Scholarly Works, Macromolecules Innovation Institute (MII)

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Research articles, presentations, and other scholarship

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Cholesterol modulates membrane elasticity via unified biophysical laws
Kumarage, Teshani; Gupta, Sudipta; Morris, Nicholas B.; Doole, Fathima T.; Scott, Haden L.; Stingaciu, Laura-Roxana; Pingali, Sai Venkatesh; Katsaras, John; Khelashvili, George; Doktorova, Milka; Brown, Michael F.; Ashkar, Rana (Springer, 2025-07)
Cholesterol and lipid unsaturation underlie a balance of opposing forces that features prominently in adaptive cell responses to diet and environmental cues. These competing factors have resulted in contradictory observations of membrane elasticity across different measurement scales, requiring chemical specificity to explain incompatible structural and elastic effects. Here, we demonstrate that - unlike macroscopic observations - lipid membranes exhibit a unified elastic behavior in the mesoscopic regime between molecular and macroscopic dimensions. Using nuclear spin techniques and computational analysis, we find that mesoscopic bending moduli follow a universal dependence on the lipid packing density regardless of cholesterol content, lipid unsaturation, or temperature. Our observations reveal that compositional complexity can be explained by simple biophysical laws that directly map membrane elasticity to molecular packing associated with biological function, curvature transformations, and protein interactions. The obtained scaling laws closely align with theoretical predictions based on conformational chain entropy and elastic stress fields. These findings provide unique insights into the membrane design rules optimized by nature and unlock predictive capabilities for guiding the functional performance of lipid-based materials in synthetic biology and real-world applications.
Mechanochemical Synthesis of Recyclable Biohybrid Polymer Networks Using Whole Biomass
Jiang, Meng; Bird, Emily; Ham, Woojung; Worch, Joshua C. (Wiley-VCH, 2025-07)
Whole-plant biomass from non-agricultural sources and waste biomass from processing agricultural products are both promising feedstocks for biopolymer production because they are abundant and do not compete with food production. However, their processing steps are notoriously tedious with the final materials often displaying inferior performance and limited scope in their properties. Here, we report a strategy to integrate whole-cell spirulina, a green-blue algae, into robust biohybrid algae-polyimine networks by leveraging a mechanochemical ball milling method. This strategy provides a greener synthetic approach to conventional solvent casting methods for polyimine synthesis; it simultaneously overcomes persistent constraints encountered in biomass processing and derivatization. The biohybrid algae-based materials retain adaptability and recyclability imparted by their underlying dynamic covalent polymer matrix and display enhanced mechanical properties compared to their all-synthetic equivalents. These advantageous properties are attributed to the unique morphology of the ball milled biohybrid materials which are facilitated by integration of the spirulina into the polymer matrix. Substituting spirulina with alternative biomass sources such as waste agricultural products also yields robust biohybrid networks, thus highlighting the broad utility of this straightforward mechanochemical synthesis to create more sustainable materials.
Effect of Sequence-Based Incorporation of Fillers, Kenaf Fiber and Graphene Nanoplate, on Polypropylene Composites via a Physicochemical Compounding Method
Lee, Soohyung; Ahn, Kihyeon; Hong, Su Jung; Kim, Young-Teck (MDPI, 2025-07-17)
Natural-fiber-reinforced polypropylene (PP) composites are gaining increasing interest as lightweight, sustainable alternatives for various packaging and applications. This study investigates the effect of filler addition sequence on the mechanical, morphological, thermal, and dynamic mechanical properties of PP-based composites reinforced with graphite nanoplatelets (GnP) and kenaf fiber (KF). Two filler incorporation sequences were evaluated: GnP/KF/PP (GnP initially mixed with KF before PP addition) and GnP/PP/KF (KF added after mixing GnP with PP). The GnP/KF/PP composite exhibited superior mechanical properties, with tensile strength and flexural strength increasing by up to 25% compared to the control, while GnP/PP/KF showed a 13% improvement. SEM analyses revealed that initial mixing of GnP with KF significantly improved filler dispersion and interfacial bonding, enhancing stress transfer within the composite. XRD and DSC analyses showed reduced crystallinity and lower crystallization temperatures in the addition of KF due to restricted polymer chain mobility. Thermal stability assessed by TGA indicated minimal differences between the composites regardless of filler sequence. DMA results demonstrated a significantly higher storage modulus and enhanced elastic response in the addition of KF, alongside a slight decrease in glass transition temperature (T_g). The results emphasize the importance of optimizing filler addition sequences to enhance mechanical performance, confirming the potential of these composites in sustainable packaging and structural automotive applications.
Binding Free Energy Analysis of Galectin-3 Natural Ligands and Synthetic Inhibitors
Newman, Luke; Welborn, Valerie (Wiley, 2025-06)
Galectin-3–ligand complexes are characterized by halogen, σ-hole bonds, hydrogen bonds, cation-π and CH-π interactions. Here, we model these non-covalent interactions with the AMOEBA polarizable force field and conduct an absolute binding free energy analysis on leading galectin-3 inhibitors. Synthetic drug molecules GB0139, GB1107, and GB1211 were estimated to have binding free energies of −4.3, −6.7, and −9.5 kcal/mol respectively. This compares to −0.3 and 1.4 kcal/mol for the natural ligands, N-acetyllactosamine type 1 and type 2, respectively. We calculated the electric fields projected along key bonds in each ligand to further rationalize these results. We find that while the hydroxyl groups of the natural ligands interact reasonably well with residues in galectin-3's binding pocket, structural dynamics weaken the binding pose and favor interactions with water, sometimes yielding to dissociation. In contrast, the more favorable binding energy of GB1211, leading inhibitor in clinical studies, is associated with strong and constant electric fields across the bonds investigated, suggesting a stiffer binding pose with a stabilizing σ-hole interaction.
Mitigating product inhibition in 2'-hydroxybiphenyl-2-sulfinase (DszB) with synthetic glycosylation
Liang, Junbao; Zheng, Yi; Welborn, Valerie (Wiley, 2025-07)
The combustion of sulfur-rich crude oil is toxic to the environment, making the removal of sulfur impurities a priority for the sustainable use of liquid fuels. Biodesulfurization via the 4S pathway is a promising approach due to its C-S bond cleavage specificity and mild operating conditions. However, biodesulfurization is not economically viable due to the slow turnover of 2′-hydroxybiphenyl-2-sulfinate desulfinase (DszB), an enzyme catalyzing the conversion of 2′-hydroxybiphenyl-2-sulfinate to 2-hydroxybiphenyl and sulfite. Previous studies have identified product inhibition as the limiting factor in DszB, whereby solvent-exposed protein loops obstruct the active site after substrate binding. This closed conformation is stabilized by hydrophobic interactions between the loops and the product. Here, we propose an artificial glycosylation strategy to mitigate product inhibition in DszB. We modeled glycated DszB in the apo, ligand-bound, and product-bound states with molecular dynamics based on the AMOEBA polarizable force field, and analyzed the chemical positioning of the reactant and product compared to the wild type (WT). We find that the addition of glucose on three Ser loop residues increases the interaction of the loops with water, overcoming the weaker product–loop interactions, and thereby enabling product release. Importantly, the enhanced flexibility of the loops was subtle enough to not heavily disrupt the chemical positioning of the reactant, which suggests that the rate acceleration would be similar to that of the WT.
Soybean Lectin Cross-Links Membranes by Binding Sulfatide in a Curvature-Dependent Manner
Okedigba, Ayoyinka O.; Ng, Emery L.; Deegbey, Mawuli; Rosso, M. Luciana; Ngo, William; Xiao, Ruoshi; Huang, Haibo; Zhang, Bo; Welborn, Valerie; Capelluto, Daniel G. S. (American Chemical Society, 2025-05-24)
Soybean (Glycine max) is a key source of plant-based protein, yet its nutritional value is impacted by antinutritional factors, including lectins. Whereas soybean lectin is known to bind N-acetyl-d-galactosamine (GalNAc), its lipid interactions remain unexplored. Using a novel purification method, we isolated lectin from soybean meals and characterized its interactions with GalNAc and the glycosphingolipid sulfatide. Isothermal titration calorimetry revealed micromolar affinity for GalNAc, whereas most GalNAc derivatives displayed weak or no binding. Lectin exhibited high-affinity binding to sulfatide in a membrane curvature-dependent manner. Binding of lectin to sulfatide promoted cross-linking of sulfatide-containing vesicles. Whereas sulfatide interaction was independent of GalNAc binding, suggesting distinct binding sites, vesicle cross-linking was inhibited by the sugar. Molecular dynamics simulations identified a consensus sulfatide-binding site in lectin. These findings highlight the dual ligand-binding properties of soybean lectin and may provide strategies to mitigate its antinutritional effects and improve soybean meal processing.
Effect of the Gel Drying Method on Properties of Semicrystalline Aerogels Prepared with Different Network Morphologies
Spiering, Glenn A.; Godshall, Garrett F.; Moore, Robert B. (MDPI, 2025-06-10)
The purpose of this study was to investigate the effect of different drying methods on the structure and properties of semicrystalline polymer aerogels. Aerogels, consisting of either globular or strut-like morphologies, were prepared from poly(ether ether ketone) (PEEK) or poly(phenylene sulfide) (PPS) and dried using vacuum drying, freeze-drying, or supercritical CO₂ extraction. Vacuum drying was found to result in aerogels with a higher shrinkage, smaller mesopores (with pore widths of 2–50 nm), and smaller surface areas compared to the use of supercritical extraction as the drying method. Freeze-dried aerogels tended to have properties between those of vacuum-dried aerogels and aerogels prepared with supercritical extraction. High network connectivity was found to lead to improved gel modulus, which increased the ability of aerogels to resist network deformation due to stresses induced during drying. The PEEK and PPS aerogel networks consisting of highly connected strut-like features were considerably stiffer than those composed of globular features, and thus shrank less under the forces induced by vacuum drying or freeze-drying. The aerogels prepared from PPS were found to have larger mesopores and smaller surface areas than the aerogels prepared from PEEK. The larger mesopores of the PPS aerogels induced lower capillary stresses on the aerogel network, and thus shrank less. This work demonstrates that preparing PEEK and PPS gels with strut-like features can allow aerogel processing with simpler evaporative drying methods rather than the more complex supercritical drying method.
Liquid Metal-Vitrimer Conductive Composite for Recyclable and Resilient Electronics
Ho, Dong Hae; Jiang, Meng; Tutika, Ravi; Worch, Joshua C.; Bartlett, Michael D. (Wiley-VCH, 2025-06-01)
Electronic devices are ubiquitous in modern society, yet their poor recycling rates contribute to substantial economic losses and worsening environmental impacts from electronic waste (E-waste) disposal. Here, recyclable and healable electronics are reported through a vitrimer-liquid metal (LM) microdroplet composite. These electrically conductive, yet plastic-like composites display mechanical qualities of rigid thermosets and recyclability through a dynamic covalent polymer network. The composite exhibits a high glass transition temperature, good solvent resistance, high electrical conductivity, and recyclability. The vitrimer synthesis proceeds without the need for a catalyst or a high curing temperature, which enables facile fabrication of the composite materials. The as-synthesized vitrimer exhibits a fast relaxation time with reconfigurability and shape memory. The electrically conductive composite exhibits high electrical conductivity with LM volume loading as low as 5 vol.%. This enables the fabrication of fully vitrimer-based circuit boards consisting of sensors and indicator LEDs integrated with LM-vitrimer conductive wiring. Electrical self-healing and thermally triggered material healing are further demonstrated with the composites. The vitrimer and LM-composite provide a pathway toward fully recyclable, mechanically robust, and reconfigurable electronics, thus advancing the field of electronic materials.
Investigating the effect of heterogeneities across the electrode|multiphase polymer electrolyte interfaces in high-potential lithium batteries
Min, Jungki; Bak, Seong-Min; Zhang, Yuxin; Yuan, Mingyu; Pietra, Nicholas F.; Russell, Joshua A.; Deng, Zhifei; Xia, Dawei; Tao, Lei; Du, Yonghua; Xiong, Hui; Li, Ling; Madsen, Louis A.; Lin, Feng (Nature Portfolio, 2025-04-01)
Polymer electrolytes hold great promise for safe and high-energy batteries comprising solid or semi-solid electrolytes. Multiphase polymer electrolytes, consisting of mobile and rigid phases, exhibit fast ion conduction and desired mechanical properties. However, fundamental challenges exist in understanding and regulating interactions at the electrode|electrolyte interface, especially when using high-potential layered oxide active materials at the positive electrode. Here we demonstrate that depletion of the mobile conductive phase at the interface contributes to battery performance degradation. Molecular ionic composite electrolytes, composed of a rigid-rod ionic polymer with nanometric mobile cations and anions, serve as a multiphase platform to investigate the evolution of ion conductive domains at the interface. Chemical and structural characterizations enable the visualization of concentration heterogeneity and spatially resolve the interfacial chemical states over a statistically significant field of view for buried interfaces. We report that concentration and chemical heterogeneities prevail at electrode|electrolyte interfaces, leading to phase separation in polymer electrolytes. Understanding the hidden roles of interfacial chemomechanics in polymer electrolytes enables us to design an interphase tailoring strategy based on electrolyte additives to mitigate the interfacial heterogeneity and improve battery performance.
A Renewably Sourced, Circular Photopolymer Resin for Additive Manufacturing
Machado, Thiago O.; Stubbs, Connor J.; Chiaradia, Viviane; Alraddadi, Maher A.; Brandolese, Arianna; Worch, Joshua C.; Dove, Andrew P. (Nature Portfolio, 2024-05-15)
The additive manufacturing of photopolymer resins by means of vat photopolymerization enables the rapid fabrication of bespoke 3D-printed parts. Advances in methodology have continually improved resolution and manufacturing speed, yet both the process design and resin technology have remained largely consistent since its inception in the 1980s1. Liquid resin formulations, which are composed of reactive monomers and/or oligomers containing (meth)acrylates and epoxides, rapidly photopolymerize to create crosslinked polymer networks on exposure to a light stimulus in the presence of a photoinitiator2. These resin components are mostly obtained from petroleum feedstocks, although recent progress has been made through the derivatization of renewable biomass3–6 and the introduction of hydrolytically degradable bonds7–9. However, the resulting materials are still akin to conventional crosslinked rubbers and thermosets, thus limiting the recyclability of printed parts. At present, no existing photopolymer resin can be depolymerized and directly re-used in a circular, closed-loop pathway. Here we describe a photopolymer resin platform derived entirely from renewable lipoates that can be 3D-printed into high-resolution parts, efficiently deconstructed and subsequently reprinted in a circular manner. Previous inefficiencies with methods using internal dynamic covalent bonds10–17 to recycle and reprint 3D-printed photopolymers are resolved by exchanging conventional (meth)acrylates for dynamic cyclic disulfide species in lipoates. The lipoate resin platform is highly modular, whereby the composition and network architecture can be tuned to access printed materials with varied thermal and mechanical properties that are comparable to several commercial acrylic resins.
Chain-length-controllable upcycling of polyolefins to sulfate detergents
Munyaneza, Nuwayo Eric; Ji, Ruiyang; DiMarco, Adrian; Miscall, Joel; Stanley, Lisa; Rorrer, Nicholas; Qiao, Rui; Liu, Guoliang (Springer Nature, 2024-11-18)
Escalating global plastic pollution and the depletion of fossil-based resources underscore the urgent need for innovative end-of-life plastic management strategies in the context of a circular economy. Thermolysis is capable of upcycling end-of-life plastics to intermediate molecules suitable for downstream conversion to eventually high-value chemicals, but tuning the molar mass distribution of the products is challenging. Here we report a temperature-gradient thermolysis strategy for the conversion of polyethylene and polypropylene into hydrocarbons with tunable molar mass distributions. The whole thermolysis process is catalyst- and hydrogen-free. The thermolysis of polyethylene and polyethylene/polypropylene mixtures with tailored temperature gradients generated oil with an average chain length of ~C14. The oil featured a high concentration of synthetically useful α-olefins. Computational fluid dynamics simulations revealed that regulating the reactor wall temperature was the key to tuning the hydrocarbon distributions. Subsequent oxidation of the obtained α-olefins by sulfuric acid and neutralization by potassium hydroxide afforded sulfate detergents with excellent foaming behaviour and emulsifying capacity and low critical micelle concentration. Overall, this work provides a viable approach to producing value-added chemicals from end-of-life plastics, improving the circularity of the anthropogenic carbon cycle.
Octopus-Inspired Adhesives with Switchable Attachment to Challenging Underwater Surfaces
Lee, Chanhong; Via, Austin C.; Heredia, Aldo; Adjei, Daniel A.; Bartlett, Michael D. (Wiley-VCH, 2024-10-09)
Adhesives that excel in wet or underwater environments are critical for applications ranging from healthcare and underwater robotics to infrastructure repair. However, achieving strong attachment and controlled release on difficult substrates, such as those that are curved, rough, or located in diverse fluid environments, remains a major challenge. Here, an octopus-inspired adhesive with strong attachment and rapid release in challenging underwater environments is presented. Inspired by the octopus’s infundibulum structure, a compliant, curved stalk, and an active deformable membrane for multi-surface adhesion are utilized. The stalk’s curved shape enhances conformal contact on large-scale curvatures and increases contact stress for adaptability to small-scale roughness. These synergistic mechanisms improve contact across multiple length scales, resulting in switching ratios of over 1000 within ≈30 ms with consistent attachment strength of over 60 kPa on diverse surfaces and conditions. These adhesives are demonstrated through the robust attachment and precise manipulation of rough underwater objects.
Polymer characterization by size-exclusion chromatography with multi-angle light scattering (SEC-MALS): a tutorial review
Matson, John B.; Steele, Anna Q.; Mase, Jonathan D.; Schulz, Michael D. (Royal Society Chemistry, 2024)
This tutorial review presents the theory and application of SEC-MALS with minimal equations and a focus on synthetic polymer characterization, serving as an entry point for polymer scientists who want to learn more about SEC-MALS. We discuss the principles of static light scattering, outline its capability to generate absolute weight-average molar mass values, and extend its application to SEC-MALS. Practical elements are emphasized, enabling researchers to appreciate how values for Mn, Mw, and Đ are determined in an SEC-MALS experiment and how experimental conditions and input values, such as the specific refractive index increment (dn/dc), influence the results. Several illustrative SEC-MALS experiments demonstrate the impact of separation quality on Mn (as opposed to Mw), the appearance of contaminants in SEC chromatograms from sample preparation, the influence of concentration on data quality, and how polymer topology affects molecular weight characterization in SEC. Finally, we address practical considerations, common issues, and persistent misconceptions.
High Modulus, Strut-like poly(ether ether ketone) Aerogels Produced from a Benign Solvent
Spiering, Glenn A.; Godshall, Garrett F.; Moore, Robert B. (MDPI, 2024-04-22)
Poly(ether ether ketone) (PEEK) was found to form gels in the benign solvent 1,3-diphenylacetone (DPA). Gelation of PEEK in DPA was found to form an interconnected, strut-like morphology composed of polymer axialites. To our knowledge, this is the first report of a strut-like morphology for PEEK aerogels. PEEK/DPA gels were prepared by first dissolving PEEK in DPA at 320 °C. Upon cooling to 50 °C, PEEK crystallizes and forms a gel in DPA. The PEEK/DPA phase diagram indicated that phase separation occurs by solid–liquid phase separation, implying that DPA is a good solvent for PEEK. The Flory–Huggins interaction parameter, calculated as χ₁₂ = 0.093 for the PEEK/DPA system, confirmed that DPA is a good solvent for PEEK. PEEK aerogels were prepared by solvent exchanging DPA to water then freeze-drying. PEEK aerogels were found to have densities between 0.09 and 0.25 g/cm³, porosities between 80 and 93%, and surface areas between 200 and 225 m²/g, depending on the initial gel concentration. Using nitrogen adsorption analyses, PEEK aerogels were found to be mesoporous adsorbents, with mesopore sizes of about 8 nm, which formed between stacks of platelike crystalline lamellae. Scanning electron microscopy and X-ray scattering were utilized to elucidate the hierarchical structure of the PEEK aerogels. Morphological analysis found that the PEEK/DPA gels were composed of a highly nucleated network of PEEK axialites (i.e., aggregates of stacked crystalline lamellae). The highly connected axialite network imparted robust mechanical properties on PEEK aerogels, which were found to densify less upon freeze-drying than globular PEEK aerogel counterparts gelled from dichloroacetic acid (DCA) or 4-chlorphenol (4CP). PEEK aerogels formed from DPA were also found to have a modulus–density scaling that was far more efficient in supporting loads than the poorly connected aerogels formed from PEEK/DCA or PEEK/4CP solutions. The strut-like morphology in these new PEEK aerogels also significantly improved the modulus to a degree that is comparable to high-performance crosslinked aerogels based on polyimide and polyurea of comparable densities.
Additive Manufacturing of Poly(phenylene Sulfide) Aerogels via Simultaneous Material Extrusion and Thermally Induced Phase Separation
Godshall, Garrett F.; Rau, Daniel A.; Williams, Christopher B.; Moore, Robert B. (Wiley-VCH GmbH, 2023-11)
Additive manufacturing (AM) of aerogels increases the achievable geometric complexity, and affords fabrication of hierarchically porous structures. In this work, a custom heated material extrusion (MEX) device prints aerogels of poly(phenylene sulfide) (PPS), an engineering thermoplastic, via in situ thermally induced phase separation (TIPS). First, pre-prepared solid gel inks are dissolved at high temperatures in the heated extruder barrel to form a homogeneous polymer solution. Solutions are then extruded onto a room-temperature substrate, where printed roads maintain their bead shape and rapidly solidify via TIPS, thus enabling layer-wise MEX AM. Printed gels are converted to aerogels via postprocessing solvent exchange and freeze-drying. This work explores the effect of ink composition on printed aerogel morphology and thermomechanical properties. Scanning electron microscopy micrographs reveal complex hierarchical microstructures that are compositionally dependent. Printed aerogels demonstrate tailorable porosities (50.0–74.8%) and densities (0.345–0.684 g cm⁻³), which align well with cast aerogel analogs. Differential scanning calorimetry thermograms indicate printed aerogels are highly crystalline (≈43%), suggesting that printing does not inhibit the solidification process occurring during TIPS (polymer crystallization). Uniaxial compression testing reveals that compositionally dependent microstructure governs aerogel mechanical behavior, with compressive moduli ranging from 33.0 to 106.5 MPa.
Molecular modeling of Poly(methyl methacrylate-block-acrylonitrile) as Precursors of Porous Carbon Fibers
Hao, Xi; Serrano, Joel; Liu, Guoliang; Cheng, Shengfeng (2023-04-22)
Inducing stratification of colloidal mixtures with a mixed binary solvent
Liu, Binghan; Grest, Gary S.; Cheng, Shengfeng (Royal Society of Chemistry, 2023-12-06)
Molecular dynamics simulations are used to demonstrate that a binary solvent can be used to stratify colloidal mixtures when the suspension is rapidly dried. The solvent consists of two components, one more volatile than the other. When evaporated at high rates, the more volatile component becomes depleted near the evaporation front and develops a negative concentration gradient from the bulk of the mixture to the liquid-vapor interface while the less volatile solvent is enriched in the same region and exhibit a positive concentration gradient. Such gradients can be used to drive a binary mixture of colloidal particles to stratify if one is preferentially attracted to the more volatile solvent and the other to the less volatile solvent. During solvent evaporation, the fraction of colloidal particles preferentially attracted to the less volatile solvent is enhanced at the evaporation front, whereas the colloidal particles having stronger attractions with the more volatile solvent are driven away from the interfacial region. As a result, the colloidal particles show a stratified distribution after drying, even if the two colloids have the same size.
Diffusiophoresis as a physical mechanism underlying small-on-top stratification in evaporating bidisperse nanoparticle suspensions
Liu, Binghan; Grest, Gary; Cheng, Shengfeng (2023-05-17)
Operando characterization and regulation of metal dissolution and redeposition dynamics near battery electrode surface
Zhang, Yuxin; Hu, Anyang; Xia, Dawei; Hwang, Sooyeon; Sainio, Sami; Nordlund, Dennis; Michel, F. Marc; Moore, Robert B.; Li, Luxi; Lin, Feng (Nature Portfolio, 2023-07)
Mn dissolution has been a long-standing, ubiquitous issue that negatively impacts the performance of Mn-based battery materials. Mn dissolution involves complex chemical and structural transformations at the electrode–electrolyte interface. The continuously evolving electrode–electrolyte interface has posed great challenges for characterizing the dynamic interfacial process and quantitatively establishing the correlation with battery performance. In this study, we visualize and quantify the temporally and spatially resolved Mn dissolution/redeposition (D/R) dynamics of electrochemically operating Mn-containing cathodes. The particle-level and electrode-level analyses reveal that the D/R dynamics is associated with distinct interfacial degradation mechanisms at different states of charge. Our results statistically differentiate the contributions of surface reconstruction and Jahn–Teller distortion to the Mn dissolution at different operating voltages. Introducing sulfonated polymers (Nafion) into composite electrodes can modulate the D/R dynamics by trapping the dissolved Mn species and rapidly establishing local Mn D/R equilibrium. This work represents an inaugural effort to pinpoint the chemical and structural transformations responsible for Mn dissolution via an operando synchrotron study and develops an effective method to regulate Mn interfacial dynamics for improving battery performance.
Uncorrelated Lithium-Ion Hopping in a Dynamic Solvent-Anion Network
Yu, Deyang; Troya, Diego; Korovich, Andrew G.; Bostwick, Joshua E.; Colby, Ralph H.; Madsen, Louis A. (American Chemical Society, 2023-03)
Lithium batteries rely crucially on fast charge and mass transport of Li+ in the electrolyte. For liquid and polymer electrolytes with added lithium salts, Li+ couples to the counter-anion to form ionic clusters that produce inefficient Li+ transport and lead to Li dendrite formation. Quantification of Li+ transport in glycerol-salt electrolytes via NMR experiments and MD simulations reveals a surprising Li+-hopping mechanism. The Li+ transference number, measured by ion-specific electrophoretic NMR, can reach 0.7, and Li+ diffusion does not correlate with nearby ion motions, even at high salt concentration. Glycerol's high density of hydroxyl groups increases ion dissociation and slows anion diffusion, while the close proximity of hydroxyls and anions lowers local energy barriers, facilitating Li+ hopping. This system represents a bridge between liquid and inorganic solid electrolytes, thus motivating new molecular designs for liquid and polymer electrolytes to enable the uncorrelated Li+-hopping transport needed for fast-charging and all-solid-state batteries.

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