General synthesis of three-dimensional alkali metal vanadate aerogels with superior lithium storage properties

Abstract

Three-dimensional (3D) aerogel materials assembled from simplex nanostructures have many advantages in the energy field, but the synthesis of alkali metal vanadate aerogels remains challenging. Herein, we demonstrate a general method for the preparation of a series of 3D alkali metal vanadate aerogels, including NaV₃O₈, NaV₆O₁₅, and K_0.25V₂O₅. The aerogels with a large porous structure built from cross-linked ultra-long nanofibers can be prepared via the hydrothermal self-assembly route followed by a freeze-drying process. The resulting aerogels, e.g. NaV₃O₈, NaV₆O₁₅, and K_0.25V₂O₅, exhibit excellent Li⁺ storage properties in terms of high specific capacity, good rate capability, and outstanding cyclic stability as cathodes for lithium batteries. Importantly, the NaV₃O₈ aerogel demonstrates an excellent long-life cyclic performance of 600 cycles at 1000 mA g⁻¹ with no capacity fading. To account for the mechanisms that affect the electrochemical properties, a systematic study is conducted. The superior performances may be due to the superior mechanical stability, good reversibility of lithium insertion/de-insertion and excellent interior structural stability. It is believed that our strategy could probably be extended to prepare other metal vanadate aerogel materials with great promise for various applications.