In-Situ Dynamic Compensation Strategy Enables Jahn-Teller Effect Suppression in Zn-Doped Dual-Active-Site Copper Hexacyanoferrate Cathodes for High-Energy and Ultra-Stable Ammonium-Ion Storage.

Copper hexacyanoferrate (CuHCF) with 3D channels and high discharge plateau is widely recognized as a highly promising cathode material for ammonium-ion (NH ) storage. However, the practical application of CuHCF has faced challenges due to limited capacity and structural instability, primarily arising from single active site and serious Jahn-Teller distortions. Herein, an innovative in-situ dynamic compensation strategy is reported to prepare Zn-doping dual-active-site CuHCF (ZnCuHCF) as high-energy and ultrastable cathode materials for NH storage. Zn doping induces fission of Cu e orbitals, causing lattice to aberrate and reach stable state, while during NH intercalation process, changes mainly in Fe t electronic orbitals help maintain stability of ZnCuHCF structure. Consequently, ZnCuHCF in 23 m NHOTf + 0.5 m Zn(OTf) aqueous electrolyte exhibits high discharge potential of 0.94 V, high capacity of 121.7 mAh g at 1 A g and impressive capacity retention of 92.1% after 10 000 cycles. To highlight, fiber-shaped aqueous Zn/NH hybrid batteries based on ZnCuHCF cathode are successfully constructed, achieving admirable energy density of 85.73 mWh g and remarkable capacity retention of 85.2% after 12 500 cycles. This work paves the way for designing CuHCF with high capacity, high voltage and robust cycling stability in NH storage for applications in wearable aqueous batteries.