Controllable solvo-hydrothermal electrodeposition of lithium vanadate uniform carnation-like nanostructure and their electrochemical performance

Abstract

In this paper, we successfully developed a novel method to synthesize uniform carnation-like lithium vanadate nanostructures by combining electrochemical deposition and solvo-hydrothermal method. The samples were characterized by field emission scanning electron microscopy, power X-ray diffraction, and thermogravimetric analysis. The results show that the LiV₃O₈·H₂O carnation-like nanostructure is 2–3 μm in diameter and assembled from nanosheets with thickness of 10–20 nm. Based on a series of experiments, we proposed a possible growth mechanism, in which the supersaturation derived from electric field and high conductivity under solvo-hydrothermal conditions due to the successive growth of lithium vanadate. In our work, we have discussed three different solvo-hydrothermal systems. It is proved that the morphology of coating materials could be conveniently controlled by selecting alcohols with different chain of alkyl. Compared with short-chain alcohol, CH₃–(CH₂)₆–CH₂–OH was beneficial to promote the oriented growth of nanosheets. Electrochemical performances of lithium vanadate cathode materials were characterized by galvanostatic charge–discharge, and LiV₃O₈ synthesized in n-octanol aqueous solution exhibits the highest capacity of 357 mAh g⁻¹ and best cycle stability. Furthermore, the influence of solvo-hydrothermal conditions on the morphology and electrochemical performance of products has also been studied.