Hybrid high-performance aqueous batteries with potassium-based cathode||zinc metal anode

Aqueous potassium-based batteries (APBs) have been widely studied for their high safety and environmentally friendly properties. However, given the limitation of the electrode material and working mechanism, the APBs need further improvement in terms of the rate performance and energy density to meet the development requirements. To address the above issues, we successfully designed and assembled APBs, for the first time using Zn metal as the anode, K1.92Cu0.62Mn0.38[Fe(CN)6]0.968·□0.032·0.35H2O as the cathode, and 2 mol L−1 Zn(SO3CF3)2 + 12 mol L−1 KSO3CF3 as the electrolyte. This hybrid-ion-battery (HIB) design offers benefits including the following: (i) improvement of the working potential of APBs by selecting Zn metal as the anode, (ii) shortened ion transport path due to the dual-cation storage mechanism, and (iii) inhibition of the growth of zinc dendrite through the electrostatic shielding effect enabled by K+, which originated from the dual-cation electrolyte. As a result, the as-assembled full battery had a high working potential of 1.75 V and excellent rate performance (83.3% of original capacity was maintained at the current density of 10,000 mA g−1). Furthermore, the in-situ electrostatic shielding effect, which can significantly inhibit the dendrite growth of the Zn anode and improve the stability of the full battery, was fully revealed by theoretical phase-field simulation and comprehensive characterizations. The fascinating structure design of HIBs sheds light on the development of high-performance APBs.