Transition metal sulfides grown on graphene fibers for wearable asymmetric supercapacitors with high volumetric capacitance and high energy density.

ABSTRACT: Fiber shaped supercapacitors are promising candidates for wearable electronics because they are flexible and light-weight. However, a critical challenge of the widespread application of these energy storage devices is their low cell voltages and low energy densities, resulting in limited run-time of the electronics. Here, we demonstrate a 1.5?V high cell voltage and high volumetric energy density asymmetric fiber supercapacitor in aqueous electrolyte. The lightweight (0.24?g cm(-3)), highly conductive (39?S cm(-1)), and mechanically robust (221?MPa) graphene fibers were firstly fabricated and then coated by NiCo2S4 nanoparticles (GF/NiCo2S4) via the solvothermal deposition method. The GF/NiCo2S4 display high volumetric capacitance up to 388?F cm(-3) at 2?mV s(-1) in a three-electrode cell and 300?F cm(-3) at 175.7?mA cm(-3) (568?mF cm(-2) at 0.5?mA cm(-2)) in a two-electrode cell. The electrochemical characterizations show 1000% higher capacitance of the GF/NiCo2S4 as compared to that of neat graphene fibers. The fabricated device achieves high energy density up to 12.3?mWh cm(-3) with a maximum power density of 1600?mW cm(-3), outperforming the thin-film lithium battery. Therefore, these supercapacitors are promising for the next generation flexible and wearable electronic devices.

SUBMITTER: Cai W 

PROVIDER: S-EPMC4888745 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature