An experimental and theoretical investigation of electrospun Newtonian and viscoelastic jets is presented. In particular, the effect of electrical conductivity and viscoelasticity on the jet profile during the initial stage of electrospinning is examined. In the theoretical study, the fluid is described as a leaky dielectric with charges only on the jet surface and viscoelastic models for polymer solutions such as Oldroyd-B and FENE-P are fully coupled with the fluid momentum equations and Gauss’ law. A theoretical model for the jet is derived using a thin filament approximation, and the resulting differential equations governing electrically charged, stable polymeric jets are solved numerically. Two different experimental systems are considered: Newtonian solutions of glycerol containing trace amounts of lithium chloride salt, and viscoelastic PIB/PB Boger fluid solutions. The experimental jet profiles from electrospinning experiments are compared with the model predictions. Our results reveal that increasing the electrical conductivity of the fluid by adding salt tends to delay the jet thinning. Increasing the fluid viscoelasticity causes a more rapid initial jet thinning, however further away from the spinneret viscoelastic jets are thicker than their Newtonian counterparts due to the higher elongational viscosity. We also investigate whether the general trends observed for these fluids can be applied to predict the qualitative behavior for the spinning of other fluid systems such as PEO/water solutions that have high conductivity and viscoelasticity.

Aqueous zinc batteries are attracting interest because of their potential for cost-effective and safe electricity storage. However, metallic zinc exhibits only moderate reversibility in aqueous electrolytes. To circumvent this issue, we study aqueous Zn batteries able to form nanometric interphases at the Zn metal/liquid electrolyte interface, composed of an ion-oligomer complex. In Zn||Zn symmetric cell studies, we report highly reversible cycling at high current densities and capacities (e.g., 160 mA cm⁻²; 2.6 mAh cm⁻²). By means of quartz-crystal microbalance, nuclear magnetic resonance, and voltammetry measurements we show that the interphase film exists in a dynamic equilibrium with oligomers dissolved in the electrolyte. The interphase strategy is applied to aqueous Zn||I₂ and Zn||MnO₂ cells that are charged/discharged for 12,000 cycles and 1000 cycles, respectively, at a current density of 160 mA cm⁻² and capacity of approximately 0.85 mAh cm⁻². Finally, we demonstrate that Zn||I₂-carbon pouch cells (9 cm² area) cycle stably and deliver a specific energy of 151 Wh/kg (based on the total mass of active materials in the electrode) at a charge current density of 56 mA cm⁻².

A general approach for fabricating free-standing metal sulfide and carbon nanofiber mats is developed via electrospinning, starting with cheap and abundant raw materials. The prepared free-standing samples have metal sulfide nanoparticles dispersed throughout the interconnected carbon fibers. When applied to LIB, the composites demonstrate excellent cyclability and rate capability.