High transition kinetics enabling high Zn utilization for high-capacity and long-lifespan nickel-zinc battery

Abstract

Aqueous nickel-zinc (Ni-Zn) battery is one promising grid energy storage device owing to its high theoretical energy density, high safety and low cost. However, the large-scale commercialization of Ni-Zn battery is significantly hindered by its low practical energy density and poor cycle lifespan caused by the low reversibility and transition kinetics between the metallic Zn and ZnO with low Zn utilization. To address these issues, a type of hierarchical porous Indium-doping ZnO micro-bowls (In-ZnO) is constructed through an in-situ chemical corrosion strategy. The abundant voids and pores facilitate the ionic transport, and simultaneously accommodate the volumetric expansion during the electrochemical transition between metallic Zn and ZnO. Density functional theory calculations further reveal that In-ZnO achieves the enhanced electrical/ionic conductivity and improved adsorption to OH–, accelerating the solid–liquid transitions of Zn-Zn(OH)42- and Zn(OH)42--ZnO, as well as the solid–solid transition of Zn-ZnO. Simultaneously, the Indium-doping inhibits the hydrogen evolution and passivation. Ascribed to the synergetic effect of the hierarchical porous structure and Indium-doping, the In-ZnO electrode demonstrates ultra-stable capacity retention of 98.6% over 1000 cycles at 9 A g-1 under 92.3% Zn utilization, and high capacity of 590.2 mAh g-1 even at high current density of 36 A g-1.