Multiple Cations Nanoconfinement in Ultrathin V₂O₅ Nanosheets Enables Ultrafast Ion Diffusion Kinetics Toward High-performance Zinc Ion Battery.

Abstract

Nanoconfinement of cations in layered oxide cathode is an important approach to realize advanced zinc ion storage performance. However, thus far, the conventional hydrothermal/solvothermal route for this nanoconfinement has been restricted to its uncontrollable phase structure and the difficulty on the multiple cation co-confinement simultaneously. Herein, this work reports a general, supramolecular self-assembly of ultrathin V₂O₅ nanosheets using various unitary cations including Na⁺, K⁺, Mg²⁺, Ca²⁺, Zn²⁺, Al³⁺, NH₄ ⁺, and multiple cations (NH₄ ⁺ + Na⁺, NH₄ ⁺ + Na⁺ + Ca²⁺, NH₄ ⁺ + Na⁺ + Ca²⁺ +Mg²⁺). The unitary cation confinement results in a remarkable increase in the specific capacity and Zn-ion diffusion kinetics, and the multiple cation confinement gives rise to superior structural and cycling stability by multiple cation synergetic pillaring effect. The optimized diffusion coefficient of Zn-ion (7.5 × 10^-8 cm² s^-1) in this assembly series surpasses most of the V-based cathodes reported up to date. The work develops a novel multiple-cations nanoconfinement strategy toward high-performance cathode for aqueous battery. It also provides new insights into the guest cation regulation of zinc-ion diffusion kinetics through a general, supramolecular assembly pathway.