Rechargeable alkaline zinc batteries: Progress and challenges

The ever-growing demands for energy storage motivate the development of high-performance batteries. Rechargeable alkaline Zn batteries get increasing attractions due to their remarkable performance, high safety, low cost, and environmental friendliness. However, the research is in the early stage with challenges that hinder the road of commercialization, such as the unsatisfactory utilization of active materials and poor stability. Recently, some excellent works are performed to boost the development of alkaline Zn batteries from the electrode optimization to electrolyte exploration and structure design. Herein, this article provides a timely spotlight on the breakthroughs in the performance and structure of well-developed Zn batteries such as Zn-Ag and Zn-Ni batteries, as well as some new types of Zn batteries like Zn-Co, Zn-Cu, and Zn-Bi batteries. The reaction mechanisms of different positive electrodes are first introduced, followed by the summary on positive electrodes, Zn electrodes, and electrolytes. Moreover, current issues and possible strategies are also highlighted.