Nanofibers for Energy Storage and Conversion Laboratory

We have two primary research thrusts in our group. We seek to understand the science of equilibrium and non-equilibrium material assembly under external fields such as extensional flow and nano-confinement using both experiments and computational modeling and simulations. We seek to develop unique design strategies to achieve material architectures that provide novel combinations of functionalities and simultaneous transport of multiple species with the aim to develop efficient energy storage and conversion devices such as supercapacitors, batteries and fuel cells.

I. Study of Material Assembly under External Fields

In this research thrust, we combine experiments and computational modeling and simulations to study self-assembly in novel polymeric materials under deformation (extensional flow and shear flow) and/or nano-confinement. For example, in one specific project, we used molecular dynamics simulations to study the morphology and kinetics of phase separation in immiscible binary polymer blends under elongational flow, a flow type that is relatively difficult to study due to the complexity arising from the shrinking dimension. This study is of fundamental significance in the optimization of elongational flows in the nanofiber fabrication process (electrospinning) used in our lab to develop high-performing energy devices, as well as many industrial processes, such as fiber spinning, blow molding, and biaxial stretching of extruded sheets (J Chem Phys 2014, 140, 134902). In another project, we are studying the self-assembly of conjugated block copolymers in electrospun nanofibers. We aim to particularly understand how the influence of extensional flow, rapid solvent evaporation (during electrospinning) and physical confinement (of nanofibers) on material assembly varies with chain rigidity and molecular weight. Conjugated block copolymers are interesting materials due to their significance in organic solar cells. The nanoscale assembly in such materials is critical for the enhancement of electron-hole dissociation and for the optimization of device efficiency (Soft Matter 2013, 9, 11014; Macromol. Mater. Eng. 2015, 300, 320; Macromol. Mater. Eng. 2014, 299, 1484).

II. Design of Novel Multi-Functional Materials for Energy Storage and Conversion Devices

In this research thrust, we integrate novel processing techniques – electrospinning-based such as core-shell electrospinning and dual electrospinning and non-electrospinning based such as electropolymerization and chemical deposition, to design electrode materials with unique nano-architectures and tailored surface functionalities for efficient energy storage and conversion devices. We strive to directly correlate electrode structures and surface chemistries to device performance. Our work involves material fabrication and processing, structural/spectroscopic characterization, understanding of physical and chemical phenomena related to device operation and electrochemical testing of complete devices.

Majority of the electrode materials we have developed and studied so far are based on freestanding nanofiber mats. These materials have unique advantages – they are device-ready and hence eliminate the need for binders and they possess high inter-fiber macroporosity enabling faster transport and power delivery.

Please click on the links below to learn about our work on supercapacitors and batteries.