Defect-engineered vanadium trioxide nanofiber bundle@graphene hybrids for high-performance all-vanadate Na-ion and K-ion full batteries

Graphene-wrapped throughout-defective nanocrystalline vanadium trioxide nanofiber bunches (V2O3−x@rGO) with high-capacity and stable Na/K storage is prepared. By employing V4+/V5+ redox-based cathodes, high-performance all-vanadate full SIBs and PIBs are successfully assembled.

The Synthesis Process and Thermal Stability of V2C MXene

The effect of etching solution on the synthesis process of two-dimensional vanadium carbide (V2C MXene) was researched. Three etching solutions were used to etch ternary carbide V2AlC at 90 °C. The three solutions were: lithium fluoride + hydrochloric acid (LiF + HCl), sodium fluoride + hydrochloric acid (LiF + HCl), and potassium fluoride + hydrochloric acid (KF + HCl). It was found that only NaF + HCl solution was effective for synthesizing highly pure V2C MXene. The existence of sodium (Na+) and chloridion (Cl−) in etching solution was essential for the synthesis. The thermal stability of the as-prepared V2C MXene in argon or air was studied. From thermogravimetry and differential thermal analysis, V2C MXene was found to be stable in argon atmosphere at a temperature of up to 375 °C. As the temperature increased, V2C MXene was gradually oxidized to form nanoparticles composed of vanadium trioxide (V2O3) and a part of V2C MXene was broken and transformed to vanadium carbide (V8C7) at 1000 °C. In air atmosphere, V2C MXene was stable at 150 °C. At 1000 °C, V2C MXene was oxidized to form vanadium pentoxide (V2O5).

Vanadium trioxide@carbon nanosheet array-based ultrathin flexible symmetric hydrogel supercapacitors with 2 V voltage and high volumetric energy density

A V2O3@C nanosheet array is used as both the cathode and the anode to construct a symmetric ultrathin flexible quasi-solid-state supercapacitor.