Rational Design of V2O5/VOPO4 Heterostructure Cathode Inducing Interface Optimization for High-Rate and Long-Cycling Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) represent an environmentally benign energy storage alternative. However, the V₂O₅ cathode suffers from limited cycling stability and rate capability due to structural instability, vanadium dissolution, and high desolvation energy caused by the large size of [Zn(H₂O)₆]²⁺ deintercalation. Address these issues, we introduce a V₂O₅/VOPO₄ (VOP) heterostructure that that reinforces the crystal structure to suppress vanadium dissolution and establishes a hydrophilic interface reducing the desolvation energy of Zn²⁺. The heterostructure additionally generates an internal electric field boosting Zn²⁺ kinetics, synergistically enhancing the rate performance. Density functional theory calculations and in situ X-ray diffraction elucidate the operating mechanism, while a suite of ex situ characterizations confirms improved structural stability, dissolution resistance, and electrochemical performance. The optimized VOP heterostructure achieves a remarkable capacity retention of 194.8 mAh g^-1 after 4000 cycles at 10 A g^-1, underscoring its effectiveness in bolstering the cathode's performance for AZIBs.