Batteries based on alternatives to lithium are now of global research interest. Magnesium metal batteries are particularly attractive for their potential high energy density. Polymer electrolytes for ...high density rechargeable batteries have been sought for decades, due to their improved thermal stability compared with liquids and their lower density and cost compared with inorganic solids. Yet, little success has so far been realized in polymer electrolytes for magnesium metal batteries. In this review, the magnesium polymer electrolyte literature is comprehensively explored. Differences between requirements for lithium polymer and magnesium polymer batteries are discussed as well as the consequences on necessary considerations for impactful magnesium polymer electrolyte research.
Solid polymer electrolyte (SPE) membranes are a critical component of high specific energy rechargeable Li-metal polymer (LMP) batteries. SPEs exhibit low volatility and thus increase the safety of ...Li-based batteries compared to current state-of-the-art Li-ion batteries that use flammable small-molecule electrolytes. However, most SPEs exhibit low ionic conductivity at room temperature, and often allow the growth of lithium dendrites that short-circuit the batteries. Both of these deficiencies are significant barriers to the commercialization of LMP batteries. Herein we report a cross-linked polyethylene/poly(ethylene oxide) SPE with both high ionic conductivity (>1.0 × 10–4 S/cm at 25 °C) and excellent resistance to dendrite growth. It has been proposed that SPEs with shear moduli of the same order of magnitude as lithium could be used to suppress dendrite growth, leading to increased lifetime and safety for LMP batteries. In contrast to the theoretical predictions, the low-modulus (G′ ≈ 1.0 × 105 Pa at 90 °C) cross-linked SPEs reported herein exhibit remarkable dendrite growth resistance. These results suggest that a high-modulus SPE is not a requirement for the control of dendrite proliferation.
Polymer–particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the ...spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle‐polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion‐transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions.
Polymer–particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created that can be exploited for applications. The fundamental approaches and bottom‐up synthesis strategies for understanding and controlling nanoparticle dispersion in polymers are reviewed. Applications of these approaches for creating polymer–particle composite electrolytes and electrodes for energy storage are also considered.
High lithium transference number, t Li+ , electrolytes are desired for use in both lithium-ion and lithium metal rechargeable battery technologies. Historically, low t Li+ electrolytes have hindered ...device performance by allowing ion concentration gradients within the cell, leading to high internal resistances that ultimately limit cell lifetime, charging rates, and energy density. Herein, we report on the synthesis and electrochemical features of electrolytes based on nanoparticle salts designed to provide high t Li+ . The salts are created by cofunctionalization of metal oxide nanoparticles with neutral organic ligands and tethered lithium salts. When dispersed in a conducting fluid such as tetraglyme, they spontaneously form a charged, nanoporous network of particles at moderate nanoparticle loadings. Modification of the tethered anion chemistry from −SO3 – to −SO3BF3 – is shown to enhance ionic conductivity of the electrolytes by facilitating ion pair dissociation. At a particle volume fraction of 0.15, the electrolyte exists as a self-supported, nanoporous gel with an optimum ionic conductivity of 10–4 S/cm at room temperature. Galvanostatic polarization measurements on symmetric lithium metal cells containing the electrolyte show that the cell short circuit time, t SC, is inversely proportional to the square of the applied current density t SC ∼ J –2, consistent with previously predicted results for traditional polymer-in-salt electrolytes with low t Li+ . Our findings suggest that electrolytes with t Li+ ≈ 1 and good ion-pair dissociation delay lithium dendrite nucleation and may lead to improved lithium plating in rechargeable batteries with metallic lithium anodes.
Nanoscale Organic Hybrid Electrolytes Nugent, Jennifer L.; Moganty, Surya S.; Archer, Lynden A.
Advanced materials (Weinheim),
September 1, 2010, Letnik:
22, Številka:
33
Journal Article
Recenzirano
Odprti dostop
Nanoscale organic hybrid electrolytes are composed of organic‐inorganic hybrid nanostructures, each with a metal oxide or metallic nanoparticle core densely grafted with an ion‐conducting ...polyethylene glycol corona ‐ doped with lithium salt. These materials form novel solvent‐free hybrid electrolytes that are particle‐rich, soft glasses at room temperature ; yet manifest high ionic conductivity and good electrochemical stability above 5V.
•Quantifiable & semi-quantifiable PFAS sampled at 38 wastewater treatment plants.•PFAS detected at the influent, effluent and biosolids at every facility sampled.•The total oxidizable precursors ...assay showed a 2- to 3-fold increase in PFAS.•Quantifiable precursor mass primarily discharging via aqueous effluent.
Both quantifiable and semi-quantifiable poly- and perfluoroalkyl substances (PFAS) were evaluated in the influent, effluent, and biosolids of 38 wastewater treatment plants. PFAS were detected in all streams at all facilities. For the means of the sums of detected, quantifiable PFAS concentrations were 98 ± 28 ng/L, 80 ± 24 ng/L, and 160,000 ± 46,000 ng/kg (dry weight basis) in the influent, effluent, and biosolids (respectively). In the aqueous influent and effluent streams this quantifiable PFAS mass was typically associated with perfluoroalkyl acids (PFAAs). In contrast, quantifiable PFAS in the biosolids were primarily polyfluoroalkyl substances that potentially serve as precursors to the more recalcitrant PFAAs. Results of the total oxidizable precursor (TOP) assay on select influent and effluent samples showed that semi-quantified (or, unidentified) precursors accounted for a substantial portion (21 to 88%) of the fluorine mass compared to that associated with quantified PFAS, and that this fluorine precursor mass was not appreciably transformed to perfluoroalkyl acids within the WWTPs, as influent and effluent precursor concentrations via the TOP assay were statistically identical. Evaluation of semi-quantified PFAS, consistent with results of the TOP assay, showed the presence of several classes of precursors in the influent, effluent, and biosolids; perfluorophosphonic acids (PFPAs) and fluorotelomer phosphate diesters (di-PAPs) occurred in 100 and 92% of biosolid samples, respectively. Analysis of mass flows showed that, for both quantified (on a fluorine mass basis) and semi-quantified PFAS, the majority of PFAS exited WWTPs through the aqueous effluent compared to the biosolids stream. Overall, these results highlight the importance of semi-quantified PFAS precursors in WWTPs, and the need to further understand the impacts of their ultimate fate in the environment.
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Magnesium batteries are a promising alternative to lithium-ion batteries due to the widespread abundance of magnesium and its high specific volumetric energy capacity. Ethereal solvents such as ...tetrahydrofuran (THF) are commonly used for magnesium-ion electrolytes due to their chemical compatibility with magnesium metal, but the volatile nature of THF is a concern for practical application. Herein, we investigate magnesium bis(hexamethyldisilazide) plus aluminum chloride (Mg(HMDS)2-AlCl3) electrolytes in THF, diglyme, and tetraglyme at varying temperature. We find that, despite the higher thermal stability of the glyme-based electrolytes, THF-based electrolytes have better reversibility at room temperature. Deposition/stripping efficiency is found to be a strong function of temperature. Diglyme-based Mg(HMDS)2-AlCl3 electrolytes are found to not exchange as quickly as THF and tetraglyme, stabilizing AlCl2 + and facilitating undesired aluminum deposition. Raman spectroscopy, 27Al NMR, and mass spectrometry are used to identify solution speciation.
Poly- and perfluoroalkyl substances (PFASs) are a class of fluorinated chemicals that are utilized in firefighting and have been reported in groundwater and soil at several firefighter training ...areas. In this study, soil and groundwater samples were collected from across a former firefighter training area to examine the extent to which remedial activities have altered the composition and spatial distribution of PFASs in the subsurface. Log K oc values for perfluoroalkyl acids (PFAAs), estimated from analysis of paired samples of groundwater and aquifer solids, indicated that solid/water partitioning was not entirely consistent with predictions based on laboratory studies. Differential PFAA transport was not strongly evident in the subsurface, likely due to remediation-induced conditions. When compared to the surface soil spatial distributions, the relative concentrations of perfluorooctanesulfonate (PFOS) and PFAA precursors in groundwater strongly suggest that remedial activities altered the subsurface PFAS distribution, presumably through significant pumping of groundwater and transformation of precursors to PFAAs. Additional evidence for transformation of PFAA precursors during remediation included elevated ratios of perfluorohexanesulfonate (PFHxS) to PFOS in groundwater near oxygen sparging wells.
Cross-linked ionomer networks of varying poly(ethylene glycol) diacrylate cross-linker chain length, ionic comonomer chemistry, and comonomer ratio have been studied for their use as polysulfide ...shuttle inhibiting separators in magnesium–sulfur (Mg–S) batteries. Through the use of X-ray scattering, polysulfide diffusion experiments, conductivity measurements, and Mg–S cell cycling, it was determined that inclusion of tethered anions in polymer networks mitigates the polysulfide shuttle effect. Polysulfide crossover through networks into a bulk electrolyte can be reduced by absorption into the polymer gel, steric rejection, and electrostatic rejection, with the predominance of these mechanisms dictated by polymer composition and structure. The best network composition allowed an initial Mg–S cell discharge capacity of 522 mAh/g compared to a discharge capacity of 365 mAh/g using a literature standard glass fiber separator. The ionomer cell saw 67% capacity retention after three cycles, whereas the glass fiber separator could not complete the first charging cycle due to the polysulfide shuttle.
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