Browsing by Author "Stadie, Nicholas P."

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Atomistic Structures of Zeolite-Templated Carbon
(American Chemical Society, 2020-03) Taylor, Erin K.; Garman, Kaitlin; Stadie, Nicholas P.
Zeolite-templated carbons (ZTCs) are a distinct class of porous framework materials in which a three-dimensional network of pores is contained between atomically thin, polycyclic hydrocarbon walls, synthesized by carbonization within a zeolite template. This class of materials arose from the goal to develop carbon-based frameworks with ordered, homogeneous microporosity (as opposed to activated carbons where the pore network is random). It has more recently been suggested that zeolite-templating may be a viable synthetic route to carbon schwarzites, an elusive class of theoretical materials with a triply periodic minimal surface and many fundamentally interesting properties. In this review, we survey the currently proposed atomistic models of ZTCs, compare them to experimental properties of ZTCs, and emphasize the significant differences that remain between actual ZTCs prepared in the laboratory and the still elusive schwarzites.
Biochar as a Renewable Substitute for Carbon Black in Lithium-Ion Battery Electrodes
(American Chemical Society, 2022-09) Kane, Seth; Storer, Aksiin; Xu, Wei; Ryan, Cecily; Stadie, Nicholas P.
Lignin-derived biochar was prepared and characterized towards potential applications as a conductive electrode additive and active lithium host material within lithium-ion batteries (LIBs). This biochar was specifically selected for its high electrical conductivity, which is comparable to that of common conductive carbon black standards (e.g., Super P). Owing to its high electrical conductivity, this biochar serves as an effective conductive additive within electrodes comprised of graphite as the active material, demonstrating slightly improved cell efficiency and rate capability over electrodes using carbon black as the additive. Despite its effectiveness as a conductive additive in LIB anodes, preliminary results show that the biochar developed in this work is not suitable as a direct replacement for carbon black as a conductive additive in LiFePO4 (LFP) cathodes. This latter insufficiency may be due to differences in particle 2 geometry between biochar and carbon black; further optimization is necessary to permit the application of biochar as a general-purpose conductive additive in LIBs. Nevertheless, these investigations combined with an assessment of greenhouse gas emissions from biochar production show that replacing carbon black with biochar can be an effective method to improve the sustainability of LIBs.
Biochar as a Renewable Substitute for Carbon Black in Lithium-Ion Battery Electrodes
(American Chemical Society, 2022-09) Kane, Seth; Storer, Aksiin; Xu, Wei; Ryan, Cecily; Stadie, Nicholas P.
Lignin-derived biochar was prepared and characterized toward potential applications as a conductive electrode additive and active lithium host material within lithium-ion batteries (LIBs). This biochar was specifically selected for its high electrical conductivity, which is comparable to that of common conductive carbon black standards (e.g., Super P). Owing to its high electrical conductivity, this biochar serves as an effective conductive additive within electrodes comprising graphite as the active material, demonstrating slightly improved cell efficiency and rate capability over those of electrodes using carbon black as the additive. Despite its effectiveness as a conductive additive in LIB anodes, preliminary results show that the biochar developed in this work is not suitable as a direct replacement for carbon black as a conductive additive in LiFePO4 cathodes. This latter insufficiency may be due to differences in particle geometry between biochar and carbon black; further optimization is necessary to permit the application of biochar as a general-purpose conductive additive in LIBs. Nevertheless, these investigations combined with an assessment of greenhouse gas emissions from biochar production show that replacing carbon black with biochar can be an effective method to improve the sustainability of LIBs.
Bulk Phosphorus-Doped Graphitic Carbon
(2018-07) Billeter, Emanuel; McGlamery, Devin; Aebli, Marcel; Piveteau, Laura; Kovalenko, Maksym V.; Stadie, Nicholas P.
A direct synthetic route to a tunable range of phosphorus-doped graphitic carbon materials is demonstrated via the reaction of benzene and phosphorus trichloride in a closed reactor at elevated temperatures (800-1050 degrees C). Graphitic materials of continuously variable composition PC,, up to a limit of approximately x = 5 are accessible, where phosphorus is incorporated both substitutionally within the graphite lattice and as stabilized P-4 molecules. Higher temperatures result in a more ordered graphitic lattice, while the maximum phosphorus content is not observed to diminish. Lower temperatures and higher initial phosphorus content in the reaction mixture are shown to correlate with higher structural disorder. Phosphorus incorporation within directly synthesized PC, as both a substitutional dopant and in the form of interstitial, stabilized molecular P-4,d is demonstrated to occur with little oxygen contamination in the bulk (<4 atom %), motivating promising future applications in fuel cells and alkali metal-ion batteries.
Divergent Electrically Conductive Pathways in Yttrium-Based 2- and 3-Dimensional Metal–Organic Frameworks
(American Chemical Society, 2024-07) Welty, Connor; Gormley, Eoghan L.; Oppenheim, Julius J.; Dincă, Mircea; Hendon, Christopher H.; Stadie, Nicholas P.
Despite most porous framework solids exhibiting insulating character, some are known to conduct electrical charge. The peak performing conductive metal–organic frameworks are composed of redox-active hexasubstituted triphenylene linkers, but the impact of redox activity on material conductivity remains enigmatic because of limited availability of direct structure–function relationships. Here, we report a hexagonal yttrium-based conductive porous scaffold, comprising hexahydroxytriphenylene connected by Y-chains (YHOTP). In comparison to its known porous cubic counterpart (Y6HOTP2), this material features a 1000-fold increase in peak conductivity in polycrystalline samples (∼10–1 S cm–1). Furthermore, through a comparison of their electronic structures, we rationalize the origin of this difference and highlight the role of charge carrier concentration in dictating bulk electrical conductivity. Together, this work provides a design principle for the development of next-generation conductive porous frameworks.
Does boron or nitrogen substitution affect hydrogen physisorption on open carbon surfaces?
(Royal Society of Chemistry, 2022-01) Rowsey, Rylan; Taylor, Erin E.; Hinson, Ryan W.; Compton, Dalton; Stadie, Nicholas P.; Szilagyi
Incorporation of heteroatoms in carbon materials is commonly expected to influence their physical or chemical properties. However, contrary to previous results for methane adsorption, no technologically significant effect was identified for the hydrogen physisorption energies (measured 4.1–4.6 kJ mol−1 and calculated qst = −ΔHads = 4.1 ± 0.7 kJ mol−1 using a comprehensive set of levels of theory) as a function of B- and N-substitution of a mid-plane C-site on open carbon surfaces.
Exploring the Limits of the Rapid-Charging Performance of Graphite as the Anode in Lithium-Ion Batteries
(The Electrochemical Society, 2022-01) Xu, Wei; Welty, Connor; Peterson, Margaret R.; Read, Jeffrey A.; Stadie, Nicholas P.
Graphite is, in principle, applicable as a high-power anode in lithium-ion batteries (LIBs) given its high intralayer lithium diffusivity at room temperature. However, such cells are known to exhibit poor capacity retention and/or undergo irreversible side reactions including lithium plating when charged at current rates above ∼2 C (∼740 mA g−1). To explore the inherent materials properties that limit graphite anodes in rapid-charge applications, a series of full-cells consisting of graphite as the anode and a standard Li[Ni0.8Mn0.1Co0.1]O2 (NMC811) cathode was investigated. Instead of a conventional cathode-limited cell design, an anode-limited approach was used in this work to ensure that the overall cell capacity is only determined by the graphite electrode of interest. The optimized N:P capacity ratio was determined as N/P = 0.67, enabling stable cycling across a wide range of charging rates (4–20 C) without inhibition by the NMC811 cathode. The results show that unmodified, highly crystalline graphite can be an excellent anode for rapid-charge applications at up to 8 C, even with a standard electrolyte and NMC811 cathode and in cells with 1.0 mAh cm−2 loadings. As a rule, capacity and specific energy are inversely proportional to crystallite size at high rates; performance can likely be improved by electrolyte/cathode tuning.
Hydrogen Adsorption in Ultramicroporous Metal–Organic Frameworks Featuring Silent Open Metal Sites
(American Chemical Society, 2023-11) Chiu, Nan Chieh; Compton, Dalton; Gładysiak, Andrzej; Simrod, Scott; Khivantsev, Konstantin; Woo, Tom K.; Stadie, Nicholas P.; Stylianou, Kyriakos C.
In this study, we utilized an ultramicroporous metal–organic framework (MOF) named [Ni3(pzdc)2(ade)2(H2O)4]·2.18H2O (where H3pzdc represents pyrazole-3,5-dicarboxylic acid and ade represents adenine) for hydrogen (H2) adsorption. Upon activation, [Ni3(pzdc)2(ade)2] was obtained, and in situ carbon monoxide loading by transmission infrared spectroscopy revealed the generation of open Ni(II) sites. The MOF displayed a Brunauer–Emmett–Teller (BET) surface area of 160 m2/g and a pore size of 0.67 nm. Hydrogen adsorption measurements conducted on this MOF at 77 K showed a steep increase in uptake (up to 1.93 mmol/g at 0.04 bar) at low pressure, reaching a H2 uptake saturation at 2.11 mmol/g at ∼0.15 bar. The affinity of this MOF for H2 was determined to be 9.7 ± 1.0 kJ/mol. In situ H2 loading experiments supported by molecular simulations confirmed that H2 does not bind to the open Ni(II) sites of [Ni3(pzdc)2(ade)2], and the high affinity of the MOF for H2 is attributed to the interplay of pore size, shape, and functionality.
Hydrogen-Type Binding Sites in Carbonaceous Electrodes for Rapid Lithium Insertion
(American Chemical Society, 2023-08) McGlamery, Devin; McDaniel, Charles; Xu, Wei; Stadie, Nicholas P.
Direct pyrolysis of coronene at 800 °C produces low-surface-area, nanocrystalline graphitic carbon containing a uniquely high content of a class of lithium binding sites referred to herein as “hydrogen-type” sites. Correspondingly, this material exhibits a distinct redox couple under electrochemical lithiation that is characterized as intermediate-strength, capacitive lithium binding, centered at ∼0.5 V vs Li/Li+. Lithiation of hydrogen-type sites is reversible and electrochemically distinct from capacitive lithium adsorption and from intercalation-type binding between graphitic layers. Hydrogen-type site lithiation can be fully retained even up to ultrafast current rates (e.g., 15 A g–1, ∼40 C) where intercalation is severely hampered by ion desolvation kinetics; at the same time, the bulk nature of these sites does not require a large surface area, and only minimal electrolyte decomposition occurs during the first charge/discharge cycle, making coronene-derived carbon an exceptional candidate for high-energy-density battery applications.
Langmuir's Theory of Adsorption: A Centennial Review
(2019-04) Swenson, Hans; Stadie, Nicholas P.
The 100th anniversary of Langmuir's theory of adsorption is a significant landmark for the physical chemistry and chemical engineering communities. Despite its simplicity, the Langmuir adsorption model captures the key physics of molecular interactions at interfaces and laid the foundation for further progress in understanding interfacial phenomena, developing new adsorbent materials, and designing engineering processes. The Langmuir model has had an exceptional impact on diverse fields within the chemical sciences (ranging from chemical biology to materials science), an impact that became clearer with the development of modified adsorption theories and continues to be relevant today.
Methane Adsorption on Heteroatom-Modified Maquettes of Porous Carbon Surfaces
(American Chemical Society, 2021-07) Rowsey, Rylan; Taylor, Erin E.; Irle, Stephan; Stadie, Nicholas P.; Szilagyi, Robert K.
Experimental and theoretical studies disagree on the energetics of methane adsorption on carbon materials. However, this information is critical for the rational design and optimization of the structure and composition of adsorbents for natural gas storage. The delicate nature of dispersion interactions, polarization of both the adsorbent and the adsorbate, interplay between H-bonding and tetrel bonding, and induced dipole/Coulomb interactions inherent to methane physisorption require computational treatment at the highest possible level of theory. In this study, we employed the smallest reasonable computational model, a maquette of porous carbon surfaces with a central site for substitution and methane binding. The most accurate predictions of methane adsorption energetics were achieved by electron-correlated molecular orbital theory CCSD(T) and hybrid density functional theory MN15 calculations employing a saturated, all-electron basis set. The characteristic geometry of methane adsorption on a carbon surface (“lander approach”) arises due to bonding interactions of the adsorbent π-system with the proximal H–C bonds of methane, in addition to tetrel bonding between the antibonding orbital of the distal C–H bond and the central atom of the maquette (C, B, or N). The polarization of the electron density, structural deformations, and the comprehensive energetic analysis clearly indicate a ∼3 kJ mol–1 preference for methane binding on the N-substituted maquette. The B-substituted maquette showed a comparable or lower binding energy than the unsubstituted, pure C model, depending on the level of theory employed. The calculated thermodynamic results indicate a strategy for incorporating electron-enriched substitutions (e.g., N) into carbon materials as a way to increase methane storage capacity over electron-deficient (e.g., B) modifications. The thermochemical analysis was revised for establishing a conceptual agreement between the experimental isosteric heat of adsorption and the binding enthalpies from statistical thermodynamics principles.
Methodological Studies of the Mechanism of Anion Insertion in Nanometer‐Sized Carbon Micropores
(Wiley, 2022-11) Welty, Connor; Taylor, Erin E.; Posey, Sadie; Vailati, Patric; Kravchyk, Kostiantyn V.; Kovalenko, Maksym V.; Stadie, Nicholas P.
Dual-ion hybrid capacitors (DIHCs) are a promising class of electrochemical energy storage devices intermediate between batteries and supercapacitors, exhibiting both high energy and power density, and generalizable across wide chemistries beyond lithium. In this study, a model carbon framework material with a periodic structure containing exclusively 1.2 nm width pores, zeolite-templated carbon (ZTC), was investigated as the positive electrode for the storage of a range of anions relevant to DIHC chemistries. Screening experiments were carried out across 21 electrolyte compositions within a common stable potential window of 3.0–4.0 V vs. Li/Li+ to determine trends in capacity as a function of anion and solvent properties. To achieve fast rate capability, a binary solvent balancing a high dielectric constant with a low viscosity and small molecular size was used; optimized full-cells based on LiPF6 in binary electrolyte exhibited 146 Wh kg−1 and >4000 W kg−1 energy and power densities, respectively.
Neutron Insights into Sorption Enhanced Methanol Catalysis
(Springer Science and Business Media LLC, 2021-06) Nikolic, Marin; Daemen, Luke; Ramirez-Cuesta, Anibal J.; Balderas Xicohtencatl, Rafael; Cheng, Yongqiang; Putnam, Seth T.; Stadie, Nicholas P.; Liu, Xiaochun; Terreni, Jasmin; Borgschulte, Andreas
Sorption enhanced methanol production makes use of the equilibrium shift of the CO2 hydrogenation reaction towards the desired products. However, the increased complexity of the catalyst system leads to additional reactions and thus side products such as dimethyl ether, and complicates the analysis of the reaction mechanism. On the other hand, the unusually high concentration of intermediates and products in the sorbent facilitates the use of inelastic neutron scattering (INS) spectroscopy. Despite being a post-mortem method, the INS data revealed the change of the reaction path during sorption catalysis. Concretely, the experiments indicate that the varying water partial pressure due to the adsorption saturation of the zeolite sorbent influences the progress of the reaction steps in which water is involved. Experiments with model catalysts support the INS findings.
Physical and chemical mechanisms that influence the electrical conductivity of lignin-derived biochar
(2021-10) Kane, Seth; Ulrich, Rachel; Harrington, Abigail; Stadie, Nicholas P.; Ryan, Cecily A.
Lignin-derived biochar is a promising, sustainable alternative to petroleum-based carbon powders (e.g., carbon black) for polymer composite and energy storage applications. Prior studies of these biochars demonstrate that high electrical conductivity and good capacitive behavior are achievable. However, these studies also show high variability in electrical conductivity between biochars (– S/cm). The underlying mechanisms that lead to desirable electrical properties in these lignin-derived biochars are poorly understood. In this work, we examine the causes of the variation in conductivity of lignin-derived biochar to optimize the electrical conductivity of lignin-derived biochars. To this end, we produced biochar from three different lignins, a whole biomass source (wheat stem), and cellulose at two pyrolysis temperatures (900 °C, 1100 °C). These biochars have a similar range of conductivities (0.002 to 18.51 S/cm) to what has been reported in the literature. Results from examining the relationship between chemical and physical biochar properties and electrical conductivity indicate that decreases in oxygen content and changes in particle size are associated with increases in electrical conductivity. Importantly, high variation in electrical conductivity is seen between biochars produced from lignins isolated with similar processes, demonstrating the importance of the lignin’s properties on biochar electrical conductivity. These findings indicate how lignin composition and processing may be further selected and optimized to target specific applications of lignin-derived biochars.
Prominent Structural Dependence of Quantum Capacitance Unraveled by Nitrogen‐Doped Graphene Mesosponge
(Wiley, 2023-12) Tang, Rui; Aziz, Alex; Yu, Wei; Pan, Zheng‐Ze; Nishikawa, Ginga; Yoshii, Takeharu; Nomura, Keita; Taylor, Erin E.; Stadie, Nicholas P.; Inoue, Kazutoshi; Kotani, Motoko; Kyotani, Takashi; Nishihara, Hirotomo
Porous carbons are important electrode materials for supercapacitors. One of the challenges associated with supercapacitors is improving their energy density without relying on pseudocapacitance, which is based on fast redox reactions that often shorten device lifetimes. A possible solution involves achieving high total capacitance (Ctot), which comprises Helmholtz capacitance (CH) and possibly quantum capacitance (CQ), in high-surface carbon materials comprising minimally stacked graphene walls. In this work, a templating method is used to synthesize 3D mesoporous graphenes with largely identical pore structures (≈2100 m2 g−1 with an average pore size of ≈7 nm) but different concentrations of oxygen-containing functional groups (0.3–6.7 wt.%) and nitrogen dopants (0.1–4.5 wt.%). Thus, the impact of the heteroatom functionalities on Ctot is systematically investigated in an organic electrolyte excluding the effect of pore structures. It is found that heteroatom functionalities determine Ctot, resulting in the cyclic voltammetry curves being rectangular or butterfly-shaped. The nitrogen functionalities are found to significantly enhance Ctot owing to increased CQ.
Stabilizing Effects of Phosphorus-Doped Silicon Nanoparticle Anodes in Lithium-Ion Batteries
(ACS Publications, 2023-01) Gordon, Isabelle P.; Xu, Wei; Randak, Sophia; Jow, T. Richard; Stadie, Nicholas P.
Phosphorus-doped silicon has been reported to exhibit improved cycling stability and/or higher capacity retention than pure silicon as the anode in lithium-ion batteries. However, crystallite size and particle morphology are difficult to decouple from compositional tuning during chemical modification. In this work, we explore direct solid-state routes to phosphorus doping of silicon powders relevant to electrochemical applications. A wide range of compositions are assessed, from 0.05 to 3.0 at % P, as well as a wide range of silicon starting materials of varying crystallinity, particle size, and particle morphology. Successful incorporation of phosphorus into the silicon lattice is best confirmed by X-ray diffraction; the Si(111) reflection shifts to higher angles as consistent with the known lattice contraction of 0.002 Å per 1 at % phosphorus. The addition of phosphorus to Si nanoparticles (100–500 nm) in the high doping regime causes grain coarsening and catalyzes an increase in crystallinity. On the other hand, dilute doping of phosphorus can be carried out without great alteration of the nanoparticulate morphology. The opposite effect occurs for very large microparticles (>10 μm), whereby the doping is concomitant with a disruption of the crystal lattice and reduction of the crystallite size. These effects are borne out in both the electrochemical stability over long-term cycling in a lithium-ion half-cell as well as in the thermal stability under high-temperature decomposition. By comparison across a wide range of pure and P-doped materials of varying particle and crystallite sizes, the independent effects of doping and structure on thermal and electrochemical stability are able to be decoupled herein. A stabilizing effect is most significant when phosphorus doping is dilute and heterogeneous (surface-enriched) within the silicon nanoparticles.
What Structural Features Make Porous Carbons Work for Redox-Enhanced Electrochemical Capacitors? A Fundamental Investigation
(American Chemical Society, 2021-02) Zhao, Yang; Taylor, Erin E.; Hu, Xudong; Evanko, Brian; Zeng, Xiaojun; Wang, Hengbin; Ohnishi, Ryohji; Tsukazaki, Takaki; Li, Jian-Feng; Stadie, Nicholas P.; Yoo, Seung Joon; Stucky, Galen D.; Boettcher, Shannon W.
The addition of redox-active molecules into electrochemical-capacitor electrolytes provides increased specific energy density. Here we illustrate the underlying operational mechanisms and design principles for carbons with hierarchical pore sizes in the micropore (0.6–2 nm) to mesopore (2–3 nm, 5–30 nm) range as electrode materials in redox-enhanced electrochemical capacitors. When using iodide as a model redox additive, we discover that the redox capacity is correlated to the pore volume of the carbon electrodes when void space is included. The fastest rates are typically observed with pore-sizes >1 nm, while slow self-discharge requires pores <1 nm. When used without an ion-selective-membrane separator, the delivered capacity correlated with the quantity of redox species held within the carbon. A commercial microporous carbon, MSC30, with substantial hierarchy in pore size, including small <0.8 nm pores and larger 1.1–3 nm pores, showed the best overall performance, illustrating key design principles.
Zeolite-Templated Carbon as the Cathode for a High Energy Density Dual-Ion Battery
(2019-04) Dubey, Romain J. -C.; Nussli, Jasmin; Piveteau, Laura; Kravchyk, Kostiantyn V.; Rossell, Marta D.; Campanini, Marco; Erni, Rolf; Kovalenko, Maksym V.; Stadie, Nicholas P.
Dual-ion batteries (DIBs) are electrochemical energy storage devices that operate by the simultaneous participation of two different ion species at the anode and cathode and rely on the use of an electrolyte that can withstand the high operation potential of the cathode. Under such conditions at the cathode, issues associated with the irreversible capacity loss and the formation of solid-electrolyte interphase at the surface of highly porous electrode materials are far less significant than at lower potentials, permitting the exploration of high surface area, permanently porous framework materials as effective charge storage media. This concept is investigated herein by employing zeolite-templated carbon (ZTC) as a cathode in a dual-ion battery based on a potassium bis(fluorosulfonyl)imide (KFSI) electrolyte. Anion (FSI-) insertion within the pore network during electrochemical cycling is confirmed by NMR spectroscopy, and the maximum charge capacity is found to be proportional to surface area and micropore volume by comparison to other microporous carbon materials. Full cells based on ZTC as the cathode exhibit both high specific energy (up to 176 Wh kg-1, 79.8 Wh L-1) and high specific power (up to 3945 W kg-1, 1095 W L-1), stable cycling performance over hundreds of cycles, and reversibility within the potential range of 2.65-4.7 V versus K/K+.