bluuebunny/crossref_metadata_2025 huggingface dataset:
Interfacial Chemistry and Electrolyte Approaches for Enabling Metal Anode Batteries
Authors: Popovic-Neuber Jelena
Published: November 2022

Continuous solid electrolyte interphase (SEI) and dendrite growth, as well as formation of ion blocking interfaces are some of the crucial issues preventing the commercialization of batteries depending on the implementation of Li/Na/K/Mg/Ca metal anodes.[1,2] In the first part of my talk, I will focus on the chemistry of formed interfaces, including growth and ion transport control. Second part of my talk deals with bulk liquid, polymer and hybrid electrolyte molecular structure approaches for circumventing dendrite formation.

Understanding of the SEI growth on alkali and alkaline earth metals in contact with liquid electrolytes under open circuit potential conditions important for shelf aging is still in its infancy. I will show that the SEI formed on Li in contact with glyme-based electrolyte grows via reaction-controlled mechanism that is rapidly substituted by the diffusion-controlled one.[3] The ionic transport and stability of the complex composite SEI material under current is highly dependent on the salt chemistry, with detrimental effects of LixSy and positive effects of the Li3N constituents. Most recent ion transport and morphological studies show that the initial SEI formed in contact with liquid electrolytes on Li, Na and Mg is nanoporous.[4,5] Based on the electrochemical impedance spectroscopy measurements in symmetric cells and related equivalent circuit models, I will discuss potential growth mechanism via SEI densification. Finally, I will present a possibility of using gas/solid synthesis for preparation of sulfide-based artificial SEIs for both liquid-based and solid-state batteries.[6]

Dendrite formation on alkali and alkaline earth metal anodes is closely related to the ion concentration gradients formed near the electrodes in contact with the electrolytes. I will discuss the method to circumvent this problem by using electrolytes with high cationic transference number. In soft matter electrolytes this is possible when (i) interfacial effect enables preferential anionic adsorption in liquid/solid electrolytes,[7] (ii) the size and steric effects control the association and mobility of the anion in the liquid electrolytes,[8] (iii) ion transport proceeds through percolating amorphous clusters in polymer-in-salt electrolytes. [9]

References:

[1] J. Popovic, Nat. Comm., 12, 6240 (2021) [2] J. Popovic, J. Electrochem. Soc., 3, 169 030510 (2022) [3] M. Nojabaee, K. Küster, U. Starke, J. Popovic, J. Maier, Small, 16, 23, 2000756 (2020) [4] K. Lim, B. Fenk, J. Popovic, J. Maier, ACS App. Mat. Int., 13 (43), 51767 (2021) [5] J. Popovic, Energy Technol., 9, 4, 2001056 (2021) [6] K. Lim, B. Fenk, K. Küster, T. Acartürk, J. Weis, U. Starke, J. Popovic, J. Maier, ACS App. Mat. Int., 10.1021/acsami.1c23923 (2022) [7] J. Popovic, G. Hasegawa, I. Moudrakovski, J. Maier, J. Mat. Chem. A, 1, 40, 7135 (2016) [8] J. Popovic, D. Höfler, J. Melchior, A. Münchinger, B. List, J. Maier, J. Phys. Chem. Lett., 9, 17, 5116 (2018) [9] J. Popovic, Macromol. Chem. Phys, 10.1002/macp.202100344 (2021)
Gesn Alloys: From Optical to Electrical Pumped Lasers
Authors: Buca Dan , El-kurdi Moustafa , Witzens Jeremy , Oehme Michael , Capellini Giovanni , Gruetzmacher Detlev
Published: November 2022

Internet of Things applications, including medical diagnostics, imaging and industrial process controls, pollution monitoring or real-time motion control, push the extension of the Si photonics towards mid-infrared range.

In recent years, group IV SiGeSn-based optoelectronic devices including light emitting, detectors, modulators, and CMOS devices have been developed. The main advantage of SiGeSn is the bandgap tunability in the range between 1.5 to 5 µm via Si and Sn compositions. Remarkably, the GeSn binary alloy becomes a direct bandgap semiconductor at a relative low Sn content of about 7-8 at.% opening the quest for the realization of monolithically integrated laser sources on Si. In this direction, from the first laser emission proof in 2015 remarkable progress has been done. Supported by epitaxial growth success, processing technology, and cavity design, the laser emission of optically pumped was continuously increased from 80K to 270K. The main role here was played by increasing the Sn content up a concentration of 17 at.%.

The next major improvement came from layer transfer technology allowing defect engineering and heat management. Their combination made possible room temperature lasing. However, the real life application requires low laser threshold. Here the use of multiple quantum wells based on SiGeSn/GeSn heterostructures and strain engineering allow a remarkable threshold reduction to values of about 1 kA/cm2. Interestingly, modeling shows that the very epitaxial challenging of having high Sn contents can be reduced by band structure engineering via introducing tensile strain and, in addition, larger gains are possible compared with high-Sn strain free layers. The optical laser spectrum at 0 °C for a GeSn layer under 1 % biaxial tensile strain is shown in Fig 1a.

The next step is the realization of an electrical pumped GeSn laser. The first data indicate that both waveguide and microdisk cavities can be electrically pumped leading to low temperature laser emission. The effect of the geometry and strain relaxation of under-etched cavities on the laser emission is under study. Figure 1b shows an exemplary spectrum and current-in light-out (LI) curve for a device with a SiGeSn/GeSn heterostructure taken at 50 K.

Figure 1
(Digital Presentation) Gesnoi Laser Technology for Photonic-Integrated Circuits
Authors: Joo Hyo-Jun , Kim Youngmin , Burt Daniel , Jung Yongduck , Zhang Lin , Chen Melvina , Luo Manlin , Parluhutan Samuel Jior , Kang Dong-Ho , Lee Chulwon , Assali Simone , Son Bongkwon , Ikonic Zoran , Moutanabbir Oussama , Cho Yong-Hoon , Tan Chuan Seng , Huang Yi-Chiau , Nam Donguk
Published: November 2022

GeSn alloys have been regarded as a promising material for creating a complementary metal-oxide-semiconductor (CMOS)-compatible light source. Despite the remarkable progress in demonstrating GeSn lasers, an unavoidable intrinsic compressive strain introduced during epitaxial growth has prevented researchers from pushing the directness of GeSn gain media to the limit and realizing practical GeSn lasers. In this paper, we demonstrate a GeSn-based 1D photonic crystal nanobeam laser on a high-quality GeSn-on-insulator (GeSnOI) substrate which allows releasing the limiting compressive strain, thus improving the threshold and operating temperature. Pump-power-dependent photoluminescence measurements show a lasing threshold density of 18.2 kW cm−2 at 4 K for the released strain-free GeSn nanobeam, which is ~2 times lower than that of the unreleased GeSn nanobeam with compressive strain. The improved bandgap directness in the released GeSn nanobeam also allows achieving lasing action at higher operating temperatures up to 90 K compared to the unreleased laser device (<70 K). We also report a straightforward geometric strain-inversion technique that harnesses the harmful compressive strain to achieve ultrahigh tensile strain in GeSnOI nanowire, drastically improving the directness of the bandstructure. We achieve ~2.67% uniaxial tensile strain in ~120 nm wide nanowires, surpassing other values reported thus far. We also demonstrate unique superlattices comprising of indirect and direct bandgap GeSn are demonstrated in a single material only by applying a periodic tensile strain. Increased directness in tensile-strained GeSn significantly enhances the photoluminescence intensity by a factor of ~2.5. Our demonstration offers an avenue toward developing practical CMOS compatible light sources.
A Near-Infrared pin Photodetector of Strain-Enhanced Ge Layer Epitaxially Grown on a Bonded Si-on-Quartz Wafer
Authors: Kuzutani Mikiya , Furuya Satoki , Piedra Lorenzana Jose Alberto , Hizawa Takeshi , Ishikawa Yasuhiko
Published: November 2022

In Si photonics, photodetectors (PDs) of a Ge epitaxial layer on Si have been widely used, which show a high photodetection efficiency, or a high responsivity in the O (1.260–1.360 µm) and C (1.530–1.565 µm) bands. However, an issue lies in a low responsivity in the longer wavelength range of L band (1.565–1.625 µm). In this regard, we have proposed a method using a Ge layer epitaxially grown on a Si-on-quartz (SOQ) wafer [1]. The tensile in-plane lattice strain, derived from the thermal expansion mismatch between the Ge layer and base substrate, is enhanced more than 0.3% in Ge on SOQ, despite ~0.2% on Si (or Si-on-insulator). The enhanced strain in Ge on SOQ extends the fundamental optical absorption edge to about 1.65 µm, leading to a potential increase in the L-band responsivity. In this study, a vertical pin PD is fabricated using a Ge layer on SOQ, showing an increased responsivity in the L band.

A bonded SQQ wafer was used as the starting substrate, fabricated by Shin-Etsu Chemical Co. Ltd. The top Si (001) layer was 200 nm in thickness, and was heavily doped p-type by B implantation. An undoped Ge epitaxial layer (500 nm) was grown by chemical vapor deposition using GeH4 as the source gas, followed by a growth of Si cap layer (50 nm) using Si2H6. In the top region of Ge layer as well as in the Si cap layer, a heavily n-type doping was carried out by P implantation, forming a vertical pin junction. Finally, a Ti/TiN electrode was formed. Responsivity spectra were measured in the wavelength range of 1.46–1.64 µm at a normal incidence. A reference pin PD was also fabricated using a Ge layer on a standard bulk Si wafer. According to x-ray diffraction measurements, the Ge layer on SOQ showed a tensile strain of 0.33%, despite 0.14% for the reference Ge on Si.

Figure 1(a) shows typical current–voltage curves for a pin diode of Ge on SOQ measured under dark and under an illumination of 1.55-µm light (1.1 mW). The diode showed a good rectifying property under dark, while under the illumination, the current in the reverse bias significantly increased, showing a reasonable PD operation. Figure 1(b) shows typical responsivity spectra at a reverse bias of 1 V for PDs of Ge on SOQ and reference Ge on Si. Circles and lines correspond to experimental data points and theoretical curves, respectively. The responsivity for Ge on SOQ was larger in the measured wavelength range of 1.46–1.64 µm, including the L band. The increased responsivity is ascribed to the enhanced tensile strain. However, the increase in the L band was found to be suppressed by a high reflectance because of the multiple reflections at the interfaces. An optimized Si cap thickness as well as an anti-reflection coating with SiO2 can increase the normal-incidence responsivity as high as 0.3 (0.1) A/W up to 1.60 (1.64) µm without an increase in the Ge thickness.

[1] Noguchi et al., J. Appl. Phys. 128, 133107 (2020).

Figure 1
(Digital Presentation) Nanowire Transistors with Bound‐Charge Engineering
Authors: Guo Hong , Prentki Raphaël
Published: November 2022

Low-dimensional electronic systems such as silicon nanowires exhibit weak screening which is detrimental to the performance and scalability of nanodevices, e.g., tunnel field-effect transistors. By atomistic quantum transport simulations, we show how bound charges can be engineered at interfaces of Si and low-κ oxides to strengthen screening. To avoid compromising gate control, low-κ and high-κ oxides are

used in conjunction. In Si nanowire tunnel field-effect transistors, we demonstrate that bound charge engineering increases the on-state current by orders of magnitude, and the combination of oxides yields minimal subthreshold swing. Finally, an analytical model is developed for Si nanowire FET assisted by bound charge engineering. We conclude that the proposed bound-charge engineering paves a way toward improved low-power transistors.
Growth and Properties of Graphene and Graphene Nanoribbons on Ge
Authors: Arnold Michael S.
Published: November 2022

The synthesis of graphene directly on Ge and on Ge deposited on Si provides a scalable route toward integrating graphene onto conventional semiconductors. This presentation will first survey the growth modes of graphene on Ge(001), Ge(011), Ge(111), Ge(112), Ge(001)-6°, and Ge(001)-9° via chemical vapor deposition (CVD), reporting on the effect of Ge surface orientation on graphene island formation and shape, strain in large-area graphene films, and the nanofaceting of the Ge below graphene.[1] We will then focus on the anisotropic growth of semiconducting graphene nanoribbons on Ge(001) and Ge(001)-9° and of nominally single crystal graphene on Ge(110).

On Ge(001), we have discovered how to drive graphene crystal growth with a large shape anisotropy through control of kinetics.[2-6] This discovery enables the direct synthesis of narrow, armchair, semiconducting nanoribbons. The ribbons are self-orienting, self-defining, and have smooth edges. The ribbons exhibit excellent transport properties (e.g., high on-state conductance and on/off ratio at room temperature) and provide a promising pathway towards the direct integration of high-performance nanocarbon electronics onto conventional semiconductor wafer platforms.

On Ge(001), nominally single crystal graphene has been reported in limited cases; however, conflicting studies have evidenced polycrystallinity. Here, the factors affecting the mosaicity of graphene on Ge(110) will be elucidated using low energy electron diffraction and microscopy data.[7]

[1] R. M. Jacobberger, D. E. Savage, X. Zheng, P. Sookchoo, R. R. Delgado, M. G. Lagally, M. S. Arnold, SUBMITTED (2022).

[2] R. M. Jacobberger, M. S. Arnold, et al., Direct Oriented Growth of Armchair Graphene Nanoribbons on Germanium, NATURE COMMUNICATIONS, 6, 8006 (2015).

[3] B. Kiraly, M. S. Arnold, M. C. Hersam, N. P. Guisinger et al., Sub-5 nm, Globally Aligned Graphene Nanoribbons on Ge (001), APPLIED PHYSICS LETTERS, 108, 213101 (2016).

[4] A. J. Way, R. M. Jacobberger, M. S. Arnold, Seed-Initiated Anisotropic Growth of Unidirectional Armchair Graphene Nanoribbon Arrays on Germanium, NANO LETTERS, 18, 898 (2018).

[5] V. Saraswat, Y. Yamamoto, H.J. Kim, R.M. Jacobberger, K.R. Jinkins, A.J. Way, N.P. Guisinger, M.S. Arnold Synthesis of armchair graphene nanoribbons on germanium-on-silicon, THE JOURNAL OF PHYSICAL CHEMISTRY C 123 (30), 18445-18454 (2019).

[6] A. J. Way, R. M. Jacobberger, N. P. Guisinger, V. Saraswat, X. Zheng, A. Suresh, J. H. Dwyer, P. Gopalan, Michael S. Arnold, SUBMITTED (2022).

[7] R. M. Jacobberger, Z. Miao, T. Yu, V. Saraswat, M. G. Lagally, M. S. Altman, M. S. Arnold, SUBMITTED (2022).
(Digital Presentation) Substrate Effects in GaN-on-Si Hemt Technology for RF FEM Applications
Authors: Yadav Sachin , Cardinael Pieter , Zhao Ming , Vondkar Komal , Peralagu Uthayasankaran , Alian Alireza , Rodriguez Raul , Khaled Ahmad , Makovejev Sergej , Ekoga Enrique , Lederer Dimitri , Raskin Jean-Pierre , Parvais Bertrand , Collaert Nadine
Published: November 2022

Abstract
: GaN-on-Si HEMTs are emerging as a viable candidate for front-end-of-module (FEM) implementation in 5G and beyond user equipment and small-cell applications [1][2]. This is because GaN HEMTs based power amplifiers and switches have high power handling capability as well as excellent switch figure-of-merit (Ron × Coff). The cost-effective integration of GaN HEMTs on silicon substrates not only benefit from standard CMOS back-end-of-the-line processing but also wafer-level integration with Si-CMOS [1][3], enabling complex functionality and better performance than the standalone counterparts. An example can be a hybrid beamformer where GaN HEMTs can enable much smaller antenna array and therefore a smaller system form factor. For 5G wireless applications, standalone or co-integrated GaN HEMT based FEMs can lead to a more energy efficient and compact system as compared to standalone Si-CMOS technologies. However, for both amplifiers and switches, GaN-on-Si HEMTs present thermal management and substrate loss related issues. In this work, we study and model the impact of GaN HEMT integration on Si substrate on RF substrate losses and non-linearities. The growth of III-N buffer is the most significant factor in determining RF losses and harmonic distortion contribution from the substrate. High temperature annealing and ion implantation steps encountered during HEMT processing can also degrade the substrate performance. In addition, we demonstrate a direct co-relation between substrate losses and harmonic distortion analogous to silicon-on-insulator technologies (Figure 1). However, the bias dependence of RF losses and harmonics show a strong time dependence (memory effects) which is more complex to model [11]. We discuss the approaches to understand and model these effects.

References:

[1] H. W. Then et al, IEEE IEDM Tech. Dig., 2021, pp. 230-234. [2] B. Parvais et al, IEEE IEDM Tech. Dig., 2020, pp. 155-158. [3] W. E. Hoke et al, J. Vac. Sci. Technol. B 30, 02B101 (2012). [4] Drillet F et al, IJMWT 13, 517–522, 2021. [5] L. Cao et al, CSMANTECH conference Tech. Dig., 2020. [6] Roda Neve et al, IEEE TED, Vol. 59, NO. 4, pp. 924-932, 2012. [7] S. Yadav et al., in IEEE IEDM Tech. Dig., 2020, pp. 159-162. [8] Rack et al, ECS Trans., 92 (4), pp. 79-94, 2019. [9] Zhu et al, IEEE Microw.
Wireless Compon. Lett., vol. 28, no. 8, pp. 377–379, 2018. [10] Raskin et al, IEEE SiRFIC, 2015.
[11] P. Cardinael et al, IEEE ESSDERC 2021, pp. 303-306.

Figure 1
Enormous Increases in Swir Detection for Gesn Strips Detector with Graphene Hybrid Structure
Authors: Lin Guochen , Zhao Yue , Yu Kai , Zheng Jun , Zhang Xiaoming , Feng Shuai , Li Chuanbo
Published: November 2022

GeSn materials with tunable bandgaps covering the full shortwave infrared (SWIR) band from 1 to 2.6 μm present a new paradigm for silicon-based SWIR photodetection. However, crystalline quality remains a major limitation for the realization of high-performance photodetectors owing to the large lattice, thermal expansion coefficient mismatching, and Sn segregation. Here, the Sn self-catalyzed growth of lateral GeSn strips on Si(111) substrates by MBE is investigated. These GeSn strips are defect-free by relaxing the large lattice mismatch and introducing (111)-parallel planar dislocations at the GeSn/Si interface. A graphene-GeSn strip hybrid structure photodetector is fabricated, which shows more than 3000 times enhancement in photocurrent and an apparent improvement in temporal response compared with the detector without graphene. A high responsivity of 1.23 A/W and 1.08 A/W at 1310 nm and 1550 nm are achieved, respectively. This work presents a new approach for micro-scale but high crystal quality material in the integration on a silicon-based platform and shows future applications in the SWIR field.
Effect of H2 for Growing Germanium–Lead Alloys By Magnetron Sputtering Epitaxy
Authors: Liu Xiangquan , Zheng Jun , Huang Qinxing , Liu Zhi , Zuo Yuhua , Cheng Buwen
Published: November 2022

Si and Ge are indirect bandgap materials, and their low light emission efficiency limits the development of silicon-based optoelectronics. Studies have shown that the introduction of Pb into Ge can make the Γ valley decrease faster than the L valley, and GePb alloys can be transformed into direct bandgap materials, thereby realizing high-efficiency luminescence of silicon-based materials. Since Pb atoms have a larger core and can provide a greater electronegativity difference for Ge, GePb alloys can be transformed into direct bandgap materials with only about 3.4% Pb. In addition, the maximum optical gain of GePb alloys is much higher than that of GeSn alloys, as revealed by first principal calculations. Therefore, the epitaxial investigation of GePb alloys is of great significance for Si photonics. In this work, Ge1-

x

Pb

x

(1.2% <
x
< 2.4%) alloys were grown by magnetron sputtering epitaxy using H2 and Ar mixture. The effects of different proportions of H2 and Ar on the growth of GePb were studied in detail. High crystal quality Ge0.984Pb0.016 alloys without Pb surface segregation were successfully fabricated. The results show that the increase of H2/Ar ratio contributes to the increase of Pb composition in GePb alloys.

Figure 1
Quantifying the Structure and Chemistry of Semiconductor Devices with the Latest Advancements in Scanning Transmission Electron Microscopy
Authors: LeBeau James
Published: November 2022

Electron microscopy has been revolutionized by the advent of the aberration corrector and advances in detector both for imaging and spectroscopy. Aberration correction dramatically improved spatial resolution into the sub-ångstrom regime, while new detectors have unlocked information about materials that was previously only imaginable.While these recent advances have proven essential to the atomic scale characterization of materials, many measurements have remained largely semi-quantitative. In particular, accuracy and precision for scanning transmission electron microscopy (STEM) was significantly hampered by the presence of sample drift and scan distortion. Until recently, this limitation has obscured the capabilities to characterize minute changes to the atomic structure that can ultimately define material properties.

In this talk, we will introduce revolving scanning transmission electron microscopy (RevSTEM) for the characterization of semiconductors. The method uses a series of fast-acquisition STEM images, but with the scan coordinates rotated between successive frames. This scan rotation introduces a concomitant change in image distortion that is then used to analyze the sample drift rate and direction. Multiple case studies will be presented to demonstrate the power of this technique to characterize electronic materials. For example, we will show how picometer level precision and accuracy enabled the capability to directly quantify ferroelectric HfO2 thin films. We will also show how RevSTEM images can be used to accurately determine crystallographic parameters in real-space, and to determine the structural origins of polarization.

When combined with modern spectroscopy tools, the technique can directly inform growth mechanisms in AlN based materials for fabrication of quantum well structures. Specifically, We will show the interface quality between various AlGaN/AlN quantum wells using a combination of high-angle annular dark-field (HAADF) imaging and energy dispersive X-ray spectroscopy (EDS). We will show that we can directly measure the lattice parameters for each layer and how they vary across each AlN/AlGaN interface. Using EDS, we correlate the lattice parameters and lattice parameter values to the chemical composition in each layer. We show that throughout multiple quantum well structures, there is an asymmetrical interface with a diffusion of Ga on one side of the AlGaN layer. Further, we will discuss fluctuation in the composition present throughout each layer and the role on the local strain distribution.
(Battery Division Postdoctoral Associate Research Award Sponsored by MTI Corporation and the Jiang Family Foundation) Thermal Runaway Modeling of Li-ion Batteries – From Fundamental Modeling to Real-Life Applications
Authors: Coman Paul
Published: November 2022

Thermal runaway in Li-ion batteries is a complex phenomenon that includes various processes that require complex modeling techniques. One needs to consider electrochemical processes, chemical processes, thermodynamics, heat transfer, and fluid dynamics to model thermal runaway. Due to the chaotic behavior and cell-to-cell and chemistry-to-chemistry variability in terms of the energy released and thermal runaway mechanism, critical assumptions must be assumed to simplify the reactions while keeping a realistic physical interpretation. This presentation will show a roadmap for modeling thermal runaway from fundamentals in single cells to practical, real-life applications, such as battery packs. Using assumptions and simplifications, thermal runaway models can help assist the design of safe battery packs and identify design features that can reduce the severity of thermal runaway propagation.
Heterogeneous, Defect-Rich Battery Particles and Electrodes: Why Do They Matter, and How Can One Leverage Them?
Authors: Lin Feng
Published: November 2022

Correlating local materials properties with global battery electrochemistry is nontrivial because battery particles and electrodes are heterogeneous and defect-rich. Pinpointing the root cause of battery performance improvement or degradation can be challenging. In this presentation, we discuss our recent progress in understanding electrode heterogeneities and structural defects in Li ion ion cathodes ranging from individual particles to electrode ensembles. We hope to shed light on these questions: How heterogeneous are the electrochemical reactions within and among active particles? What are the roles of structural defects (point defects, dislocations, grain boundaries, cracks) in directing electrochemical reactions? Are analytical techniques capable of characterizing these heterogeneities with good statistical representativeness? How will the characterization results inform better design of chemical heterogeneity, such as engineered dopant distribution, to improve battery performance? Can we tailor structural defects to improve battery performance? We will also showcase some examples of our low/no-cobalt cathode developments.
Kinetics of Coupled Ion-Electron Transfer for Li-Ion Intercalation
Authors: Zhang Yirui , Fraggedakis Dimitrios , Gao Tao , Zhuang Debbie , Stephens Ryan , Bazant Martin , Shao-Horn Yang
Published: November 2022

Understanding the microscopic mechanism of Li-ion insertion in intercalation solids is crucial for the design of energy storage devices with optimal power and energy densities. Li intercalation kinetics has been traditionally treated by the phenomenological Butler-Volmer kinetics, but remains poorly measured and understood. For example, reported lithium intercalation kinetics for LiCoO2 in carbonate-electrolytes vary by 4-5 orders of magnitude. In this study, we developed experimental electrochemical methods for Li+-concentration-dependent Tafel kinetic measurements, and showed that the current of intercalation in LixCoO2 and NMCs was proportional to the fraction of empty Li+ sites. Exchange current densities and reorganization energies were also extracted for various electrode and electrolyte combinations. These results provide unique experimental evidence to support the microscopic mechanism of Li+ intercalation, where the electron and ion transfers are described by the theory of coupled ion-electron transfer (CIET). The proposed ion intercalation mechanism was also validated through the rate-dependent discharge capacity for eight electrode materials including LiFePO4 and graphite, which decreases linearly with the increasing discharge current under reaction-limited conditions. Our findings suggest that the proposed mechanism applies to a variety of intercalation materials used in energy storage, and governs the power density at low and moderate applied current densities. The possibility of modifying the reaction-limited current with electrodes and electrolytes opens new directions for interfacial engineering of Li-ion batteries.
Influence of Aviation Conditions on Lithium-Ion Batteries
Authors: Hoenicke Pia , Khatri Roni , Willich Caroline , Bauer Christiane , Osama Mohamed
Published: November 2022

Stopping climate change and global temperature rise needs a determined course of action in several technology fields and the development of ZERO-CO2 aircrafts and low emission battery-ICE aircrafts, as well. Batteries in hybrid-electric or fully-electric aircrafts are an option to decrease emissions. The battery requirements for the aviation sector regarding specific energy, energy density and safety are high. Lithium-ion batteries are today the only commercially available technology to meet these requirements, but adequate technology readiness is only proven for the automobile sector while TRL levels 8 and 9 for implementation readiness of batteries in the aviation sector is still ongoing. A crucial aspect for aviation applications is the operation behavior in high altitude including low temperature, wide humidity ranges and especially low pressure. There is little published information available on the effects of low pressure on battery performance. Therefore, different commercially available lithium-ion batteries were tested from atmospheric pressure down to 250 hPa, which corresponds to a flight altitude up to 10,000 m, according to the International Standard Atmosphere (ISA). Since NMC and NCA cathode materials are promising for aviation due to their high specific energy, and LFP cells are promising because of their high safety, the following batteries were selected:

20 Ah HP602030 LFP cylindrical cell (EAS Batteries GmbH, GER).

10 Ah HE 341440 NCA cylindrical cell (EAS Batteries GmbH, GER).

12 Ah SLPB065070180 NMC pouch cell (Kokam Co. Ltd., KOR)

To examine the influence of pressure on the battery behavior, constant current discharge tests at 1C 0.5C and 2C rates as well as impedance measurements in 10% SOC steps were performed in a climate controlled low-pressure chamber. The batteries were operated under different temperatures and in controlled low pressure. The pressure was first set to atmospheric pressure as a reference and then lowered to 750 hPa, 500 hPa and 250 hPa. To further examine altitude influences, current cycles and impedance spectroscopy were performed at different temperature and humidity values.

The behavior of the cylindrical cells showed hardly any pressure dependency, while the examined pouch cell’s behavior did show a pressure dependency.

All batteries showed strong temperature dependency but hardly any humidity dependency.

In this presentation the influence of pressure, temperature and humidity on voltage, capacity, resistance and impedance of the afore mentioned batteries will be discussed. The batteries are compared regarding their aviation applicability with special respect to low pressure. The parameters for each environmental condition can then be used to parameterize a battery model suitable for aviation applications.
Industrial Perspectives on Innovation: Sustainability, Safety, Scalability, and Advanced Performance
Authors: Yakovleva Marina , Fitch Brian , Xia Jian
Published: November 2022

Industry continues to look forward to innovative and to sustainable solutions that can improve battery performance, safety, and manufacturing efficiency. Livent is looking forward to bringing LIOVIX™ to the market as a product to help meeting these growing requirements while opening pathways for the development of next generation battery technology.

LIOVIX™, proprietary lithium metal product, is a unique printable formulation of lithium metal and other specialty materials that can improve the performance of lithium-ion batteries, reduce manufacturing costs, and enable the next generation of battery technology, all while enhancing safety and sustainability.

LIOVIX™ can be printed on a battery’s anode during electrode manufacturing in a process called pre-lithiation. Pre-lithiation employs an external, sacrificial source of lithium to offset the first cycle loss of lithium due to SEI formation allowing more efficient use of lithium from the cathode and raising the cell energy density. However, pre-lithiation techniques that are scalable at giga-factory throughput speeds have yet to be demonstrated. LIOVIX™ technology is easily scalable using industry standard coating and printing equipment and is adaptable to any anode or cathode chemistry where an independent source of lithium is required. LIOVIX™ can be used in anodes with a range of silicon content, because lithium loading can be accurately controlled based on the applications’ requirements. Incorporation of this technology has led to higher columbic efficiency at the first cycle, better cell capacity, and longer life batteries. In fact, the application of LIOVIX™ has been demonstrated to improve a battery’s output and to extend its useful life for a variety of battery chemistries (Figure 1).

LIOVIX™ is an important technology for the development and commercialization of solid-state batteries using lithium metal. These next generation batteries will address many of the challenges and limitations of today’s liquid electrolyte-based battery systems. LIOVIX™ can be directly printed on current collectors and can act as an anode in solid state batteries. It can also be printed on other anode material to improve the first cycle columbic efficiency and cell performance. It can reduce the interface resistance between anode and solid electrolyte layer.

Commercialization of battery systems that use metallic lithium anodes is strongly dependent on the industry’s ability to manufacture these anodes cost effectively at scale. Using LIOVIX printable lithium technology thin lithium foils in the range of 10um – 30um have been demonstrated at the desired width.

Figure 1
Development of Earth-Abundant Cathodes for Vehicle Applications and Beyond
Authors: Gutierrez Arturo , Chen Jiajun , Vu Anh , Lin Yulin , Wen Jianguo , Dogan Fulya , Balasubramanian Mahalingam , Croy Jason R.
Published: November 2022

The predicted growth in electrification of the grid-storage and transportation sectors has seemingly left the research community a significant responsibility in developing a more robust portfolio of materials solutions. Specifically, it has become clear that beyond simply meeting/exceeding the current technical requirements, new technologies would do well to align with the goals of sustainable development in supporting market growth. Current state-of-the-art, Li-ion cathodes, based heavily in Ni, will continue to play an important role. However, alternatives to these chemistries will be critical in diversifying supply chains and expanding the available portfolio of electrode materials towards a more sustainable future. Among the potential candidates for next-generation cathodes are Lithium- and Manganese-rich oxides. These oxides remain attractive because of their intrinsically high, specific capacities/energies and the economic benefits they offer through earth-abundant, Mn-rich (>50%) compositions.

This presentation will discuss research and development efforts at Argonne National Laboratory aimed at advancing cathode materials that are rich in manganese and have the potential to be cost competitive for electric vehicle applications and beyond. Research efforts into mitigation of issues related to several identified critical barriers, such as impedance, will be discussed.
High Throughput Studies of Li-La-Zr-O Garnet Solid Electrolytes
Authors: Anderson Ethan , Jonderian Antranik , McCalla Eric
Published: November 2022

Development of next-generation Li-ion batteries has increasingly focused on all-solid batteries employing either ceramic, polymer, or glass electrolytes in order to address shortcomings in currently commercialized liquid electrolyte Li-ion batteries including safety, limited lifetime, and lower energy densities resulting from instability with respect to Li metal anodes.[1] Lithium lanthanum zirconium oxide (LLZO) is a leading candidate for solid Li-batteries due to its high Li-ion conductivity, stability in air and against Li metal, and compatibility with high-voltage cathodes.[2],[3]

Despite significant progress being made, our understanding of LLZO is limited by the relatively small number of compositions which have been studied; especially considering the leading contender is a pseudo-quaternary oxide (Ga-doped LLZO) and many studies are now utilizing multiple dopants.[4]

Herein, we have applied a high-throughput methodology for synthesizing, characterizing, and testing sets of 64 LLZO electrolytes at the mg-scale. We employ a citrate sol-gel synthesis method whereby reagent solutions are dispensed across a well-plate to give a composition gradient. After drying the samples and burning off the citrates, the resulting powders are pressed into pellets using a custom-made 64-pellet die and the pellets are sintered at the desired temperature. The high-throughput characterization techniques utilized include powder X-ray diffraction, electrochemical impedance spectrometry and electrochemical cycling in order to test electrolyte stability; with each method performed on up to 64 samples simultaneously.

Using our methodology, we have studied over 700 samples to produce a full phase stability diagram for the Li-La-Zr-O pseudoternary system. We find that within the Li-La-Zr-O system, there is significant solubility of Li into the La2Zr2O7 pyrochlore structure commonly found as an impurity in LLZO synthesis due to lithium loss. We also find that LLZO appears as both tetragonal and cubic forms throughout the system, with the cubic LLZO appearing in an extremely restricted region that is difficult to access as pure phase due to lithium loss, while excess lithium leads to the tetragonal LLZO. Li conductivity measurements show that both cubic and tetragonal undoped LLZO have similar bulk conductivities, but there is only a limited region near the formal Li7La3Zr2O12 composition where grain boundary conductivity is high. Our methodology is also applied to a comprehensive doping study where over 40 different dopants are evaluated and promising dopants are tested in co-doped compositions.

[1] D. Aurbach et al., Electrochimica Acta
2004, 50, 247-254.

[2] Q. Liu, et al., J. Power Sources
2018, 389, 120-134.

[3] T. Thompson, et al., ACS Energy Letters
2017, 2, 462-468.

[4] F. Zheng, et al., J. Power Sources
2018, 389, 198-213.
Resolving Chemical and Spatial Heterogeneities at Complex Electrochemical Interfaces in Li Ion Batteries
Authors: Marbella Lauren
Published: November 2022

The development of cheap, high energy density electrode materials for Li ion batteries (LIBs) is critical to reaching net zero emissions targets and mitigating climate change. To this end, Ni- and Mn-rich transition metal oxide cathodes simultaneously offer high energy densities as well as cost effective solutions for LIBs. Despite the immense potential of these materials, both Ni- and Mn-rich cathodes suffer from severe interfacial instabilities that lead to crystallographic rearrangement of the active material surface, transition metal dissolution, and the formation of a cathode electrolyte interphase (CEI) layer on the composite surface during electrochemical cycling. While changes in the crystallographic structure of these materials are readily detected with diffraction-based methods, probing the chemistry associated with transition metal dissolution and characterizing the disordered, heterogeneous CEI layer have proven to be substantially more challenging. In this talk, I will discuss our efforts to use a combination of solid-state nuclear magnetic resonance (SSNMR) spectroscopy and X-ray photoemission electron microscopy (XPEEM) to provide information on the CEI deposited on composite cathode films with high chemical and spatial resolution (on the order of nanometers). In situ and operando magnetic resonance spectroscopies are used to correlate specific cathode degradation modes with electrolyte oxidation events. The final properties of the resulting CEI architectures are evaluated in the context of battery performance, where poor capacity retention and high interfacial resistance in LIBs is related to specific surface moieties on the cathode composite.
Boron-Doped Methylated Amorphous Silicon for Negative Electrodes in Li-Ion Batteries
Authors: Phung Tram Ngoc , Feng Yue , Petitjean Timothée , Henry-de-Villeneuve Catherine , Rosso Michel , Ozanam François
Published: November 2022

In spite of its outstanding capacity for alloying with lithium, silicon cannot be practically used as a negative electrode for Li-ion batteries: its large volume expansion upon lithiation leads to a poor capacity retention [1]. Promising results have been obtained by incorporating methyl groups in amorphous silicon (methylated amorphous silicon). This material exhibits an improved stability upon electrochemical cycling while keeping a capacity close to that of pure silicon [2]. However, the conductivity of methylated amorphous silicon may be a strong limitation, especially at high methyl content: for example, 10% methylated amorphous silicon is 10000 more resistive than pure amorphous silicon.

Doping is a well-known method to enhance the electronic conductivity of semiconductors, even if the dopant activity is lower in amorphous semiconductors than in crystalline ones. 2% boron doping increases the conductivity of 10% methylated amorphous silicon by five orders of magnitude compared to the undoped material.

Boron doped methylated silicon thin films (100nm thick) with various methyl content were cycled in the range 0.025V – 1V at C/2 rate (electrolyte: LP30 with 5%FEC). 10% methylated amorphous silicon with 2% boron doping exhibits a capacity retention of 70% after 500 cycles of full lithiation/delithiation, an improved performance as compared to the undoped material (see Figure 1a). Interestingly, boron doping allows for using higher methyl content without demanding pre-conditioning procedures for the electrochemical cycling of the material. The stability upon cycling is found to be further increased for 15% and 20% methylated electrodes, with a capacity retention exceeding 80% over 1000 cycles of full lithiation/delithiation (Figure 1b). This figure comes at the expense of a decreased total capacity (which remains 3 to 4 times larger than that of the current carbon electrodes). The SEI evolution and structural changes are currently investigated using operando ATR FTIR and ex-situ Raman spectroscopies, in order to rationalize the factors limiting the Coulombic efficiency to 99.7%. References

[1] M. N. Obrovac, L. Christensen, D. B. Le and J. R. Dahn, J. Electrochem.Soc,
154, A849-A855 (2007).

[2] L. Touahir, A. Cheriet, D. Alves. Dalla Corte, J.-N. Chazalviel, C. Henry-de-Villeneuve, F. Ozanam, I. Solomon, A. Keffous, N. Gabouze and M. Rosso, J. Power Sources,
240, 551-557 (2013).

Figure 1
Binder Effect on Electrochemical Performance of Silicon Anodes
Authors: Sun Fei , Rosborough Niccolo , Clarke Nathan , Smith Stacey , Mazzeo Brian A. , Wheeler Dean
Published: November 2022

Binder is a crucial component of high-capacity silicon anodes. It allows the active material to cohere to itself and surrounding materials. In the past few years, there have been divergent conclusions on the cell performance of anodes using water-based PAA vs. LiOH-PAA binder [1-3]. While there is agreement that LiOH-PAA facilitates the coating process, cell performance between these two binders is not settled.

The difference in cell performance may be due to the pH value or the extra Li+ in the binder, both of which change when LiOH is added to PAA. In this work we examined these two factors separately to determine their effect on cell performance. Our hypothesis is that the extra Li+ could facilitate ion transfer and the low pH could affect current collector corrosion and silicon oxidation. NH3(aq) is used to adjust the binder slurry pH and experimental results are compared between NH3-PAA and LiOH-PAA electrodes otherwise made with the same pH value. Similarly, we compared performance of NH3-PAA anodes with different pH values.

Multiple experiments were done to compare aspects of cell performance. Overall electrochemical performance was examined by cell cycling. Ionic conductivity was determined by an impedance test. Contact resistances to the current collector were measured with an apparatus developed in our lab. Silicon oxidation state was determined by XRD. Morphology of the anode can be compared by SEM.

In our cycling results silicon half cells with LiOH-PAA binder had a 10% higher capacity than those with PAA binder (Fig. 1), all other factors being constant. And the LiOH-PAA film had a lower impedance value which confirms the hypothesis that extra Li+ could facilitate ion transfer. The PAA anode had a lower contact resistance to the current collector than did the LiOH-PAA anode. This result agrees with Xiong’s work [3], which claims that the corrosion of current collector when using PAA slurry could form a more rigid coating surface and thus lead to the surface cracking and lower the capacity. Other parts of this work including cycling performance and XRD are still in progress and will be reported.

Hays, K.A., et al., Journal of Power Sources, 2018. 384: p. 136-144.

Hu, B., et al., Journal of Power Sources, 2019. 416: p. 125-131.

Xiong, J., et al., ACS Applied Materials & Interfaces, 2021. 13(24): p. 28304-28323.

Figure 1
Si Anode for All Solid State Batteries
Authors: Meng Shirley
Published: November 2022

The development of silicon anodes for lithium-ion batteries has been largely impeded by poor interfacial stability against liquid electrolytes. I will show how to enable the operation of a 99.9 weight % microsilicon anode by using the interface passivating properties of sulfide solid electrolytes. Advanced interface and bulk characterization, and quantification of interfacial components, showed that such an approach eliminates continuous interfacial growth and irreversible lithium losses. Microsilicon full cells were assembled and found to achieve high areal current density, wide operating temperature range, and high areal loadings for the different cells. The promising performance can be attributed to both the desirable interfacial property between microsilicon and sulfide electrolytes and the distinctive chemomechanical behavior of the lithium-silicon alloy. I will also discuss a few exciting future directions for nanosilicon with solid state electrolytes.
Printed Graphite Electrodes for Fast Charging Lithium-Ion Batteries
Authors: Wang Guanyi , Emani Himanaga , Palaniappan Valliammai , Xiong Jie , Yang Jian , Mathew Kevin , Zhou Bingyao , Beasley Sarah , Ahmadi Soma , Maddipatla Dinesh , Lu Wenquan , Atashbar Massood , Wu Qingliu
Published: November 2022

Fast charging capability has become one of the key features of lithium-ion batteries (LIBs) to facilitate the rapid growth of the electric vehicle (EV) market. However, charging thick electrodes in conventional EV batteries at high current densities always leads to adverse battery performance and safety issues. To address these challenges, thick graphite electrodes with patterned porous architecture were developed through a facile printing process. With selected graphite and developed formula, an appropriate graphite ink was printed onto the copper foil through the screen printing with designed patterned pore channels. The porous structure including pore diameter and pore-to-pore distance was controlled via adjusting the designed patterns on the screens. The presence of porous structure was confirmed through microscopic images. The printed graphite electrodes exhibited superior electrochemical behaviors over traditional electrodes in terms of rate capability and cycle life. It is believed that the improved battery performance is associated with the improved Li-ion transport arising from the patterned porous structure in printed electrodes. Results from the electrochemical impedance spectroscopy (EIS) indicate that, compared with traditional electrodes without patterned pores, printed electrodes have significantly reduced tortuosity. The post-mortem analysis of cycled cells demonstrates that the printed electrodes have the capability to suppress the Li plating related to fast charging rates. Combining with the advantages of low cost and high throughput, the printed electrode with patterned pores, thus, has the potential of replacing conventional electrodes in commercial LIBs to realize the fast-charging application.

Keywords: Graphite, Printing, Fast charging, Li-Ion Batteries