Tunable preparation of chrysanthemum-like titanium nitride as flexible electrode materials for ultrafast-charging/discharging and excellent stable supercapacitors

A novel chrysanthemum-like titanium nitride (CL-TiN) has been synthesized through hydrothermal method combining reduction and nitridation treatment. The morphology of CL-TiN can be successfully obtained by strict controlling heating rates. The CL-TiN is characterized as microspherical structure with an average diameter of 2 μm and is assembled from two-dimensional leaf-like nanorods with a width of 200 nm and a length of 500 nm. The CL-TiN is employed to construct supercapacitors and exhibits excellent capacitive performance due to efficient ion diffusion as well as good structural stability. The specific capacitance of the CL-TiN in a three-electrode system is 23.35 F g-1 at a current density of 1.0 A g−1. Importantly, the capacitance retention still maintains 90.0% after 10 000 cycles at a scan rate of 0.1 V s−1. Furthermore, a symmetric flexible-solid-state supercapacitor (FSS-SC) based on CL-TiN nanostructures with Na2SO4/carboxymethyl cellulose (CMC) gel as electrolyte is assembled. The supercapacitor shows excellent volumetric capacitance (7.48 F cm-3 at 0.05 A cm−3), high energy density (0.34 mW h cm−3) and ultrafast-charging/discharging performance. The cycling stability is remarkable with a capacitance increase of about 36.7% after 20 000 cycles. This work could give a promising guidance for designing and fabricating ultrafast-charging/discharging and excellent stable supercapacitors.