PNNL

Abstract

A new concept of membrane-free interfacial battery based on a biphasic system was proposed for the first time. A battery with an aqueous and a non-aqueous phase was constructed, where the electrochemical reaction occurs at the interface between the two immiscible phases. The interfacial battery can internally eliminate the use of membranes and avoid the contamination of active species. The proof-of-concept is demonstrated by a zinc-bromine flow battery. An aqueous ZnBr2 solution was used as negative electrolytes, while, Br2 in CCl4 was served as positive electrolytes. The electrochemical reactions occurred at the interface between CCl4 and water, since the Br-/Br2 couple has totally no activity in CCl4. The interfacial Zn/Br2 battery demonstrated a very impressive performance with a CE of 96% and an EE of 81% at a current density of 15 mA cm-2. The high solubility of electrolyte enables the interfacial battery with a super high energy density of 62.6 Wh/L. In addition, an excellent cycle stability of the battery was demonstrated by continuously running for more than 200 cycles. This novel membrane-free interfacial battery provides a new and promising option for economic stationary energy storage.