Dual storage mechanism via hydrogen bonding and redox in 1D MOF-pillared vanadium oxide for high-performance aqueous...

Aqueous ammonium-ion batteries (AAIBs) have emerged as promising energy storage systems because of their inherent safety, low cost, and environmental friendliness, where developing high-performance electrode materials remains a critical challenge. Herein, a composite cathode material (Cu-BTA/VO) is designed and synthesized by intercalating 1D π-d conjugated c-MOF conductive metal-organic framework (conductive metal-organic framework, Cu-BTA) into the interlayers of vanadium oxide (VO). Cu-BTA acts as a structural pillar, expanding the interlayer spacing of VO to 11.6 Å, facilitating rapid ammonium-ion (NH₄⁺) diffusion, while its conjugated structure enhances the electronic conductivity of the composite. Benefiting from the synergistic dual storage mechanism-vanadium valence variation (V⁵⁺ ↔ V⁴⁺) and reversible C=N/C-N bond rearrangement, Cu-BTA/VO delivers superior NH₄⁺-storage performance. The composite achieves a high specific capacity of 223 mAh g^-1(0.1 A g^-1), and retains 75% after 2000 charge-discharge cycles at 2 A g^-1. Density functional theory (DFT) calculations confirm the reduced electron transfer barrier, optimized NH₄⁺ adsorption energy, and enhanced interfacial charge transfer in Cu-BTA/VO. Furthermore, the assembled PTCDI//Cu-BTA/VO full cell achieves a maximum energy density of ∼96 Wh kg^-1, maintains 65% capacity retention after 600 cycles, and successfully lights an LED bulb continuously for over 30 min. This work provides a novel strategy for interlayer engineering of vanadium-based materials by 1D c-MOF and offers insights into dual-mechanism design for high-performance AAIBs.