טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentHalfon Elad Binyamin
SubjectDeveloping Electrodes Which Can Transition Between Static
and Flowable Modes
DepartmentDepartment of Energy
Supervisor Assistant Professor Matthew E. Suss
Full Thesis textFull thesis text - English Version


Abstract

The rapid rise in the world’s population and standard of living is driving a dramatic increase in both energy and clean water demand. Intense research is focused on improving technologies to desalinate water and store energy in ways that are environmentally cleaner, more energy efficient, and readily scalable. Recently flow electrodes have been studied as a means to replace standard static electrodes in electrochemical systems for storing energy or desalinating water. In redox flow batteries (RFBs), flowable electrodes have been used in order to fully decouple spatially the energy stored (in tanks) and power delivered (in the battery) for battery chemistries relying on metal electrodeposition or ion intercalation. In capacitive deionization (CDI), flowable electrodes allow for continuous desalination of the feedwater, as the particles can be discharged downstream rather than in the cell itself.  

While flowable electrodes enable important functionalities not available to static electrodes, they suffer from significantly lower electric conductivity, typically of order 1 to 10 mS/cm. This low electric conductivity significantly impedes the electrochemical processes efficiency and prevents adoption of flowable electrodes in commercial systems. To overcome this challenge, we propose a novel switchable electrode to combine the benefits of static and flowable electrodes. In the following research we have demonstrated an electrode which can be switched between a flow-through static mode and flowable mode in operando. We provide first-time measurements of the electrode’s electric conductivity as it undergoes velocity cycling and transitions between modes. The electrode achieves a gigantic conductivity of over 10,000 mS/cm while in static mode, and can be repeatedly switched between static and flowable modes. We explored the effect of interparticle forces acting in the electrode, and showed that tuning such effects allows us to tune the velocity where we observe the transition between modes. Such switchable electrodes can in the future enable novel, highly versatile electrochemical systems.