High-voltage K/Zn dual-ion battery with 100,000-cycles life using zero-strain ZnHCF cathode

Abstract

Rechargeable zinc-based batteries (RZBs) using low-cost zinc metal anodes are feasible for large-scale energy storage, but the developments currently are restricted by the poor performances. Here we constructed a particular dual-ion battery (DIB) based on zinc hexacyanoferrate (ZnHCF) cathode, zinc metal anode, and non-aqueous K+/Zn2+ hybrid ions electrolyte. It was revealed that K+-ions occupied almost all the cavities in ZnHCF at high voltage over 1.7 V (vs. Zn2+/Zn), which effectively blocked Zn2+-ions insertion. The ZnHCF showed a zero-strain characteristic during the repeated K+-ions intake/removal. Meanwhile, the charge screening effect of additive K+-ions on optimizing the zinc electrodeposition process ensured the reversible and dendrite-free Zn plating/stripping. The DIBs demonstrated excellent rate performances (57 and 47 mAh gcathode‒1 at 2000 and 5000 mA g‒1, respectively) and incredibly 100,000-cycles life with 74% capacity retention.