Achievement of Advanced Alkaline Ni-Zn Batteries with Good Durability and High Areal Capacity of 10 Mah Cm -2  Via the Synergistic Regulation of Dual Electrolyte Additives

Abstract

Though obvious advantages in terms of safety, cost, green and electrochemical performance (mainly concerned with power and energy density, and temperature compatibility) accompanied by long history, the widely application of alkaline Ni-Zn batteries, a number of traditional aqueous batteries, is still under great restrictions owing to the poor durability (commonly lower than 100 cycles). In this work, an effective electrolyte modification process using dual additives of hydroxy-rich carboxymethyl cellulose (CMC) that can inhibit hydrogen evolution reaction (HER) and suppress Zn dendrites, and benzyltrimethylammonium bromide (BTMAB) that can mitigate passivation and oxygen evolution reaction (OER) is developed. Meanwhile, our home made C coated ZnO (ZnO@C) microspheres were used as initial anode materials without the using of any other expensive composites. With a fixed areal charge capacity of 10 mAh cm-2, the flat type full cell matched with commercial Ni(OH)2 cathode can deliver a high average discharge capacity of ~9.6 mAh cm-2 (corresponding to an average CE of 96%) for a long lifespan of over 390 cycles, which drops to 8.2 mAh cm-2 at 400th cycle accompanied by a sudden polarization rising. The cumulative discharge capacity of the full cell can reach ~4000 mAh cm-2 in 420 cycles’ cycling, much larger than that using commercial Zn/ZnO anode and the ZnO@C anode in unmodified or single additive modified electrolyte (less than 1500 mAh cm-2).

Keywords: Alkaline Ni-Zn batteries, Dendrite free, Carboxymethyl cellulose, Quaternary ammonium