[CCoE Notice] Thesis Defense Announcement: Flexible and Stretchable Lithium-Ion Batteries Based on Solid Polymer Nanocomposite Electrolyte

[Grayson, Audrey A]

Flexible and Stretchable Lithium-Ion Batteries Based on Solid Polymer Nanocomposite Electrolyte
Mejdi Kammoun
Defense Date: Monday, December 5th   2016
Time: 9:00AM
Location: Large Conference Room ME Department
Committee members: Dr. Haleh Ardebili, Dr. Yashashree Kulkarni, Dr. Jae-Hyun Ryou, Dr. Dong Liu, Dr. Yan Yao
Abstract
The prevalence of flexible electronics including the ubiquitous touch-screens, roll-up displays, implantable medical devices and wearable sensors has motivated the development of high performance flexible energy storage devices. High energy density lithium-ion batteries (LIBs) are the leading candidates to convert into flexible and stretchable batteries to integrate with the flexible and stretchable applications. The ultimate challenge is to obtain mechanical flexibility while conserving the high electrochemical performance of conventional LIBs including high capacity and cycling stability.
In this study, two types of polymer nanocomposite electrolytes are investigated for battery and fuel cell applications. The first polymer studied is based on Nafion, and a key problem in PEMFCs is the dehydration of Nafion and the subsequent low performance especially at higher temperatures. We introduced a bio-friendly coconut shell activated carbon (AC) nanoparticles into the Nafion membranes. We showed that a small amount (i.e. 0.7%) of AC nanofillers could dramatically enhance proton conductivity without significantly compromising the mechanical properties.
The second type of polymer for lithium-ion battery application is based on the polyethylene oxide (PEO)|Li salt system. It offers enhanced safety, stability and thin-film manufacturability compared to the traditional organic liquid electrolytes. The electrochemical properties of the pure polymer are improved by adding 1% graphene oxide (GO) nanosheets. We developed a high performance flexible Li ion battery based on the solid polymer nanocomposite electrolyte.  The flexible battery exhibits a capacity higher than 0.1 mAh/cm2 at 1 mA current and excellent cycling stability over 100 charge/discharge cycles.
PEO/GO electrolyte was also incorporated in a novel design of spiral stretchable battery capable of large out-of-plane deformation. The spiral Li-ion battery displays robust mechanical stretchability and an energy density of 4.862 mWh/cm3 at 650% out-of-plane deformation and provides an average capacity above 0.1 mAh/cm2 in different stretching configurations.
We also investigated the temperature effects on solid polymer electrolyte based batteries. A 1-D LIB model that predicts the discharge behavior of coin cell batteries at different temperatures was developed. The modeling simulations based on electrochemical-thermal coupling show good agreement with experimental results and provide fundamental insights on the battery operation at different conditions.
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