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 similar to 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 similar to 53.66 mF cm(-2) at 6.66 mA cm(-2) with capacity loss of only similar to 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 similar to 44.10 mF cm(-2) at 6.66 mA cm(-2). This ultrafast SSC has a low relaxation time constant of similar to 2.80 ms and shows excellent capacity retention (95% after 10 000 charge-discharge cycles) with similar to 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.