Tailored porous carbons enabled by persistent micelles with glassy cores

Williams, Eric R.; McMahon, Paige L.; Reynolds, Joseph E.; Snider, Jonathan L.; Stavila, Vitalie; Allendorf, Mark D.; Stefik, Morgan

doi:10.1039/d1ma00146a

Cited by 13 publications

(40 citation statements)

References 66 publications

(88 reference statements)

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“…This strategy has been employed to halt micelle chain exchange during kinetic studies 77 for trapping diverse micelle morphologies 100−107 and was recently expanded to the context of polymer templates. 76 Glassy-PMTs were thus prepared using an established procedure based on PEO-b-PS. Mesoporous microparticles were again prepared with PPO using a series of M:T values and were measured by SAXS (Figure 3b).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The PEO-b-PS micelles were prepared by dissolving 1.0 g of PEOb-PS in 10 mL of THF in a large round-bottom flask. 76 To this solution was added 10 mL of deionized water in a dropwise fashion and with frequent swirling of the flask. Next, 100 mL of anhydrous methanol was added.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…It was previously shown that a procedure such as this is important to remove all good solvents which act as plasticizers. 76 Subsequently, anhydrous MgSO 4 was added in excess to the solution until a cloudy precipitate was observed, indicating a preliminary state of dryness. The mixture was passed through a Gelman Sciences glass fiber filter paper with 1 μm pores to remove this precipitate and yield a transparent solution with a much lower water content.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…An improved PMT strategy was developed to yield the first mesoporous microparticles prepared from block polymers that independently control the pore and wall thickness based upon micelles with glassy cores (glassy-PMT). 76 This use of micelles with robust kinetic entrapment was necessary to preserve the micelle shape and size throughout the full synthesis. This contrasts with prior evaporative casting works which were subject to multiparameter changes when glassy templates were plasticized 9 , 2 6 or when low-T g templates were used.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Persistent micelle templates (PMTs) uniquely enable nanostructures with independent tunability of the pore and wall dimensions. ,− Most processes using block polymer structure-directing agents are based upon equilibration, and thus, the architectural dimensions are determined by free-energy minimization. In contrast, the PMT strategy is based upon kinetic control where block polymer micelles are used as templates with an invariant size.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Mesoporous TiO₂ Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

et al. 2021

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Mesoporous microparticles are an attractive platform to deploy high-surface-area nanomaterials in a convenient particulate form that is broadly compatible with diverse device manufacturing methods. The applications for mesoporous microparticles are numerous, spanning the gamut from drug delivery to catalysis and energy storage. For most applications, the performance of the resulting materials depends upon the architectural dimensions including the mesopore size, wall thickness, and microparticle size, yet a synthetic method to control all these parameters has remained elusive. Furthermore, some mesoporous microparticle reports noted a surface skin layer which has not been tuned before despite the important effect of such a skin layer upon transport/encapsulation. In the present study, material precursors and block polymer micelles are combined to yield mesoporous materials in a microparticle format due to phase separation from a homopolymer matrix. The skin layer thickness was kinetically controlled where a layer integration via diffusion (LID) model explains its production and dissipation. Furthermore, the independent tuning of pore size and wall thickness for mesoporous microparticles is shown for the first time using persistent micelle templates (PMT). Last, the kinetic effects of numerous processing parameters upon the microparticle size are shown.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Mesoporous TiO₂ Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

et al. 2021

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Understanding Rapid Intercalation Materials One Parameter at a Time

Bergh

Stefik

2022

Adv Funct Materials

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Demand for fast, energy‐dense storage drives the research into nanoscale intercalation materials. Nanomaterials accelerate kinetics and can modify reaction path thermodynamics, intercalant solubility, and reversibility. The discovery of intercalation pseudocapacitance has opened questions about their fundamental operating principles. For example, are their capacitor‐like current responses caused by storing energy in special near‐surface regions or rather is this response due to normal intercalation limited by a slower faradaic surface‐reaction? This review highlights emerging methods combining tailored nanomaterials with the process of elimination to disambiguate cause‐and‐effect at the nanoscale. This method is applied to multiple intercalation pseudocapacitive materials showing that the timescales exhibiting surface‐limited kinetics depended on the total intercalation length scale. These trends are inconsistent with the near‐surface perspective. A revised current‐model without assuming special near‐surface storage fits experimental data better across wide timescales. This model, combined with tailored nanomaterials and the process of elimination, can isolate material‐specific effects such as how amorphization/defect‐tailoring modifies both insertion and diffusion kinetics. Avenues for both faster intercalation pseudocapacitance and increased energy density are discussed. A relaxation time argument is suggested to explain the continuum between battery‐like and pseudocapacitive behaviors. Future directions include synthetic methods emphasizing tailored defects and analytical methods that minimize assumptions.

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Highly Reversible Lithiation of Additive Free T‐Nb₂O₅ for a Quarter of a Million Cycles

Wechsler,

Gregg,

Stefik

2023

Adv Funct Materials

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Fast energy storage via intercalation requires quick ionic diffusion and often results in pseudocapacitive behavior. The cycling stability of such energy storage materials remains understudied despite the relevance to lifetime cost. Orthorhombic niobium oxide (T‐Nb2O5) is a rapid ion intercalation material with a theoretical capacity of 201.7 mAh g−1 (Li2Nb2O5) and good cycling stability due to the minimal unit cell strain during (de)intercalation. Prior reports of T‐Nb2O5 cycling between 1.3–3.1 V versus Li/Li+ noted a 50% loss in capacity after 10 000 cycles. Here, cyclic voltammetry is used to identify the role of the voltage window, state of charge, and potentiostatic holds on the cycling stability of mesoporous T‐Nb2O5 thin films. Films cycled between 1.2–3.0 V versus Li/Li+ without voltage holds (Li1.1Nb2O5) exhibited extreme cycling stability with 90.8% capacity retention after 0.25 million cycles without detectable morphological/crystallographic changes. In contrast, the inclusion of 60 s voltage holds (Li2.18Nb2O5) led to rapid capacity loss with 61.6% retention after 10 000 cycles with corresponding X‐ray diffraction evidence of amorphization. Cycling with other limited voltage windows identifies that most crystallographic degradation occurs at higher extents of lithiation. These results reveal remarkable stability over limited conditions and suggest that T‐Nb2O5 amorphization is associated with high extents of lithiation.

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Tailored porous carbons enabled by persistent micelles with glassy cores

Abstract: Porous nanoscale carbonaceous materials are widely employed for catalysis, separations, and electrochemical devices where device performance often relies upon specific and well-defined regular feature sizes. The use of block polymers...

Cited by 13 publications

References 66 publications

Mesoporous TiO₂ Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

Mesoporous TiO₂ Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

Understanding Rapid Intercalation Materials One Parameter at a Time

Highly Reversible Lithiation of Additive Free T‐Nb₂O₅ for a Quarter of a Million Cycles

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Tailored porous carbons enabled by persistent micelles with glassy cores

Abstract: Porous nanoscale carbonaceous materials are widely employed for catalysis, separations, and electrochemical devices where device performance often relies upon specific and well-defined regular feature sizes. The use of block polymers...

Cited by 13 publications

References 66 publications

Mesoporous TiO2 Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

Mesoporous TiO2 Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

Understanding Rapid Intercalation Materials One Parameter at a Time

Highly Reversible Lithiation of Additive Free T‐Nb2O5 for a Quarter of a Million Cycles

Contact Info

Product

Resources

About

Mesoporous TiO₂ Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

Mesoporous TiO₂ Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

Highly Reversible Lithiation of Additive Free T‐Nb₂O₅ for a Quarter of a Million Cycles