A High‐Voltage n‐type Organic Cathode Materials Enabled by Tetraalkylammonium Complexing Agents for Aqueous Zinc‐Ion Batteries

Abstract Tetrabutylammonium (TBA) salt of hexacyano‐substituted cyclopropane dianion (Cp(CN) 6 2 − ) is prepared through a facile two‐step synthetic protocol from commercially available materials and fully characterized as a high‐voltage n ‐type organic cathode in rechargeable aqueous zinc‐ion batteries (AZIBs). The addition of tetrabutylammonium triflate (TBAOTf) to the electrolyte mitigates dissolution issues, leading to enhanced cycling stability. Remarkably, the Cp(CN) 6 2 − cathode demonstrates a high discharge voltage of 1.43 V in AZIBs and retains 85% of its capacity after 1000 cycles at a high loading of 10 mg cm − 2 and a cycling rate of 10 C . These results, combined with spectroscopic analyses, elucidate a reversible two‐electron redox process of Cp(CN) 6 2 − facilitated by the insertion/de‐insertion of TBA cation. These findings underscore the potential of Cp(CN) 6 2 − as a conversion‐based n ‐type cathode in energy storage applications.