Advanced Manufacturing Office Research Articles

Neodymium Metal Production Via Chloride Based Molten-Salt Electrolysis

The extraction and purification of metals such as aluminum has relied on the electrowinning process for decades. The Hall-Héroult process, developed in 1885, utilizes a molten salt electrolyte to electrochemically produce aluminum metal (Al) and carbon dioxide (CO2).1–3 Similar molten salt techniques exist for a variety of other metals including the rare earth metal Neodymium (Nd). Neodymium has seen significant increases in demand from increased production of wind turbines, electric vehicles, and hard disk drives that use neodymium–iron–boron (Nd–Fe–B) permanent magnets. 4,5 The current procedure for neodymium processing uses a neodymium and lithium fluoride molten salt electrolyte with a sacrificial carbon anode to convert neodymium oxide (Nd2O3) and carbon to neodymium metal and CO2.4,6 As an unfortunate byproduct of the fluoride containing molten salt, perfluorocarbons (PFCs) can also be produced simultaneously. The formation of PFCs combined with the emission of other greenhouse gases (CO,CO2) makes the current process dangerous and undesirable from an environmental standpoint. Due to this, few places currently produce neodymium metal and virtually none is produced in the United States, creating supply chain risks with dire consequences.5 An alternative molten salt process has been proposed where rather than directly converting neodymium oxide to neodymium metal, the oxide is first converted to chloride salt form by reaction with hydrochloric acid. The neodymium salt is then dissolved into a chloride salt based melt and neodymium is electroplated via the below set of reactions.7,8 Cathode: 2NdCl3 + 6e- → 2Nd(solid) + 6Cl- Anode: 6Cl- → 3Cl2 + 6e- Overall: 2NdCl3 → 2Nd(solid) + 3Cl2 This process has several distinct advantages. The chlorine reaction eliminates the need for a sacrificial anode material as well as the production of carbon dioxide. The chloride based molten salt also eliminates the formation of PFCs. The chlorine is then recycled to make more hydrochloric acid for use in converting neodymium oxide to chloride.This talk focuses on recent advances to improve purity and lower energy consumption (kWh/kg). We evaluate anode and cathode behavior during this neodymium chloride molten salt process. Over-potential and stability of various anode materials are investigated in order to minimize energy consumption and ensure long life of process materials. A new stable analytic cathode is demonstrated which is lowers chlorine over-potential by more than 200 mV at current density of 250 mA/cm2.The effect of various plating conditions such as current density and substrate material are investigated to determine impact on deposit quality, coulombic efficiency, and metal purity. Highly porous Nd deposits are known to form in chloride molten salt but are undesirable due to the energy required to separate out the high volume fraction of salt remaining in the solid sponge. Effects of temperature and electrolyte composition on deposit morphology are investigated and improvements toward densifying the sponge to minimize post electrolysis purification are reported. This proof of concept work aims to develop a safe, sustainable and environmentally friendly path towards large scale production of rare earth elements. Reactor design and cathode efficiency results are based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy under the Advanced Manufacturing Office, Award Number DE-EE0009434. Anode design work was supported through the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. Portions of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. T. R. Beck, Electrochem. Soc. Interface, 23, 36–37 (2014).G. G. Botte, Electrochem. Soc. Interface, 23, 49–55 (2014).W. E. Haupin, J. Chem. Educ., 60, 279–282 (1983).M. F. Chambers and J. E. Murphy, Electrolytic production of neodymium metal from a molten chloride electrolyte.B. Sprecher, R. Kleijn, and G. J. Kramer, Environ. Sci. Technol., 48, 9506–9513 (2014).V. S. Cvetković et al., Met. 2020, Vol. 10, Page 576, 10, 576 (2020).R. Akolkar, J. Electrochem. Soc., 169, 043501 (2022).D. Shen and R. Akolkar, J. Electrochem. Soc., 164, H5292–H5298 (2017).

(Invited) Rare Earth Metal Production Via Chloride Based Molten-Salt Electrolysis

The extraction and purification of metals such as aluminum has relied on the electrowinning process for decades. The Hall-Héroult process, developed in 1885, utilizes a molten salt electrolyte to electrochemically produce aluminum metal (Al) and carbon dioxide (CO2) from aluminum oxide (Al2O3) and carbon.1–3 Similar molten salt techniques have been developed for a variety of other metals including the rare earth metal Neodymium (Nd). Neodymium is of particular interest recently with significant increases in demand being driven by the increased production of technologies such as wind turbines, electric vehicles, and hard disk drives that require neodymium in the form of neodymium–iron–boron (Nd–Fe–B) permanent magnets. 4,5 The current procedure for neodymium processing uses a neodymium and lithium fluoride molten salt electrolyte with a sacrificial carbon anode to convert neodymium oxide (Nd2O3) and carbon to neodymium metal and CO2.4,6 As an unfortunate byproduct of the fluoride containing molten salt, perfluorocarbons (PFCs) can also be produced simultaneously. The formation of PFCs combined with the emission of a significant amount of other greenhouse gases (CO,CO2) make the current process for neodymium electrowinning is dangerous and undesirable from an environmental standpoint. However rare earth metal production remains profitable enough that illegal processing operations make up a significant portion of the world’s supply of rare earth elements like neodymium. 7,8 Due to this, few places currently produce neodymium metal and virtually none is produced in the United States, creating supply chain risks with dire consequences.5 An alternative molten salt process has been proposed in which the fluoride salts have been replaced with chloride salts consisting of lithium chloride (LiCl) and potassium chloride (KCl). Rather than directly converting neodymium oxide to neodymium metal, the oxide is first converted to chloride salt form by reaction with hydrochloric acid. The neodymium salt is then dissolved into the LiCl-KCl molten salt and neodymium is electroplated via the below set of reactions.9,10 Cathode: 2NdCl3 + 6e- → 2Nd(solid) + 6Cl- Anode: 6Cl- → 3Cl2 + 6e- Overall: 2NdCl3 → 2Nd(solid) + 3Cl2 This process has several distinct advantages. Utilizing the chlorine reaction eliminates the need for a sacrificial anode material as well as the production of carbon dioxide. The chloride based molten salt also eliminates the formation of PFCs. The chlorine produced could then be recycled to make more hydrochloric acid for use in converting neodymium oxide to chloride.This talk focuses on recent advances to improve purity and lower energy consumption (kWh/kg). Our work evaluates anode and cathode behavior during this neodymium chloride molten salt process in order to determine its viability. Overpotential and stability of various anode materials are investigated in order to minimize energy consumption and ensure long life of process materials. The effect of various plating conditions such as current density and substrate material are investigated to determine impact on deposit quality, coulombic efficiency, and metal purity. Additional purification techniques such as vapor distillation procedures are developed to ensure a product that is viable for industrial use. This proof of concept work aims to develop a safe, sustainable and environmentally friendly path towards large scale production of rare earth elements. Reactor design and cathode efficiency results are based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy under the Advanced Manufacturing Office, Award Number DE-EE0009434. Anode design work was supported through the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. Portions of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. T. R. Beck, Electrochem. Soc. Interface, 23, 36–37 (2014).G. G. Botte, Electrochem. Soc. Interface, 23, 49–55 (2014).W. E. Haupin, J. Chem. Educ., 60, 279–282 (1983).M. F. Chambers and J. E. Murphy, Electrolytic production of neodymium metal from a molten chloride electrolyte.B. Sprecher, R. Kleijn, and G. J. Kramer, Environ. Sci. Technol., 48, 9506–9513 (2014).V. S. Cvetković et al., Met. 2020, Vol. 10, Page 576, 10, 576 (2020).H. Vogel, B. Friedrich, H. Vogel, and B. Friedrich, Int. J. Nonferrous Metall., 6, 27–46 (2017).J. C. K. Lee and Z. Wen, Nat. Sustain. 2018 110, 1, 598–605 (2018).R. Akolkar, J. Electrochem. Soc., 169, 043501 (2022).D. Shen and R. Akolkar, J. Electrochem. Soc., 164, H5292–H5298 (2017).

Li2CO3 As the Parasitic Reaction Root for Exacerbated Material Degradation and Performance Deterioration of Ni-Rich Cathode

Nickel-rich transition metal oxides is widely regarded as promising cathode materials for high energy density lithium-ion batteries for emerging applications in electric vehicles. However, achieving high energy density in Ni-rich cathodes is generally accompanied with substantial obstacles of lifetime and safety. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions to material degradation at the surface of cathode materials is not well understood. In this work, we report the parasitic-reaction-driven structural degradation in LiNi0.83Mn0.1Co0.07O2 cathode by altering interfacial chemistry by synthesizing cathode material in different environments. Our home-build high precision leakage current (HpLC) system verifies that Li2CO3 impurity generated in harsh synthesis environment is a nature root of electrolyte decomposition and parasitic reactions on Ni-rich cathodes. Different rates of parasitic reactions are strongly correlated to drastic discrepancy in electrochemical performance of Ni83 cathodes at different synthesis conditions. The post-mortem characterizations reveal that parasitic reactions promote severe rock-salt phase transformation with more Ni reduction and O deficiency at the surface of cathode materials. This study suggests the significance of developing impurity-free and mitigated parasitic reactions in Ni-rich transition metal oxides for enabling high energy density. Acknowledgement Research at the Argonne National Laboratory was supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. Argonne National Laboratory is operated for the DOE Office of Science by UChicago Argonne, LLC, under Contract DE-AC02-06CH11357. Figure 1

(Invited) U.S. DOE Initiatives Supercharging Advanced Battery Manufacturing Innovation

The Department of Energy’s Advanced Manufacturing Office (AMO) continues to invest in energy storage research, development, demonstration, and deployment (RDD&D) to help stakeholders improve efficiency, cut costs, and make materials, devices, and systems with superior performance. Despite recent promising advances, manufacturing capabilities are still necessary to meet the expected demand for energy storage as we move toward a clean energy economy. Strengthening the domestic manufacturing supply chains is also another important task to pursue in parallel.AMO and the Vehicle Technologies Office (VTO) both funded projects through a Battery Manufacturing Lab Call to address capability gaps and engineering challenges for enhanced lithium-ion batteries, with a focus on de-risking, scaling, and accelerating adoption of new technologies through public-private partnerships. These projects successfully demonstrate how the advanced technologies are increasingly being used to solve battery manufacturing challenges. In addition, flow battery systems manufacturing projects funded by AMO are focusing on developing efficient, scalable manufacturing processes, and robust supply chains for flow battery system components.In this talk, the status and accomplishments of the projects will be highlighted. In addition, there will be a robust discussion of a wide variety of AMO’s efforts in the context of technical and manufacturing challenges regarding scale-up and performance that still prevent the electrochemical energy storage community from achieving cost targets and commercial viability.

Rare Earth Metal Production Via Molten-Salt Electrolysis

The extraction and purification of metals such as aluminum has relied on the electrowinning process for decades. The Hall-Héroult process, developed in 1885, utilizes a molten salt electrolyte to electrochemically produce aluminum metal (Al) and carbon dioxide (CO2) from aluminum oxide (Al2O3) and carbon.1–3 Similar molten salt techniques have been developed for a variety of other metals including the rare earth metal Neodymium (Nd). Neodymium is of particular interest recently with significant increases in demand being driven by the increased production of new technologies such as electrified vehicles and magnetic data storage that require neodymium in the form of neodymium–iron–boron (Nd–Fe–B) permanent magnets. 4,5 The state of the art procedure for neodymium processing, similar to the aluminum process, utilizes a neodymium and lithium fluoride molten salt electrolyte with a sacrificial carbon anode to convert neodymium oxide (Nd2O3) and carbon to neodymium metal and carbon dioxide.4,6 As an unfortunate byproduct of this process performed in a fluoride containing molten salt, perfluorocarbons (PFCs) can also be produced simultaneously alongside carbon dioxide from the sacrificial anode. The formation of PFCs combined with the emission of a significant amount of greenhouse gas (carbon dioxide) make the current process for neodymium electrowinning undesirable from an environmental standpoint.7 An alternative molten salt process has been proposed in which the fluoride salts have been replaced with chloride salts consisting of lithium chloride (LiCl) and potassium chloride (KCl). Rather than directly converting neodymium oxide to neodymium metal, the oxide is first converted to chloride salt form by reaction with hydrochloric acid. The neodymium salt is then dissolved into the LiCl-KCl molten salt and neodymium is electroplated via the below set of reactions.8,9 Cathode: 2NdCl3 + 6e- → 2Nd(solid) + 6Cl- Anode: 6Cl- → 3Cl2 + 6e- Overall: 2NdCl3 → 2Nd(solid) + 3Cl2 This process has several distinct advantages. Utilizing the chlorine reaction eliminates the need for a sacrificial anode material as well as the production of carbon dioxide. The chloride based molten salt also eliminates the formation of PFCs. The chlorine produced could then be recycled to make more hydrochloric acid for use in converting neodymium oxide to chloride. Our work evaluates anode and cathode behavior during this neodymium chloride molten salt process in order to determine its viability. Overpotential and stability of various anode materials are investigated in order to minimize energy consumption and ensure long life of process materials. The effect of various plating conditions such as current density and substrate material are investigated to determine impact on deposit quality, coulombic efficiency, and metal purity. Additional purification techniques such as vapor distillation procedures are developed to ensure a product that is viable for industrial use. This proof of concept work aims to develop a safe, sustainable and environmentally friendly path towards large scale production of rare earth elements. Reactor design and cathode efficiency results are based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy under the Advanced Manufacturing Office, Award Number DE-EE0009434. Anode design work was supported through a subcontract from the Ames Laboratory with funding from the Department of Energy - Energy Efficiency and Renewable Energy under contract No. DE-AC02-07CH11358; Agreement No. 26110-AMES-CMI. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. T. R. Beck, Electrochem. Soc. Interface, 23, 36–37 (2014).G. G. Botte, Electrochem. Soc. Interface, 23, 49–55 (2014).W. E. Haupin, J. Chem. Educ., 60, 279–282 (1983).M. F. Chambers and J. E. Murphy, Electrolytic production of neodymium metal from a molten chloride electrolyte.B. Sprecher, R. Kleijn, and G. J. Kramer, Environ. Sci. Technol., 48, 9506–9513 (2014).V. S. Cvetković et al., Met. 2020, Vol. 10, Page 576, 10, 576 (2020).H. Vogel, B. Friedrich, H. Vogel, and B. Friedrich, Int. J. Nonferrous Metall., 6, 27–46 (2017).R. Akolkar, J. Electrochem. Soc., 169, 043501 (2022).D. Shen and R. Akolkar, J. Electrochem. Soc., 164, H5292–H5298 (2017).

(Invited) Manufacturing 3D Electrode Architectures Via Acoustophoresis

Achieving high-energy and high-power density Lithium-ion batteries (LIBs) with fast charge behavior is critical for the future of electric vehicle applications. Conventional LIBs have planar anode and cathode electrode stacks that can be optimized for energy or power, but not both simultaneously due to fundamental ion transport limitations with increasing electrode thickness. Three-dimensional (3D) electrode architectures1,2 can remove these performance trade-offs through engineered ion-transport in thick electrodes. However, scalable manufacturing methods for patterning these architectures over large areas at meaningful time scales is still limited. As a path to solving this challenge, we leverage both modeling and experiments to investigate the feasibility of deploying acoustophoresis to assemble and pattern 3D battery electrodes. Acoustophoresis employs acoustic standing waves to focus particles and enables near micron-scale control over particle placement in a fluid medium at time scales < 1 second. Prior research has shown the potential for rapid assembly of particles with this approach,3,4 making acoustic-based processing a promising methodology for manufacturing 3D electrodes over large areas. In this talk, we expand a previously developed model4 that solves differential equations of acoustic forces to track particle trajectories and define how the acoustic forces are influenced by slurry viscosity, particle loading, and particle morphology. Our initial experiments with different material systems, including LiNi0.6Mn0.2Co0.2O2 (NMC-622), help validate our model and process conditions to as a path towards acoustophoretic fabrication of 3D electrode architectures. References C. L. Cobb and S. E. Solberg, J. Electrochem. Soc., 164, A1339–A1341 (2017).C. L. Cobb and M. Blanco, Journal of Power Sources, 249, 357–366 (2014).D. S. Melchert et al., Materials & Design, 109512 (2021).R. R. Collino et al., Materials Research Letters, 6, 191–198 (2018). Acknowledgements 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 Advanced Manufacturing Office (AMO) Award Number DE-EE0009112. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

(Invited) Battery Design for Fast Charging

Lithium-ion batteries (LIBs) has been broadly applied in electric vehicles (EVs) and the market adoption of EVs can be further improved with enhanced fast charging capabilities. The state-of-the-art chemistries, such as LiNixMnyCo1-x-yO2 (NMC) and graphite, are capable for fast charging. However, the electrodes are limited to thin coating due to mass transport limitation, which results in low energy density and high cost [1]. For example, the United States Department of Energy (DOE) issued a call for proposal in 2017 to enable extreme fast charging with a target of cell energy density higher than 180 Wh/kg which is much lower than that under normal application.The energy density of LIBs depends on the materials properties and cell engineering. In this presentation, the impact of cell design on energy density under fast charging will be discussed. Specifically, design in electrodes, current collectors, electrolyte, and separator will be elaborated to show their correlation to fast charging application [2-3]. Acknowledgment This research at Oak Ridge National Laboratory (ORNL), managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) Vehicle Technologies Office (VTO) and Advanced Manufacturing Office (AMO).

(Invited) Developments of Wbg GaN-on-GaN Vertical Power Devices & Uwbg Ga2O3, Algao, and Heterostructures

In this talk, metalorganic chemical vapor deposition (MOCVD) development of GaN-on-GaN targeting for vertical power devices will be presented. To achieve vertical GaN PN diodes with high breakdown voltage (Vbr) and low on resistance (Ron), it is critical to develop thick GaN drift layer with low controllable doping (Nd-Na) and high electron mobility. Key impurities in MOCVD GaN serving as charge compensation centers were identified. For example, mechanisms of Fe incorporation in MOCVD GaN were identified and addressed [1]. Source of C incorporation is mainly from metalorganic precursor (TMGa), and the C concentration in GaN is highly dependent on MOCVD growth condition, particularly the growth rate. Typically, as GaN growth rate increases, C incorporation increases undesirably. To address this key challenge for achieving high quality thick GaN drift layer, we developed a laser-assisted MOCVD (LA-MOCVD) growth technique to enable fast GaN epitaxy while suppressing C incorporation. The effects of LA-MOCVD GaN growth parameters on GaN growth rate, impurity incorporation and charge transport properties will be discussed. GaN PN diodes with breakdown voltage ~ 3kV are demonstrated.This talk will also discuss our recent developments of ultrawide bandgap (UWBG) Ga2O3, (AlxGa1-x)2O3, and heterostructures [2-5]. Challenges and opportunities for developing (AlxGa1-x)2O3 on Ga2O3 substrates with different crystal orientations ((010), (100), (-201)) be discussed. Band offsets between AlGaO/GaO heterostructures were determined based on high quality epitaxy of AlGaO/GaO heterostructures. Experimental results agree very well with the values predicted from theoretical density functional theory (DFT). Growth techniques based on MOCVD and low pressure chemical vapor deposition (LPCVD) will be compared and discussed. Acknowledgement: The authors acknowledge the funding support from Advanced Research Projects Agency-Energy (ARPA-E) DE-AR0001036, U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Advanced Manufacturing Office, FY18/FY19 Lab Call, the Air Force Office of Scientific Research FA9550-18-1-0479 (AFOSR, Dr. Ali Sayir) and the National Science Foundation (1810041, 1755479, 2019753). [1] Y. Zhang, Z. Chen, W. Li, H.-S. Lee, M. R. Karim, A. R. Arehart, S. A. Ringel, S. Rajan, H. Zhao, J. Appl. Phys., 127, 215707, 2020.[2] Z. Feng, A F M A. U. Bhuiyan, M. R. Karim, H. Zhao, Appl. Phys. Letts., 114, 250601, 2019.[3] A F M A. U. Bhuiyan, Z. Feng, J. M. Johnson, Z. Chen, H. -L. Huang, J. Hwang, H. Zhao, Appl. Phys. Lett., 115, 120602, 2019.[4] A F M A. U. Bhuiyan, Z. Feng, J. M. Johnson, H.-L. Huang, J. Sarker, M. Zhu, M. R. Karim, B. Mazumder, J. Hwang, and H. Zhao, APL Materials, 8, 031104, 2020.[5] A F M A. U. Bhuiyan, Z. Feng, J. M. Johnson, H.-L. Huang, J. Hwang, and H. Zhao, Appl. Phys. Letts, 117, 252105, 2020.

Architecting Three-Dimensional Lithium-Ion Battery Electrodes Using Acoustic Focusing

Achieving high energy and power density Lithium-ion batteries (LIBs) with fast charging times is critical for enabling wide-spread adoption of electric vehicles. Conventional LIBs have planar electrodes that can be optimized for energy or power, but not both simultaneously. Three-dimensional (3D) electrodes such as those with line1,2 and grid3 patterns have demonstrated the ability to mitigate these performance trade-offs. These electrodes facilitate fast ion transport in thick electrodes, translating to faster charge times.3 However, scalable manufacturing methods for patterning 3D electrodes over large areas with small pore channels are needed. To meet this need, we leverage modeling and experiments to investigate the feasibility of using acoustic forces to fabricate line patterned electrodes. Acoustic focusing enables micron-scale control over particle placement in a fluid medium using acoustic standing waves; this has been shown to enable rapid assembly of particles, making it a promising process methodology for fabricating 3D electrodes.4 In this work, we expand a model5 that solves differential equations of acoustic forces to track particle trajectories. This model is used to capture the acoustic focusing behavior of LIB electrode materials to define how slurry viscosity, particle loading, and particle size can be modulated to achieve electrode geometries that optimize energy, power, and fast charging characteristics. Lithium Nickel Manganese Cobalt Oxide is selected as our electrode patterning material due to its relevance for electric vehicle applications. We compare our modeling results to experimental work to analyze battery material compatibility with acoustic focusing. References C. L. Cobb and S. E. Solberg, J. Electrochem. Soc., 164 (7), A1339-A1241 (2017).J. Park, S. Hyeon, S. Jeong, and H. Kim, J. Ind. Eng. Chem., 70, 178-185 (2019).K. Chen et al., J. Power Sources, 471, 228475 (2020).D. S. Melchert et al., Mater. Des., 202, 109512 (2021).R. R. Collino, T. R. Ray, L. M. Friedrich, J. D. Cornell, C. D. Meinhart and M. R. Begley, Mater. Res. Lett., 6, 191–198 (2018). Acknowledgements 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 Advanced Manufacturing Office (AMO) Award Number DE-EE0009112. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Effects of Processing Time, Mixing Speed, and Mixer on Agglomerates in Fuel Cell Cathode Inks

To prepare a catalyst ink, the large agglomerates of platinum on carbon (Pt/C) powder must be broken down into the primary aggregate particles. This physical process is necessary to form a homogenous mixture that produces uniform and defect-free coatings, as well as maximizing electrochemical performance. Large agglomerates of Pt/C catalyst can limit oxygen diffusion and reduce contact area between ionomer and active Pt area in polymer electrolyte membrane fuel cells (PEMFCs) and electrolyzer catalyst layers. Proper mixing of the catalyst ink before deposition is critical in breaking up these agglomerates, but excessive mixing wastes time and energy and, in some cases, may even damage the catalyst particles.1 There have been several studies of ultrasonication time and energy affecting cathode performance and agglomerate size.1–3 However, there has been considerably less work on mechanical mixing methods, which are more relevant for large-scale manufacturing.This work explores the impact of mixing time and speed on Pt/C agglomerate size using five different mechanical mixers including ball milling and rotor-stator mixers with distinct geometries. Optical micrograph analysis of these rod-coated catalyst layers reveals an exponential decay of particle agglomerates as a function of mixing time, eventually reaching a steady state where there is little to no change in the number of particles over 15 μm in diameter. For a given mixer geometry, mixing speed determines the lowest attainable particle size distribution with higher speeds leading to greater breakup of agglomerate particles (see Figure 1). Rheometry is utilized as a complementary technique to assess the degree of ink mixing completion. Continuous mixing renders higher ink shear viscosity values until plateauing at similar time intervals at which an unvarying particle size distribution is observed. In-situ electrochemical testing of these thin gas diffusion electrodes (GDEs) is employed to correlate the process-driven parameters that govern ink agglomerate size and rheology with fuel cell performance.This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE- AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) Advanced Manufacturing Office (AMO).This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Advanced Manufacturing Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.(1) Wang, M.; Park, J. H.; Kabir, S.; Neyerlin, K. C.; Kariuki, N. N.; Lv, H.; Stamenkovic, V. R.; Myers, D. J.; Ulsh, M.; Mauger, S. A. Impact of Catalyst Ink Dispersing Methodology on Fuel Cell Performance Using In-Situ X-Ray Scattering. ACS Appl. Energy Mater. 2019, 2 (9), 6417–6427. https://doi.org/10.1021/acsaem.9b01037.(2) Pollet, B. G. Let’s Not Ignore the Ultrasonic Effects on the Preparation of Fuel Cell Materials. Electrocatalysis 2014, 5 (4), 330–343. https://doi.org/10.1007/s12678-014-0211-4.(3) Pollet, B. G. The Use of Ultrasound for the Fabrication of Fuel Cell Materials. Int. J. Hydrog. Energy 2010, 35 (21), 11986–12004. https://doi.org/10.1016/j.ijhydene.2010.08.021.Caption: Figure 1. Plot of number of catalyst agglomerates particles with equivalent diameter larger than 15 µm as a function of rotor-stator rotational speed and time. Figure 1

Advanced Manufacturing Office Multi‐Topic Announcement (DOE)

Federal Grants & ContractsVolume 45, Issue 18 p. 4-5 Grants alerts Advanced Manufacturing Office Multi-Topic Announcement (DOE) First published: 16 August 2021 https://doi.org/10.1002/fgc.31896Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume45, Issue1819 August 2021Pages 4-5 RelatedInformation

(Invited) Layered Electrodes for Lithium-Ion Batteries

Development of lithium-ion batteries has dramatically boosted market adoption of electric vehicles. However, extending driving range is still necessary to further widespread adoption of lithium-ion batteries in electric vehicles, which relies on increased energy density. Increasing electrode areal loading is one effective approach to boost energy density as it reduces the weight fraction of current collectors and the volume fraction of separators, which do not contribute to battery capacity [1]. However, increased energy density in thick electrodes is usually achieved at the expense of power density mainly due to transport limitation of lithium ions through the porous electrodes. This results in electrolyte depletion and lower utilization of the electrodes [2].To tackle the sluggish mass transport rates, novel electrode architectures are required. There have been various methods for creating unique electrode architectures to reduce electrode tortuosity and facilitate lithium ion diffusion, including laser ablation, co-extrusion, advanced slot-die coating, and freeze tape casting [3-5]. In this presentation, we will discuss design of layered electrodes for superior energy and power performance. Results from both experiment and simulation are included where effect of particle size of active materials, thickness ratio between layers and electrode porosity in each electrode layer were explored. It is demonstrated that the appropriate layered structure can more than double the power density compared to a traditional one. Acknowledgment This research at Oak Ridge National Laboratory (ORNL), managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) Advanced Manufacturing Office (AMO).

Rapid in Situ Detection of Ammonia with Surface Enhanced Raman Spectroscopy

Rapid and reliable ammonia detection is of great significance to environmental monitoring and heterogeneous electrocatalysis, wherein ammonia serves as a product or reaction intermediate. Non-perturbative and sensitive or even in operando ammonia detection is of particular interest to the rapidly booming field of the electrochemical nitrogen reduction reaction for ambient and distributed ammonia synthesis.1 Various ex-situ analytical methods have been applied or recently developed, including colorimetric methods, nuclear magnetic resonance (NMR) and liquid chromatography − mass spectrometry (LC-MS).2–5 In this talk, we will present a novel approach to ammonia detection, with the aid of surface enhanced Raman scattering (SERS).6 This is a simple, fast and sensitive method that provides chemical selectivity to ammonia. In addition, there is no need for a complex sensor design, specific beam path geometry, or chemical modifications of the solution. The method features a detection of sub-1 ppm ammonia concentrations in less than 1 second, which paves the way to ultrasensitive in operando electrochemical experiments in the conventional H-cell or other assemblies. Considering the short spatial reach of plasmonic enhancement, the observed signals correspond to approximately 104–105 molecules detected locally at the region of interest. Moreover, the concept of SERS detection does not enforce any limitations on the identity or morphology of the electrode so long as it can be placed close enough to the SERS substrate. Then, the SERS substrate can be easily engineered according to specific experimental constraints to probe the ammonia near the electrode surface. This enables the possible detection of local ammonia in closest proximity to the reaction site. Acknowledgement We gratefully acknowledge the support from DOE-EERE Advanced Manufacturing Office award via Sandia National Laboratories (AOP 34920). We would also like to acknowledge the NSF grant CHE-0960179 and the UNM Center for Advanced Research Computing for computational resources. Reference J. G. Chen et al., Science, 360, eaar6611 (2018)S. Z. Andersen et al., Nature, 570, 504–508 (2019)R. Y. Hodgetts et al., ACS Energy Lett., 736–741 (2020)A. C. Nielander et al., ACS Catal., 9, 5797–5802 (2019)W. Yu, N. S. Lewis, H. B. Gray, and N. F. Dalleska, ACS Energy Lett., 1532–1536 (2020)Y. Liu et al., iScience, 23, 101757 (2020) https://doi.org/10.1016/j.isci.2020.101757. Figure 1

Solidification dynamics in metal additive manufacturing: analysis of model assumptions * *This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. Research was co-sponsored the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office and the Office of Electricity Delivery and Energy Reliability (OE)—Transformer Resilience and Advanced

Solidification characteristics in the meltpool drive the process-microstructure relationship which helps dictate the material properties of as-built parts in additive manufacturing; therefore, being able to accurately and quickly simulate the size, shape, and solidification characteristics in the melt pool is of great interest to the field. This study investigates various important physical phenomena (dynamic material properties, fluid-flow, radiation and vaporization) which can either be included or neglected in a continuum finite volume model (FVM) and their effect on the solidification conditions. Additionally, since the simplest form of such a model (conduction only) has an analytic solution which is much faster, its viability is also considered. Since the inclusion of some of these physical phenomena will inherently change the net energy input as well as the amount of energy needed to achieve melting of a control volume, each set of included phenomena had an effective absorption efficiency which was calibrated to closely match the dimensions of the melt pool to that of the ground truth data. The ground truth data for this study was defined to be the output of the FVM which included all the physical phenomena (OF). This study then goes on to compare the effects on solidification conditions each of these calibrated models has. It was found that most of the change in solidification conditions comes from the inclusion of latent heat. A posterior correlation factor (PCF) is then introduced to enable an analytic model to predict similar solidification conditions to OF model.

Rapid Non-Destructive Wafer Detection and Tracking of Defects in Bulk and Epitaxially Grown Gallium Nitride

Defects in bulk semiconductor crystals are especially damaging to devices, producing catastrophic electrical and optical failures or even limiting lifetime performance and reliability, while driving materials growth costs. New methods for rapid and non-destructive characterization of materials are needed to help overcome limitations in fabrication throughput and application reliability of wide-bandgap power electronics substrates, especially in the development of emerging bulk Gallium Nitride (GaN). Rapid materials characterization methods will help inform the fabrication process parameters impact on materials defects formation, while speeding-up materials development and, ultimately, the deployment of low defect commercially viable and reliable bulk GaN substrates. Here we present an approach for multi-modal defect non-destructive imaging of device-relevant GaN defects with high resolution and high sensitivity. The scanning GaN defects detection system is based on laser pump-and-probe photoluminescence and photothermal measurements that are compared to diode device reliability data from accelerated lifetime testing. We determine that defects detected at optical frequencies reliably predict lifetime performance issues of power electronic devices operating at near DC frequencies[1, 2]. Bulk and epi grown GaN wafer imaging data and test platform device data are correlated to help validate the proposed multi-modal defect detection approach for the reliable detection of defects relevant to the performance of GaN power electronic devices.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. 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 Advanced Manufacturing Office, FY18/FY19 Lab Call. J. H. Yoo, A. Lange, J. Chesser, S. Falabella, and S. Elhadj, "A Survey of Transparent Conducting Films and Optoelectrical Materials for High Optical Power Applications," Physica Status Solidi a-Applications and Materials Science 216, (2019).J.-H. Yoo, S. Rafique, A. Lange, H. Zhao, and S. Elhadj, "Lifetime laser damage performance of β-Ga2O3 for high power applications," APL Materials 6, 036105 (2018). Figure 1

Influence of Ink Formulation and Drying Conditions on Ionomer Distribution in High-Performance Roll-to-Roll-Coated Gas-Diffusion Electrodes

To enable mass production of fuel cell membrane electrode assemblies (MEAs) catalyst layers production will require continuous roll-to-roll (R2R) coating processes.1 Gas diffusion electrodes (GDEs) are advantageous for mass production because the catalyst layer can be directely coated on the microporous layer of the gas diffusion media without the need for a decal-transfer process. It is known that the water-to-alcohol ratio in the catalyst ink influences the interactions of the ionomer with the catalyst leading to different distributions of ionomer in spray-coated catalyst layers.2 It is also known that during drying of colloidal mixtures, like fuel cell inks, factors such as drying rate, particle size, and agglomeration influence how the materials distribute themselves throughout the thickness of the dired film.3,4 Thusfar there have only been limited studies to understand how process conditions such as ink formulation and drying temperature influence the distribution of ionomer and catalyst coated using scalable methods.5 This understanding is especially important for GDEs since it is known that having a sufficient amount of ionomer at the catalyst layer-membrane interface is critical for high performance.6 In this study we have focuse on determining how the ratio of water to 1-propanol in the catalyst ink ink and drying temperature influence the distribution of ionomer throughout the thickness of the catalyst layer. Using a combination of Kelvin probe and x-ray photoelectron spectroscopy we show that an ionomer-rich surface is promoted by a higher drying rate and a water-rich catalyst ink. In contrast, a 1-propanol catalyst ink leads to a lower concentration of ionomer on the top surface. Using x-ray computed tomography, we are able to characterize the ionomer distribution throughout the thickness of the layer. We find that, in addition to promoting an ionomer-rich top surface, water-rich inks lead to a more homogenous distribution of ionomer, whereas a 1-propanol-rich ink leads to a more irregular distribution. It is found that MEA performance is improved by selecting conditions and ink formulations that promote ionomer enrichment at the top surface to facilitate a good interface with the membrane. MEAs prepared with a 75 wt% water catalyst ink with a 0.9 I/C have equivalent performance to spray-coated GDEs. Critically, these R2R-coated GDEs do not need an additional ionomer overlayer like the spray-coated GDEs do, reducing the number of processing steps in a manufacturing setting. This work shows that with the appropriate selection of materials, ink formulation, and processing conditions gas-diffusion electrodes are a viable pathway for fuel cell manufacturing.This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. The submitted manuscript was created, in part, by UChicago Argonne, LLC, Operator of Argonne National Laboratory, Argonne, U.S. Department of Energy Office of Science laboratory, operated under Contract No. DE-AC02- 06CH11357. This research used the resources of the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility, operated for the DOE Office of Science by Argonne National Laboratory, also under Contract No. DE-AC02-06CH11357. Funding provided by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office and Advanced Manufacturing Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. Debe, M. K. Electrocatalyst approaches and challenges for automotive fuel cells. Nature 486, 43–51 (2012).Van Cleve, T. et al. Dictating Pt-based Electrocatalyst Performance in Polymer Electrolyte Fuel Cells; from Formulation to Application. ACS Appl. Mater. Interfaces 11, 46953–46964 (2019).Makepeace, D. K. et al. Stratification in binary colloidal polymer films: experiment and simulations. Soft Matter 13, 6969–6980 (2017).Cardinal, C. M., Jung, Y. D., Ahn, K. H. & Francis, L. F. Drying regime maps for particulate coatings. AIChE J. 56, 2769–2780 (2010).Orfanidi, A., Rheinländer, P. J., Schulte, N. & Gasteiger, H. A. Ink Solvent Dependence of the Ionomer Distribution in the Catalyst Layer of a PEMFC. Journal of the Electrochemical Society 165, F1254–F1263 (2018).Mauger, S. A. et al. Fabrication of High Performance Gas-Diffusion-Electrode Based Membrane-Electrode Assemblies. J Power Sources 450, 227581 (2020).

(Invited) MOCVD GaN-on-GaN Towards Vertical Power Devices & MOCVD Development of β-Ga2O3

Gallium nitride (GaN) has been considered as a promising candidate for power device applications due to the wide band gap (3.4 eV), high critical electric field (3 MV/cm) and high electron mobility (>1000 cm2/Vs). Baliga’s figure of merit (BFOM) of GaN is more than 500 times higher than silicon (Si) and more than three time higher than silicon carbide (SiC). Due to the availability of native GaN substrates, it is feasible to develop high performance GaN vertical power devices on low-defect GaN substrate. GaN-on-GaN vertical PN diode with record high VBR ~5 KV was reported [1], presenting the potential of GaN as a high-performance material for power devices. Compared with SiC, the performance of GaN vertical PN diodes is still limited by its high background doping in n-type drift layer at mid-1015 to low-1016 cm-3 range. Therefore, it is of great importance to study the sources and incorporation mechanisms of unintentionally doped background impurities in metal-organic chemical vapor deposition (MOCVD) GaN growth, to control the impurity incorporation, in order to maximize device performance for GaN based vertical power devices. This talk will discuss the dependence of MOCVD growth conditions on the impurity incorporations such as C, Si, O, H, and Fe. Quantitative SIMS and CV measurements are used for material characterization.Ultrawide bandgap (UWBG) gallium oxide (Ga2O3) with a band gap of 4.5-4.9 eV, represents an emerging semiconductor material with excellent chemical and thermal stability. The monoclinic β-phase Ga2O3 represents the thermodynamically stable crystal among the known five known phases (α, β, γ, d , ε). The breakdown field of β-Ga2O3 is estimated to be 6-8 MV/cm. These unique properties make β-Ga2O3 a promising candidate for high power electronic device and solar blind photodetector applications. Single crystal β-Ga2O3 substrates can be synthesized by scalable and low cost melting based growth techniques. MOCVD growth technique was used to develop high quality β-Ga2O3 thin films and its ternary alloy (AlxGa1-x)2O3. Control of background and n-type doping in β-Ga2O3 will be discussed. Record carrier mobilities of 194 cm2/V·s at room temperature and ~10,000 cm2/V·s at low temperature were measured for MOCVD β-Ga2O3 thin films [2]. MOCVD growth of β-AlGaO targeting for Al composition of > 40% will be discussed [3, 4]. Acknowledgement: The authors acknowledge the funding support from Advanced Research Projects Agency-Energy (ARPA-E) DE-AR0001036, U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Advanced Manufacturing Office, FY18/FY19 Lab Call, the Air Force Office of Scientific Research FA9550-18-1-0479 (AFOSR, Dr. Ali Sayir) and the National Science Foundation (1810041, 1755479). [1] H. Ohta, N. Asai, F. Horikiri, Y. Narita, T. Yoshida, and T. Mishima, Jpn. J. Appl. Phys. 58, SCCD03 (2019).[2] Z. Feng, A F M A. U. Bhuiyan, M. R. Karim, H. Zhao, Appl. Phys. Letts., 114, 250601, 2019.[3] A F M A. U. Bhuiyan, Z. Feng, J. M. Johnson, Z. Chen, H. -L. Huang, J. Hwang, H. Zhao, Appl. Phys. Lett., 115, 120602, 2019.[4] A F M A. U. Bhuiyan, Z. Feng, J. M. Johnson, H.-L. Huang, J. Sarker, M. Zhu, M. R. Karim, B. Mazumder, J. Hwang, and H. Zhao, APL Materials, 8, 031104, 2020.

Scale-up of Metal-Supported Solid Oxide Fuel Cells

Metal-supported solid oxide fuel cells (MS-SOFC) offer the advantages of low-cost structural materials (e.g. stainless steel), mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability. Because of rapid-start capability, MS-SOFCs may be well-suited for portable, ruggedized, fast-start, intermittent-fuel, transportation, or other unique and innovative applications. The LBNL approach focuses on symmetric-architectured, co-sintered, ScSZ-based MS-SOFCs with porous metal supports on both anode and cathode sides, and catalysts deposited into both electrodes via infiltration (Fig 1). These features provide for a mechanically rugged cell that can be processed with low-cost scalable techniques, and for high surface-area catalysts that are deposited after sintering, thereby avoiding interdiffusion or coarsening during cell sintering.LBNL’s previous work on MS-SOFCs includes demonstration of A) Over 1000h operation in both hydrogen fuel cell and steam electrolysis modes [1,2], B) stable operation with direct internal reforming of ethanol-water blend fuel [3], C) startup within 10 sec for a bare cell and more than 200 rapid thermal cycles for a cell mounted on a test rig manifold [1,4], D) dynamic load-following with operating temperature fluctuating rapidly under load [5], and E) tolerance to multiple deep redox cycles [1].Previous demonstrations were achieved with button cells in the range 3 to 7 cm2 total cell area. In this work, the MS-SOFC cell area is scaled up to 50 cm2 and higher, Fig 2. Scale-up of the stainless steel and zirconia cell architecture is straightforward. The cell structure is prepared by tapecasting large sheets and laser cutting to size, which is amenable to making any size or shape cell. Due to the symmetric nature of the cell architecture, the large cells remain flat after sintering.Uniform catalyst deposition over a large area is, however, challenging. A number of improvements to the infiltration technique were developed, including: pre-oxidation of the stainless steel to enhance wetting of the aqueous catalyst precursor solution into the porous cell surface; development of highly concentrated Pr-oxide and Ni/doped-ceria precursor solutions that are shelf stable and low-viscosity; and, aerosol spray deposition of those solutions to uniformly coat the entire cell. With the improved infiltration, nearly identical performance for button and large cells is achieved. Spray deposition of shelf-stable aqueous solutions is also anticipated to be much more relevant to industrial-scale cell manufacturing, relative to LBNL’s previous molten salt infiltration technique.AcknowledgementsThe information, data, or work presented herein was funded in part by the Advanced Research Projects Agency – Energy (ARPA-E), U.S. Department of Energy under work authorization numbers 13/CJ000/04/03 and 18/CJ000/04/01. Funding for this work was provided by LBNL and the U.S. Department of Energy Advanced Manufacturing Office through a Technology Commercialization Fund grant number TCF-18-15740. This work was funded in part by the U.S. Department of Energy under contract no. DE-AC02-05CH11231.References Tucker, M.C., J. Power Sources 369 (2017) 6-12Shen, F., R. Wang, and M.C. Tucker, in preparationDogdibegovic, E., Y. Fukuyama, M.C.Tucker, Journal of Power Sources, 449 (2020) 227598Tucker, M.C., and A.S. Ying, International Journal of Hydrogen Energy, 38 (2017) 24426-24434Tucker, M.C., J. Power Sources, 395 (2018) 314-317 Figure 1

(Invited) Point Defects and Doping in Ga2O3 and Related Alloys

Ga2O3 and related alloys are a promising platform for realizing wide-band gap semiconductors for use in a number of next-generation electronic devices exploiting their large band gaps and controllable electrical conductivity. Ga2O3 exhibits a band gap (4.8 eV) that can be tuned by In and Al incorporation, with Al-containing alloys increasing the band gap in contrast to In incorporation. While control over defect concentrations and n-type doping of Ga2O3 is rapidly improving, the dopability of alloys has remained largely unexplored. Here we describe the behavior of point defects and n-type dopants in Ga2O3 and consider the prospects of doping in the larger-gap Al-containing alloys using first-principles modelling approaches based on hybrid functional calculations. We consider a number of conventional dopants such as Si, Ge and Sn, as well as newer dopants that have been identified as effective alternatives. These results provide guidance for doping in Ga2O3 and related alloys incorporated into heterostructure devices.This work was partially performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and partially supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.

In Situ X-Ray Scattering Characterization of PEMFC Catalyst Ink Microstructure during Ink Processing

Catalyst layers for proton exchange membrane fuel cells (PEMFCs) are typically prepared by first dispersing a catalyst powder, comprised of platinum or platinum alloy nanoparticles supported on carbon blacks, with ionomer in solvent followed by extensive mixing using a variety of methods. The purpose of the ink mixing and processing procedure it to break up large agglomerates of the catalyzed carbon powder (>10 µm) and form a uniform dispersion, However, care must be taken to limit damage to the catalyst particles. Following the dispersing process, the catalyst ink is applied to the surface of the substrate (membrane, diffusion media, or transfer liner) through a variety of coating processes (painting, spraying, screen printing, etc.) [1]. In addition to creating coating defects, large agglomerates resulting from inadequate ink processing can limit catalyst utilization, inhibit mass transport in the catalyst layer, and damage the membrane and possibly also the gas diffusion layer. This can lower beginning-of-life performance by creating transport barriers for oxygen, hydrogen, and protons, and can increase membrane pinhole formation and electrical shorts, thus limiting the cell lifetime. This presentation will describe ink compositions and processing techniques for efficient coating of catalyst layers while optimizing cell performance and lifetime and minimizing ink processing time and cost [2, 3]. Ultra-small angle X-ray scattering (USAXS) was used to measure the agglomerate size distribution during ink mixing/processing. The experimental setup for the USAXS evaluation of inks during sonication is shown in Figure 1. A flask containing catalyst ink was immersed in an ice bath and sonicated using a water bath and/or a horn sonicator and pumped through a thin-walled capillary tube situated in the X-ray beam using a peristaltic pump. The effects of catalyst ink composition and processing variables on catalyst agglomerate size and ink properties were evaluated using different solvents, ionomer-carbon ratios, support types, and sonication time. The proper ink composition and sonication method that facilitate the break-up of carbon agglomerates with the minimum amount of time were determined. The electrochemically-active surface areas of the catalyst after the ink processing were determined using aqueous electrochemical methods to determine the extent of damage to the catalyst after processing (e.g., dislodging of catalyst particles from the support). The correlation of ink processing conditions and agglomerate structure with fuel cell performance will also be described. Acknowledgements This work was supported by the U.S. Department of Energy (DOE), Energy Efficiency&Renewable Energy, Advanced Manufacturing Office, Roll-to-Roll Advanced Materials Manufacturing DOE Laboratory Consortium. This research used the resources of the Advanced Photon Source (APS), a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.