Understanding inks for porous-electrode formation

Abstract

Scalable manufacturing of high-aspect-ratio multi-material electrodes are important for advanced energy storage and conversion systems. There is a need to understand how one goes from a colloidal state through processing to a functional porous electrode. Such knowledge enables ink-engineering for electrode performance and durability optimization.

Linking Perfluorosulfonic Acid Ionomer Chemistry and High-Current Density Performance in Fuel-Cell Electrodes

“…However, the deviation from the linear trend of R WE in Figure starts at different I/C ratios for the three ionomers, demonstrating that the observed nonlinear behavior is not solely a function of ionomer mass content. To explain this, we examine the ink pH and agglomerate size following the work of Berlinger et al ,, Replotting the R WE data as a function of the sulfonate–anion concentration per gram of carbon collapses the curves in Figure such that their nonlinear rises coincide at the sulfonate–anion loading of 0.75 mmol/g carbon (see Figure ), which confirms the role of sulfonate–anion or proton–species interactions.…”

“…Within inks, electrostatic and nonelectrostatic specific interactions between the ionomer and the solvent, the ionomer and the particle, and the solvent and the particle govern the aggregation behavior and ionomer morphology, which in turn control the electrode structure. 42,55,56 In this study, all parameters except for the ionomer content are maintained constant, suggesting that electrode structural changes can be attributed to the ionomer. However, the deviation from the linear trend of R WE in Figure 6 starts at different I/C ratios for the three ionomers, demonstrating that the observed nonlinear behavior is not solely a function of ionomer mass content.…”

“…, water/nPA mixture as used in this study), and carbon-supported catalyst nanoparticles. Within inks, electrostatic and non-electrostatic specific interactions between the ionomer and the solvent, the ionomer and the particle, and the solvent and the particle govern the aggregation behavior and ionomer morphology, which in turn control the electrode structure. ,, …”

Linking Perfluorosulfonic Acid Ionomer Chemistry and High-Current Density Performance in Fuel-Cell Electrodes

“…However, the deviation from the linear trend of R WE in Figure starts at different I/C ratios for the three ionomers, demonstrating that the observed nonlinear behavior is not solely a function of ionomer mass content. To explain this, we examine the ink pH and agglomerate size following the work of Berlinger et al ,, Replotting the R WE data as a function of the sulfonate–anion concentration per gram of carbon collapses the curves in Figure such that their nonlinear rises coincide at the sulfonate–anion loading of 0.75 mmol/g carbon (see Figure ), which confirms the role of sulfonate–anion or proton–species interactions.…”

“…Within inks, electrostatic and nonelectrostatic specific interactions between the ionomer and the solvent, the ionomer and the particle, and the solvent and the particle govern the aggregation behavior and ionomer morphology, which in turn control the electrode structure. 42,55,56 In this study, all parameters except for the ionomer content are maintained constant, suggesting that electrode structural changes can be attributed to the ionomer. However, the deviation from the linear trend of R WE in Figure 6 starts at different I/C ratios for the three ionomers, demonstrating that the observed nonlinear behavior is not solely a function of ionomer mass content.…”

“…, water/nPA mixture as used in this study), and carbon-supported catalyst nanoparticles. Within inks, electrostatic and non-electrostatic specific interactions between the ionomer and the solvent, the ionomer and the particle, and the solvent and the particle govern the aggregation behavior and ionomer morphology, which in turn control the electrode structure. ,, …”

Nanoscale Mapping of Extrinsic Interfaces in Hybrid Solid Electrolytes

“…However, LLZO tends to aggregate during the processing step. The shear rates experienced during tape casting (10-100 s À1 ) 52 are not sufficient to completely break the internal structure (Figure S1B), resulting in a heterogeneous distribution of aggregated LLZO particles within the hybrid electrolytes. To further probe the origins of property heterogeneity in hybrid electrolytes, we used synchrotron X-ray nano-tomography.…”

Inherent Acidity of Perfluorosulfonic Acid Ionomer Dispersions and Implications for Ink Aggregation

“…The measured pH of PFSA dispersions diluted to different concentrations in solvents containing 90, 70, 50, and 30% water (balance n PA) is plotted in Figure . Each solvent ratio shows a linear dependence of pH on Nafion concentration, where the Nafion loadings are chosen to represent those occurring in different CL fabrication processes . Furthermore, water-rich dispersions exhibit more acidic behavior, whereas n PA-rich dispersions are less acidic.…”

Linking Perfluorosulfonic Acid Ionomer Chemistry and High-Current Density Performance in Fuel-Cell Electrodes

“…However, the deviation from the linear trend of R WE in Figure starts at different I/C ratios for the three ionomers, demonstrating that the observed nonlinear behavior is not solely a function of ionomer mass content. To explain this, we examine the ink pH and agglomerate size following the work of Berlinger et al ,, Replotting the R WE data as a function of the sulfonate–anion concentration per gram of carbon collapses the curves in Figure such that their nonlinear rises coincide at the sulfonate–anion loading of 0.75 mmol/g carbon (see Figure ), which confirms the role of sulfonate–anion or proton–species interactions.…”

“…Within inks, electrostatic and nonelectrostatic specific interactions between the ionomer and the solvent, the ionomer and the particle, and the solvent and the particle govern the aggregation behavior and ionomer morphology, which in turn control the electrode structure. 42,55,56 In this study, all parameters except for the ionomer content are maintained constant, suggesting that electrode structural changes can be attributed to the ionomer. However, the deviation from the linear trend of R WE in Figure 6 starts at different I/C ratios for the three ionomers, demonstrating that the observed nonlinear behavior is not solely a function of ionomer mass content.…”

“…, water/nPA mixture as used in this study), and carbon-supported catalyst nanoparticles. Within inks, electrostatic and non-electrostatic specific interactions between the ionomer and the solvent, the ionomer and the particle, and the solvent and the particle govern the aggregation behavior and ionomer morphology, which in turn control the electrode structure. ,, …”

Nanoscale Mapping of Extrinsic Interfaces in Hybrid Solid Electrolytes

“…However, LLZO tends to aggregate during the processing step. The shear rates experienced during tape casting (10-100 s À1 ) 52 are not sufficient to completely break the internal structure (Figure S1B), resulting in a heterogeneous distribution of aggregated LLZO particles within the hybrid electrolytes. To further probe the origins of property heterogeneity in hybrid electrolytes, we used synchrotron X-ray nano-tomography.…”

Inherent Acidity of Perfluorosulfonic Acid Ionomer Dispersions and Implications for Ink Aggregation

“…The measured pH of PFSA dispersions diluted to different concentrations in solvents containing 90, 70, 50, and 30% water (balance n PA) is plotted in Figure . Each solvent ratio shows a linear dependence of pH on Nafion concentration, where the Nafion loadings are chosen to represent those occurring in different CL fabrication processes . Furthermore, water-rich dispersions exhibit more acidic behavior, whereas n PA-rich dispersions are less acidic.…”

Linking Perfluorosulfonic Acid Ionomer Chemistry and High-Current Density Performance in Fuel-Cell Electrodes

“…However, the deviation from the linear trend of R WE in Figure starts at different I/C ratios for the three ionomers, demonstrating that the observed nonlinear behavior is not solely a function of ionomer mass content. To explain this, we examine the ink pH and agglomerate size following the work of Berlinger et al ,, Replotting the R WE data as a function of the sulfonate–anion concentration per gram of carbon collapses the curves in Figure such that their nonlinear rises coincide at the sulfonate–anion loading of 0.75 mmol/g carbon (see Figure ), which confirms the role of sulfonate–anion or proton–species interactions.…”

“…Within inks, electrostatic and nonelectrostatic specific interactions between the ionomer and the solvent, the ionomer and the particle, and the solvent and the particle govern the aggregation behavior and ionomer morphology, which in turn control the electrode structure. 42,55,56 In this study, all parameters except for the ionomer content are maintained constant, suggesting that electrode structural changes can be attributed to the ionomer. However, the deviation from the linear trend of R WE in Figure 6 starts at different I/C ratios for the three ionomers, demonstrating that the observed nonlinear behavior is not solely a function of ionomer mass content.…”

“…, water/nPA mixture as used in this study), and carbon-supported catalyst nanoparticles. Within inks, electrostatic and non-electrostatic specific interactions between the ionomer and the solvent, the ionomer and the particle, and the solvent and the particle govern the aggregation behavior and ionomer morphology, which in turn control the electrode structure. ,, …”

Nanoscale Mapping of Extrinsic Interfaces in Hybrid Solid Electrolytes

“…However, LLZO tends to aggregate during the processing step. The shear rates experienced during tape casting (10-100 s À1 ) 52 are not sufficient to completely break the internal structure (Figure S1B), resulting in a heterogeneous distribution of aggregated LLZO particles within the hybrid electrolytes. To further probe the origins of property heterogeneity in hybrid electrolytes, we used synchrotron X-ray nano-tomography.…”

Inherent Acidity of Perfluorosulfonic Acid Ionomer Dispersions and Implications for Ink Aggregation

“…The measured pH of PFSA dispersions diluted to different concentrations in solvents containing 90, 70, 50, and 30% water (balance n PA) is plotted in Figure . Each solvent ratio shows a linear dependence of pH on Nafion concentration, where the Nafion loadings are chosen to represent those occurring in different CL fabrication processes . Furthermore, water-rich dispersions exhibit more acidic behavior, whereas n PA-rich dispersions are less acidic.…”