bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the Electrolyte Degradation of Lithium-Ion Cells with Silicon-Containing Anodes
Authors: Petit Jan , Heugel Philipp , Joos Martin , Klein Franziska , Tübke Jens
Published: September 2023

Silicon with a high gravimetric capacity of 3579 mAh g-1 of the pure material becomes increasingly common in the anode of lithium-ion batteries to increase energy density on the full cell level. However, silicon changes its volume excessively during (de-)lithiation making it prone to ageing. In commercial cells, it is typically applied as SiOx in small quantities in a composite anode together with graphite.

Gas analytical studies of Gr/SiOx||NMC622 cells with varying silicon content and carbonate-based electrolyte are presented. The electrolyte consists of 1M LiPF6 in EC:DEC (1:1, v/v) + 5 wt-% FEC. The focus of this study is on investigations of ageing processes such as electrolyte decomposition during formation cycling. All measurements were carried out using specially developed multifunctional test setups and accordingly modified test cells. The different cell specifications were examined by operando mass spectrometry (MS) and post-mortem gas chromatography-mass spectrometry (GC-MS).

Strong gas formation leads to a loss of electrolyte, which can cause the cell to dry out and consequently limit the cycle life. Gas analysis is a suitable method to identify decomposition products as well as to illustrate degradation reactions. Operando MS can be used to detect gaseous substances produced by (electro)chemical processes as a function of the state of charge. Furthermore, a post-mortem GC-MS analysis was performed to identify the individual substances qualitatively.

The cyclic formation of several degradation products can be determined. Among others, carbon dioxide, hydrogen as well as ethane are identified as characteristic decomposition products of the electrolyte. In addition, the decomposition path of the conducting salt can be detected. Another main result is the evidence of the presence of silicon-containing gaseous fragments as a function of the Si-content in the composite anode.

These gas analytical studies of silicon graphite composite anodes provide an important contribution to the understanding of the degradation reactions taking place. The results shown help to illustrate them and give information about the influence of the silicon content on electrolyte degradation.

Figure 1
Effects of Nitrogen-Doping or Alumina Films on Graphene as Anode Materials of Lithium-Ion Batteries Verified by in Situ XRD
Authors: Lin Chuen-Chang , Chen Guang-Jhong
Published: September 2023

First, graphene is directly grown on nickel foil without additional catalysts by chemical vapor deposition (CVD). Next, the graphene is modified by nitrogen-doping and alumina is deposited onto the graphene by magnetron sputtering. The charge specific capacity of N-doped graphene is higher than that of graphene since 2 Theta of in situ XRD characteristic peaks for N-doped graphene moves toward a lower angle (about 24) which is smaller than that (about 25) for graphene, then the gap between graphene layers for N-doped graphene is larger than that for graphene according to Bragg’s Law and N-doped graphene demonstrates the additional in situ XRD characteristic peak (LiC6) in comparison to graphene only with the in situ XRD characteristic peak (LiC12). Furthermore, because 2 Theta of in situ XRD characteristic peaks for Al2O3/graphene also moves toward a lower angle (about 24) and Al2O3/graphene also shows the additional in situ XRD characteristic peak (LiC6), the charge specific capacity of Al2O3/graphene is also higher than that of graphene.
LiNi0.33Mn0.33Co0.33O2 Cathode Active Material Recovery from Ethaline: Leaching, Co-Precipitation and Annealing with in-Situ XRD Monitoring
Authors: Yetim Delphine , Karar Youcef , Lepretre Jean-Claude , Svecova Lenka
Published: September 2023

The growth of the Li-ion batteries (LIB) market and the associated economies of scale have made possible the optimization of the production processes and significantly contributed to the reduction of the manufacturing costs. As a consequence, and facing the growing demand, developed countries will inevitably be confronted in the near future with huge quantities of waste LIBs (around 700k tons by 2035, against 15k tons currently)[1]. The development of efficient and environmentally friendly recycling processes is therefore a major challenge for the energy transition. This work processes a highly efficient way for the LiNi0.33Mn0.33Co0.33O2 cathode active material recycling by leaching in a choline chloride/ethylene glycol (ethaline) deep eutectic solvent, with a liquid/solid mass ratio of 50, that was doped with a small quantity of HCl. The addition of the latter at 4 molar equivalents (i.e. the final concentration of the acid in the DES is about 0.82 mol. L-1) allows to leach all the metals quickly at 80 °C with a yield >99%. Co-precipitation was induced by 0.2 M Li2CO3 addition with 99% efficiency. The recovered mixed carbonate was mixed with Li2CO3 and was then transformed into the oxide form by thermal annealing. The degree of transformation was monitored using in situ X-ray diffraction, recording the XRD spectra every 45 minutes. The obtained results indicate that the lithiation process occurs during the pre-annealing phase at 500 °C. Maintaining then the temperature at 900 °C for 10 hours results in a highly crystalline material free of any impurity. Finally, batteries made from the recycled powder exhibit a good discharge capacity of about 130 mAh.g-1 at a 0.2 C rate after 100 cycles as well as a coulombic efficiency of more than 99%.

Reference:

[1] Hearing of Ms Christel Bories (Eramet CEO) by the French Senate http://videos.senat.fr/video.1230390_5d1200992ac17.audition-de-mme-christel-bories
PV Silicon Recovery for Lithium Ion Battery Anodes
Authors: Coyle Jaclyn , Gaulding Ashley
Published: September 2023

As solar photovoltaic (PV) devices across the globe reach the end of their approximately 30-year lifetimes, an emerging challenge is how to handle the waste from large volumes of end-of-life (EOL) PV modules. It is projected that the cumulative mass of EOL PV modules could be up to 8 million tonnes (Mt) by 2030 so recovery of high value materials from these EOL modules through a cost efficient recycling process would minimize environmental impacts compared to disposing them in landfills[1]. A typical recycling process for EOL PV modules involves mechanical disassembly, separation of the tempered cover glass and silicon wafer followed by purification and recovery of other constituents such as Pb or Ag with the goal of reinstating the recovered materials as a PV module. However, since new module prices continue to decline and the recovered PV modules typically have a shorter lifetime and lower efficiency, the economic value of using the recovered PV materials to manufacture a new PV module is uncertain[2]. Since silicon, particularly boron-doped, is a promising candidate for next-generation anodes for lithium-ion batteries (LIB), recovering the silicon from PV modules for use in LIB anodes could be an attractive alternative. In this study we leverage the National Renewable Energy Laboratory (NREL)’s expertise in PV Si reliability and access to multiple types of EOL PV modules to study the merits of B-doped silicon recovery from silicon PV panels with regard to silicon anode cycling performance and calendar life. A simple ball milling process was developed to prepare recycled Si from EOL PV modules for use as in a LIB anode. In this talk we will be discussing the recovery efficiency, purification requirements and key anode performance metrics of recycled PV silicon materials.

IRENA, I.-P., End-of-Life Management: Solar Photovoltaic Panels 2016: International Renewable Energy Agency and International Energy Agency Photovoltaic Power Systems.

A. Wade, P.S., K. Drozdiak, E. Brutsch. Beyond Waste – The Fate of End-of-Life Photovoltaic Panels from Large Scale PV Installations in the EU. The Socio-Economic Benefits of High Value Recycling Compared to Re-Use. in 33rd European Photovoltaic Solar Energy Conference and Exhibition. 2017.
Generalized Inversion of Electrochemical Impedance Data for Battery Systems
Authors: Li Michael L. , Bazant Martin Z.
Published: September 2023

Electrochemical Impedance Spectroscopy (EIS) is a key technique for taking a snapshot of an electrochemical system near equilibrium conditions. Due to the richness of the complex-valued dataset and its simple experimental operation, it is currently being investigated as a test to diagnosis battery health and degradation details. Nevertheless, challenges with use of EIS is in interpreting the measured impedance. Current methods for analysis involving either fitting simplified equivalent circuit models or inverting distribution of relaxation times with a singular basis function. Because of these methods' simplifications, their results sometime fail to capture both the complex and heterogeneous underlying physics.

Here, we present a novel algorithm for the inversion of EIS data for battery systems, which generalizes the inversion problem to any given linear equivalent circuit model, allowing for the analysis of complicated electrochemical systems. Importantly, this algorithm provides two clear benefits. First, it allows for the analysis of both bounded and unbounded processes, something quite common to battery systems and is vital in understanding non-obvious relationships in degraded batteries. Second, the distribution of independent processes, which can correspond to different physical phenomena, are also inverted by this algorithm. These distributions contain vital features in the identification and prediction of battery state-of-health. Overall, this tool will be indispensable in the analysis of degradation extent over battery aging, and provide an algorithmic framework for interpreting EIS measurements of complicated electrochemical systems.
(Invited) A Framework for in-Line Analysis and Quantification of Battery Aging Mechanisms Using Electrochemical Signatures Under Fast-Cycling Conditions
Authors: Weddle Peter J , Kim Sangwook , Chen Bor-Rong , Yi Zonggen , Gasper Paul , Colclasure Andrew M. , Smith Kandler , Gering Kevin L. , Tanim Tanvir R. , Dufek Eric J.
Published: September 2023

Rapid, in-situ Li-ion battery state-of-health quantification is challenging. Li-ion battery aging modes can vary significantly with chemistry, operating conditions, cycling demands, electrode design, and operation history. In literature, Li-ion battery aging modes are typically lumped into categories such as loss-of-lithium-inventory (LLI), loss-of-active-material (LAM) in either electrode, and/or impedance rise. Importantly, as a cell ages, optimal and safe operating conditions need to be adapted to account for battery degradation. The present research describes a framework for identifying battery aging modes in-operando using fast-rate voltage charge/discharge responses. Once developed, the model can be used to quickly identify the battery aged state, without relying on slow reference performance tests. The framework first develops a physically based Li-ion battery model that captures aging effects (i.e., LLI and LAM). Once the aging model is calibrated to known battery performance at aged states, the model is used to generate synthetic voltage responses under a variety of aged conditions. These synthetic responses are then used to train a machine-learning model. In the end, the machine-learning model is used, in conjunction with experimentally measured voltage profiles, to identify cycle-by-cycle battery state-of-health variables of real cells in operando. The framework is used to identify battery state-of-health for two different electrode loadings and for cells charged a variety of fast-rate conditions (i.e., 1C, 4C, 6C, and 9C).

Figure 1
Mathematical Toolbox for Joint Structural and Electrochemical Analysis of Lithium-Ion Battery Cells
Authors: Karaki Hassan , Kretschmer Katja , Schröder Daniel
Published: September 2023

Increasing interest in the automotive field for electrification has led to an increased demand for lithium-ion batteries (LIB). LIB remain the most popular and widely applied energy storage technology. The microstructure of the positive electrode of LIBs governs its electrochemical performance. For this reason, it is quite imperative to determine an optimal electrode microstructure design to achieve the best possible energy properties. Mechanistic simulation models can be a powerful tool in analyzing the effect of microstructural parameters on the battery cell performance. Not only do they negate costs for necessary materials, but they also allow analysis and optimization while avoiding time-consuming experiments.

Doyle-Fuller-Newman (DFN) models, being pseudo-2-dimensional (P2D), are computationally less expensive than their higher dimension counterparts; however, they often apply the Bruggeman relation to compute effective parameters such as the electrode conductivity of the electrode. Despite its simple implementation (i. e. a correction factor to reflect effective parameters), the Bruggeman relation delivers inaccurate results. [1, 2]

In this work [1], we coupled a DFN model with the structure surrogate model from [2], excluding the Bruggeman relation. The model predicts the effective transport parameters and thus the battery performance more accurately. With this coupled model, we investigated the effect of the cathode mass loading and density on the achievable volumetric discharge energy density. [1] Furthermore, we developed a numerical optimization tool, which can predict the optimal structural parameters for maximum energy density. Our findings suggested different optimal designs for different current densities; whereas higher mass loading was preferred at lower C-rates, it was less favorable at higher C-rates. The concentration profiles of lithium-ions across the cathode thickness at the end of discharge suggest transport limitations to be the main reason behind this. As a further step, we carried out an uncertainty analysis to determine the robustness of the optimal designs to structural fluctuations with respect to their energy density.

Our findings provide a deeper understanding into the influence of structural parameters on the discharge performance of lithium-ion battery cells, using only simulative methods. Additionally, our methodology of numerical optimization and subsequent uncertainty analysis allows for a quick and simple method for determining optimal structural parameters and their robustness against fluctuations. This approach can assist to produce battery cell electrodes with an optimized design in industry as well as help simulative and experimental researchers to further investigate optimal electrode design.

[1] Karaki et al., Energy Technology 2022

[2] Laue et al., E. Acta 2019

Figure 1
An Electrochemical-Thermal-Mechanical Model for Large Format Lithium Ion Batteries
Authors: Schiffler Marc , Schmidt Adrian , Lindner Adrian , Weber Andre
Published: September 2023

The intercalation reaction in Lithium-Ion batteries causes significant volume changes in the active material phases during cycling. Due to spatial limitations in common battery applications, this entails mechanical stresses on different length scales and thereby influencing performance and lifetime of the battery[1]. Mechanical effects are closely linked to electrochemical and thermal processes in the cell, giving rise to complex interactions that are difficult to predict. Moreover, large cell dimensions, which become ever so common in today’s battery industry, further increase complexity due to local variations of state variables. Therefore, modeling is essential to enhance understanding of the governing- and limiting processes.

In this contribution we present a fully coupled multi-scale-, multi-physics-model that combines an electrochemical model on the particulate electrode level, namely an extended Newman model featuring a particle size distribution, and a homogenized cell material model, displaying anisotropic electrical-, thermal- and mechanical properties. To include mechanical effects into a multi-physics-model[2] a new approach is considered. We apply the poroelastic theory to describe the mechanical behavior governed by the interaction of the porous electrode matrix and the infiltrated electrolyte. The use of homogenization techniques allows to keep the computational effort in check, while still doing justice to the complexity of a three-dimensional-, multi-scale-, and multi physics problem. The model is parametrized in-house by applying different electrochemical-, mechanical-, and microstructural characterization methods. The model, its parameterization and validation as well as selected simulation results will be presented.

Acknowledgements

This work was funded by the Deutsche Forschungsgemeinschaft (DFG) in the framework of the research training group SiMET (281041241/GRK2218).

[1] Y. Zhao, P. Stein, Y. Bai, M. Al-Siraj, Y. Yang, B.-X. Xu, Journal of Power Sources
2019, 413, 259–283.

[2] A. Schmidt, D. Oehler, A. Weber, T. Wetzel, E. Ivers-Tiffée, Electrochimica Acta
2021, 393, 1–14.
(Invited) Understanding the Impact of the Stoichiometry on Cation-Mixing in Ni-Rich Cathodes
Authors: Komurcuoglu Cem , Xiao Yunhao , Li Xinhao , Li Zheng , West Alan C. , Urban Alexander
Published: September 2023

Although LiNiO2 is chemically similar to LiCoO2 and offers a nearly identical theoretical capacity, LiNiO2 and related Co-free Ni-rich cathode materials suffer from degradation during electrochemical cycling. Especially the formation of Li/Ni anti-site defects can lead to a reduced cyclability and poor capacity retention. We report evidence that such cation mixing in LiNiO2 is linked to the difficulty of synthesizing the material in its ideal stoichiometric composition. In practice, off-stoichiometries (Li1-xNi1+xO2) can hardly be avoided. We determined the Ni migration mechanism in ideal and off-stoichiometric LiNiO2 using first-principles calculations and identified the energetically most probable pathways for Ni migration and for the phase transition to the spinel structure. Our results show that off-stoichiometries promote the formation of Li/Ni defects. Furthermore, we find that the formation of the spinel phase is a highly concerted mechanism, explaining why the phase transition is usually not observed during cycling at room temperature. Our study is a first step towards understanding degradation in Co-free cathodes and underlines the importance of considering defects in materials modeling.
(Invited) Electrochemical Engineering: From Membranes to MW Green Hydrogen Stacks
Authors: Yan Yushan
Published: September 2023

With the increasing availability and rapid price decrease of clean electrons, electrochemical engineering has become a frontier for fundamental research, innovation, entrepreneurship, and industrialization, making enormous contributions to the global decarbonization effort. In this presentation, I will share our journey and lessons from having a simple concept – hydroxide exchange membrane or HEMs – more than fifteen years ago to the founding of Versogen to the commercialization of the PiperION membranes to the development of a pure-water fed MW stack for green hydrogen production.
Monosubstituted Low Molecular Weight Anthraquinone for Energy-Dense and Long-Life Redox Flow Batteries
Authors: Amini Kiana , Kerr Emily F. , George Thomas Young , Alfaraidi Abdulrahman , Jing Yan , Tsukamoto Tatsuhiro , Gordon Roy G. , Aziz Michael J.
Published: September 2023

Redox flow batteries (RFBs) are large-scale energy storage technologies that are attractive due to their safety, flexible design, and long life. Among different types of RFBs, aqueous organic systems have gained a lot of attention due to the possibility of tailoring the redox properties by modifying the organic chemical structure. We introduce 2-2-propionate ether anthraquinone (abbreviated 2-2PEAQ), which is a singly substituted anthraquinone that is synthesized via a facile synthetic route from potentially inexpensive precursors. 2-2PEAQ has the lowest molecular weight (MW = 296.07 g/mol) among the anthraquinone derivatives reported to date that can deliver an extremely low capacity fade rate (<0.02%/day), low membrane permeability (<1 x 10-13 cm2/s), high solubility (≥1 M transferrable electrons) and acceptable redox potential (OCV >~1.0 V vs. Fe(CN)6
3-/4-) for use in aqueous organic flow batteries. Having a smaller MW per mole transferrable electrons in species that can be synthesized via simple synthesis routes is highly preferable because both attributes correlate with low mass production cost. We will discuss the degradation mechanisms of 2-2PEAQ and report its performance in the negolyte of a redox flow battery under practically relevant conditions, advancing the prospects for commercialization of grid-scale aqueous organic redox flow batteries.
Physics-Based Modelling of Hybrid Cathode Li/CFx-SVO Batteries Under Pulse Discharge
Authors: Liang Qiaohao , Gomadam Partha , Tamirisa Prabhakar , Bazant Martin Z.
Published: September 2023

Power sources of implantable cardioverter-defibrillators (ICD) require high energy density to ensure longevity and sufficient rate capability to provide high power pulses for treating abnormal heart rhythms. Such demands have led to the design of Li/CFx-SVO battery, which leverages the excellent energy density of carbon monofluoride (CFx) and power density of silver vanadium oxide (SVO) through the use of a CFx-SVO hybrid cathode. A phenomenological model based on porous electrode theory was previously developed for Li/CFx-SVO, but it overlooked phase separation in SVO, Li+ diffusion limitations in particles, and reaction heterogeneity across particles. It was thus unable to accurately predict the voltage over-recovery behavior during transitions from medium to low currents, capture relaxation behavior after high current pulses without the use of unrealistically large capacitance values, or interactions between active materials in the hybrid electrode.

In this work, we present a computational model of Li/CFx-SVO battery based on Multiphase Porous Electrode Theory for hybrid electrodes (Hybrid-MPET). Hybrid-MPET framework allows us to model the phase separation during reduction of SVO, concentration gradients in SVO particles and the evolution of reaction heterogeneities across an ensemble of particles under different current rates. As a result, our Hybrid-MPET model excels at predicting voltage-capacity behavior under constant current or constant load discharge, is capable of providing physical explanation of voltage over-recovery and voltage relaxation, and captures the interactions between SVO and CFx particles during transient currents. The Hybrid-MPET models are validated against experimental data from Li/CFx-SVO batteries of different designs, and show consistent modelling capability across different electrode thickness, particle lengthscales, and discharge timescales. Our work demonstrates how physics-based models can help provide fundamental understanding of experimental phenomenon, and we further discuss how the Hybrid-MPET framework could open up new opportunities to study the performance of hybrid electrode batteries and support their engineering design in a broader range of devices.

Figure 1
(Invited, Digital Presentation) Discovery to Product: A Reflection on the Path from Electrochemical Materials Research to Traction Batteries to the Commercialization of Electric Vehicles
Authors: Verbrugge Mark
Published: September 2023

We live in an age wherein many industry analysts and surveys indicate that within the not-too-distant future, perhaps within 10 years, battery electric vehicles (BEVs) will outsell vehicles employing internal combustion engines. How did we arrive at this point in history?

In this talk, I will overview some of the key drivers I’ve seen in my nearly four decades of work on the research, development, and commercialization of BEVs. The path I’ve witnessed has been highly nonlinear, making trend predictions along the way difficult. Collaborations, including Public-Private Partnerships, Joint Ventures, and relationships, have been of vital importance. In addition, I’ve found that in attempting to participate in the path of invention to commercialization, having a firm basis on governing foundational principles is an indispensable asset. In my case, learning from predecessors and colleagues about electrochemical materials and characterization and elements of battery cell modeling provided the requisite foundation.

Last, I’ll note that clear and compelling communication within a company and externally is necessary to bring inventions to innovation and commercialization. It is only through such communications that necessary resource allocation emerges.
(Invited) Approaches for Mechanistic Understanding of Electrodeposition Processes for Fabricating Micro/Nano Structures and Devices
Authors: Homma Takayuki , Kunimoto Masahiro , Yanagisawa Masahiro
Published: September 2023

Electrochemical deposition processes have precise controllability, selectivity and uniformity, and have been widely applied for fabricating various functional micro/nano structures and devices. In order to achieve further higher controllability for developing reliable process for manufacturing, molecular-level understanding of the deposition processes is required. Furthermore, this can be be also utilized to understand various applications such as the electrode processes of secondary batteries using metal anodes and so on. For this, we have attempted to apply theoretical approaches such as density functional theory (DFT) and kinetic Monte Carlo (KMC) calculations[1.2], as well as experimental methods such as surface enhanced Raman microscopy equipped with plasmonic sensors[3-5]. In this paper, these approaches with some of the resent results will be described. The analysis using DFT calculations provided the molecular-level insights for the catalytic activity of the electroless deposition reaction process at the surface, with the effects of the additive species and solvation. Also, in combination with the KMC calculation, multi-scale simulation for the nucleation and growth process at the Zn anode surface for the secondary battery was attempted. While these approaches enable quantitative discussion for the mechanistic understanding of the processes, we also attempted to obtain "real" data from experimental approaches. For this, we applied surface enhanced Raman scattering (SERS) and developed "plasmonic sensors" with controlled nanostructures to obtain high signal enhancement at electrode-electrolyte interface. We have developed two types of the plasmonic sensors which could achieve extremely high sensitivity. Multi-confocal type SERS microscopy was also developed for mapping and imaging analyses of the electrode surface as well as local pH distributions. By using these techniques, various processes at the electrode surfaces and interfaces have been investigated and modelling of the processes has been carried out.

This work was financially supported in part by “Development of Systems and Technology for Advanced Measurement and Analysis” program from Japan Science and Technology Agency, and Grant-in-Aid for Scientific Research, MEXT, Japan.

[1] Y. Onabuta, M. Kunimoto, H. Nakai, T. Homma, Electrochim. Acta, 307, 536 (2019).

[2] Y. Onabuta, M. Kunimoto, S. Wang, Y. Fukunaka, H. Nakai, T. Homma, J. Electrochem. Soc., 169, 092504 (2022).

[3] M. Yanagisawa, M. Saito, M. Kunimoto, T. Homma, Appl. Phys. Express, 9 , 122002 (2016).

[4] M. Kunimoto, F. Yamaguchi, M. Yanagisawa, T. Homma, J. Electrochem. Soc., 166, D212 (2019).

[5] T. Wang, M. Kunimoto, M. Yanagisawa, M. Morita, T. Abe, T. Homma, Energy Env. Mat., in press (2022).
(Invited) Electro-Swing Adsorption for CO2 Emissions Mitigation – from Concept to Start-up
Authors: Hatton T. Alan , Voskian Sahag
Published: September 2023

The increasingly devastating effects of changing climate patterns can be attributed largely to global warming through the continuing accumulation in the environment of anthropogenic greenhouse gases such as carbon dioxide. While reduction of CO2 emissions at relatively concentrated (4-20%) point sources is a crucial component of mitigation strategies for the abatement of the CO2 impact on global temperature rise, it has become increasingly evident that direct removal of accumulated CO2 (at 420ppm, 0.042%) from the environment will also be needed if we wish to limit the global temperature rise by the turn of the century to less that 2°C. Legacy carbon capture processes rely on thermal swings, with elevated temperatures required to break the chemical bonds formed during the cooler capture stage to liberate the CO2 as a pure product stream and regenerate the sorbent. There has recently been a surge of interest in using electrochemically mediated processes for carbon capture and release which can be operated isothermally, are modular, with easy scale out, and can be installed without need for complex heat integration processes. Moreover, they can use renewable and other non-carbon energy resources.

In this presentation, we will trace the development of an electrochemical swing adsorption approach for the capture of CO2, originally conceived in 2015, through to the incorporation of a start-up, Verdox, in 2019 to exploit the technology in both point source and direct air capture applications. This approach exploits the ability of certain redox species, such as quinones, to bind strongly with CO2 when in a reduced state, but which have no affinity for the acid gas when oxidized. The activation by reduction and subsequent de-activation by oxidation of the capture agent can be achieved electrochemically with the redox species either in solution or immobilized on electrode surfaces; it is this latter strategy that we will discuss here. The challenges in electrode development, including the identification and economical synthesis of appropriate redox species for the binding of the CO2, and enhancement of chemical and physical robustness with acceptable uptake kinetics, will be discussed, with projections on the future introduction to industrial applications.
Development and Scaling up of the Purification and Regeneration Integrated Materials Engineering (“PRIME”) Process for Cathodes Direct Recycling and Upcycling
Authors: Li Weikang , Chen Zheng , Meng Ying Shirley
Published: September 2023

Lithium-ion batteries (LIBs) are the primary power source for portable electronic devices, electric vehicles (EVs), and energy storage systems (ESS) due to their high energy and power densities. However, with an average lifespan of mostly 5-10 years, million tons of end-of-life (EoL) LIBs will be produced by 2030. Recycling spent LIBs will bring new opportunities in reducing constraints imposed by material scarcity, enhancing environmental sustainability, and providing a safer and more resilient circular supply chain. The current commercialized recycling methods, including pyrometallurgy and hydrometallurgy, require extreme conditions, such as high temperatures and strong acids, to destroy the chemical bonds. The subsequent extraction process is lengthy, with high energy consumption and cost. A new direct recycling pathway has been brought to the field, defined as recycling valuable components without breaking down the chemical structure. Direct recycling can be efficient, cost and energy effective, but the currently developed methods can only be demonstrated at a lab scale due to the lack of robustness and tedious pre-treatments. Recently, we have identified that the direct recycling method combining hydrothermal relithiation and subsequent short annealing can successfully restore the composition, structural defects, and electrochemical performance of different spent cathode materials to the same level as the pristine material. More importantly, the method is extended to recover spent cathode materials with various impurities, such as conductive agents, binders, residual salts, and aluminum shreds. Such purification has been integrated into the regeneration process, which enables a practical pathway for cathode direct recycling. The related technology is named “Purification and Regeneration Integrated Materials Engineering (“PRIME”) and has been granted by the Department of Energy (DOE) under Bipartisan Infrastructure Law (“BIL”). The PRIME process merges the advantages of direct cathode recycling techniques with the novel purification strategy to improve the quality of recovered cathode materials with significantly reduced unit operation steps, which can be scaled up to an industrial level. Meanwhile, the PRIME process can recover the cathode with high consistency and yield. This new direct recycling process will provide a solid technical foundation for mass production of the next generation of LIBs recycling.
Experimental and Virtual Screening of Phenazine and Phenothiazine Derivatives in Aqueous Solution for Electrochemical Carbon Capture
Authors: Seo Hyowon , Zhang Difan , Hatton T. Alan
Published: September 2023

Molecular redox-active compounds, including quinone and aza-aromatics, have emerged as tools for capturing carbon dioxide using renewable electricity. Given the vast and highly diverse chemical space of the candidate compounds, accessing their electrochemical properties in a rapid way is attractive for both experimental and virtual screening approaches.

Here we present a study on the experimental screening of a series of commercial redox-active compounds. Phenazine and phenothiazine dyes have been experimentally tested for applications in electrochemical carbon capture, for which they are finding increasing applications as redox mediators due to their unique redox properties in aqueous solution. Nicotinamide has been used as a redox-inactive solubilizing agent to increase the solubilities of general phenazine and phenothiazine derivatives for rapid experimental screening of commercial compounds without time-consuming synthetic modifications. Cyclic voltammetry in aqueous solutions under nitrogen and carbon dioxide indicated reversible behavior in the pH swing of an aqueous solution. Bulk electrolysis experiments demonstrated the chemical stability of phenazine and phenothiazine derivatives. The redox properties and the chemical stability make phenazine and phenothiazine derivatives interesting candidates for future use as redox-active materials in electrochemical carbon capture.

We also present progress towards a virtual screening for the optimization of electrochemical and physicochemical properties of redox-active compounds. Based on our experimental screening of commercial phenazine and phenothiazine compounds identifying neutral red as the lead compound, a virtual screening was performed for optimization of electrochemical and physicochemical properties using machine learning. The virtual screening development steps include (1) chemical library generation using neutral red as a lead compound, (2) molecular property prediction based on quantum chemical calculations, (3) aqueous solubility prediction using machine learning, (4) data processing and database creation, and (5) experimental validation of the optimized compounds for the use of electrochemical carbon capture.

Figure 1
(Best Paper Award, Invited) Manufacturing of Nanosheets and Multilayer Nanogaps in Silicon
Authors: Lerch Wilfried , Heigl M , Bui-Tran T.X.A , Eisele Ignaz , Merkel R.
Published: September 2023

Nanogap technology is the basic concept for many promising devices such as localized SOI, multichannel FETs, and resonant tunneling diodes.

It will be shown that intrinsic bulk strain in single crystalline silicon can be used to create homogeneous nanogaps with a few nanometer gap distance. The strain has been created by epitaxial growth of Si1-xGex/Si multi-layer stacks on 200 mm (100) silicon wafers. The stacks were patterned by RIE to reveal the side walls for subsequent lateral etching with gaseous hydrochloric acid. In accordance with former investigations [1] we found that a selectivity up to 1000:1 for Si1-xGex/Si can be achieved for Ge-concentrations >30% and growth temperatures T<650°C. XRD measurements, SEM pictures and wagon wheel test structures prove that for the anisotropic lateral etching behavior intrinsic strain is the dominant factor. Furthermore, the crystal orientation plays a dominant role (Fig. 1). Based on this behavior multilayer nanogaps with spacings <10 nm had been fabricated.

In a subsequent process nanogaps down to 5 nm have been successfully filled completely with dielectrics and/or metals by low temperature (T<450°C) plasma oxidation, LPCVD as well as ALD (Fig. 2). The resulting nanosheets can be used for device applications.

Vertical diodes and lateral MOS transistors with nanogaps and nanosheets have been fabricated. Diodes with a SiO2 gap filling show perfect Fowler-Nordheim tunneling, which proves the high quality of the gap filling process. The electrical properties of nanogap-MOSFETs and various nanogap-diodes will be presented.

[1] Destefanis et al., Semiconductor Sci. Technol. 23, 1 (2008)

Fig. 1: Wagon wheel structure showing the etch anisotropy of 8 nm SiGe layer in Si

Fig. 2: SEM cross section of a multistack of 6 SiGe layers selectively etched and completely filled with LPCVD oxide
(Invited) Improvements in Thermal Budget and Film Properties Using Low Pressure Cure Technology for Advanced 3D Integration Packaging
Authors: Song Kay , Karim Zia , Tan Xinxuan , Bhat Abhishek , Sautter Kenneth , Mingardi A , Vangoidsenhoven D
Published: September 2023

3D advanced integration with Fan-Out Wafer-Level Packaging (FOWLP) and Fan-Out Panel Level Packaging (FOPLP) offers multiple benefits: heterogenous chip design and stacking, increased interconnect density, and improved performance. However, it also brings new requirements for more compact form factors, low thermal budget materials and processing, and lower cost. The materials, process, and fabrication of heterogenous integration on redistribution layers (RDLs) consisting of metal and polymer dielectrics have become important enablers of the move to advanced packaging applications. To achieve the low-stress and low-cost benefits required by advanced integrated devices, thermal budgets must be reduced throughout the heterogenous integration flow -- including the dielectric curing step, which demands the use of low temperature processing and reduced cure times.

In this presentation, the low temperature and low pressure thermal polymerization of dielectric polyimides used for redistribution layers (RDLs) is reviewed. Specifically, this presentation illustrates the significant impact of the low pressure cure process in reducing temperature (20° to 50° lower) and cure times (up to a 50% reduction) while providing better mechanical (elongation%, tensile strength, Young’s modulus), thermal (TG, Td 1%, Td 5%), and electrical (Dk, Df, dielectric breakdown strength - DBS) properties for different types of dielectric polyimides, including the Fujifilm LTC-9300 series, the Asahi BL-300 series, and the Toray LT-8300 and PW-1500 series. The post-curing polymerization ratio (FT-IR) and film stress were studied and are described. Finally, a proposed mechanism for the described dielectric polyimides’ polymerization under reduced pressure is discussed.

Ongoing developments in design, materials, process and fabrication for FOWLP and FOPLP devices continue to drive progress in 3D heterogenous integration. This study of thermal processing of dielectric polyimides at low pressure and shorter time demonstrates a promising technique to improve overall process flow by reducing thermal budget, stress, and cost.
Low Temperature Wafer Bonding of Silicon Carbide/Aluminum Nitride
Authors: Huang Wei-Chi , Ruan Jian-Long , Kuo Yang-Kuao , Lee Benjamin T.-H.
Published: September 2023

Because of the wide energy gap material properties and high compatibility with existing silicon material processing, silicon carbide (SiC) has become the preferred material for power management chips that have been used in electric vehicles. On the other hand, aluminum nitride (AlN) material has become the first choice for carrying wafers due to its high strain-resistant mechanical properties, strong dielectric coefficient, excellent thermal conductivity, and high etching resistance. In this study, the surface chemistry of silicon carbide was changed into an AlN-based material to perform wafer bonding processing to develop low-temperature bonding technology for silicon carbide/aluminum nitride materials. We found through experiments that it is quite difficult for a SiC wafer to bond with an AlN wafer even if the surfaces ofthe SiC wafer and the AlN wafer are subjected to conventional surface activation treatment using oxygen plasma or argon plasma. The possible reason is that although the surface of the SiC wafer is bombarded by oxygen or argon plasmas to generate some dangling bonds, the chemical properties of Si-C and Al-N, such as electronegativity, make it difficult to generate chemical bonds between the matching surfaces of SiC/AlN. Through a material modification technology, a high-temperature sputtering method is used to make highly active AlN clusters sputtered from the target directly bond with SiC and finally form a thin AlN layer that strongly adheres to the surface of the SiC wafer. And then through the bonding of AlN/AlN homogeneous materials, although the surface roughness measurement (RMS) cannot satisfy the condition of being less than 5 angstroms for wafer bonding, the goal of low-temperature bonding can be achieved by capillary bonding. Therefore, the SiC surface is changed into an AlN-based thin layer by high-temperature sputtering, which can further chemically bond with the AlN wafer surface by capillary bonding to achieve the low-temperature bonding of SiC/AlN, as shown in Figure 1.

Reference

1. Shao-Ming Nien, Jian-Long Ruan, Yang-Kuao Kuo, and Benjamin Tien-Hsi Lee, Low-temperature rough-surface wafer bonding with aluminum nitride ceramics implemented by capillary and oxidation actions, Ceramics International, Volume 48, Issue 6, 2022

Figure 1
Heteroleptic Titanium Complexes Bearing Amidoxime Ligands As Precursors for TiN Thin Films ALD
Authors: Lee GA Yeon , Eom Taeyong , Chung Taek-Mo
Published: September 2023

This presentation reports the synthesis of three novel titanium complexes containing amidoxime ligands as potential precursors for titanium nitride (TiN) thin films fabricated using atomic layer deposition (ALD). A series of ligands, viz., N'-methoxy-N-methylacetimidamide (mnnoH), N'-ethoxy-N-methylacetimidamide (ennoH), and N'-methoxy-N-methylbenzimidamide (pnnoH), were successfully synthesized and used to produce Ti(mnno)(NMe2)3 (4), Ti(enno)(NMe2)3 (5), and Ti(pnno)(NMe2)3 (6). Thermogravimetric analysis curves of complexes 4–6 revealed a single-step weight loss up to 200 °C. Pyrolysis occurred beyond 200 °C. Among the three new complexes, 5 was liquid at room temperature. Therefore, an ALD process for the growth of TiN was developed using Ti(enno)(NMe2)3 (5) as a novel precursor. A TiN thin film was deposited from the Ti(enno)(NMe2)3 (5) precursor and NH3 plasma, and self-limiting growth was achieved by varying the injection/purge duration. TiN thin film growths were observed with a growth per cycle (GPC) of 0.03–0.075 nm∙cy-1 at deposition temperatures between 150 and 300 °C, while the measured resistivity was as low as 250 μΩ·cm. The high reactivity of the precursor promotes nucleation, resulting in TiN thin films with smooth, good step coverage, and preferentially orientated microstructure.
(Invited) Probing and Utilizing Hot Carriers for Plasmonic Photoelectrochemical Processes
Authors: Park Jeong Young
Published: September 2023

The detection of hot electrons and understanding the correlation between hot electron generation and surface phenomena are challenging questions in the surface science and catalysis community. Hot electron flow generated on a gold thin film by photon absorption (or internal photoemission) appears to be correlated with localized surface plasmon resonance. It has been found that the hot electron flux generated under photon absorption and exothermic chemical reaction is the major mediator of energy conversion process [1-3]. In this talk, I introduce the research direction to attempt to detect the surface plasmon driven hot carrier at the nanometer scale by using scanning probe microscopy. To detect and utilize the hot electron flows at the macroscale level, the metal-semiconductor nanodiodes were constructed. At the nanometer scale, we utilized photoconductive atomic force microscopy to observe photoinduced hot electrons on a triangular Au nanoprism on n-type TiO2 under incident light. This is the direct proof of the intrinsic relation between hot electrons and localized surface plasmon resonance. We observed surface plasmon induced hot hole by using the system of Au nanoprism on p-type GaN [4]. I will discuss the impact of hot carriers in the photocatalytic activity under photoelectrochemical water splitting by using Au-based plasmonic nanostructures [5].

References

[1] J. Y. Park et al. Chemical Reviews 115, 2781-2817 (2015).

[2] J. Y. Park et al. Accounts of Chemical Research 48, 2475-2483 (2015).

[3] S. W. Lee et al. Surface Science Reports 76 100532 (2021).

[4] H. Lee et al. Advanced Science 7, 2001148 (2020).

[5] K. Song et al. ACS Energy Lett. 6, 4, 1333–1339 (2021).
(Invited) Highly Emissive CdTe Quantum Dots Passivated with Novel Branched Ligands as Fluorescent Sensors
Authors: Choudhary Yogesh , Nageswaran Gomathi
Published: September 2023

Fluorescent-based sensors attract enormous attention due to their facile nature, simplicity, superior selectivity and sensitivity, and better reproducibility and reliability. The sensing parameters, such as detection limit, dynamic range, and the possibility for multiplexed detection, rely hugely on the physicochemical properties of the fluorophore used. Therefore, the choice and rational design of fluorescent probes demand considerable attention. The growing interest in highly fluorescent semiconductor quantum dots as sensors or imaging probes is evident from the numerous reports available in the literature. Unlike conventional organic dyes, novel fluorescent quantum dots-inorganic nanocrystals have manifold advantages. QDs have symmetric and narrow emission profiles, high absorption efficiency in the UV region, high quantum yields, especially in the NIR region, exorbitant photo and temporal stability, and shallow photo-bleaching effect. The optical properties of QDs are primarily defined by the nature of constituent materials, size and shape, surface chemistry, and the nature of dangling bonds. The applicability of CdTe QDs was limited in the biological realm mainly due to the highly toxic nature of its constituent materials. The use of benign ligands is one procedure to be adopted to overcome this impediment. Also, the stability of the QDs warrants the limited bleaching of the material. The aqueous solubility of the material is another requirement to be satisfied. The functional groups in ligands also play a significant role in determining the stability of QDs and the utility of the QDs synthesized, as it can advocate the possibility of reactions and recognition of suitable analytes in sensing schemes. This talk will discuss the choice of organic ligands with side methyl chains that can supplement or be used in alternatives to the existing ligands for synthesizing QDs. We have employed easy and facile colloidal synthetic procedures for an extended period for manipulating the size of QDs formed, which can be further implemented for the sensing of various analytes. The side methyl chain added several benefits for the QDs synthesis, such as providing better stability of the QDs and in the sensing scenario.