there are well-established routes to improve the kinetics associated with ion transport through the bulk electrolyte and solid-electrolyte-interphase, similar strategies for the charge-transfer barrier are limited. Our collective work aims to design the Li+ solvation structure in liquid electrolytes and to understand its impact on Li metal performance using reduced temperature operation as a tool. Specifically, we have found that the induction of ion-pairs between Li+ and anions improves such operation due to a reduction in desolvation energy understood through both experimental and advanced computational means. We have leveraged this understanding to develop electrolytes for both sulfur-type and > 4 V Li metal full batteries capable of cycling down to -60 oC. This work represents an effort to advance the understanding of electrolyte/electrode interactions from the perspective of the Li+ ion in solution.
Next Generation Batteries: Status and Challenges of High Energy Rechargeable Lithium Batteries
Authors: Liu Jun
Published: November 2022

Batteries play a critical role in modern society. The electrification of transportation and deep decarbonization of the energy infrastructure require the development and deployment of high energy, low-cost battery materials and technologies. Among the many different battery chemistries investigated, rechargeable batteries using lithium metal anode remain as one of the most feasible approaches for next generation high-performance and low-cost batteries. Here we will discuss and summarize the progresses and status of the research supported by the Battery500 Consortium. The consortium addresses both fundamental level materials and mechanistic problems and cell level integration and manufacturing challenges. The scope includes developing new electrolytes to reduce the side reactions and improve lithium metal deposition/stripping efficiency, improving cathode cycling stability and cathode utilization, understanding and controlling solid electrolyte interfacial reactions, cell design, optimization and validation. The consortium has made significant progress towards high energy cells (>350 Wh kg-1) and stable cycling life (>600 cycles). The research from the consortium also sheds new lights on the degradation and failure mechanisms of high energy lithium cells and the associated the interfacial reactions.
From Order to Disorder: NMR Insights into Ionic Conduction in Li-Ion Solid Electrolytes
Authors: Sebti Elias , Jones Seamus , Segalman Rachel , Canepa Pieremanuele , Clement Raphaele J , Evans Hayden
Published: November 2022

Nuclear magnetic resonance (NMR) spectroscopy provides detailed insights into the working principles of ionic and mixed conductors used in rechargeable battery applications. Notably, NMR is sensitive to crystalline, disordered or even amorphous phases that arise during electrochemical cycling, and can provide atomic-level structural information, as well as insights into the dynamics of ion motion. In this talk, I will present our recent work on Li-ion conducting rocksalt halides [1] and Li-conducting polymeric ionic liquids [2]. Using a combination of synchrotron X-ray diffraction/scattering, electrochemical impedance spectroscopy (EIS), solid-state NMR, pulsed field gradient NMR (PFG-NMR), NMR relaxometry, and first principles calculations, we provide a multiscale understanding of ion diffusion processes and link these findings to local structure features, crystallinity, and materials synthesis/processing conditions.

[1] Sebti, E., Evans, H., Chen, H., Richardson, P., White, K., Giovine, R., Koirala, K. P., Xu, Y., Gonzalez-Correa, E., Wang, C., Brown, C., Cheetham, A., Canepa, P., Clément, R.*, "Stacking Faults Assist Lithium-Ion Conduction in a Halide-Based Superionic Conductor", J. Am. Chem. Soc., accepted. DOI: 10.1021/jacs.1c11335.

[2] Jones, S., Nguyen, H., Richardson, P., Chen, Y.-Q., Wyckoff, K., Hawker, C., Clément, R., Fredrickson, G., Segalman, R., "Design of Polymeric Zwitterionic Solid Electrolytes with Superionic Lithium Transport", ACS Cent. Sci., 8(2), 169-175 (2021). DOI: 10.1021/acscentsci.1c01260.
Detection of Li Deposition on Si/Graphite Anodes from Commercial Li-Ion Cells - a Post-Mortem GD-OES Depth Profiling Study
Authors: Fluegel Marius , Richter Karsten , Wohlfahrt-Mehrens Margret , Waldmann Thomas
Published: November 2022

A new semi-quantitative method based on Post-Mortem glow discharge optical emission spectroscopy (GD-OES) depth profiling was developed to detect Li deposition on Si/graphite anodes. By means of the detected amounts of Li, Si and O in the GD-OES depth profiles, a corridor is determined, in which the minimum amount of Li deposition is found. Three different commercially available 18650 cell types containing Si/graphite as anode active material were acquired to evaluate the newly developed method. Those three cell types were initially characterized in detail by means of SEM/EDX, GD-OES, ICP-OES, and Hg porosimetry regarding their cell chemistry and electrode properties. One cell type was a high-power cell due to its high anode porosity and low anode coating thickness. The other two cell types were high-energy cells, which have thick anode coatings and low porosities.

We aged the cells at 45 °C until their SOH was 80% and analysed the aging behaviour using SEM, DVA, GD-OES, and in coin half-cells. GD-OES depth profiling revealed that no Li plating occurs during cycling aging at 45 °C. Contrary to this, Li plating was detected on the anodes of all three cell types by the new GD-OES method after the high-power cell was aged at -20 °C and the high-energy cells were aged to 0 °C.

Cells, which were previously aged at 45 °C until 80% SOH have afterwards been cycled under the same conditions, which led to Li plating in the fresh cells. Cell types exhibiting predominantly loss of anode active material (LAAM) as aging mechanism during the first aging at 45 °C, still suffered from Li plating during the second aging. However, if the main aging mechanism during the initial aging was loss of cyclable Li inventory (LLI), the cells did show a significantly reduced tendency for Li plating, even though the same conditions caused Li plating in the fresh cells.

Analysis of the aged anodes using coin half-cells revealed that the loss of anode material was caused by the deactivation of Si anode material. SEM images of the anode cross-section indicate that the deactivation is most likely mainly induced by the formation of a thick film surrounding the Si particles.

In combination with complementary methods like SEM, ICP-OES, and coin half-cell analysis, the newly developed GD-OES method yields in profound understanding of the aging behaviour of state-of-the-art Li-ion cells contain Si/graphite anodes.

Figure 1
Covalent Surface Functionalization of Silicon for Enhanced Cycling Performance
Authors: Arano Khryslyn G. , Armstrong Beth L. , Boeding Ethan D. , Korkosz Rachel J. , Malkowski Thomas F. , Veith Gabriel M.
Published: November 2022

Silicon (Si)-based negative electrodes often have these two prerequisites for improved performance: submicron or nanoscale dimension and additives (generally for electrolytes). In this work, a single approach was implemented to achieve the beneficial effects of both. Functionalized Si particles with an average diameter of less than 300 nm and with good polydispersity indices (0.2 to 0.3) were successfully generated by ball-milling the Si with vinylene carbonate (VC) and polyethylene oxide (PEO). Surface characterization using x-ray photoelectron spectroscopy (XPS) confirms the modification of the Si surface and the presence of the additives even after the electrode fabrication processes. We demonstrate through half-cell cycling that the addition of small amounts of VC result in increased specific capacities compared to the neat Si, i.e., ~370 mAh.g-1 higher for Si-VC electrode after the formation cycles. On the other hand, the presence of PEO introduces a passivating film on the surface of Si that hinders Li+ transport to the electrode as indicated by electrochemical impedance spectroscopy (EIS), resulting in reduced specific capacities, i.e., ~325 mAh.g-1 less relative to the neat Siafter formation. Nevertheless, the Si-PEO system exhibited the most promising cycling stability compared to the neat Si and Si-VC electrodes after extended cycling. Similar observations were drawn from full cell studies using high voltage NMC 811 cathodes, confirming the viability of our approach for the improvement of Si-based next generation lithium-ion batteries.
Evaluation of Porous Lithium Lanthanum Zirconium Oxide (LLZO) Anode Host Structures for Li-Metal Batteries
Authors: Hegazy Amir , Higashiya Seiichiro , Mckinney James , Efstathiadis Harry
Published: November 2022

Lithium metal batteries are considered to be a leading candidate for next generation batteries due to their higher energy density and potential for safer operation when combined with solid-state electrolyte materials. However, they are still facing different challenges. A key challenge of lithium metal batteries is the volume expansion over cycling due to the non-uniform deposition of lithium on the anode leading to lithium dendrite formation compromising the battery safety, and poor lifetime. Herein, we report the use of porous Lithium Lanthanum Zirconium Oxide (LLZO) anode structures, in which lithium from the cathode is deposited into the pores during initial charging. The goal of this study is to study postmortem the lithium deposition in the porous host after different cycling conditions to measure the 7Li and 6Li isotopes depth profile by nuclear reaction analysis (NRA), namely, Proton Induced γ-Ray Emission (PIGE) and by Deuteron Induced Particle Emission (DIPE), respectively. The advantages of using NRA are that it gives an absolute measurement of Lithium without sample reliant calibration, it is a nondestructive technique, highly selective for specific light nuclides such as Lithium, and it is not affected by coordination effect.

We demonstrate two different fabrication methods of porous LLZO structures, namely, electrospinning and electrospraying. Then, the fabricated LLZO structures are tested electrochemically using a half cell configuration to examine plating/stripping behavior as a function of current density and to track the overpotential evolution over cycling. Finally, the cycled anodes are investigated using NRA in particular Li concentration inside porous anode, at separator/anode interface and anode/current collector interface. Characterizing the concentration gradient of Li species within the porous and at the various interfaces can help define the current density limitations of solid-state Li metal batteries and identify Li loss failure modes so that cell lifetime can be improved.
Surface Modification as a Key Factor for Spherical, Co-Free, High Capacity Li-Mn-Rich Layered Materials - from Small into the Kg Scale
Authors: Klein Florian , Pfeifer Claudia , Lindén Mika , Wohlfahrt-Mehrens Margret , Axmann Peter
Published: November 2022

Driven by the climate change the entire industry undergoes a structural change. Energy storage solutions, like lithium ion batteries (LIBs), become more and more important.1 The development of new materials with higher specific energy, lower costs and reduced amount of critical raw materials, such as Co and Ni, is one of the most important key points. Li-Mn-rich layered oxides with the general formula of x Li2MnO3 · (1-x) LiMn1-y-zNiyCozO2 are one promising class of next-generation high-energy cathode materials for Li-ion batteries with specific energies beyond 900 Wh kg-1 due to the combination of cationic and anionic redox reactions.2
However, this type of material suffers from high initial irreversible capacity loss, structural changes during long-term cycling, transition metal dissolution and a large voltage hysteresis.3 Commonly used mitigation strategies are doping to stabilize the crystal lattice and modifying the particle surface to minimize side-reactions of the active material with the electrolyte and the initial irreversible capacity loss.4

We will show the development and up-scaling of a Co-free Li-Mn-rich layered material with spherical morphology (HE-NMx), synthesized via coprecipitation reaction with subsequent lithiation and calcination process. Surface modification of the materials turned out to be one key factor influencing the specific capacity and electrochemical cycling stability of the HE-NMx. Based on the findings, the impact of selected post-treatment steps on electrochemical performance will be discussed and will be related to structural properties, obtained from a broad variety of analytical methods. Depending on the post-treatment specific capacities up to 274 mAh g-1 were reached. Scalability of the route will be shown by the successful scale-up of the most promising candidate into the 5 kg scale.

M. Child, D. Bogdanov and C. Breyer, Energy Procedia,
155, 44–60 (2018).

M. Bettge, Y. Li, K. Gallagher, Y. Zhu, Q. Wu, W. Lu, I. Bloom and D. P. Abraham, J. Electrochem. Soc.,
160(11), A2046-A2055 (2013).

M. Armand, P. Axmann, D. Bresser, M. Copley, K. Edström, C. Ekberg, D. Guyomard, B. Lestriez, P. Novák, M. Petranikova, W. Porcher, S. Trabesinger, M. Wohlfahrt-Mehrens and H. Zhang, J. Power Sources,
479, 228708 (2020).

X. Zhang, R. Yu, Y. Huang, X. Wang, Y. Wang, B. Wu, Z. Liu and J. Chen, ACS Sustainable Chem. Eng.,
6(10), 12969–12979 (2018).
Designing Cathode Morphology for Materials with Solid Transport Limitation
Authors: Tewari Deepti , Gutierrez Arturo , Croy Jason R. , Srinivasan Venkat
Published: November 2022

Lithium manganese rich (LMR-NMC) material is a great candidate for next generation high energy density cathodes. It has high specific capacity, low cost, and decreased usage of Cobalt. However, these materials display poor rate capabilities attributed in part due to low lithium diffusion in cathode particle. The LMR-NMC cathode particles (size ~ 5 to 15 microns) are agglomeration of nanoscale primary particles. In this work, we focus on the link between morphology and performance. There are two characteristic diffusion lengths associated with the morphology of LMR-NMC. The diffusion length associated with primary particle radius and the diffusion length associated with the agglomeration of primary particles. The agglomerate diffusion length varies significantly with how the primary particles agglomerate. Presence of intra-agglomerate closed pores results in higher agglomerate diffusion length compared to open and well dispersed arrangement of primary particles. The electrochemical performance is better with smaller primary and agglomerate diffusion lengths. Tailoring the synthesis of cathode particles to obtain the desired diffusion characteristics is promising avenue to optimize the performance of LMR-NMC cathode materials.

Figure 1
The Search for the Materials That Are Attractive to "Natural" Li Diffusion
Authors: Ociepa Jozef
Published: November 2022

"Natural" Li diffusion is defined as the process of Li atom/ions migration under a concentration gradient and activated by thermal energy from atomic vibrations of the host structure at room temperature. This process of passive Li diffusion is important for a better understanding of the active diffusion processes that are happening in lithium-ion batteries (LIBs), where external energy component such as electrical potential is applied. It is expected that materials that exhibit good “natural” Li diffusion properties will perform much better under the external electrical potential. This approach offers a unique opportunity to observe the free movement of lithium atoms/ions into the solid structure and simplify the understanding of diffusion processes especially if single-crystal structures are used. The single-crystal structures are free from grain boundaries and the lithium diffusion process is limited to lattice diffusions such as interstitial, vacancies, and dislocations. This approach allows for categorizing materials that are attractive to lithium diffusion based on the pure lattice component. The characterizing techniques are Auger electron spectroscopy (AES) for tracing Lithium concentration on the surface (Li-KVV peak at 52 eV) and Low Energy Electron Diffraction (LEED) for surface crystallography changes. The lithium concentration gradient is created on the surface of the host material by the evaporation of ultra-thin film of lithium with an effective thickness of 10 Angstrom under ultra-high vacuum conditions.

The data obtained from these experiments are showing different lithium diffusion behavior on the selected materials and there is an indication of three categories of the studied materials. 1-Rapid lattice diffusion of Li into HOPG and no change in the surface crystalline structure. 2-Moderate lattice diffusion of Li into CVD Diamond, SiC-6H, LiNbO3, and TiO2 and some change in the surface crystalline structure. 3-No lattice diffusion of Li into Si single crystals, Ga2O3 and SrTiO3, and no long-range order in the surface crystalline structure.

Most likely rapid diffusion occurs only in graphite but there are several materials with moderate diffusion properties, and these are potential for novel LIBs electrodes or chemically stable interfaces with enhanced performance. The materials with passive no-diffusion properties present challenges in application to LIBs as there is a special need to create active diffusion paths because there is no lattice diffusion contribution.

In addition, this method of tracing lithium passive diffusion using AES is suitable for comparing fabricated polycrystalline LIBs electrodes as a metrology tool for quality control.
Investigating Mixed Cationic and Anionic Redox Chemistry in Chalcogen Based Cathodes for Li-Ion Batteries
Authors: Nagarajan Sudhan , Hwang Sooyeon , Balasubramanian Mahalingam , Thangavel Naresh Kumar , Arava Leela Mohana Reddy
Published: November 2022

Current state-of-the-art Li-ion batteries are reaching their theoretical limit with respect to the capacity, a property largely limited by cathode materials that have so far relied solely on cationic-redox of transition-metal ions (e.g., M3+/4+ in LiMO2 where M is Co, Ni, and Mn) for driving the electrochemical reactions. Recently, the introduction of new anion-redox cathode materials can lead to a doubling of capacity by accommodating multielectron redox chemistries that have gained research interest. (1) However, current anion-redox cathode materials based on Li-rich layered oxides (represented by the formula Li1+xM1-xO2 where M is Co, Ni, and Mn) suffer from voltage fade, large hysteresis, and sluggish kinetics, which originate mysteriously from the anionic redox activity of oxygen ligand itself. (2) It is widely accepted that the covalency between transition metal – oxygen ligand in traditional cathode materials needs to be altered to take advantage of anion redox chemistry. Here, we present an alternative approach of incorporating improved metal – ligand covalency by less electronegative chalcogen sulfur ligands in the cathode structural framework where the metal d-band penetration into ligand p-band thereby utilizing mixed anionic and cationic redox chemistry. (3) Through this design strategy, we investigated anion redox activity in layered cathode material based on Li2SnS3, and their lithiation/delithiation properties were evaluated through in-depth electrochemical analysis. Further, the charge contributors during electrochemical reactions were identified by spectroscopy analysis, and morphological evolution due to mixed anionic and cationic redox reactions were evaluated using high-resolution transmission electron microscopy(HR-TEM) and high annular dark field-scanning transmission electron microscopy(HAADF) investigations.The results reveal the multi redox induced structural modifications and its surface amorphization with nanopore formation during cycling. Findings from this research will inspire Ni and Co free chalcogen cathode design and various functional materials in the pursuit of next generation cathode materials.

References

J. R. Croy, M. Balasubramanian, K. G. Gallagher, A. K. Burrell, Review of the US Department of Energy’s “Deep Dive” effort to understand voltage fade in Li-and Mn-rich cathodes. Accounts of chemical research
48, 2813-2821 (2015).

G. Assat, J. M. Tarascon, Fundamental understanding and practical challenges of anionic redox activity in Li-ion batteries. Nature Energy
3, 373-386 (2018).

S. Nagarajan, S. Hwang, M. Balasubramanian, N. K. Thangavel, L. M. R. Arava, Mixed Cationic and Anionic Redox in Ni and Co Free Chalcogen-Based Cathode Chemistry for Li-Ion Batteries. Journal of the American Chemical Society
143, 15732-15744 (2021).
Facile in-Situ Polymerized Polymer Electrolytes in All Solid-State Lithium-Ion Batteries
Authors: Sankara Raman Ashwin , Jhulki Samik , Johnson Billy , Narla Aashray , Yushin Gleb
Published: November 2022

With the push towards renewable energy sources and “green” technologies, lithium-ion batteries (LIBs) have proven to be necessary across multiple technological realms, the biggest of which is currently the electric vehicle (EV) and grid storage markets. But the popular choice of liquid organic electrolytes in LIBs suffers from safety concerns, which motivated significant innovations in safer solid-state electrolytes. Among them, solid polymer electrolytes (SPEs) have shown great potential due to their processability, flexibility and tunability of physical properties. The past decade has seen rapid evolution in the development of SPE LIBs, but most of them still stand inadequate. SPEs are typically processed either by using solvents, or by using them in their solid state, to blend with the active electrode materials. While these systems are often subject to additional compression to promote continuous electrolyte-electrode interface, they still suffer from the almost unavoidable formations of voids, and inhomogeneous contact between the active materials and the SPEs. Furthermore, most of these processes require excessive amounts of SPEs, and yet result in a large interfacial resistance.

Here we introduce a novel one-step manufacturing strategy for polymer electrolytes in solvent-free SPE LIBs. The process involves in-situ polymerization of a liquid-monomer precursor directly infiltrated into a dry jelly roll or individual electrodes to form SPE cells. Our microscopy and FIB experiments confirmed a near-perfect polymer infiltration in porous cathodes, while electro-chemical tests confirmed excellent characteristics of cathode-electrolyte interfaces. The cycling performance of lithium iron phosphate (LFP) half cells using thus produced and infiltrated SPE showed very good stability and columbic efficiency. In addition to single-ion conductive SPEs, we tested hybrid SPE systems where Li salts were added into the single-ion conductive SPEs to improve rate and capacity utilization.
Study of a Rechargeable Lithium-Ion Battery Based on a Copper Hexacyanoferrate Cathode
Authors: Muñoz Eduardo , Rojas Victor , Cáceres Gustavo , López Silvana , Navarrete Emilio , Herrera Francisco , Caballero Álvaro , Gomez-Camer Juan Luis
Published: November 2022

Rechargeable lithium-ion batteries are among the most promising battery technologies to meet energy conversion and storage requirements. However, this technology is still limited due to its high cost, which prevents its use on a large scale. Therefore, cheaper energy storage systems with long cycle life, high power/efficiency, and safety are in great demand and interest. Prussian blue analogs are promising candidates for use in large-scale energy storage applications due to their long-life cycles, high power density, and high energy efficiency [1]. Along with the change of the transition metal, some structural parameters and some fundamental properties of these compounds can be changed, affecting some parameters such as the battery's storage capacity.

This work studied the electrochemical insertion of lithium ions into Copper Hexacyanoferrate (CuHCF). This compound was synthesized by a hydrothermal process using a factorial design for determining the significance variables, i. e., precursor concentrations, temperature, and reaction time, on the electrochemical performance of the battery. The samples obtained were characterized by FESEM, TEM, XRD, and TGA. The results show cubic structures with a high degree of crystallinity and an evident dependence of the crystallite size (50 - 140 nm) with the variation of the synthesis conditions. Finally, lithium-ion batteries were measured using a CuHCF cathode (theoretical charge 85.1 mAhg-1). The capacity values depended on the crystallite size, obtaining the best results in the synthesis under lower concentrations, reaction time, and temperature. This sample was submitted to deep charge/discharge cycles at a rate of C/20, where the capacity value was close to 60 mAhg-1 (right image). This demonstrates the influence of the crystallite size on the material's performance, managing to find the optimal synthesis conditions to maximize the battery capacity.

References.

[1] 1. Marzhana Omarova, Aibolat Koishybay, Nulati Yesibolati, Almagul Mentbayeva, Nurzhan Umirov, Kairat Ismailov, Desmond Adair, Moulay-Rachid Babaa, Indira Kurmanbayeva, Zhumabay Bakenov, Electrochim. Acta, 184 (2015) 58-63.

Figure 1
Phase Stability of Ta-Doped Tetragonal Li7La3Zr2O12 (t-LLZO) Solid-State Electrolyte: A First-Principle Cluster Expansion Study
Authors: Maphoto Refiloe Innocencia , Ledwaba Raesibe Sylvia , Malatji Kemeridge Tumelo , Masedi Mallang Cliffton , Ngoepe Phuti Esrom
Published: November 2022

Using first-principles calculations and cluster expansion, this study generates new possible stable phases of t-LLZO containing a supervalent cation, Ta, on the Zr-site as a way to enhance the conductivity of the tetragonal crystal structure. The Monte-Carlo simulation was then used to provide further insight into the behaviour of the Ta-doped phases as a function of temperature under the canonical ensemble. The cluster expansion binary ground-state diagram generated 28 new multi-component Li5La3Zr2-xTaxO12 structures that are miscible. It is found that all the structures are thermodynamically stable with negative enthalpy of formation. The Monte-Carlo temperature profile shows no phase separation, and the system mixes well at ~900K. Further density functional theory calculations were performed on the most stable generated Ta-doped LLZO structures to determine the structural properties of the structures for their application as active solid-state electrolytes. It is found that the generated structures exhibit good structural stability due to the smooth decrease in calculated lattice parameters, which indicates that the smaller the difference between the dopant ionic radius and the critical dopant radius, the higher the conductivity. Therefore, the findings provide a better understanding of the phase stability of the generated Ta-doped LLZO structures, which paves the way for further analysis of the rate of lithium-ion diffusion and the mobility of the lanthanum, zirconium, tantalum, and oxygen ions in the systems at high temperatures.
Thermal Runaway Reactions Modeling in Lithium-Ion Batteries
Authors: Gundlapally Santhosh R
Published: November 2022

Lithium-ion batteries are ubiquitously used as power source in a variety of applications due to their superior performance and reliability. However, thermal runaway of Li-ion batteries is a serious concern due to risks associated with such catastrophic event, and hence elucidating the different chemical reactions involved in the thermal runaway phenomenon is a highly active area of research. It is both cost and time prohibitive to experimentally assess the different battery pack designs for the possibility of thermal runaway event, and hence mathematical models play critical role in the battery safety research. Thermal runaway of battery pack is usually initiated by one or a small group of cells which are affected by abuse conditions such as internal short circuit, nail penetration, overcharging, etc., and then depending on the battery pack design and thermal management, thermal runaway can propagate to neighboring cells resulting in fires that can sustain for long time. Since understanding chemistry leading to thermal runaway at cell level is crucial, many studies, both experimental and modeling, have focused on this topic.

Some of the important reactions involved in the onset of thermal runaway are primary SEI decomposition, secondary SEI formation due to reaction between electrolyte and intercalated lithium ions, electrolyte decomposition, separator melting, and cathode decomposition. Since it is difficult to directly measure the different species involved in these reactions, calorimetric based approaches are used to determine the reaction parameters; DSC and ARC are widely used for this purpose. The model consists of system of differential equations which can be solved as a function of time for species fractions and cell temperature. In this work, we have developed flexible and easy to use framework for solving thermal runaway model equations. Both the electrochemical reactions and thermal runaway reactions are solved together with the aim of tighter two-way coupling between these two different processes. Using this model, we analyze the different reaction mechanisms proposed in the literature. We discuss the models for pressure build up in the cell, venting, and combustion of the vented gases.
(Invited) Imaging and Measuring Electronic Materials
Authors: Niefind Falk , Winchester Andrew , Pookpanratana Sujitra
Published: November 2022

Photoemission (PES) has been an essential metrology in the field of materials physics for over 30 years. The electronic band structure of a solid is a fundamental property which defines how a material will be used and integrated into device form. Topographic features and defects can impact electronic structure, therefore influence extrinsic properties when integrated in device form. Developing metrology that is sensitive to electronic properties at these length scales is desired. Here, we apply lab-based photoemission electron microscopy (PEEM) to gain insight in key structure – function relationships.

Controlling doping during growth of semiconductors is critical as it has impact on device engineering – whether to form components in logical circuits or regions for Ohmic contact formation. For some semiconductor nanowires (NW), the doping density is varied along the long axis of the NW and knowing where the transition and its strength between doping regimes is important for device engineers. Here, we have imaged GaN NW grown with n-doped and n++-doped regions of approximately 6 μm in length and 200 nm in diameter that have been dispersed on a silicon substrate. Using a deep ultraviolet photon source, we observe an inflected change in the contrast along the long axis of the NWs (about 2 μm from one end) which we attribute to the n-n++ interface. This inflection is about 100 nm wide, and provides insight into the space-charge region formed at this electronic interface.

We will also present on expanding our lab-based PEEM capability with integration to a tunable laser-based deep UV system (80 MHz, 140 fs). This added capability will provide additional imaging sensitivity to polar semiconductors such as III-nitrides. We will present some initial results with this system currently being commissioned on device-grade GaN and β-Ga2O3.
(Invited) Modeling Oect Devices for Circuit Simulations
Authors: Calvet Laurie Ellen , Li Zonglong , Tseng Hsing , Weißbach Anton , Kleemann Hans
Published: November 2022

Organic electrochemical transistors (OECTs) can be distinguished from conventional organic thin film transistors (OTFTs) by the use of an electrolyte in their gate stack. This results in a unique set of device properties, most notably, mixed ionic and electronic transport. Modeling of these devices has mainly been realized using MOSFET-like equations (often called the ‘Bernards model’) and extensions, which use a circuit diagram to include the different parasitics and capacitances involved [1]. While these models provide qualitative agreements with OECT devices, their quantitative agreement may not be sufficient for realizing circuit simulations. Physically, the discrepancy between the model and the devices are likely to stem from the assumption that the electrolyte behaves as a parallel plate capacitor, as in a conventional MOSFET. Recently, another model based on thermodynamics has been proposed that treats the OECT as a thermodynamic binary system with entropic mixing as the driving force for device operation [2]. Here we explore these different models and then show how they can be used to understand circuit behavior of OECTs.

The authors thank the ANR and the Bundesministerium für Bildung und Forschung (BMBF) for funding of the BAYOEN project under contract ANR-21-FAI1-0006-01 and 01IS21089.

[1] J Rivnay et al Organic electrochemical transistors. Nature Reviews Materials, 3(2):1–14, 2018

[2] M. Cucchi et al ‘Thermodynamics of Organic Electrochemical Transistors’, accessed on researchsquare.com, https://doi.org/10.21203/rs.3.rs-1143463/v1

Figure 1
Fabrication and Characterization of p-Type Thin-Film Transistors Using Sete Active Layer Deposited by Pulsed Laser Ablation
Authors: Choi Kyunghee , Nam Sooji , Oh Himchan , Oh Ji-Young , Cho Sung Haeng
Published: November 2022

We fabricated p-type thin-film transistors(TFTs) using SeTe films deposited by pulsed laser ablation at room temperature. The TFTs were thermally annealed at different temperatures (150°C, 200°C, 250°C) under oxygen ambient. It was found that the thermal annealing can improve the crystallinity and induce the surface oxidation of the SeTe films. This gave rise to enhancement the performance of the TFTs. As the annealing temperature increases, the field-effect mobility and the on/off current ratio was increased and the off-state current was decreased. The 250°C-annealed TFT shows the best performance with a high filed effect mobility of 3.5cm2/Vs and a high on-off current ratio of 1X105. We also successfully demonstrated a CMOS inverter with the p-SeTe and a n-ITZO TFT. The CMOS inverter exhibits a gain of ~12 at a transition voltage of ~0.8V under a supply voltage of 5V.
Process Development of Amorphous Indium Tin Gallium Oxide (ITGO) Thin Film Transistors
Authors: Powell Eli , Kabir Muhammad Salahuddin , Zhu Bin , Manley Robert G. , Hirschman Karl D.
Published: November 2022

The invention of portable electronic devices had a huge impact on the growing interest in flat panel displays. Since the first report in 2004 on amorphous Indium Gallium Zinc Oxide (a-IGZO) thin film transistors (TFTs), many companies have become interested in this material. The main advantage of a-IGZO over conventional amorphous silicon TFTs is its steep subthreshold, low off state current, and high channel mobility. However, the demand for larger displays with higher resolution and refresh rates is driving the demand for TFTs with higher performance, while avoiding the cost and complexity associated with low temperature polycrystalline silicon. There is an increased focus on alternative amorphous oxide semiconductors for use as TFT channel materials, due to the success of a-IGZO.

The focus of this study is an investigation on Indium-Tin-Gallium-Oxide (ITGO) TFTs. Unpassivated bottom-gate devices were fabricated with a 30nm a-ITGO film, sputter deposited with 1% and 10% oxygen gas ambient, followed by a 2 hour anneal at 300oC in oxygen. Devices fabricated with PO2 = 1% resulted in a highly conductive channel. Devices with PO2 = 10% displayed semiconducting behavior and a shallow subthreshold. This trend held for all device dimensions tested; lengths of 24µm, 12µm, and 6µm with a width of 24µm. Compared to a-IGZO devices with a length of 4µm, ITGO devices with a length of 12µm exhibit an equivalent current drive, implying a 3 to 4 times improvement in mobility.

Following aging in room ambient for multiple days, a-ITGO devices displayed improved yet left-shifted transfer characteristics. In unpassivated a-IGZO devices, similar behavior can also be observed and is attributed to an inhomogeneous trap distribution across the channel. As the exposed channel reacts with room air, oxygen vacancies are filled resulting in a more homogeneous trap distribution. A radial variation of device performance from the center of the wafer to the edge was also observed. When measuring devices towards the edge of the wafer a considerable left shift in transfer characteristics was observed. This variation in device performance is believed to be attributed to non-uniformities in the as deposited ITGO film and will be related to material optical parameters.

Figure 1
(Invited) Challenging for High-Performance Oxide-TFT Based Inverters
Authors: Nomura Kenji
Published: November 2022

Metal oxide-Thin-film transistor (oxide-TFT)-based inverter circuit is a critical technology for the development of next-generation cost-effective ubiquitous device applications for wearable information and healthcare technology. However, in contrast to the success of n-channel oxide-TFT that already implemented in state-of-art high-performance flat-panel-displays, the development of oxide-inverter technology, especially p-channel oxide-TFT, still remains the largest challenging in oxide-TFT technology. The absence of reliable high-performance oxide-TFT inverter is mainly attributed to the insufficient device performances of p-channel oxide-TFTs, and especially large off-current causes large device power-consumption. Therefore, developing p-channel oxide-TFT exhibiting a low off-current and sharp s-value is indispensable for low-power operational oxide-inverter circuits.

This talk discuss how we improve p-channel oxide TFT performance for oxide-TFT-based inverters. After we review the recent progress of oxide-TFT-based inverter and p-channel oxide-TFTs, we identify the current issues and the remaining challenging for oxide-inverters.

To improve the device performances of p-channel oxide-TFT such as SnO-TFT, I present an atomically-ultra-thin oxide channel technology, which offers several advantages such as effective gate control of a conductive metal oxide channel in full-carrier depletion operation mode. This is a promising to improve the devcie performances for several oxide-TFTs having a high carrier-doped oxide channel. To the end, we discuss the device characteristics for oxide-TFT-based-inverter for the ultra-thin oxide-TFT-based CMOS and NMOS inverters.
A Light Shield Temperature Sensor for a Display Backplane
Authors: Yu Eun Seong , Kang Seo Jin , Lee Hyuk Su , Bae Byung Seong
Published: November 2022

Liquid Crystal Display (LCD) and Organic Light Emitting Diode (OLED) display are operated by voltage or current driving. Several types of Thin-Film Transistor (TFT) are used in the backplane of a display, LTPS and a-IGZO TFTs are those. As the applied voltage increases to increase the brightness of the display, heat generation also increases at the channel of the TFT. Such heat generation increase the temperature, which degrades the characteristics of the TFT, and decrease the lifetime of the organic device. Therefore, in order to keep the quality of the display, it is necessary to monitor the temperature of the display and control related signals to implement optimal image quality. There are various temperature sensors which can be used to detect such a temperature change in a display. In the case of using a discrete temperature sensor, the process and cost are increased by attaching the temperature sensor additionally. However, in the case of a temperature sensor integrated into the display, an process for the temperature sensor is not necessary. One way to integrate is using resistance changing material with a reference resistor outside. In this case, temperature accuracy can be reduced when the reference resistance changes due to the influence of the external temperature. To solve the problem, external reference resistance is removed in this proposed sensor scheme. Figure 1 shows the developed thin-film temperature sensor, which consists of two wires connected in series. The temperature coefficients of Molybdenum (Mo) and Indium Tin Oxide (ITO) are different from each other, and that of ITO is about 1.2 times or more than that of Mo. In this scheme, no external resistance is required. In addition, to reduce the process steps, a thin film temperature sensor is designed to replace a light shield layer which is formed at the bottom of the active layer to prevent the input of light. The two thin film materials are connected in series and the voltages at a connecting point are measured. The generated heat transferred to the temperature sensor was tested for repeatability and accuracy. The thin-film temperature sensor was designed to be located at the bottom of a-IGZO Top Gate TFT structure to check the heating during the operation of TFT. an interlayer insulation film was deposited on the temperature sensor before deposition of the active layer. The temperature of the TFT was measured by a temperature sensor Figure 1. shows the schematic cross-sectional structure of the developed oxide TFT with an integrated temperature sensor.

Figure 1
Design of Highly Positive Triboelectric Materials Via Controlling Local Dipole
Authors: Kang Donghyeon , Kim Jihye , Kim Sang-Woo
Published: November 2022

The design of positive triboelectric materials is highly required to realize high-performance triboelectric generators. Here, we establish a novel design protocol for highly positive triboelectric materials via the maximization of local dipole and suggest nitrogen-based dimethylol urea, diazolidinyl urea, and imidazolidinyl urea as promising positive triboelectric materials. The mechanism that nitrogen-based materials provide highly positive triboelectric properties is investigated using density functional theory calculation. Highly electronegative atoms (e.g. nitrogen and oxygen) attract electrons from neighboring atoms, resulting in the formation of negative local dipoles in the highest occupied molecular orbital consisting of non-bonding electrons, thereby forming an electron-donating environment. We confirmed the proposed design protocol by quantitatively investigating the triboelectric properties of nitrogen-based materials and analyzing the charge transfer characteristics based on local dipole interactions.