The conventional flow-through structured ICRFBs have to employ thick carbon felts (typically 3.0-6.0 mm) as the electrodes to circumvent high pump loss, which inevitably results in high ohmic resistance, low operating current densities (around 80 mA cm^-2) as well as cumbersome and costly cell stacks. Increasing the operating current density/power density is an effective strategy to reduce the cell stack size and cost. Recently, a flow-field structured ICRFB with thin carbon paper electrodes demonstrates a significantly increased operating current density of 200 mA cm^-2 at the energy efficiency of 79.6% mainly due to the reduced ohmic resistance [1]. Further enhancement of ICRFB performance is achieved by adopting the interdigitated flow fields, which enhances the active species transport at the porous electrode and enables a more uniform catalyst distribution [2]. In addition, the effects of design parameters including electrode compression ratio, electrode pretreatment intensity, membrane thickness and catalyst loading on the ICRFB charge-discharge performance have been are investigated [3]. Results show that: i) with a thin NR-211 membrane and a high electrode compression ratio of 62.5%, the operating current density of the ICRFB can reach as high as 480 mA cm^-2 at an energy efficiency of higher than 80%; ii) the bismuth catalyst loading has insignificant effect on the battery performance in the range of 0.52-10.45 mg cm^-2; iii) the moderately oxidative thermal pretreatment of the electrode improves the energy efficiency compared to the as-received electrode while the electrode prepared with a harsh pretreatment deteriorates the battery performance; and iv) for the present ICRFBs operating at both 25^oC and 65^oC, the dominant loss is identified to be ohmic loss rather than kinetics loss.

References

[1] Y.K. Zeng, X.L. Zhou, L. An, L. Wei, T.S. Zhao, A high-performance flow-field structured iron-chromium redox flow battery, J. Power Sources, 324 (2016) 738-744.

[2] Y.K. Zeng, X.L. Zhou, L. Zeng, X.H. Yan, T.S. Zhao, Performance enhancement of iron-chromium redox flow batteries by employing interdigitated flow fields, J. Power Sources, 327 (2016) 258-264.

[3] Y. Zeng, T. Zhao, X. Zhou, L. Zeng, L. Wei, The effects of design parameters on the charge-discharge performance of iron-chromium redox flow batteries, Appl. Energy, 182 (2016) 204-209.