Electrochemical synthesis of titanium nitride nanoparticles onto titanium foil for electrochemical supercapacitors with ultrafast charge/discharge

An ultrafast electrochemical supercapacitor that can deliver charge at a high rate of >1 V s−1 has great potential to supply instantaneous high power to electronic devices. Herein, a titanium nitride (TiN)-nanoparticle-modified titanium foil electrode is prepared by potentiostatic electrolysis at +5 V in an ammoniacal solution of KCl. Spectroscopic and morphological analyses reveal the formation of crystalline, homogeneous, and pure TiN nanoparticles with an average size of ∼30 nm on the Ti foil. In a three-electrode system, the optimized TiN nanoparticle-based electrode exhibits excellent rate performance and reversibility up to 3 V s−1 within the operational voltage window of 0–1.6 V. It delivers a high specific capacitance of ∼53.66 mF cm−2 at 6.66 mA cm−2 with capacity loss of only ∼3% after 10 000 charge/discharge cycles. A symmetric supercapacitor (SSC) based on the as-prepared optimized TiN nanoparticle-electrode also displays ultrafast charge/discharge characteristics with a specific capacitance of ∼44.10 mF cm−2 at 6.66 mA cm−2. This ultrafast SSC has a low relaxation time constant of ∼2.80 ms and shows excellent capacity retention (95% after 10 000 charge–discharge cycles) with ∼100% coulombic efficiency. These results demonstrate the high electrochemical stability and reversibility of TiN nanoparticles, which are promising for the development of high-performance ultrafast supercapacitors.