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 Br-2 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. (c) 2007 Elsevier B.V. All rights reserved.