Development of semi-solid alkaline flow battery

Flow battery is an attractive energy storage system due to its ability to decouple power and energy outputs, and its less stringent geometric requirement. However, commercial flow battery technology suffers from low energy density (~z40 Wh/Lcatholyte), high membrane cost (~$ 500/M 2 and species crossover. One elegant method to overcome all this problems is utilize flowable semisolid electrode. Although there have been several reports in the literature regarding performance of various semi-solid flow batteries, there is still lack of understanding on how to design the suspension electrode and its impact on flow cell design and performance. In this thesis, we emphasize on three main properties, namely stability, conductivity and flowability for high performing suspension electrode for Zn-Ni alkaline battery chemistry. Firstly, we recognized interplay of forces acting on particles in a suspension electrode and designed suspending medium with jammed Carbopol© microgel structures to prevent sedimentation of the large particles. Secondly, we determined percolation threshold of conductive additive and investigated its effect on electrochemical performance of the semi-solid electrodes in a closed static cell. We found that conductive additive concentration should be well above percolation threshold to obtain maximum discharge capacity of Ni(OH)2. Thirdly, based on the understanding from conductivity and stability of the suspension, we designed catholyte (~ 5 M Ni(OH)2) and tested its electrochemical performance in a static cell. We were able to achieve energy density of 137 Wh/Latholyte, about 3 times of commercial flow battery. We then assessed flowability of the suspensions. Catholyte and anolyte had yield stress of 204 Pa and 447 Pa respectively. We found that by choosing appropriate flow cell stack design energy loss due to pumping can be minimized to < 1% for continuous flow. Finally, flow cells were designed to test the electrochemical performance of these suspensions in an open system.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2018

Author dc:creator

• Narayanan, Thaneer Malai

Advisor dc:contributor.advisor

• Yang Shao-Horn.

• Mechanical Engineering.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/120228

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/120228