bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Approach to Fabricate Semiconducting 2-D Metal-Organic Frameworks Based Thermoelectric Devices
Authors: Gonzalez-Juarez Maria , Flores Eduardo , Martin-Gonzalez Marisol , Nandhakumar Iris , Bradshaw Darren
Published: July 2021

In recent years, there has been special interest in developing devices capable to harvest and store energy from natural resources without the generation of pollution. Thermoelectric generator (TEG) is an emergent technology to harvest energy, especially in those environments in which heat waste is involved. These solid-state devices are capable of generating an output voltage as a function of a temperature difference. The conversion of thermal energy into electrical energy in these devices is attributed to the Seebeck effect. The efficiency of a TEG is evaluated through the dimensionless figure of merit, Z. In order to achieve a competitive the figure of merit, a material with a high Seebeck coefficient, electrical conductivity and low thermal conductivity is desirable.

Conductive metal organic frameworks (c-MOFs) are hybrid materials composed of inorganic and organic building blocks, in which metal nodes are coordinated to highly conjugated organic linkers.1,2 The overlap between the metal and ligand frontier orbitals facilitates the charge transport in these materials. Porosity and heterogeneity in atomic species and linkers are features that have led to a predictably low thermal conductivity3, a key aspect to optimize Z, making MOFs potential candidates for TEG. To implement their practical use, the synthesis and study of ultrathin c-MOFs nanosheets have recently been reported4; however, the processing at large scale of these materials is still a challenge.

In this work we present an electrochemical approach to the growth of conducting thin films of the 2D c-MOF Cu3(HHTP)2 (where HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene). Bulk Cu3(HHTP)2 was synthesized solvothermally according to the literature5 and we have subsequently fabricated thin films of this important framework by anodic electrochemical synthesis.6 We report the first thermoelectric measurements of this framework both in bulk and thin film form which resulted in Seebeck coefficients of -7.24 μV K-1 and -121.4 μV K-1 with a power factor of 3.15x10-3 μW m-1 for the film respectively. The study of conducting MOFs and their performance as TEG is expected to expand and offer alternatives to non-toxic, scalable and high-efficiency novel TEG materials.

[1] P. Q. Liao, J. Q. Shen, J. P. Zhang, Coord. Chem. Rev.
373, 22, 2018

[2] L. Sun, M. G. Campbell, M. Dincă, Angew. Chem. Int.
55, 3566, 2016

[3] Huang , A. McGaughey , M. Kaviany , Int. J. Heat Mass Transf. 50, 393, 2007

[4] W. Zhaoa, et al., Coord. Chem. Rev.
377, 44, 2018

[5] M. Hmadeh, et al., Chem. Mater.
24, 3511, 2012

[6] Ameloot, R. et al., Chem. Mater. 21, 2580–2582, 2009
(Invited) Towards a Molecular Understanding of Dynamic Fe-Based Oxygen Evolution Catalysts
Authors: Boettcher Shannon W.
Published: July 2021

Heterogeneous electrocatalysts for the oxygen evolution reaction (OER) are complicated materials with dynamic structures. They exhibit potential-induced phase transitions, potential-dependent electronic properties, variable oxidation and protonation states, and disordered local/surface phases. These properties make understanding the OER, and ultimately designing higher-efficiency catalysts, challenging. Measurements of intrinsic activity show that, by far, the most-active phases for OER under alkaline conditions are Fe-containing mixed-metal oxyhydroxides, but exactly how they function remains controversial. I will discuss our work to understand the key properties of these catalysts, including morphology, composition, and molecular/electronic structure, and how they evolve and are dynamic under active catalytic conditions. These concepts inform design strategies for higher-performance catalyst architectures and for their incorporation into practical electrolyzer devices to make clean hydrogen fuel from inexpensive renewable electricity.

Figure 1
(Invited) Copper Electrodeposition for Catalysis and Devices
Authors: Gewirth Andrew A. , Schmidt Ralf , Chen Xinyi
Published: July 2021

This talk discusses two aspects related to Cu electrodeposition.

In the first area, we discuss our use of Cu electrodeposition to create very active catalysts for the CO2 reduction reaction (CO2RR). We describe how using appropriate additives highly porous Cu and Cu-alloy surfaces can be created. We also show how electrodeposition can be used to incorporate polymers, the addition of which yields exceptionally active catalysts for ethylene production. The activity of these surfaces is interrogated using spectroscopy, which reports on the effect of oxides, pH, and alloy identity on product speciation.

In the second area, we evaluate the effect of chain length for a series of alkyl sulfonic acid additives on Cu electrodeposition by using a combination of electrochemical and Raman spectroscopic methods. The spectroscopy reports on the relative degree of cis and trans character in adsorbed additives, which is correlated with activity.
(Invited) Electrochemical Liquid Phase Epitaxy of Crystalline Silicon Films
Authors: Maldonado Stephen , Downes Nathanael
Published: July 2021

This presentation summarizes our sum knowledge to date on the topic of low temperature electrodeposition of crystalline Si. The motivation is to realize a low energy, low cost route towards inexpensive solar-grade Si. A brief commentary on the importance of this goal with respect to renewal energy prospects will first be provided. Subsequently, an introduction to the concept of hybrid electrodeposition-melt flux crystal growths will be given. A description of the general process of electrochemical liquid phase epitaxy (ec-LPE) will be presented. Then, an examination of factors specifically relevant to Si ec-LPE will be detailed. Our latest results in the realization of micron-thick Si films by this process will be described. Insights on the impact of the metallurgy of the liquid metal, the composition of the liquid electrolyte, and the design of the ec-LPE cell will be presented. Finally, a description of the short and long term requirements needed to advance ec-LPE beyond a lab curiousity will be discussed.
Comparative Study of Sheet Resistance Stability of Electro-Deposited Ni/Co - Alloy Thin Films
Authors: Rindo Masashi , Okamoto Naoki , Saito Takeyasu , Kitajima Akira
Published: July 2021

Cu is conventionally used for interconnect material in most of high performance and high integration of logic devices because Cu has low conductivity as 1.7×10－8 Ω･m and also has excellent electromigration resistance. However, Cu requires a barrier layer for eliminating Cu diffusion into SiO2 or Si. Because of the limitation of the barrier layer thickness, the effective resistance of the wiring including the barrier layer greatly increases with decreasing of the width of Cu wiring less than 10 nm. Therefore, many researches have been reported about the development of barrier layer-free wiring technology using Co or Ru with low resistivity compared to Cu wiring system. Ni has similar physical properties e.g. resistivity, thermal expansion coefficient, diffusion coefficient, etc. like Co or Ru, however, few research on electrical properties has been done so far. In this study, Ni, Ni-Co alloys, and Co are deposited by electrodeposition and crystallographic structure and electrical properties were evaluated.

A Ni or W (5 nm) seed layer were deposited onto thermally grown SiO2/Si(001) substrates (10 mm sq.) at R.T. by RF sputtering. After forming the seed layer, Ni or Ni-Co alloy or Co thin film (50 nm) was deposited. Table 1 shows the composition of electrodeposition bath. After the deposition, all samples were annealed in argon atmosphere (0.1 Torr) at 450°C for 30 minutes. Elemental analysis was done by Energy Dispersive X-ray spectrometry (EDX). The crystal structure, Chemical bonding state and electrical properties were evaluated by X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and 2-terminal Method, respectively, before and after annealing.

Figure 1 shows the sheet resistance change of Ni, Ni-Co alloy, or Co films before and after 450°C - 30 minutes annealing using (a) Ni and (b) W as a seed layer. There was no significant difference in sheet resistance between the Ni or W seed layer samples. In the case of Ni or Ni-Co alloy films, the sheet resistance after annealing was very stable for both seed layers, Ni and W. On the other hand, the sheet resistance of Co films increased and they were considered to be oxidized by XPS and XRD results. Co film by electrodeposition was oxidized but Ni and Ni-Co alloy films were not oxidized by annealing, so they are better wiring metal than Co in terms of oxidation resistance.

Figure 1
Electrochemical Atomic Layer Deposition and Etching – Enabling Technologies for Atomically-Precise Fabrication of High-Performance Interconnects
Authors: Akolkar Rohan
Published: July 2021

Moore’s law drives miniaturization of transistors and interconnects in nano-electronics circuits. As critical interconnect dimensions approach the 1 nm length scale, the semiconductor industry will need revolutionary advances in: (i) novel materials and integrated approaches to fabricate interconnects with lower resistance; and (ii) processing technologies for atomically-precise fabrication of novel materials and structures. In the present talk, we will outline the fundamental aspects of electrochemical atomic layer deposition (e-ALD) and etching (e-ALE) processes that enable atomically-precise fabrication of advanced interconnects. We will highlight the key uniqueness of our e-ALD approach, namely the utilization of underpotentially-deposited Zn adlayers to facilitate e-ALD of metals. This uniqueness extends considerably the range of materials accessible via e-ALD to include emerging interconnect materials beyond Cu, i.e., Pt-group metals, non-noble metals such as Co and its alloys, as well as non-metals. Furthermore, our e-ALD approach enables fabrication of novel Zn-silicate based self-forming barriers, which allow for integrated dual-damascene fabrication approaches with significant reductions in interconnect resistance. Void-free metallization of sub-10 nm features utilizing e-ALD will be demonstrated. Finally, efforts to build a library of materials accessible via e-ALD and its etching analog (e-ALE) will be described, and recent progress in building a multi-scale predictive e-ALD process model will be discussed.
Materials for Metal-Air Batteries
Authors: Staser John , Movil Omar , Daramola Damilola , Namaeighasemi Arash
Published: July 2021

Metal-air batteries have received significant attention lately due to their inherent safety, potentially high capacity and use of relatively inexpensive materials. We will present results from our work on a Zn-air battery using novel polymer electrolyte membranes and cathode electrocatalysts. The membrane enhances capacity due to higher ionic conductivity, while the electrocatalyst facilitates low-overpotential operation for the oxygen reduction reaction. In this presentation, we will discuss the use of functionalized graphene oxide (FGO) nanocomposite ion exchange membranes and Fe-Mn cathode electrocatalyst.
Case Study: Hybrid Fuel-Cell / Engine Electric Generator
Authors: Sullivan Neal P. , Cadigan Chris , Chmura Christopher , Braun Rob
Published: July 2021

Applications for high-temperature electrochemical devices continue to broaden with the expansion of societal needs in efficient power generation and renewable-energy storage. For example, opportunities are emerging for high-efficiency electric power generation through hybridization of fuel cells with reciprocating engines. Electrochemical synthesis of fuels may serve as a means for renewable energy storage. This includes hydrogen generation through water electrolysis, CO2-to-fuels, and green ammonia synthesis. These diverse applications share a number of commonalities, one being the improved performance brought by pressurized operation of the electrochemical device. Such conditions approach and often exceed the operational limits of today’s state-of-the-art electrochemical equipment, bringing questions regarding performance, dynamic response, and durability. In this presentation, we report on our efforts to explore these operational boundaries using 5-kWe solid-oxide fuel cell stack test modules provided by Ceres Power, Ltd. (Horsham, U.K.). The research is part of a federally funded, university-industrial R&D program to demonstrate an 100-kWe, 70%-efficiency electric generator, targeting markets in distributed generation. The high efficiency is achieved through a hybrid fuel-cell / engine power plant coupled with turbomachinery and power electronics. The unique hybridization strategy necessitates pressurized operation of the fuel cells; this boosts performance, but brings questions regarding durability and operational benefits. We are now using the pressurized stack test stand to explore these tradeoffs, and prepare for development of multi-stack modules. The data collected feeds computational models for stacks, systems, and operational control. The infrastructure provides a valuable resource for expanding the relevance and market potential of high-temperature electrochemical devices.

Figure 1
PRC Surface Finishing of Additively Manufactured Impellers
Authors: Hall Timothy , Liu Danny , Garich Holly , Taylor E. Jennings , Snyder Stephen
Published: July 2021

Powder bed methods of additive manufacturing (AM) use either an electron beam (Electron Beam Melting – EBM) to sequentially melt powder, layer by layer, to build up a 3-dimensional object directly from a powder bed according to a computer aided design file. Complexity is free with AM processes, so parts such as the impeller are natural candidates for AM.

With EBM. there are four steps to build each layer in a build. First, the beam is scanned to preheat the powder bed without melting, second, the contours (outer edge) of the area to be melted is traced and powder melted, third, the hatch (area within the contours) is melted and finally any supports that need to be built to support higher layers of the part being built are added. The side face of a part adjacent to powder after an EBM build.

The major concerns for incorporation of AM into structural parts are (1) microstructural anisotropy/inhomogeneity, (2) porosity – open near the surface and closed internally and (3) surface finish that is strongly dependent on the orientation of the surface relative to the build direction. Improving the surface finish is critical for certain applications. While finish machining can be used where surfaces are accessible, one benefit of the complexity of part shape is the possibility of building parts with internal channels, inaccessible to machining.

Therefore, this paper will discuss recent developments toward the demonstration of a process to electrochemically finish the internal passages of grade 5 titanium shrouded impellers produced by additive manufacturing. Specifically, we will discuss developments toward achieving optimal electrochemical processing conditions, surface finish, nominal tooling, and performance through structural spin test evaluations. Unlike conventional surface finishing processes that either use media or machine tools to physically modify the surface, electrochemistry can be used as a non-contact flexible approach, to finish hard to reach surfaces such as the internal channels of shrouded impellers that maybe inaccessible to conventional processes. This paper will focus on pulse/pulse reverse electrofinishing processes developed by Faraday Technology and the technique to scale this approach to functional parts of interest.

Acknowledgements: The financial support of USAF Contract No. FA8814-15-C-0007 is acknowledged.
Techno-Economic Analysis of CO2-to-Fuel with a Proton-Conducting Ceramic Sabatier Electrolyzer
Authors: Pritchard Tyler , Pan Zehua , Braun Rob , Sullivan Neal P.
Published: July 2021

As intermittent renewable electricity generation achieves higher market penetration, the need for robust storage and dispatch capabilities become more pronounced. In this report, we present a techno-economic analysis based around a levelized cost of storage (LCOS) calculation for a Sabatier Electrolyzer to illustrate the value proposition of electrolyzer technology. The Sabatier Electrolyzer is illustrated in Figure 1A; the CO2 feed to the fuel electrode is upgraded to CH4 through heterogeneous catalysis with hydrogen. The hydrogen is produced through water electrolysis at the steam electrode. When driven by surplus electricity, the Sabatier Electrolyzer presents an energy-storage option with CO2-to-fuels.

The electrolyzer features a proton-conducting ceramic electrolyte (BaCe0.4Zr0.4Y0.1Yb0.1O3-d) that has shown encouraging performance under fuel-cell and H2O-electrolysis applications. The Sabatier chemistry (CO2 + 4 H2 = CH4 + 2 H2O) occurs within the porous fuel electrode, a nickel-ceramic composite, where protons emerging from the ceramic phase react with CO2 or recombine to form H2 over the nickel phase. The exothermic Sabatier reaction can be balanced by the endothermicity of H2O electrolysis improving plant-level thermal balance and higher efficiency.

This report explores the economic potential of a commercial-scale Sabatier electrolyzer plant from the perspective of levelized cost of storage (LCOS). This LCOS is based on similar analyses conducted for lithium-ion batteries, flow batteries, flywheels, and pumped-hydro facilities. The model combines plant-level round-trip efficiency (RTE), overnight capital costs, variable operations and maintenance (O&M) costs, and charging costs into a time value of money (TVM) financial model. The model is exercised to estimate the lifetime cost of energy storage for the plant.

The protonic-ceramic electrolyzer presents a perhaps unusual materials set. While protonic-ceramic fuel cells have demonstrated high performance and encouraging durability at the lab scale, the materials have also shown undesirable electronic conduction that can substantially decrease electrolysis efficiency, boosting costs. The electrochemical model captures the substantial impact of protonic-ceramic electrochemical performance on LCOS, and is validated by lab-scale experimental measurements of protonic-ceramic Sabatier Electrolyzer cells. Results were scaled to yield the commercial-scale LCOS.

Sensitivity analyses demonstrate the primary cost drivers behind the commercial-scale Sabatier Electrolyzer plant. Key cost drivers include Faradaic efficiency, methane yield, utility cost of electricity, and cost of sequestered CO2. Depending on operational parameters, the LCOS of the commercial-scale Sabatier Electrolyzer plant ranges from $4,319 down to $348 per MWh of storage potential.

Figure 1
Revealing Relationships between Surface Facets and Performance of LiNiO2 Cathodes
Authors: Kim Minkyung , Chen Guoying
Published: July 2021

Ni-rich layered oxides with a general formula of LiNi1-xMxO2 (M = Mn, Co, Al etc.) are currently considered the most promising cathode materials for lithium-ion batteries (LIBs). In order to further increase energy density, higher Ni content is desirable. Previous studies, however, showed that surface-related degradation reactions become more severe with increasing Ni content, especially at high operating voltages.2 Recent theory work has suggested that surface facets play an important role in the reactivities between LiNiO2 (LNO) and the electrolyte.3 Experimental understanding of the overall relationships between Ni-rich oxide surface and reactivities, on the other hand, is largely missing.

In this study, we synthesized single-crystal LiNiO2 with different shapes and surface orientations, including Cubic with predominately (104)-family surfaces, Octahedron with predominately (012)-family and Truncated-polyhedron with mixed (001)-, (104)- and (012)-family surfaces. Note that synthesis of Ni-rich layered oxides with dominating (104) surfaces was not reported previously. We found that the Cubic-LNO sample consistently outperformed all other samples in terms of cycling stability and thermal stability, confirming (104) surface is preferrable for LNO cathodes with better cycle life and thermal safety. Our study not only identifies the optimal particle surface but also provides design insights for future development of Ni-rich layered oxide cathodes.

References

Bianchini, M.; Roca-Ayats, M.; Hartmann, P.; Brezesinski, T.; Janek, J., There and Back Again -The Journey of LiNiO2 as a Cathode Active Material. Angewandte Chemie International Edition
2019,
58 (31), 10434-10458.

Liang, L.; Zhang, W.; Zhao, F.; Denis, D. K.; Zaman, F. u.; Hou, L.; Yuan, C., Surface/Interface Structure Degradation of Ni‐Rich Layered Oxide Cathodes toward Lithium‐Ion Batteries: Fundamental Mechanisms and Remedying Strategies. Advanced Materials Interfaces
2019,
7 (3), 1901749.

Cho, E.; Seo, S.-W.; Min, K., Theoretical Prediction of Surface Stability and Morphology of LiNiO2 Cathode for Li Ion Batteries. ACS Applied Materials & Interfaces
2017,
9 (38), 33257-33266.
(Invited) Electro-Chemo-Mechanical Degradation of LiNiO2-Derived High-Ni-Content Cathode Materials
Authors: Xin Huolin , WANG Chunyang , Lin Feng , Mu Linqin
Published: July 2021

High-Ni and low-Co or Co-free layered cathode materials have become the focus of intense research in the battery community, and have rekindled interest in high-capacity layered lithium nickelate (LiNiO2). Despite increased capacity and reduced cost, LiNiO2 and LiNiO2-based high-Ni cathodes suffer from rapid capacity loss and severe chemomechanical degradation. Specifically, as lithium is deintercalated from LiNiO2, the material undergoes severe oxygen release and phase transformations, and develops cracks at both the nano- and micro-scales, leading to reduced capacity and interfacial instabilities. In this talk, I will report our recent findings on the intricate connection between oxygen loss and LiNiO2 mechanical degradation and a new strategy that can inhibit both effects.

This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Award Number: DE-EE0008444.
Hard Magnetic Composite: FePt Nanoparticles Grown within Nanostructured Silicon
Authors: Rumpf Klemens , Granitzer Petra , Gonzalez-Rodriguez Roberto , Coffer Jeffery , Reissner Michael
Published: July 2021

In this work porous silicon (PSi) and silicon nanotubes (SiNTs) are presented as a platform for filling with FePt nanostructures which offer a hard magnetic behavior. The difference of the magnetic characteristics between the two systems is figured out.

The porous silicon is produced by anodization of a highly doped n-type silicon wafer in a 10 wt% HF solution [1]. The morphology offers separated pores of about 60 nm and a mean distance between the pores of 50 nm. The SiNTs are fabricated in using an array of ZO wires as template, subsequent silicon deposition and finally etching off the ZO [2]. The inner diameter of the tubes and also the wall thickness can be tuned by the fabrication process. In this work SiNTs with comparable inner diameter to the PSi structure are used. FePt nanoparticles (NPs) are chemically grown inside the pores and the tubes, respectively whereat the molar ratio of Fe is varied (Pt:Fe 1:1, 1:3 and 1:6). For this purpose a 3 component solution consisting of H2PtCl6, Fe(NO3)3 and citric acid is used, whereas the ratio of the components is modified.

Magnetic characterization of the samples is performed by VSM (Vibrating Sample Magnetometer), the structure is analyzed by SEM, TEM and EDX.

The magnetic response of the two different composite systems is investigated. PSi/FePt shows a higher coercivity and remanence than SiNTs/FePt and thus a higher hard magnetic performance. The variation of the coercivities between SiNTs/FePt and PSi/FePt is about 57%.

Considering the FePt deposits with different molar ratio of Fe the coercivities vary in a range of 5% in the case of both template types. Comparing FePt loaded samples with Co loaded samples in all cases an increase of the coercivity and of the remanence is observed for FePt, whereat in the case of PSi as template material the increase is significantly stronger than in the case of SiNTs samples. Figure 1 shows the comparison of the hysteresis of PSi and SiNTs filled with FePt NPs.

Hard magnetic materials within nanostructured silicon give rise for on-chip applications using 3 dimensional arrays of nanomagnets.

Figure 1: Field dependent magnetization measurements of PSi and SiNTs filled with FePt NPs, respectively showing a higher coercivity in the case of PSi.

[1] K. Rumpf, P. Granitzer, H. Michor, NRL 11, 398 (2016).

[2] X. Huang, R. Gonzalez-Rodriguez, R. Rich, Z. Gryczynski, J.L. Coffer, Chem. Comm. 49, 5760 (2013).

Figure 1
Application of in-Situ Radiography to Porous Carbon Felt Electrodes in Vanadium Redox Flow Batteries
Authors: Gebhard Marcus , Roth Christina , Schnucklake Maike , Schneider Jonathan , Cheng Ming , Hilger Andre , Manke Ingo
Published: July 2021

Porous carbon felts are routinely applied as electrodes in vanadium redox flow batteries. They offer several advantages, such as low cost, low weight, good electron conductivity, and chemical inertness. However, due to their comparatively low activity in catalyzing the vanadium reactions at the anode and cathode side of the battery, an activation treatment is required to enhance the kinetics. In the literature, a heat-treatment at 400 °C in air has been reported as sufficient to introduce more oxygen functional groups at the surface, also improving the wettability of the felt and its contact with the electrolyte significantly. In this context, it is however not clear, which mechanisms are responsible for the observed performance increase. In another approach, bismuth is deposited on the carbon felts to enhance the V2+/3+ reaction in the anolyte. While a better battery performance is indeed observed, the bismuth is assumed to be dissolved and re-deposited during the charge-discharge cycles.

The aim of this work is to utilize in-situ X-ray radiography to study both the activation process and the catalytic enhancement effect due to bismuth decoration in more detail. We will highlight the potential of in-situ (synchrotron) radiography for the investigation of electrode/electrolyte interaction, pore filling and electrolyte flow behaviour complementing other more routine characterization techniques nicely [1]. To elucidate the effect of air activation, pristine and heat-treated carbon felts have been brought into contact with water, sulfuric acid and an acidic vanadium solution and ex-situ contact angles determined. This study was complemented by in-situ X-ray radiography, in which an in-house built flow cell served to monitor the electrolyte flow through the porous felt materials (pristine and heat-treated). The effect of the heat-treatment can be clearly discerned in water, see figure 1 (top: pristine felt, bottom: heat-treated felt). In contrast, when the commercial vandium electrolyte was being used, the differences between pristine and heat-treated felt vanished. Consequently, only a negligibly higher pore filling degree was observed for the treated felts, while all felts were flooded in less than 1 minute. [2]

Apart from the phenomena described above, we will also highlight the potential of in-situ radiography with respect to Bi-decorated felts during operation. [3]

[1] L. Eifert, N. Bevilacqua, K. Köble, K. Fahy, L. Xiao, M. Li, K. Duan, A. Bazylak, P.-C. Sui, R. Zeis, ChemSusChem 13 (2020) 3154.

[2] M. Gebhard, M. Schnucklake, A. Hilger, M. Röhe, M. Osenberg, U. Krewer, I. Manke, C. Roth, Energy Technol. 8 (2020) 1901214.

[3] M. Gebhard, T. Tichter, J. Schneider, J. Mayer, A. Hilger, M. Osenberg, M. Rahn, I. Manke, C. Roth J. Power Sources 478 (2020) 228695.

Figure 1
Understanding the Structural and Electrochemical Properties of LiNi0.9Co0.1O2 Ni-Rich Cathode in Lithium Ion Batteries
Authors: Aryal Shankar , Kahvecioglu Ozgenur , Durham Jessica , Lipson Albert , Pupek Krzysztof
Published: July 2021

Advances in next generation Li-ion battery technology have been trending towards utilizing Nickel-rich cathode materials. One of the Ni-rich compositions, LiNi0.9Co0.1O2, have the potential to increase energy density while further reducing costs due to the reduced Cobalt content. This composition forms a highly layered structure, which provides superior electrochemical performance. In particular, it showed > 220 mAh/g initial discharge capacity at 0.1C rate but the capacity fades quickly with cycling. The main factors behind this performance deterioration with cycling are structural transformation of the cathode to the rock salt phase, parasitic reactions between the Nickel-rich cathode and electrolyte and gas release. Here, we report physical and electrochemical properties of industrial grade LiNi0.9Co0.1O2 cathode material synthesized by utilizing continuous co-precipitation reaction in a Taylor Vortex Reactor.

A thorough investigation of the mechanisms that make this material underperform other similar compositions was performed. In particular, the rate and long term cycling performance of the cathode material in half and full cell configuration were investigated. Synchrotron X-ray diffraction and X-ray absorption spectroscopy (XAS) of pristine and cycled cathodes after long term cycling will be discussed to understand the degradation mechanism. In-situ XAS at Nickel and Cobalt K-edge during the first two initial cycles will be discussed in detail to unravel the local structural changes and redox activity of Ni and Co in LiNi0.9Co0.1O2 cathode. Overall, this presentation will give a detailed understanding of this material’s synthesis, structure-property relationships, chemistry and electrochemical performance, which give new insights into the roles of Co and Mn in Ni-rich cathode materials.
(Invited) Anionic Redox Chemistry in Layered Oxide Cathodes
Authors: Tong Wei
Published: July 2021

Li-ion battery remains as the critical energy storage device and starts to invade the large electrical vehicle (EV) market. Extensive efforts have been devoted to developing advanced layered oxide cathodes, including both stoichiometric and Li-rich layered oxides, for Li-ion batteries of even better performance. For all these cathodes, there is a clear need for the high-voltage cycling to obtain an even higher practical capacity. However, the redox reactions become more complex when charged at high voltages. Beyond the conventional transition metal (TM) redox, anionic oxygen becomes active and participates in the electrochemical reaction in these cathodes. The anionic oxygen activity involves both the reversible oxygen redox and irreversible oxygen loss accompanied by other byproducts resulting from the undesirable side reactions at high voltages.

In the past, my group has been focusing on understanding the redox chemistry, including both cationic and anionic redox reactions, in both stoichiometric and Li-rich layered oxide cathodes, especially towards the high-voltage cycling. We specifically investigated the electronic states of TM and O using combined electrochemical, soft X-ray absorption (XAS), resonant inelastic X-ray spectroscopy (RIXS) and in situ differential electrochemical mass spectrometry (DEMS) in the high voltage region to elucidate the explicit redox chemistry in various layered oxide cathodes. This presentation will highlight a summary on the different TM and O redox behaviors in these technologically relevant cathode materials for a close comparison. Of particular interest is the fundamental understanding of how the anionic oxygen participates in the electrochemistry of layered oxides with the presence of different Li and TM stoichiometry.
Estimating ‘Cycles to Failure’ As a Function of Depth of Discharge (DOD) for Lithium Ion Batteries
Authors: Deshpande Rutooj , Uddin Kotub
Published: July 2021

Estimating the life of lithium ion batteries is a longstanding issue for electric vehicles as well as energy storage applications. For grid scale storage applications, this is particularly pertinent given that the commercial viability of projects is closely correlated with the accuracy of battery degradation estimations. A large volume of literature therefore is devoted to understanding various degradation mechanisms in lithium ion batteries and developing both diagnostic and prognostic degradation models. In this context, estimating calendar aging resulting from the chemical decomposition of electrolyte solution is relatively well established. Developing a cycle life counterpart however has been more challenging. The convoluted nature of interactions between various degradation mechanisms during cycling results in complex physics-based life models; coupled with a lack of detailed battery life testing data, these models are often difficult to adopt in application, both in academic and industrial settings. To this end, empirical relations such as analogues of the Wöhler curve are used to estimate the ‘cycles to failure’ for battery cycling with various ‘Depth of discharges (DODs)’. In a previous publication, Deshpande et al. [1] proposed that at lower discharge/charge rates of battery operation, SEI cracking and reforming is a dominant mechanism of cell capacity loss for continuous cycling. These ideas are further exploited in this article to develop a pragmatic physics-based model for estimating Li-ion battery cycle life combining the effects of SEI growth and SEI cracking-reforming mechanisms. Such a model is of particular interest to grid scale energy storage applications where the operating C-rates are relatively mild and operational life is long. Beyond proposing a physics- based model to estimate ‘cycles to failure’ for various DODs, we also validate the model against long duration cycling datasets from the battery energy storage literature. The simplicity of the model and its adaptability for batteries with sparsely available datasets makes it highly useful.

Figure 1
Quantification of the Internal Void Network upon Optimization of Synthesis Conditions for Lithium-Ion Cathode Materials
Authors: Allen Eva Michelle , De Andrade Vincent , Cabana Jordi
Published: July 2021

Current industrial methodologies for lithium-ion battery cathode materials are suited to the production of well-defined, dense, spherical secondary particle structures assembled from nanocrystalline primary particles. Specifically, LiNixMnyCozO2 (LNMC) cathode material is synthesized by first growing the hydroxide precursor, NixMnyCoz(OH)2 (NMC), through a coprecipitation method using a stoichiometric ratio of mixed transition metal sulfate solutions, sodium hydroxide, and ammonia hydroxide pumped into a continuous stirred tank reactor (CSTR). Each new composition of cathode material requires an extensive synthesis parameter optimization study to refine the even formation of metal species, density, and uniformity of size and shape of the final cathode material. The characterization and visualization of the three-dimensional secondary cathode structure, internal morphology, and void network is an elusive task using traditional scanning electron microscopy (SEM) because it is 2D technique that requires the use of mechanical cross-sectioning which can cause the deformation of the internal structure. Yet the variation of the internal structure and density changes within LNMC secondary particles can have large effects on both the cycling kinetics, capacity, and lifetime of the final cathode material.

In this study, we present a five-parameter optimization study of Ni0.25Mn0.25Co0.50(OH)2 (NMC112) using our lab-built CSTR. The optimization and morphological changes of the primary and secondary particles during high temperature lithiation is investigated further. Using synchrotron-based transmission X-ray microscopy tomography (TXM) in combination with a novel deep learning semantic segmentation process, the three-dimensional cathode structure and internal pore network of LNMC112 particles was mapped across different lithiation temperature and reaction times. The deep learning semantic segmentation allowed for the quantification of void volume, shape, size, and final overall density of the cathode secondary particles. The results of these morphological differences show effects in both the kinetics and cyclability through galvanostatic cycling. The quantification of the three-dimensional cathode microstructure shown in this study is agnostic of the specific cathode composition. Therefore, it is highly suited to better inform optimization targets of the coprecipitation synthesis, as well as illuminating the importance the internal pore network of secondary particles.
NMR Study of LiCo0.96Al0.04O2 As a Positive Electrode Material for Li-Ion Batteries: Homogeneity and Role of Doping on Mechanisms
Authors: ER-Rami Fatima-Ezzahra , Duffiet Marie , Cabelguen Pierre-Etienne , Auvergniot Jeremie , Maxime Blangero , Carlier-Larregaray Dany , Delmas Claude
Published: July 2021

LiCoO2 (LCO) is one of the most widely used positive electrode materials in lithium-ion batteries due to its high volumetric energy density which can be further improved by charging at high voltages. However, working at high potential (above 4.3 V vs. Li+/Li) causes a deterioration in cycling performance induced by structural instabilities, electrolyte oxidation and Co dissolution. Extensive studies have been devoted to increasing energy density by increasing the cutoff voltage. The substitution of cobalt with various metals is one of the classic methods, the choice of aluminum as dopant for example is based on several criteria: low cost and non-toxicity, a similar radius for Al3+ compared to Co3+ (0.535 Å vs. 0.545 Å) facilitates the replacement of the latter and maintains the structure leading to the complete solid solution LiCo1-yAlyO2.

We will focus here on LiCo0.96Al0.04O2, synthesized by the solid route and characterized by 7Li, 27Al and 59Co Nuclear Magnetic Resonance (NMR) and synchrotron X-Ray Diffraction (XRD). In addition to the characterization of the mean structure by XRD, the NMR allows us to study the local environments of the different nuclei. 27Al MAS NMR and synchrotron XRD studies revealed that the Al-doping in this material is homogeneous. 7Li MAS NMR indicates that its stoichiometry (Li/M=1.00) is ideal. The electrochemical study has shown that the phase transitions occurring during delithiation of LiCoO2, were partially eliminated by aluminum doping even with a low doping amount and the high potential mechanisms appear to be different. In order to better understand the role of Al-doping on the mechanisms involved during cycling, several phases LixCo0.96Al0.04O2 were prepared by electrochemical deintercalation and studied by 7Li, 59Co, and 27Al NMR and by XRD.

During lithium deintercalation, Co3+ is oxidized to Co4+ then one unpaired electron is generated in the t2g band of Co atoms (t2g
5eg
0). For 0.8 ≤ x ˂ 1.00 the 7Li MAS NMR shows that the system behaves locally as two phase domain: domain with localized electrons and domain with delocalized ones on Con+ ions (Knight shift), even for very low amount of deintercalation (x=0.98), thus the XRD results confirm the existence of the biphasic domain. Whereas, a single phase domain is observed for the deintercalated materials with 0.4 ≤ x ≤ 0.8 and also at the NMR time of scale a single signal (Knight shift) is observed. This signal increases in intensity at the expense of 0 ppm and shifts to the higher isotropic displacement values up to x=0.5 then decreases, thus the evolution of the chex lattice parameter is correlated with the signal shift. For x = 0.3 and x = 0.2: a new broad signal appears probably due to formation of new Li environment in stacking faulted layers (O1 type). These different contributions will be more detailed on the presentation.
Prototyping of a Low-Cost Ion-Selective Electrode Sensor Unit for Determination of Lead Ions in Aqueous Samples
Authors: Delestre Jordan , Wang Po-Yen , Tang Xiaochao
Published: July 2021

Exposure to lead via drinking water is a substantial health hazard. The current common practice of measuring lead levels in drinking water is to use analytical chemical analysis that involves sophisticated laboratory instruments. As lead contamination in drinking water is often a close-to-home contamination caused by corroded lead service pipes connecting households to main lines or lead-based pluming within the households, a low-cost and portable device that can be conveniently deployed to individual households to monitor lead levels in drinking water would offer consumers the opportunity to obtain first-hand information about the lead levels in their drinking water. The main objective of this study is to develop and prototype a portable low-cost device for detecting lead levels in drinking water. The lead-detecting device consists of two primary components: lead ion-selective electrode (ISE) sensing membrane and a microcontroller-based measuring unit. ISE membrane has proven to show low detection limits, good selectivity, low cost and great potential to be integrated in a miniature device. The ISE membrane in this study utilized polymeric membrane as the matrix with lead-selective ionophores embedded in the matrix. Hydroxyl type Vinyl Chloride-vinyl Acetate Terpolymer was used to create polymeric membrane matrix and allowed for all components to be housed in the membrane. The selected ionophore was Tert-Butylcalix(4)Arene-Tetrakis with its primary function is to differentiate and transport a specific ion (in this case, Pb2+ ions) through a membrane. A limit of detection of 1.0 ´ 10-8 M was achieved along with a linear Nernstian response over a lead concentration range from 1.0 ´ 10-8 M to 1.0 ´ 10-4 M. Durability test of the membrane showed a lifetime close to 30 days. A low-cost printed circuit board (PCB) was custom designed and created as an amplification unit to measure the ISE’s electromotive force (EMF). The custom-built device was able to capture the limit of detection (LOD) of the ISE sensing membrane and showed reasonably good consistency in comparison to measurements from commercial potentiostat.
(Invited) Heterogeneous Packaging Integration for AI Workloads
Authors: Sikka Kamal
Published: July 2021

Semiconductor scaling to smaller dimensions has led to tremendous improvement in electronic systems performance. Computer systems that used to occupy several rooms are now available in the palm of your hand. However, as semiconductor scaling saturates, other paradigms are necessary for improving the systems performance. One such paradigm of performance improvement is advanced packaging of heterogeneous chips from different semiconductor nodes, different construction and different sources - often called heterogeneous integration (HI). HI is necessary because system performance is required to grow 1000x over the next 7-10 years, especially for Artificial Intelligence (AI) applications. A subset of AI, called machine learning, relies of artificial neural networks that simulate a human brain. In this talk, we compare and contrast the different HI packaging options which include conventional 2D single-chip and multi-chip packages with high-density laminates, package-on-package (PoP) configurations, 2.5D silicon interposers, silicon bridge packages, and fully 3D stacked packages. Many of these configurations are being developed in the IBM AI Hardware Research Center (AIRC). We also describe the tooling and EDA infrastructure required for the successful development of these packaging solutions.
Process-Induced ReRAM Performance Improvement of Atomic Layer Deposited HfO2 for Analog In-Memory Computing Applications
Authors: Consiglio Steven , Higuchi Hisashi , Ando Takashi , Jamison Paul , Seo Soon-Cheon , Kong Dexin , Kim Youngseok , Tapily Kandabara , Clark Robert D , Hopstaken Marinus , Cartier Eduard , Tsunomura Takaaki , Wajda Cory S , Soave Robert , Narayanan Vijay , Leusink Gert J
Published: July 2021

Neuromorphic computing represents a potential paradigm shift from conventional von Neumann computing architecture and shows promise for achieving massive parallelism and power efficiency for such data-centric tasks as image recognition and language processing. Based on the concept of synaptic plasticity, human-like machine learning can be potentially realized by use of arrays of electronic synapses that function in an analogous manner to biological neurons. One of the key features of this type of computing is the ability to control synaptic weights in an analog-like fashion for use in both inference and training applications.

A number of existing device technologies in non-volatile memory systems exhibit attractive characteristics for such synaptic devices.[1,2] In particular, resistive switching devices (resistive random-access memory or ReRAM) can change and store their conductance value (G) in response to electrical stimuli making them potentially enabling for deep learning applications involving synaptic weights. For ReRAM devices, HfO2-based thin films can be utilized for filamentary oxide ReRAM and are an attractive option due to their fab-friendly processing and current implementation in high-volume manufacturing.

In this study, we evaluated atomic layer deposition (ALD) for the growth of HfO2 for integration in both front-end-of-line (FEOL) and back-end-of-line (BEOL) compatible test structures on 300 mm wafers in order to optimize electrical performance for use as synaptic device elements in neuromorphic architectures. The effect of oxidant in the ALD process was evaluated and it was shown that H2O outperformed O3 in terms of better uniformity and lower forming voltage. By utilizing a hydrogen-based plasma either after the deposition or inserted as an intermediate step during deposition we were able to further decrease forming voltage for a fixed dielectric thickness. Reducing deposition temperature to 200°C in conjunction with the hydrogen-based plasma treatment offered an additional tuning knob to further reduce forming voltage. Stable high-resistance switching (> 100 kΩ) with analog behavior in scaled BEOL devices was also obtained using this optimized HfO2-based ReRAM. Additionally, a tight distribution of forming voltage was obtained ensuring that 99.9999% devices in a 14 nm ReRAM module can be formed below the targeted voltage.

References

Kuzum et al., Nanotechnology, 24, 382001 (2013)

W. Burr et al., Advanced in Physics:X, 2, 89 (2016)