Cation‐in‐Mesopore Complex for 20 Ah‐Level Aqueous Battery

Metallic Zn-based aqueous batteries (ZABs) have arisen as one of the most promising safe energy storage solutions, yet practical development, especially for the Ah-level ZABs, is severely plagued by unmanageable side reactions and notorious dendrite proliferation. Here, we propose a cation-in-mesopore (CiM) complex chemistry by confining Zn²⁺ within single-mesopore cavities to construct a novel paradigm of 20 Ah-level ZABs. Molecule dynamic and X-ray absorption near-edge structure analyses reveal that the single-mesopore SiO₂ (smSiO₂) traps Zn²⁺, replacing H₂O molecules in the primary sheath and forming Zn²⁺-smSiO₂ complexes. In situ electrochemical digital holography, in situ interface Fourier-transform infrared spectroscopy, and H-bonds density analyses clearly confirm that Zn²⁺-smSiO₂ complexes migrate and adhere onto the metallic Zn, facilitating the formation of mesopore weak H-bonds interface by disrupting the aggregation of solvated H₂O. Consequently, the Zn anode operates over 800 h under 55% depth of discharge, effectively suppressing H₂O degradation and dendrite growth. The Zn//VO₂ pouch battery demonstrates capacities of 20.5 Ah at 0.2 A g^-1 and 8.59 Ah at 1 A g^-1, and energy density of 65 Wh kg^-1 and 96 Wh L^-1. The proposed cation-in-mesopore complex chemistry may mark a substantial step forward towards more sustainable and reliable ZABs.