Design of iron‐based Prussian blue analogues via transition metal incorporation for aqueous Ni–Zn batteries

Nickel‐zinc aqueous batteries have great potential for application in the field of advanced energy storage and conversion due to their environmental‐friendliness, high safety, and ideal output voltage (~ 1.75 V). Herein, Fe‐PBA, NiFe‐PBA, and NiCoFe‐PBA are synthesized by a facile coprecipitation strategy, and the structure of NiCoFe‐PBA is optimized by modulating the doping ratios of Ni 2+ and Co 2+ . Compared with other PBA materials, the unique crystal structure of NiCoFe‐PBA‐3 provides a stable framework. During the charge and discharge cycles, it provides sufficient channels for the rapid diffusion of zinc ions (Zn 2+ ), reduces the ion diffusion resistance, and enhances the reaction kinetics. Specifically, the assembled NiCoFe‐PBA‐3//Zn battery exhibits the satisfactory performance in aqueous electrolyte: The maximum energy density is 0.23 mWh cm −2 and the peak power density is 16.56 mW cm −2 . The presence of multiple metal centers in NiCoFe‐PBA leads to an enhanced electronic conductivity. The multiple metal centers in NiCoFe‐PBA, which improves its conductivity and thereby increases the overall capacity of the battery. This work provides new ideas for designing PBA materials for high‐efficiency electrochemical devices.