Synthesis Of Vanadium-based Nanomaterials And Their Electrochemical Performance For Supercapcitors

Vanadium oxide and their derivatives have tremendous application potential as electrode material in energy storage field owing to their special layer structure and multi-form of oxidation states, which have unique physicochemical properties. Now, the common problems of the vanadium-based electrode materials are include low real specific capcity, poor cycling stability and rate capability. With the development of nanotechnology, there has been great interest in synthesizing novel vanadium-based nanomaterials with special morphology, structure and components. Based on the hydrothermal treatment, different vanadium-based nanomaterials with novel morphology have been synthesized by optimizing the preparation strategies. This article mainly studied the grow mechanism and electrochemical performance of the as-prepared materials. The main research work and results are shown as follows:NH4+ group was used to intercalate the interlayer to improve the conductivity and cyclic stability for vanadatesby two aspects affect. The intercalated NH4+ improved the conductivity, and the other one is broaden the interlayer space and stablize the interlayer structure as pillars. We developed a novel method which combined sol-gel method and hydrothermal method to prepare(NH4)2V6O16?1.5H2 Onanobelts. The as-prepared(NH4)2V6O16?1.5H2 Onanobelts are up to several tens of micrometers long, 50nm-100 nm thick, and 200nm-1um wide. The discharge capacity is more then 220F/g when tested at current density of 50 m A/g in 1mol/L Na NO3 electrolyte. However, the cyclic performance is bad. The capacity retention was about 50% after 62 cycles at 200 m A/g.For the poor cycling capacity and rate capability of(NH4)2V6O16?1.5H2 O ultralongnanobelts, through experiments we found that the poor mechanical performance and solubility in water electrolyte were probably resulted in these problems. In order to synthesize new electrode materials with better structure and components, we developed a novel polyalcohol-hydrothermal method. The as-prepared materials have solid core with the nanorods distributed around the core radially, which looks like the nano-urchin. The structure of the samples are stable, the morphology and structure didn’t change greatly while annealing at 350℃ and grinding. Through XPS analysis, proved the vanadium in the products are mix valance state, which maybe contribute to better capacity. The charge capacity at first cycle can be more then 500F/g, while discharge capacity can reach up to 372F/g, when tested at current density of 200 m A/g in 1mol/L Na NO3 electrolyte. Unfortunately, the cyclic performance are still very pool, the capacity retention was only about 33% after 54 cycles at 200 m A/g.The proposed polyalcohol-hydrothermal can synthesis many different kinds of nanomaterials, including 0D to 3D nanomaterials by adjusting the experiment parameters simply. Through annealing at different atmosphere can synthesize the corresponding vanadium oxide. Therefore, the facile polyalcohol-hydrothermal method could be a useful route to design other novel vanadium-based nanomaterials and provides many alternative electrode materials for supercapacitors.