VO₂(B)/Graphene Composite-Based Symmetrical Supercapacitor Electrode via Screen Printing for Intelligent Packaging.

More multipurpose and convenient demand driven by Radio Frequency Identification (RFID) and intelligent packaging require flexible power sources. A VO₂(B)/graphene (VO₂(B)/GN) core-shell composite was successfully synthesized by the hydrothermal treatment with V₂O₅ and graphite. The as-obtained sample was characterized by XRD, FT-IR, SEM, TEM, and XPS measurements. In addition, the electrochemical properties of VO₂(B)/GN were tested. Due to its great electrochemical performance and mechanical properties, graphene could increase the electrochemical performance and strengthen the structural stability of the material at the same time. With increasing loading amount of GN, the specific capacitance of VO₂(B)/GN increased correspondingly. With 20% GN loading, the initial discharge specific capacity could reach 197 F g-1 at 0.5 A g-1, and 160 F g-1 at 1 A g-1 in 0.5 M Na₂SO₄ electrolyte, which is better than that of pure rod-like VO₂(B). The capacitance of the VO₂(B)/GN (20%) composite electrode retains 95.49% after 1000 cycles, which is higher than that of a pure VO₂(B) electrode (85.43%), indicating that the VO₂(B)/GN composite possesses better cycling stability. Moreover, a symmetrical solid-state supercapacitor (SCs) using VO₂(B)/GN(20%) as the anode was assembled. Four printed SCs were connected in series to light up a 1.5 V red LED. This demonstrates its potential application in intelligent packaging to trace food safety.