(6ct) Characterization of Conducting Polymers for Lithium Battery, Transistor, Thermoelectric Applications

Authors: 
Patel, S. N., University of California, Santa Barbara

My Ph.D. research at UC Berkeley under the advisement of Prof. Nitash Balsara involved the synthesis and characterization of simultaneous electronic and ionic conducting block copolymers (P3HT-block-PEO) for lithium battery electrodes.  Block copolymers can self-assemble and form co-continuous nanoscale domains, which are necessary for enabling redox reactions of the active material (LiFePO4).  In addition, the block copolymer serves as a binder to hold the redox-active material particles together. This simplifies the electrode design as one material serve both binding and charge transport functions.  The application of this material in a lithium battery with LiFePO4 showed specific capacity reaching the theoretical limit and with minimal capacity fade after ten cycles, thus demonstrating feasibility of P3HT-b-PEO as a conductive binder material.  Furthermore, the ability of the conductive binder to switch between electronically conducting and insulating states in the positive electrode provides an unprecedented route for automatic overdischarge protection within the battery.  This is in stark contrast to traditional lithium ion batteries where external electronics is used to provide overdischarge protection.

My current research as postdoctoral researcher at UC Santa Barbara (since May 2013) focuses on structure-property relationships of semiconducting polymers for organic field-effect transistors (OFETs) and organic thermoelectrics.  One of the research directions under the advisement of Prof. Ed Kramer has been the structural characterization of aligned semiconducting polymers where the measured mobility has been greater than 20 cm2/Vs.  A combination X-ray scattering and electron microscopy techniques provides evidence for exceptional alignment of the polymer chains. This allows for an efficient intrachain charge transport between source/drain contacts, thus resulting in the measured high mobility.  Another research direction under the advisement of Prof. Michael Chabinyc has focused on how various processing conditions effect the thermoelectric properties (Seebeck coefficient, electronic conductivity, and thermal conductivity) of highly doped semiconducting polymers.          

My Ph.D. and postdoctoral research provides a unique background in electrochemistry, polymer physics, and solid-state physics which have been applied to lithium batteries, organic transistors, and organic thermoelectrics.   My proposed research will build upon my diverse Ph.D. and postdoctoral research background.  The foundation of my research group will focus on the versatility of conductive polymers for not only energy storage and conversion applications, but topics branching away from previous research applications.

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