Semi-flowable Zn semi-solid electrodes as renewable energy carrier for refillable Zn–Air batteries

Abstract

Today's society relies on energy storage on a day-to-day basis, e.g. match energy production and demand from renewable sources, power a variety of electronics, and enable emerging technologies. As a result, a vast range of energy storage technologies has emerged in the last decades. Among them, rechargeable Zn–Air batteries have held great promises for a long time. However, the severe challenges related to the reversible O2 reactions and poor cyclability at the positive and negative electrodes, respectively, have severely hindered the success of this technology. Herein, electrically-conducting and semi-flowable Zn semi-solid electrodes are proposed to revive the appealing concept of a mechanically–rechargeable alkaline Zn–Air battery, in which the spent negative electrodes are easily substituted at the end of the discharge process (refillable primary battery). In this proof-of-concept study energy densities of ca. 1500 Wh L−1 (1350 Ah Lelectrode−1 and utilization rate of 85%) are achieved thanks to the compromised flowability of the proposed Zn semi-solid electrodes. In this way, semi-solid Zn electrodes become a type of green energy carrier having intrinsic advantages over gas and liquid fuels. Zn semi-flowable electrode can be generated elsewhere using renewable sources, easily stored, transported, and used to produce electricity.