Highly reversible anode with Bi and ZnO dual chemistry for aqueous alkaline battery

Zn has been recognized as a promising anode material for aqueous alkaline rechargeable batteries (AARBs). However, the further development of Zn anodes suffers from uncontrollable dendrite growth, Zn corrosion and passivation in alkaline electrolyte. To address these issues, we demonstrate a Bi–ZnO hybrid composite as a stable and high-capacity anode for high-energy AARBs. The integration of Bi and ZnO can not only inherit the high capacity and suitable redox potential from ZnO, but also ensure good cycling stability by lowering the Zn nucleation overpotential and boosting the reversibility of Zn plating/stripping. Benefiting from these advantages, the Bi–ZnO anode presents higher Coulombic efficiency than ZnO anode. When employed in AARB, the Bi–ZnO anode also shows impressive durability with 101.6% capacity retention after 2000 cycles, superior to ZnO anode (20.1%). Besides, the Bi–ZnO anode exhibits a high capacity (238 mAh g−1) and energy density (214 Wh kg−1). Moreover, the reaction mechanism of Bi–ZnO anode is proved to be Bi/Bi3+ redox reaction and Zn/Zn2+ stripping/plating reaction.