Integration of Zn-Ag and Zn-Air Batteries: A Hybrid Battery with the Advantages of Both.

We report a hybrid battery that integrates a Zn-Ag battery and a Zn-air battery to utilize the unique advantages of both battery systems. In the positive electrode, Ag nanoparticles couple the discharge behaviors through the two distinct electrochemical systems by working as the active reactant and the effective catalyst in the Zn-Ag and Zn-air reactions, respectively. In the negative electrode, in situ grown Zn particles provide large surface areas and suppress the dendrite, enabling the long-term operating safety. The battery first exhibits two-step voltage plateaus of 1.85 and 1.53 V in the Zn-Ag reaction, after which a voltage plateau of 1.25 V is delivered in the Zn-air reaction, and the specific capacity reaches 800 mAh gZn-1. In addition, excellent reversibility and stability with maintaining high energy efficiency of 68% and a capacity retention of nearly 100% at 10 mA cm-2 are demonstrated through 100 cycles, outperforming both conventional Zn-air and Zn-Ag batteries. This work brings forth a conceptually novel high-performance battery, and more generally opens up new vistas for developing hybrid electrochemical systems by integrating the advantages from two distinct ones.