Evaluation of carbon cryogels used as cathodes for non-flowing zinc–bromine storage cells

Monolithic megaloporous carbon cryogels were examined for their potential applications as cathodic electrodes in secondary zinc–bromine cells. This work investigates the possibility of using their particular macroporous texture as microscopic bromine tanks in a zinc/bromine battery. The electrochemical behaviour of a cell based upon such a Br2 electrode was studied and discussed in terms of energy yields, energy storage capability and cycle life. Good storages (over 20 Wh kg−1) could be obtained during the first 2 h of cell charging for currents between 10 and 20 mA g−1. The energy yield remains almost constant during a fairly large number of cycles, basically for weak charges (e.g. 25 C g−1). Our findings show that the good cyclability of the cathodic electrode is a consequence of the liquid state of the active bromine phase.