Toward stable zinc aqueous rechargeable batteries by anode morphology modulation via polyaspartic acid additive

Zn metal has been regarded as one of the most promising metal anodes for aqueous batteries, but it still suffers from undesirable dendrites growth and serious side-reaction during cycling. So far, various additives have been developed to achieve uniform deposition of zinc, but they have failed to fundamentally overcome intrinsic fragile morphology of the deposited metallic zinc. Herein, the polyaspartic acid (PASP) was introduced into aqueous electrolyte to cope with the problems in two aspects. One is to modulate the morphology of deposited metallic Zn from large, fragile and loosely piled platelets to small and homogeneous spherical particles, to achieve dendrite-free Zn deposition by PASP additive. On the other hand, the ability to resist the side-reaction on Zn anode can be significantly improved via PASP additive. Both ensure the cyclic stability and high Coulombic efficiency (CE) during the reversible Zn plating and stripping. With the addition of PASP, Zn || Zn symmetrical cells can stably cycle over 3200 h at 0.5 mA cm−2 and 2000 cycles at 20 mA cm−2, while Zn || V2O5 full cells can maintain a CE of nearly 100% for 2500 cycles at 10 A g−1. We believe that the use of PASP as electrolyte additive is a feasible approach for practical applications of the aqueous rechargeable zinc batteries in the future.