2019
2018
Nanoconfined Polymer Electrolytes for Rechargeable Thin Film Lithium-ion Batteries
Liquid solutions of lithium salts are widely used as the electrolytes for rechargeable lithium-ion batteries. A long-proposed alternative replaces the liquid electrolyte with a solid polymer ion-conductor, which reduces flammability, enhances mechanical integrity and eases the manufacturing of arbitrarily-shaped flexible devices. We explore the properties of solid polymer electrolytes (SPE) under nanoconfinement, using flexible-device-compatiable fabrication techniques. We present studies of model ionic conduction devices made by confining polyethylene oxide (PEO)-based electrolytes within nanometer-scale volumes fabricated by high-resolution lithography and plasma etching. We are investigating this system for its potential to provide high ionic conductivity and strong barrier properties for battery applications. We fabricated cylindrical and trench-like (grating) nano-templates using both interference lithography and electron-beam lithography, with controllable feature sizes ranging from ~200 nm to as small as ~20 nm; these nano-architectures are then controllably filled with PEO incorporating lithium salts. We characterize the nanoconfined SPE with synchrotron grazing-incidence wide-angle X-ray scattering (GIWAXS) studies.
2017
Nanoconfined Polymer Electrolytes for Rechargeable Thin Film Lithium-ion Batteries
The electrolyte is a critical component in rechargeable lithium-ion batteries, which largely determines device lifespan and performance. The high volatility and reactivity of the salts and solvents in contemporary liquid-state electrolytes are not only prone to performance decay but also raise safety concerns. A long-proposed solution replaces the liquid battery electrolyte with a solid polymer ion-conductor. The high rigidity of solid electrolytes enhances the mechanical integrity of the device, improving damage resistance. We are pursuing nanoconfinement as an approach for strengthening solid polymer electrolytes. We present studies of model ionic conduction devices made by confining polyethylene oxide (PEO) within nanometer-scale volumes fabricated by high-resolution lithography and plasma etching. We are investigating this system for its potential to provide high ionic conductivity and strong barrier properties for battery applications. We fabricated cylindrical and trench-like (grating) nano-templates using both interference lithography and electron-beam lithography, with controllable feature sizes ranging from ~200 nm to as small as ~20 nm; these nano-architectures are then controllably filled with PEO incorporating lithium salts. We compare measurements of the nanoconfined ionic conductivity with the molecular structure obtained via synchrotron grazing-incidence wide-angle X-ray scattering (GIWAXS) studies.