Flexible and Stretchable Lithium Ion Batteries Using Fabric-Based Electrodes and Solid Polymer Electrolyte

Date

2018-05

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Abstract

The development of stretchable and wearable energy storage devices including lithium ion batteries are strongly motivated by tantalizing applications such as smart garments, wearable communication, flexible display devices, and medical implants. Such lithium ion batteries require a stable performance while experiencing mechanical deformations such as bending, stretching, compression, and twisting. Therefore, in addition to mechanical flexibility, the batteries need to be ideally stretchable. Although there has been a noticeable progress in developing flexible and stretchable energy storage devices such as supercapacitors and solar cells, a similar technical maturity has not yet been achieved in stretchable lithium ion batteries. Current designs generally suffer from many problems including low energy and/or power density, limited deformability, poor stability in stretched configurations, short cycle life, and presence of large amounts of toxic and flammable liquid electrolytes. Furthermore, most reported designs rely on stretchable architectural designs using one or more rigid components and do not demonstrate stretchability of the entire device. The focus of this dissertation is the development and characterization of a flexible and stretchable lithium ion battery that meets the requirement of stretchability of each and all the components of the battery including electrodes, electrolyte, and encapsulation. The lithium ion battery in this study is developed in the view of eventual integration in flexible and stretchable smart textile applications. The study initially investigates the feasibility of using a stretchable fabric as a current collector and a platform for a stretchable electrode in lithium ion batteries. The inherently electrically conductive silver fabric is demonstrated as a viable choice for fabric-based stretchable electrodes. Stretchable silver-fabric LiCoO2 cathode and graphite anode are fabricated and their mechanical and electrochemical properties are characterized. The compatibility of the developed electrodes with a stretchable solid polymer electrolyte (i.e. poly(ethylene oxide) is investigated and the amount of the required liquid electrolyte to achieve a desirable discharge capacity is optimized. Furthermore, fabrication and characterization of a fully flexible and stretchable fabric-based lithium ion battery is reported. The stretchable lithium ion battery composed of silver fabric LiCoO2 cathode and graphite anode, poly(ethylene oxide) solid polymer electrolyte, and an elastic encapsulation. Both the electrochemical and mechanical performances of the fabric-based stretchable lithium ion battery are presented and discussed.

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Keywords

Stretchable, Batteries, Lithium-ion batteries (LIB)

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