Figure 8. Reversible colour changes of another iron-based hybrid flow battery; left: discharging, right: charging

From

Colourful Chemistry – from Hybrid Flow Batteries to a Powerful Redox Flow Battery with Impressive Colour Changes for a Phenomenological Approach

Jana Novotny, Dominik Quarthal, Marco Oetken

World Journal of Chemical Education. 2019, 7(2), 120-135 doi:10.12691/wjce-7-2-12