A Dual Active Site Organic-Inorganic Poly(O-Phenylenediamine)/NH4V3O8 Composite Cathode Material for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries, considered one of the important candidate technologies for green and environmentally friendly large-scale energy storage, hinge upon the performance of cathode materials as the key factor driving their development. Vanadate oxide is a promising cathode material due to its high theoretical capacity; furthermore, in order to accelerate the reaction kinetics, ion or molecular intercalation is often utilized. However, non-electrochemically active intercalants tend to cause capacity degradation. In this study, a one-step hydrothermal method is employed to intercalate electrochemically active poly-o-phenylenediamine (PoPDA) into the interlayers of NH4V3O8 (NVO), with graphene oxide (GO) being used to further improve the conductivity of the composite material (NVO/PoPDA@GO). The insertion of PoPDA expands the interlayer spacing of the NVO, alters the charge distribution, and enhances the migration rate of Zn2+ among the hybrid materials. Additionally, PoPDA serves as a support within the interlayers, improving the material stability. Moreover, the reversible transformation and rearrangement of chemical bonds (C & boxH;N/C & horbar;N) in PoPDA allows for coordination with Zn2+, providing additional capacity. As a result, NVO/PoPDA@GO exhibits excellent electrochemical performance, releasing a specific capacity of 433 mAh g(-1) at 0.5 A g(-1), even with a capacity of 224 mAh g(-1) at 5 A g(-1). This work provides a promising direction for the preparation of organic-inorganic composite cathode materials with dual active components.