Achievement of advanced alkaline Ni-Zn batteries with good durability at a 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, environmental compatibility and electrochemical performance (e.g, power and energy density), the commercial application of alkaline Ni-Zn batteries, a number of traditional aqueous batteries, is still under great restrictions owing to the poor durability (commonly less 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 the appearance of a peak in the charge curve. The cumulative discharge capacity of a full cell can reach ∼4,000 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 1,500 mAh cm−2).