Novel electrolytes
are required for the commercialization of batteries
with high energy densities such as lithium metal batteries. Recently,
fluoroether solvents have become promising electrolyte candidates
because they yield appreciable ionic conductivities, high oxidative
stability, and enable high Coulombic efficiencies for lithium metal
cycling. However, reported fluoroether electrolytes have similar molecular
structures, and the influence of ion solvation in modifying electrolyte
properties has not been elucidated. In this work, we synthesize a
group of fluoroether compounds with reversed building block connectivity
where ether moieties are sandwiched by fluorinated end groups. These
compounds can support ionic conductivities as high as 1.3 mS/cm (30
°C, 1 M salt concentration). Remarkably, we report that the oxidative
stability of these electrolytes increases with decreasing fluorine
content, a phenomenon not observed in other fluoroethers. Using Raman
and other spectroscopic techniques, we show that lithium ion solvation
is controlled by fluoroether molecular structure, and the oxidative
stability correlates with the “free solvent” fraction.
Finally, we show that these electrolytes can be cycled repeatedly
with lithium metal and other battery chemistries. Understanding the
impact of building block connectivity and ionic solvation structure
on electrochemical phenomena will facilitate the development of novel
electrolytes for next-generation batteries.
Cross-linked polymer electrolytes containing structurally dynamic disulfide bonds have been synthesized to investigate their combined ion transport and adhesive properties. Dynamic network polymers of varying cross-link densities are synthesized via thiol oxidation of a bisthiol monomer, 2,2′-(ethylenedioxy)diethanethiol, and tetrathiol cross-linker, pentaerythritol tetrakis(3-mercaptopropionate). At optimal loading of lithium bis(trifluoromethane-sulfonyl-imide) (LiTFSI) salt, the ionic conductivities (σ) at 90 °C are about 1 × 10 −4 and 1 × 10 −5 S/cm at the lowest and highest cross-linking, respectively. Notably, in comparison to the equivalent nondynamic network, the dynamic network shows a positive deviation in σ above 90 °C, which suggests the enhancement of ion transport occurs from the difference in structural relaxation on account of the dissociation of disulfide bonds. Lap shear adhesion and conductivity tests on ITO-coated glass substrates reveal the dynamic network exhibits a higher adhesive shear strength of 0.2 MPa (vs 0.03 MPa for the nondynamic network) and higher σ after the application of external stimulus (UV light or heat). The adhesive strength and σ are stable over multiple debonding/rebonding cycles and, thus, demonstrating the utility of these structurally dynamic networks as solid polymer electrolyte adhesives.
Bisphenol A or BPA is a ubiquitious industrial chemical found in a variety of plastic containers intended for food storage and in the epoxy resin linings of metal food and beverage cans, where it is used to prevent corrosion, food contamination, and spoilage. BPA has been recently linked to a wide variety of medical disorders and is known to have estrogenic activity with genomic as well as non-genomic estrogen-receptor mediated effects. Given rapidly increasing prevalence rates of metabolic disorders like obesity and Type 2 diabetes, BPA has recently come under intense scrutiny in scientific and lay communities as a potential endocrine disrupting compound with diabetogenic effects. The purpose of this review is to critically examine available literature investigating the link between BPA and alterations in metabolic health. Here, we discuss typical levels of exposure to BPA in daily life and analyze both epidemiological human data and mechanistic preclinical studies that have tested associations between BPA and obesity and diabetes. Finally, we summarize the current policies and views of national and international regulatory agencies regarding the safety of BPA use.
Carbonate-based electrolytes are widely used in Li-ion batteries but are limited by a small operating temperature window and poor cycling with silicon-containing graphitic anodes. The lack of non-carbonate electrolyte alternatives...
Amorphous Li3PS4 (LPS) solid-state electrolytes are promising for energy-dense lithium metal batteries. LPS glasses, synthesized from a 3:1 mol ratio of Li2S and P2S5, have high ionic conductivity and can...
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