Project Targets

Main target of the joint research project is the development of the key technologies for the cost-effective manufacturing of a micro tubular redox flow battery with increased energy and power density for stationary appliances. The suitability of planar All Vanadium Redox Flow Batteries (VRB) for this purpose has been shown in various demonstrational projects. The comparatively low energy density (max. potential: 37.5 Wh/kg [1]) of the VRB as well as the cost intensive manufacturing of planar cell stacks require significant improvements as a prerequisite for a broad market entrance. To achieve these goals, in this project the fluid electrolyte of the VRB on the cathode shall be replaced by an air/water steam electrode (where air resp. water is taken from the surrounding). Thus the energy density might basically be doubled compared to a VRB. To achieve a better cost effectiveness, a micro tubular cell structure will be developed.

Redoxreactions during charging of VLRFB

Positive halfcell:

2H2O -> 4H+ + O2 + 4e-

Negative halfcell:

4V3+ + 4e- -> 4V2+

Redoxreactions during discharge

Positive halfcell:

4H+ + O2 + 4e- -> 2H2O

Negative halfcell:

4V2+ -> 4V3+ + 4e-

Standard cell voltage:

E0= E0Luft/H2O - E0V2+/V3+

E0= 1,23V - (-0,26V) = 1,49V


[1] Rahman F, Skyllas‐Kazacos M. Vanadium redox battery: Positive half‐cell electrolyte studies. J Power Sources 2009; 189:1212‐19.