Abstract
The roundtrip electrochemical energy efficiency is improved from 63% to 76% at a current density of 200 mA cm-2 in an all-vanadium redox flow battery (VRFB) by utilizing modified carbon paper electrodes in the high-performance no-gap design. Heat treatment of the carbon paper electrodes in a 42% oxygen/58% nitrogen atmosphere increases the electrochemically wetted surface area from 0.24 to 51.22 m2 g-1, resulting in a 100-140 mV decrease in activation overpotential at operationally relevant current densities. An enriched oxygen environment decreases the amount of treatment time required to achieve high surface area. The increased efficiency and greater depth of discharge doubles the total usable energy stored in a fixed amount of electrolyte during operation at 200 mA cm-2.
| Original language | English |
|---|---|
| Pages (from-to) | 333-338 |
| Number of pages | 6 |
| Journal | Journal of Power Sources |
| Volume | 294 |
| DOIs | |
| State | Published - Jul 10 2015 |
Funding
The authors would like to acknowledge Dr. C.-N. Sun for assistance in capacitance measurements, N. Cantillo-Cuello for assistance with BET surface area measurements, and Drs. E.L. Redmond and D.S. Aaron for fruitful discussion. The authors would also like to acknowledge the Office of Naval Research for support of this work under Long Range Broad Agency Announcement (BAA) N00014-12-1-0887 as well as Tennessee Solar Conversion and Storage using Outreach, Research and Education (TN-SCORE; NSF EPS # 1004083 ). A portion of this work (GMV-XPS) was supported by U.S. Department of Energy's Office of Basic Energy Science (DOE-BES, DE-AC0500OR22725 ), Division of Materials Sciences and Engineering, under contract with UT-Battelle, LLC.
Keywords
- Carbon paper
- Electrode
- Kinetics
- Surface area
- Thermal activation
- Vanadium redox flow battery
