Direct measurement of vanadium cross-over in an operating redox flow battery

A redox flow battery (RFB) is an electrochemical energy storage device in which the storage medium is in the form of liquid electrolyte, which is stored in external reservoirs separate from the cell stack. The storage capacity of such systems is limited by the size of the external tanks, making the RFB an ideal technology for grid level energy storage. The vanadium redox flow battery (VRB) is a particularly attractive variant of the RFB, due to its use of a single transition-metal element in both the positive and negative electrolytes. However, the performance of the VRB is affected by the cross-over of electrolytes through the ion-exchange membrane which separates the positive and negative electrolytes. Cross-over causes degradation of energy storage efficiency and long term capacity loss. Previous studies of ion cross-over have focused primarily on the measurement of ion diffusion across ion exchange membranes in the absence of electrical current. In this work a novel VRB cell is described in which ion cross-over can be measured directly in the presence and absence of electrical current. Measurements are made of cross-over using this cell with three different types of ion exchange membrane in both charge and discharge modes. The results reported in this work show that the rate of ion cross-over can be greatly enhanced or suppressed depending upon the magnitude of the current flow and its direction relative to the ion concentration gradient.

Name thesis:degree_name

Master of Science in Engineering

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Materials Science and Engineering

Grantor

The University of Texas at Austin

Year dc:date.issued

2013

Author dc:creator

• Sing, David Charles

Advisors dc:contributor.advisor

• Manthiram, Arumugam
• Meyers, Jeremy P.

• Redox flow batteries
• Vanadium redox flow batteries
• Electrical energy storage
• Membrane cross-over
• Cation-exchange membranes

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/2152/22228

OAI identifier oai:identifier

oai:repositories.lib.utexas.edu:2152/22228