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

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 10C. 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.