bluuebunny/crossref_metadata_2025 huggingface dataset:
Ab Initio calculations of Low-Energy Quasiparticle Lifetimes in Bilayer Graphene
Authors: Spataru Catalin D. , Leonard Francois
Published: August 2024

Motivated by recent experimental results

we calculate from first-principles the lifetime of low-energy quasiparticles in bilayer graphene (BLG). We take into account the scattering rate arising from electron-electron interactions within the GW approximation for the electron self-energy and consider several p-type doping levels ranging from 0 to ~ 2.4x1012 holes/cm2. In the undoped case we find that the average inverse lifetime scales linearly with energy away from the charge neutrality point, with values in good agreement with experiments. The decay rate is approximately three times larger than in monolayer graphene, a consequence of the enhanced screening in BLG.

In the doped case, the dependence of the inverse lifetime on quasiparticle energy acquires a non-linear component due to the opening of an additional decay channel mediated by acoustic plasmons.

This work was supported by the LDRD program at Sandia National Laboratories (SNL). SNL is a multimission 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.

The views expressed in the article do not necessarily represent the views of the U.S. Department of Energy or the United States Government.
(Invited) Two-Dimensional Layered Materials and Their Mixed-Dimensional Hybrids for Electrochemical Applications
Authors: Yao Fei
Published: August 2024

Compared with their 3D counterparts, two-dimensional (2D) van der Waals (vdW) materials exhibit quantum confinement where charge carriers are spatially confined at the physical boundaries. Particularly, when mixing 2D materials with other low-dimensional (LD) materials, they exhibit enormous potential in electrochemical energy applications due to the unique properties arising from reduced dimensionality and, more importantly, material integration synergy.

In this work, 2D transition metal dichalcogenides (MoS2) and their mixed low-dimensional hybrids (MLDHs) are introduced with an emphasis on the hybrid structure construction using the one-step solvothermal synthesis technique and their electrochemical applications. Fundamental insight into the synergistic effect of the MLDHs integration in terms of active site exposure, surface area enlargement, electrical conductivity improvement, and structural phase engineering for advancing the development of Li-ion batteries (LIBs) and electrocatalytic hydrogen evolution reaction (HER) will also be discussed. Specifically, in the case of LIBs, 2D-based binary hybrids (i.e., MoS2/MXene) deliver a Li-ion storage capacity of 540 mA h g−1 at 100 mA g−1 and a stable cycle performance up to 300 cycles. In sharp contrast, the 2D-based ternary MLDHs (i.e., MoS2/MXene/CNT) exhibit a higher Li-ion storage capacity (1500 mAh g−1 at 100 mA g−1), outstanding cycle stability (up to 300 cycles) and excellent rate capability (500 mAh g−1 at 4000 mA g−1) as an anode of LIBs. In the case of HER, the MLDH heterostructures show an overpotential of 169 mV with a low Tafel slope of 51 mV/dec and can be cycled to 1000 cycles. Leveraging the unique microreactor platform based on the 2D vdW platform, a mechanistic understanding of charge transport dynamics at the electrified electrode and current collector interface will be highlighted.

The knowledge gained on how mixed-dimensional physics and chemistry will shed light on the design principle of the electrode materials for electrochemical energy storage and conversion and deepen the understanding of the process-structural-property-performance (PSPP) relationship of the vdW-based hybrid structures.
Atomically Precise Vacancy Lattices in Epitaxially Grown FeBr2 and CoBr2 on Au(111)
Authors: Maier Sabine
Published: August 2024

The generation of extensive 2D periodic patterns of point defects in 2D materials, such as vacancy lattices, has been a challenging task until now. Here, we report on 2D transition metal dihalides grown epitaxially on Au(111) featuring periodically assembled halogen vacancies that result in alternating coordination of the transition metal ion and can function as antidot lattices. [1] Using low-temperature STM/ncAFM and LEED, we identified the structural properties of intrinsically patterned FeBr2 and CoBr2 monolayers grown epitaxially on Au(111). Density-functional theory indicates that Br-vacancies are favored due to low formation energies, and the formation of a vacancy lattice substantially reduces the lattice mismatch with the underlying Au(111). We demonstrate that interfacial strain engineering presents a versatile strategy for controlled patterning in 2D with atomic precision over several hundred nanometers to solve a longstanding challenge of growing atomically precise antidot lattices.

[1] https://doi.org/10.48550/arXiv.2305.06489
(Invited) Precise Determination of Exciton Binding Energy of Organic Semiconductors
Authors: Yoshida Hiroyuki
Published: August 2024

Strongly bound excitons in organic semiconductors are crucial for the operation of organic optoelectronic devices. However, accurate experimental data on the exciton binding energy of organic semiconductors are lacking. In this study, we determine the exciton binding energy as the difference between the optical and transport bandgaps with a precision of 0.1 eV. From the systematic study of the exciton binding energy of 42 organic semiconductors (15 non-fullerene acceptors, 4 fullerene acceptors, 13 low-bandgap polymers, 7 organic light-emitting diode materials, and 3 crystalline materials), we found that the exciton binding energy is a quarter of the transport gap regardless of the material. We interpret this unexpected relationship in terms of a hydrogen atom model.
(Invited) Synthesis and Optical Properties of Chiral Spiro π-Conjugated Compounds with Donor–Acceptor Structure
Authors: Nakano Koji
Published: August 2024

Chiral spiro π-conjugated compounds with donor–acceptor structures were synthesized. Carbazol-9-yl, 9,9-dimethylacridin-10-yl, phenoxazin-10-yl donor units were introduced on the spiro-fused acceptor unit with sulfonyl groups. The donor units were found to have great impact on the longest absorption maximum and emission maximum. The chiral spiro π-conjugated compounds with 9,9-dimethylacridin-10-yl or phenoxazin-10-yl donor units showed delayed fluorescence. All of three compounds exhibited circularly polarized luminescence both in solution and solid states.
(Invited) Synthesis of Multi-Metallic Nanoparticles for Advanced Catalysts
Authors: Yamamoto Kimihisa
Published: August 2024

Dendrimers are highly branched organic macromolecules with successive layers or “generations” of branch units surrounding a central core. Organic inorganic hybrid versions have also been produced, by trapping metal ions or metal clusters within the voids of the dendrimers. Their unusual, tree-like topology endows these nanometer-sized macromolecules with a gradient in branch density from the interior to the exterior, which can be exploited to direct the transfer of charge and energy from the dendrimer periphery to its core.

We show that PtCl4, SnCl2, FeCl3, and so on complexes to the imines groups of a spherical polyphenylazomethine dendrimer in a stepwise fashion according to an electron gradient, with complexation in a more peripheral generation proceeding only after complexation in generations closer to the core has been completed. By attaching an electron-withdrawing group to the dendrimer core, we are able to change the complexation pattern, so that the core imines are complexed last. By further extending this strategy, it should be possible to control the number and location of metal ions incorporated into dendrimer structures, which might and uses as tailored catalysts, building blocks, or fine-controlled clusters for advanced materials. The metal-assembly in a discrete dendrimer molecule can be converted to a size-regulated metal particle with a size smaller than 1 nm as a molecular reactor. Due to the well-defined number of metal clusters in the subnanometer region, its property is much different from that of bulk or general metal nanoparticles. The chemistry of nanocatalysts on the sub-nanometer scale is not yet well understood because precise multi-metallic nanoparticles are difficult to synthesize with control over size and composition. The template synthesis of multi-metallic sub-nanocalaysts is achieved using a phenylazomethine dendrimer as a macromolecular template.
(Invited) Exploring Catalyst Characteristics through in-Situ Studies of Solid-Liquid Interfaces
Authors: Lin Yan Gu
Published: August 2024

Scientists are driven by the urgent need to combat global climate warming and environmental pollution, leading to the development of highly efficient and eco-friendly energy technologies. Hydrogen, a key player in achieving deep decarbonization for net-zero carbon dioxide emissions by 2050, is currently produced through the widely used steam-methane reforming process, which, unfortunately, relies on fossil fuels and generates significant CO2 as a byproduct. This process is environmentally unfriendly and unsustainable, emphasizing the necessity for green hydrogen production. The sun emerges as a clean, renewable, and abundant energy source, offering an ideal solution to the environmental challenges posed by fossil fuels. Hydrogen, an excellent fuel for fuel cell applications, must be generated from renewable and carbon-free resources, particularly utilizing natural energies like sunlight. Enter the photoelectrochemical cell, a promising method for hydrogen generation. This cell comprises semiconductor photoelectrodes capable of harnessing light energy to directly split water. Photocatalysis, leveraging light energy for chemical reactions, holds the key to large-scale solar energy storage, overcoming challenges such as cost and efficiency. Despite over four decades of dedicated research, photocatalysis still faces hurdles in terms of cost and efficiency, hindering progress in this crucial field. A major obstacle lies in the limited understanding of the mechanisms underlying its low performance. To address this challenge, I will overview several experimental studies that have successfully unveiled catalytic reactions at solid/liquid interfaces in real time, focusing on the electrochemical interface of photocatalysis and electrocatalysis. These studies utilize operando X-ray characterization, providing unique insights into the actual reaction mechanisms.
Structure and Properties of Novel Macrocylic Structures: A First Principles Perspective
Authors: Kronik Leeor
Published: August 2024

Understanding of the structure and properties of novel macrocyclic structures can be enhanced strongly through the juxtaposition of experimental data and first principles computational data. In this lecture, I will review recent examples of such insights. Specifically, I will discuss structure, bonding, and electronic properties in fused iron corroles, in boron subphthalocyanine halides and pseudohalides, and in a novel polymorph of Cu Phthalocyanine.
Structural Analysis of Cathode Slurry Under Flow Using New Probe for Rheo-Impedance Measurements
Authors: May Jeremy , Kawata Yuki , Kanai Jun , Okui Hajime
Published: August 2024

A battery slurry will experience a variety of shear stresses as it goes through the manufacturing process. The full characterization of a slurry for quality control is challenging due to the complex and changing relationship between active material particles, binder, and the carbon black conductive network as a function of these different shear environments. Rheology is a powerful tool for measuring suspension stability and the viscosity at different shear stresses. However, it cannot characterize the structure of the carbon black conductive network because the rheological properties are dominated by the larger active material particles. Poor distribution or aggregation of the carbon black additive will create an electrode with higher electrical resistance, resulting in more heat generation and a shorter cycle life. Electrochemical impedance spectroscopy is an information dense technique that probes the sample using an alternating current or potential at a range of frequencies. Amongst its many applications, EIS can discriminate between simultaneous events that take place over different time scales, such as the measurement of conductivity within a solid electrode vs the ionic conductivity of the electrolyte. Combining these techniques into a simultaneous measurement will characterize the rheological behavior and the structure of the carbon black conductive network under flow and temperature conditions that are relevant for a manufacturing environment. A novel probe for the simultaneous measurement of rheological properties and electrochemical impedance spectroscopy (Rheo-EIS) is herein presented. A structural analysis of Li-ion battery cathode slurries and carbon paste is used to demonstrate the technique.
On-Surface Synthesis of Macrocycles, Non-Planar Carbon Ribbons and Heteroatom-Doped Nanographenes
Authors: Maier Sabine
Published: August 2024

On-surface synthesis via covalent coupling of adsorbed molecules on metal surfaces has attracted significant attention recently due to its potential to fabricate low-dimensional carbon materials with atomic precision. The bottom-up, atomically precise synthesis of carbon nanostructures enables the tailoring of their electronic properties at a molecular level. To understand and control the surface-chemistry-driven synthesis, many efforts have been made to design innovative precursors, explore novel reaction schemes, and utilize templating effects from the substrate.

My presentation focuses on high-resolution scanning probe microscopy experiments combined with density functional theory to demonstrate recent highlights on the assembly of surface-supported low-dimensional carbon structures on metal surfaces. First, the assembly and electronic structure of planar π-extended cycloparaphenylene macrocycles, representing the first nanographene with an all-armchair edge topology, will be presented [1]. The second part will discuss the bottom-up synthesis of covalently-linked non-planar carbon ribbons and their electronic properties depending on their adsorption geometry. Finally, I will conclude with the on-surface cyclomerization of oxygen heterocycles to understand the on-surface synthesis of furan and pyran derivatives from ketone-functionalized precursors on metal surfaces.

[1] Xiang, et al. Nature Chem., 2022 14, 871–876.
A3Ti5NbO14 (A = H, Li and K) Family: Ionic Exchange, Physical and Electrochemical Properties
Authors: Neveu Audric , Jean Justine , Boullay Philippe , Kovrugin Vadim , Sagot Armance , Raj Hari , Pralong Valerie
Published: August 2024

A new layered titanoniobate, Li3Ti5NbO14, a member of the AxM2nO4n+2 family, has been synthesized using a molten salt reaction between H3Ti5NbO14 and an eutectic “LiOH/LiNO3”. This compound crystallizes in the P21/m space group with a=9.266(1) Å, b=3.781(3) Å, c=8.95(1) Å, and b=113.9(1) ° It exhibits |Ti5NbO14| layers similar to K3Ti5NbO14, but differs from the latter by a “parallel configuration” of its |Ti5NbO5| ribbons between the two successive layers. The topotactic character of the reaction suggests that exfoliation plays a prominent role in the synthesis of this new form. This new phase intercalates reversibly 2 lithium through a first-order transformation leading to a capacity of 100 mAh/g at a potential of 1.67 V vs Li/Li+.
(Invited) The Evolving SiC Market and Impact on CMP Supply Chain
Authors: Rhoades Robert
Published: August 2024

Silicon carbide (SiC) is a wide bandgap semiconductor with physical and electrical properties that provide superior performance in high-voltage or high-power applications. Compared to the more established silicon devices, SiC provides better thermal conductivity, ~10x higher breakdown voltage, faster switching speeds and lower resistivity. Even with the performance advantages, the adoption rate of SiC is slowed by high cost and the inherent difficulty of processing this material. SiC is extremely hard (just below diamond on the hardness scale) and chemically inert which makes processing boules into wafers rather difficult. This presentation will contrast some of the basic differences between process methods developed for silicon and other semiconductor materials versus those required for SiC.

Demand for high-quality single crystal SiC substrates continues to rise as the worldwide demand for electric vehicles, charging infrastructure, green energy production, and more efficient power devices in general requires more and more SiC devices. SiC wafer manufacturers are trying to ramp output as quickly as possible but technical difficulties of processing SiC are often a limiting factor. In spite of aggressive capital spending by many of the major players, the actual growth in substrate production has been constrained to around 15% CAGR even though demand would support a much faster ramp. As end use markets continue to evolve, ripple effects are also evident in the underlying supply chains, such as CMP pads and slurries.
(Invited) Ultrathin Gap Nanoantenna: Crystal Phase Transitions and Luminescent Properties
Authors: LaPierre Ray , Diak Ethan
Published: August 2024

We report Te-doped GaP nanowires (NWs) with positive tapering and radii measuring as low as 5 nm grown by the self-assisted vapor-liquid-solid mechanism using selective-area molecular beam epitaxy. The occurrence of the ultrathin nanoantenna showed a dependence on pattern pitch (separation between NWs) with a predominance at 600 nm pitch, and exhibited radius oscillations that correlate with polytypic zincblende/wurtzite segments. A growth model explains the positive tapering of the NW leading to an ultrathin tip from the suppression of surface diffusion of Ga adatoms on the NW sidewalls by Te dopant flux. The model also provides a relationship between the radius modulations and the oscillations of the droplet contact angle, predicting the quasi-periodic radius oscillations and corresponding crystal phase transitions. The GaP NWs showed strong low temperature micro-photoluminescence exciton-related emission, indicating a bandgap difference between the zincblende/wurtzite segments, with phonon replicas due to the transverse optical phonon mode. These results establish a link between dopants and the ability to control NW morphology, crystal phase and luminescent properties with possible applications in thermoelectrics, quantum emitters and photodetectors.
(Invited) Core-Multi-Shell Design: Unlocking Multimodal Capabilities in Lanthanide-Based Nanoparticles
Authors: Liu Nan , Puccini Abigale , Homann Christian , Hemmer Eva
Published: August 2024

The remarkable optomagnetic properties of the lanthanides (Ln) make Ln-based materials ideal for biomedical applications, including diagnostic (e.g., imaging, nanothermometry) and therapeutic (e.g., drug delivery, photodynamic therapy) approaches. This is due the unique electronic properties of the f-elements allowing for upconversion and near-infrared emission under near-infrared excitation as well as high magnetic moments. Yet, challenges remain, including low emission intensity and efficiency of small nanoparticles (NPs), and reliable, fast synthesis routes. As material chemists, we tackle these challenges with new designs of Ln-NPs by chemically controlled synthesis, application-oriented surface chemistry, and understanding of structure-property-relationships. We developed a straightforward and rapid microwave-assisted synthesis approach towards core-multi-shell Ln-NPs. Careful architecture design and choice of RE3+ dopant ions allow to tune the optical properties of the resultant nanoparticles, i.e., upconversion and near-infrared emission. This presentation will shed light on recent results with respect to microwave-assisted synthesis of Ln-NPs as well as structural and optomagnetic properties, seeking biomedical application.

For instance, multimodal bioimaging probes merging optical imaging, magnetic resonance imaging (MRI), and X-ray computed tomography (CT) capabilities have attracted considerable attention due to their potential biomedical applications. This includes nanoparticles that combine upconverting Er3+/Yb3+ and magnetic NaDyF4 for optical/T2-weighted MRI/CT multimodal capabilities. A known drawback of multimodal probes that merge the upconverting Er3+/Yb3+ ion pair with magnetic Dy3+ ions for T2-weighted MRI is the loss of upconversion emission due to Dy3+ poisoning. The synthesis of controlled nanoparticle architectures with tuned inner NaGdF4 shell thicknesses separating Dy3+ and Er3+/Yb3+ allow to shed light on this distance-dependent loss of upconversion due to Yb3+ → Dy3+ energy transfer. As a result, the Ln-NP architecture was tuned to not only restore but enhanced the upconversion emission. In addition to multimodal imaging, Ln-NPs are promising candidates for application in nanothermometry due to the distinct, temperature-induced changes in their spectral features. We seek the development of novel Ln-NP nanothermometers for new opportunities in the near-infrared biological transparency windows (1000 to 2000 nm), by doping RE3+ ions, such as Er3+ and Tm3+ as well as unconventional Pr3+, into core-multi-shell lanthanide-based nanoparticles.
Study on Electrochemical Characteristics of Crystal Structure Changes Effects of Silicon Anode Materials for Lithium Ion Batteries
Authors: Yang Minji , Kim Dong-Young , Shim Jae-Hyun
Published: August 2024

Graphite is widely used as a representative anode material in commercialized lithium-ion secondary batteries. However, with a theoretical capacity of 370 mAh/g, it is difficult to manufacture high-capacity/high-density lithium-ion secondary batteries. Therefore, research is actively underway to find high-capacity substances to replace graphite. Silicon anode materials are currently attracting attention as next-generation high-capacity cathode materials. Silicon forms Li4.4Si when fully charged through an alloying/dealloying process with lithium during the reaction. Graphite is intercalation/deintercalation in reaction with lithium and LiC6 is formed when fully charged. That's why silicon has a theoretical capacity of 3800 mAh/g, about 10 times that of graphite.

However, silicon is a high-capacity electrode material that overcomes the theoretical capacity limit of graphite, and has the disadvantage of experiencing volume expansion of about 400% during repeated charge/discharge cycles. Problems such as material cracks due to volume expansion can affect the safety of the battery. Various studies are being conducted to solve silicon-related challenges to effectively utilize silicon materials. Previous studies have explored the use of binders or additives to mitigate volume expansion. In addition, various types of silicon materials such as Si alloy and SiOx are being developed to suppress volume expansion through matrix formation. Nevertheless, despite the development of silicon materials, structural changes in the charging and discharging process of silicon remain unclear.

This study aims to analyze the structural changes that occur during the charging and discharging process of silicon. The experiment evaluates the electrochemical characteristics of crystalline silicon and amorphous silicon and compares the behavior and structural changes during charging/discharging. The volumetric expansion measurements are performed with electrochemical characterization, and ex-situ X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses are performed for comparison with crystal structural changes.
(Invited) Deciphering the Interfacial Chemistry and Degradation Pathway of Layered Cathode Materials
Authors: Mu Linqin
Published: August 2024

Cathode materials such as layered oxides play a crucial role in determining batteries' energy density and safety. LiNixMnyCozO2 (NMC), as the dominating cathode, has been successfully commercialized for many years. In addition, there is a consensus that integrating NMC cathodes into all-solid-state batteries (ASSBs) is an effective way to achieve high energy densities. However, NMC cathodes are still facing many challenges, particularly, during the perusing of the high Ni concentration and high cut-off voltages. In the presentation, we will discuss the interface degradation of the NMC cathode at multiple length scales. By comprehensive imaging and spectroscopic techniques, we could bridge the degradation phenomenon from the electrode scale to the atomic scale. We will present the challenges of characterizing the surface properties of the cycled layered cathode and summarize our strategies that can enhance the surface stability of NMCs. Our fundamental understanding will inform the design principles at multiple length scales in batteries. Shifting our focus to solid-state batteries (SSBs), there is a growing body of research on SSBs incorporating NMC cathodes and argyrodite solid electrolytes (SEs). However, these advanced ASSBs face significant challenges in terms of low initial Coulombic efficiency and rapid capacity degradation. Therefore, we also try to understand the interfacial degradation mechanisms in composite SE-NMC cathodes in this talk.
(Invited) Photophysical Properties and Photodynamics in CdSe Quantum Dots as Photocatalysts and Photosensitizers
Authors: Kilina Svetlana V.
Published: August 2024

Interactions between dye molecules and the semiconductor quantum dots (QDs) has a strong effect on both solar-to-electrical and solar-to-chemical energy conversion processes. In both types of applications, the charge transfer from the photoexcited QD to the molecule play a crucial role. Applying DFT-based non-adiabatic molecular dynamics, we have revealed ultrafast hole transfer (~10 fs) from the CdSe QD to the Ru(II) dye, following by a slow component (~100 fs) associated with the redistribution of population throughout QD states. The ultrafast interfacial QD-to-dye hole transfer is rationalized by strong non-adiabatic couplings between the QD surface states and the high frequency vibrational modes of isocyanide ligands in the dye. We also have studied the effect of the complex heterostructures of Janus QDs, where a half of the QD is made from CdSe and another half is from PbSe forming an interface along a specific crystalline direction. Our calculations show that the Pb-enriched (111) crystalline direction of the interface enhances optical response of the QDs. The hole relaxation is much slower than the electron relaxation, followed by the hole transfer to the dye. The hole transfer is sensitive to the polarity of the environment, rather than the ways of dye’s attachment to the surface. We also found that in nonstoichiometric QDs, a loss of a passivating ligand affects the electronic structure in the same way as injection of an electron in Cd-rich QDs or hole injection in Se-rich QDs. Moreover, electron injection to the Se-rich QDs results in highly optically active redshifted transitions associated with the introduced charge. Overall, our calculations provide atomistic insights into QD-to-molecule charge transfer, giving researchers an additional handle for enhancing QD photophysical properties by means of the QD stoichiometry, interface structure, and QD-molecule engineering.
(Invited) Toward Ultrathin Flexible Quantum Dot Light-Emitting Diodes and Photodetectors for the Wearable Electronics
Authors: Choi Moon Kee
Published: August 2024

Flexible optoelectronic devices, encompassing light-emitting diodes (LEDs) and photodetectors, capable of seamlessly transforming their shapes, represent a prominent trend in next-generation electronics. Quantum dots, widely employed as emitters and light absorption layers, are chosen for their high luminous performance, size-dependent color tunability, and excellent light absorption properties. Moreover, their solution processability and ultrathin form factor make them particularly appealing for the development of ultrathin wearable optoelectronic devices.

Here, we introduce ultrathin flexible quantum dot light-emitting diodes and photodetectors designed for wearable electronics. Utilizing intaglio transfer printing, we can produce high-definition red-green-blue quantum dot LEDs, suitable for integration into skin-attachable displays. Moreover, our ultrathin, self-powered, heavy-metal-free photodetectors, based on copper indium selenide nanoparticles, showcase outstanding optical performance (specific detectivity: 2.10 × 1012 Jones at zero-bias) and find application in wearable photoplethysmography (PPG) sensors.
(Invited) Quantum Physics in Quantum Dots/Graphene Nanohybrids Broadband and Flexible Photodetectors
Authors: Wu Judy
Published: August 2024

Colloidal semiconductor quantum dots/graphene (QD/Gr) heterojunction nanohybrids have recently emerged as a promising candidate for broadband photodetection. The QD/Gr nanohybrids are quantum sensors that take advantages of the quantum confinement in QDs for spectral tunability and that in graphene for superior charge mobility, leading to high photoconductive gains. Therefore, the QD/Gr nanohybrids provide a unique platform for design of broadband, flexible photodetectors that can have high quantum efficiency and hence high detectivity (D*) enabled by the strong quantum confinements in both QDs and graphene. This presentation highlights the recent progress made on QD/Gr nanohybrids broadband photodetection ranging from ultraviolet, to visible and infrared. The focus of the talk will be on understanding the quantum physics governing the performance of the QD/Gr nanohybrids photodetectors including noise, photoresponse, response speed and the figure of merit D*.
Novel DNA-Based Polymer Solid Electrolytes for Lithium-Ion Batteries
Authors: CHENG Xiong , LI Man , Li Yang , Song Seunghyun , Vallem Sowjanya , Bae Joonho
Published: August 2024

Solid electrolytes are becoming increasingly popular due to their safety [1], and the application of organic biomolecules in electrochemical devices is also an important strategy for sustainable development [2]. Recently, we have studied the application of DNA in electrochemical energy storage devices [3]. A novel PVDF@DNA solid polymer electrolyte was designed in this work, we studied the effect of different DNA addition amounts on polymer solid electrolytes. DNA as a plasticizer-like additive, reduces the crystallinity of the polymer solid electrolyte and improves its ionic conductivity [4]. At the same time, due to the Lewis acid effect of DNA, it can promote the dissociation of lithium salt when interacting with lithium salt anions, and it can also fix the anions, causing more free lithium ions in the electrolyte, thus improving its ionic conductivity. The polymer solid electrolyte with DNA shows relatively better performance. Hence, the DNA-based polymer solid electrolyte fabricated in this study has substantial potential for application in LSBs.

Acknowledgement

This work was supported by the National Research Foundation of Korea (NRF-2021R1A2C1008272). This work was supported by Ministry of Trade, Industry and Energy, KEIT, under the project title "International standard development of evaluation methods for nano-carbon-based high-performance supercapacitors for electric vehicles" (project # 20016144).

References

[1] Liang J. et al. Recent progress on solid-state hybrid electrolytes for solid-state lithium batteries. Energy Storage Materials 21 (2019) 308-334.

[2] Dutta, D. et al. N7-(carboxymethyl)guanine-Lithium Crystalline Complex: A Bioinspired Solid Electrolyte. Scientific Reports 6 (2016) 24499.

[3] Xue Y. et al. DNA-directed fabrication of NiCo2O4 nanoparticles on carbon nanotubes as electrodes for high-performance battery-like electrochemical capacitive energy storage device. Nano Energy 56 (2019) 751–758.

[4] Li Z. et al. Ionic Conduction in Polymer-Based Solid Electrolytes. Advanced Science 10 (2023) 2201718.
Development of Epoxy-Resin Based Solid Electrolytes for Multifunctional Structural Batteries
Authors: Ford Elena , Black Scott , Gupta Mohit , Guduru Pradeep , Karan Naba
Published: August 2024

A structural battery is defined as being multifunctional; it is a load bearing system with some electrochemical energy storing capability. The electrolyte system is the key enabler for a multifunctional structural battery as it must possess sufficient ionic conductivity (~10-4S/cm) and mechanical strength (Youngs’s modulus ~ 600-900 MPa) simultaneously. Polymeric systems offer the best possible scenario for practical realization of multifunctional structural batteries due to a set of favorable properties, such as reasonable ionic conductivity, easy processability etc. In the present work, we focus on the development of a dual-phase structural battery electrolyte to optimize ionic conductivity and mechanical performance simultaneously. An epoxy resin-based system is chosen due to its high mechanical strength and its ability for in-situ polymerization that leads to a unique microstructure promoting multi-functionality. Diglycidyl ether of Bisphenol A (DGEBA) accounts for the epoxy to provide hard segments in the matrix and is cured by an amine compound (Jeffamine T-403). A liquid electrolyte is added to the system for improving ionic conductivity without compromising its mechanical strength substantially. Multiple liquid components consisting of lithium salt and solvents are considered -lithium bis(trifluoromethanesulfonyl)imide (LITFSI) dissolved in a solution of ethylene carbonate (EC) and dimethyl methyl phosphonate (DMMP) and LiTFSI dissolved in 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI). Ionic conductivity of the electrolyte systems as a function of temperature is measured utilizing electrochemical impedance spectroscopy. Uniaxial load tests are performed to evaluate the mechanical properties (e.g., Young’s modulus, Yield strength) of the epoxy-based electrolyte systems with and without the addition of the ion conducting liquids. Comparative data on the epoxy-based systems containing varying amounts of liquid components will be presented.
Tracking Degradation of Sulfolane-Based Electrolytes in 5 V LNMO Cells
Authors: Pechberty Clément , Johansson Patrik
Published: August 2024

Lithium-ion batteries (LIBs) are today the most used energy storage for portable electronics and electric vehicles – but are laden with concerns of materials scarcity and availability, alongside performance and cost. The development of high-voltage cobalt-free cathode active materials, such as LiNi0.5Mn1.5O4 (LNMO), represents one promising route for next-generation LIBs, due to a combination of high capacity and low cost. Combining LNMO with conventional LIB electrolytes, based on carbonate solvents, however, typically leads to severe capacity fading due to a range of different degradation mechanisms1, not the least due to the high electrochemical potential reached during charge, up to 5 V vs. Li+/Li°.

Here we use a range of sulfolane-based electrolytes to improve the stability2 and track the degradation by intermittent current interruption (ICI), which is a rather new protocol to determine the internal resistance of battery cells during cycling3. The ICI data is presented in the form of heat maps, in order to better visualize the variation of internal resistance as function of the cell voltage. Furthermore, Raman spectroscopy is used to identify the decomposition products resulting from the degradation and the data is correlated with the ICI data. Overall this allows us to shine further light on the prospects of sulfolane-based electrolytes for 5 V cells as compared to conventional LIB electrolytes such as e.g. LP40.

References

Guo, K. et al. High‐Voltage Electrolyte Chemistry for Lithium Batteries. Small Science
2, 2100107 (2022).

Xu, J. Critical Review on cathode–electrolyte Interphase Toward High-Voltage Cathodes for Li-Ion Batteries. Nano-Micro Letters vol. 14 (2022).

Yin, L. et al. Implementing intermittent current interruption into Li-ion cell modelling for improved battery diagnostics. Electrochim Acta
427, (2022).
Effect of Anisotropy on Lithium Dendrite Growth
Authors: Zhang Jin , Voorhees Peter W.
Published: August 2024

Lithium dendrite formation is one of the leading causes of performance degradation and safety hazards in lithium batteries. Understanding dendrite evolution and its morphology during cycling can provide the critical insight into improving battery performance and safety. Recent experimental studies with cryo-electron microscopy have revealed anisotropic morphologies of lithium metal during deposition. Lithium, being a crystalline material, exhibits different surface energies and reaction rates depending on the crystal surfaces. In this study, we apply a quantitative electrochemical phase-field model to study the impact of thermodynamic and kinetic anisotropy on lithium morphology during battery cycling. We examine scenarios involving the alignment or misalignment of lithium crystals with the applied current. We observe that due to the rapid deposition rates, lithium dendrites tend to grow along crystal directions with high kinetics, resulting in a needle-like morphology. Furthermore, we study the effect of anisotropy magnitude on morphology selection, as well as the interaction between neighboring dendrites during cycling and the effect of various factors, including the applied current and electrolyte properties. Overall, this study elucidates the relationship between lithium dendrite morphology and various factors, ultimately contributing to the development of improved batteries with enhanced performance and safety.
Stable Anode-Free All-Solid-State Lithium Battery through Tuned Metal Wetting on the Copper Current Collector
Authors: Mitlin David
Published: August 2024

Stable anode-free all-solid-state battery (AF-ASSB) with sulfide-based solid-electrolyte (SE) (argyrodite Li6PS5Cl, LPSCl) is achieved by tuning wetting of lithium metal on “empty” copper current-collector. Lithiophilic 1 μm Li2Te is synthesized by exposing the collector to tellurium vapor, followed by in-situ Li activation during the first charge. The Li2Te significantly reduces the electrodeposition/electrodissolution overpotentials and improves Coulombic efficiency (CE). During continuous plating experiments using half-cells (1 mA cm-2), the accumulated thickness of electrodeposited Li on Li2Te-Cu is more than 70 μm, which is the thickness of Li foil counter-electrode. Full AF-ASSB with NMC811 cathode delivers an initial CE of 83% at 0.2C, with a cycling CE above 99%. Cryo-FIB sectioning demonstrates uniform electrodeposited metal microstructure, with no signs of voids or dendrites at the collector-SE interface. Electrodissolution is uniform and complete, with Li2Te remaining structurally stable and adherent. By contrast, unmodified Cu current-collector promotes inhomogeneous Li electrodeposition/electrodissolution, electrochemically inactive “dead metal”, dendrites that extend into SE, and thick non-uniform solid electrolyte interphase (SEI) interspersed with pores. Density functional theory and mesoscale calculations provide complementary insight regarding nucleation-growth behavior. Unlike for conventional liquid-electrolyte metal batteries, the role of current collector/support lithiophilicy has not been explored for emerging AF-ASSBs.
One-Dimensional Van Der Waals V2Se9 As a Conversion-Type Anode Material for Advanced Li Rechargeable Batteries
Authors: Hwang Sunhyun , Yoon Won-Sub
Published: August 2024

Volume expansion of active materials during lithium storage is one of the main issues in Li-ion batteries (LIBs) that should be addressed. In particular, large volume changes and particle cracking are problematic for electrode materials based on conversion reaction, which are considered attractive anode materials with high energy densities. In this study, a one-dimensional van der Waals (1D vdW) material, V2Se9, is proposed as a conversion-type anode material for LIBs. The V2Se9 electrode material has a 1D chain molecular structure with vdW interactions between chains to form a bulk crystal structure. The spaces between the 1D chains act as structural buffers and provide short Li+ diffusion paths that can improve the electrochemical performance of the electrode materials. The V2Se9 electrode exhibits a high reversible capacity of 563.3 mAh g-1 at 100 mA g-1 and a high rate capability of 109.1 mAh g-1 at 3200 mA g-1. The capacity retention of V2Se9 electrodes is 83.72 % after 100 cycles. Synchrotron X-ray diffraction and X-ray absorption spectroscopy reveal the formation of Li2Se and V metal, indicating that Li ion storage occurs via the conversion reaction. The structural stability of V2Se9 is demonstrated using SEM measurements of the discharged and charged V2Se9 electrodes during cycling. These results demonstrate the reaction mechanism of V2Se9 and highlight the potential of 1D vdW materials as high-performance anode materials in LIBs.
Hybrid Aerosol Jet Printing and Electrodeposition of Ferrite-Sandwiched Inductors
Authors: Manzi Jacob , Sui Yongkun , Tarantino Joshua , Tsui Lok-kun , Neely Jason , Lavin Judith Maria
Published: August 2024

The additive manufacturing (AM) of inductors of suitable size to be integrated into packaged electronics is attractive to customize the device characteristics for the specific application. Magnetic ferrite cores are widely used in conventional inductors, however, wire wound inductors can be brittle, heavy, bulky. Planar spiral inductors in a sandwich configuration present a promising alternative. Aerosol jet printing, a direct write AM technology, can deposit metal inks at a resolution of < 10 µm. Metal nanoparticle inks have limited conductivity at < 40% bulk. Building a higher profile may result in loss of resolution. Electrodeposition offers the ability to plate thick layers of highly conductive metals, including copper and nickel which are normally hard to access as nanoparticle inks compatible with aerosol jetting. We have previously shown the construction of a multi-layer flyback transformer with this hybrid aerosol jet and electrodeposition method. [1]

We present a three-layer planar inductor with the first layer being a 1.3mm stack of ferrite sheets (Fair-Rite) with a 9 mm x 9 mm footprint integrated onto a circuit board. The intermediate layer consists of a spiral inductor made by aerosol jet printing UTDots Ag40X silver nanoparticle ink as the seed layer. To achieve high accuracy, the inductor was printed with a rotary axis stage. Electrodeposition in an acidic CuSO4 plating bath on top of the Ag seed layer resulted in thicknesses of 50 µm. A submicron layer of Ni is added for oxidation protection by electrodeposition from a Ni-Sulfamate bath. Lastly, a top 1.3 mm ferrite stack, with laser cut holes, is added to provide pass throughs for wire bonding. Figure 1 shows a micrograph of an inductor as printed, after electrodeposition, and with the top ferrite layer. Electrical measurements including impedance characteristics will be presented.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. The SAND No. is SAND2023-14571A.

Figure 1. Construction of a ferrite-sandwiched inductor with (a) the aerosol jet printing of an Ag seed layer, (b) after electroplating of Cu and Ni.

References: [1] Tsui, L.; Hartmann, T. M.; Dye, J.; Lavin, J. M. IEEE Trans. Components, Packaging, and Manufacturing Tech. (2023), 13, 8, 1302-1309.

Figure 1
A Comparative Study of Numerical Methods for Lithium-Ion Battery Electrochemical Modeling
Authors: Lucero Joseph Neil , Xu Le , Cooper Julian , Allam Anirudh , Onori Simona
Published: August 2024

Lithium-ion battery (LIB) with high specific energy density and long cycle life is one widely used energy storage technology. In order to ensure longevity and safety of the battery system, a battery management system (BMS) that relies on battery model is required. With the development of BMS technique, more attention has been given to electrochemical models that provide insights into the battery internal states. In general, battery electrochemical models consist of partial differential equations (PDEs) describing the thermodynamic and electrochemical process inside the cell, and those PDEs can only be solved numerically due to their complexity.

Existing battery simulation software utilize numerical methods such as finite difference method (FDM), finite volume method (FVM), and finite element method (FEM) to solve PDEs in battery models. However, there are little discussions for the selection of a specific numerical methods. In our recent study [1], we compare two spatial discretization methods commonly used to numerically solve the governing PDEs of LIB electrochemical models, namely FDM and FVM, in terms of model accuracy and mass conservation guarantee. First, we provide the mathematical details of the spatial discretization process for both FDM and FVM to solve the battery single particle model (SPM), this result has not been shown in any publication before. Second, we propose a new Hermite extrapolation based FVM scheme leading to higher accuracy when compared to the normally used linear extrapolation based FVM scheme. Then, SPM parameters are identified using experimental data, and a comprehensive parameter sensitivity analysis is conducted under different current input profiles to study parameter identifiability. Finally, model accuracy and mass conservation analysis of the FDM and FVM schemes are presented. Our study shows that the FVM scheme with Hermite extrapolation leads to accurate and robust control-oriented battery model while guaranteeing mass conservation and high accuracy. Also, the proposed new FVM scheme can be extended to solve other battery models, such as SPM model with electrolyte and Doyle-Fuller-Newman model. Moreover, we provide findings of mass conservation analysis for FDM and FVM schemes, which we hope can facilitate BMS model selection.

References

[1] Xu, L.; Cooper, J.; Allam, A.; Onori, S., "Comparative Analysis of Numerical Methods for Lithium-Ion Battery Electrochemical Modeling," Journal of The Electrochemical Society, 2023. 10.1149/1945-7111/ad1293