Barium Doped Dual Pillar Stabilized Calcium Vanadate Hydrate for High Performance Aqueous Zinc Ion Batteries

Abstract

To meet the stringent requirements for safety, sustainability, and cost-effectiveness in large-scale energy storage systems, aqueous zinc-ion batteries (AZIBs) have attracted considerable attention in recent years. However, layered vanadium oxides, one of the most promising cathode materials, often suffer from structural degradation and sluggish kinetics during cycling, which severely limits the overall performance of the batteries. Herein, we regulate the interlayer architecture of calcium vanadate hydrate (CaV8O20⋅4H2O, CVO) through partial substitution with large-radius Ba²⁺, forming CaxBa1-xV8O20⋅4H2O (CBVO). The incorporation of Ba2+ expands the interlayer spacing while preserving the layered framework, establishing a dual-pillar configuration with Ca2+ that balances structural rigidity and lattice adaptability. This structural modulation lowers the Zn²⁺ migration barrier and suppresses strain accumulation during repeated insertion/extraction. As a result, the optimized CBVO electrode exhibits fast, reversible Zn2+ storage with a high specific capacity of 360.9 mAh g-1 at 0.1 A g-1 and maintained 91% capacity retention after 3500 cycles at 5 A g-1. Kinetic analysis reveals a transition toward pseudocapacitive behavior, while in situ XRD identifies a reversible Zn2+/H+ co-intercalation mechanism. This work establishes interlayer cation engineering as a general strategy for high-rate and durable multivalent ion storage.