Vanadium flow battery adapts to temperature

Insufficient thermal stability of vanadium redox flow battery (VRFB) electrolytes at elevated temperatures (>40 °C) remains a challenge in the development and commercialization of this technology, which otherwise presents a broad range of technological advantages for the long-term storage of intermittent renewable energy.

A schematic of a vanadium flow battery is depicted in Figure 1, in which two external tanks are used to carry vanadium ions in their various oxidation states (V 2+, V 3+, VO 2+, and VO 2+) with one redox pair present in each tank.

Xi J, Jiang B, Yu L, Liu L (2017) Membrane evaluation for vanadium flow batteries in a temperature range of −20–50 °C. J Membrane Sci 522:45–55 Ye Q, Shan TX, Cheng P (2017) Thermally induced evolution of dissolved gas in water flowing through a carbon felt sample. Int J Heat Mass Transf 108:2451–2461

The stability of the vanadium electrolyte is also highly dependent on the temperature. Temperatures above 40 °C in the positive electrolyte and below 10 °C in the negative electrolyte commonly induce formation of solid V 2 O 5 and VSO 4 precipitates, respectively. [ 2]

This dependence is of critical importance during battery operation; since the SOC of the solution for each half-cell electrolyte could be changed, the vanadium concentrations may differ accordingly because of the ionic diffusion processes across the membrane and thus the solution conductivities vary.

Authors to whom correspondence should be addressed. These authors contributed equally to this work. The vanadium flow batteries that employ the vanadium element as active couples for both half-cells, thus avoiding cross-contamination, are promising large-scale energy storage devices.