Preparation and characterization of Schiff base metal complexes for high performance supercapattery

Abstract

With the urgent need for portable electrochemical energy storage (EES) devices, it is significant to develop energy storage devices with superior energy-power densities, long-term cycling durability and low cost. Supercapattery combines the benefits of supercapacitors and batteries with splendid specific power and good cycling stability. In this work, we synthesize Schiff base of O-tolidine and terephthalaldehyde (OTTP) and its metal complex (M-OTTPs, M= Co2+, Ni2+, Zn2+) via a feasible one-step strategy as electrode materials. The as-obtained M-OTTPs possess remarkable electrochemical property on account of the coordination effect on metal ions and N atoms, and the volume hindrance caused from metal ions entering affects the π-π accumulation in the skeleton of the Schiff base. With metal ions entering into the Schiff base molecular structure, the electrochemical properties of M-OTTPs improve apparently in comparison with OTTP. Ni-OTTP electrode exhibits the excellent specific capacitance of 561.8 C g − 1 at the current density of 0.5 A g − 1 with extraordinary rate capability in three electrode system. An alkaline (6 M KOH electrolyte) supercapattery hybrid device (Ni-OTTP//AC) is manufactured from Ni-OTTP as the positive electrode and activated carbon (AC) as the negative electrode, which possesses the high energy density of 34.58 Wh kg−1 at the power density of 613.24 W kg−1. The M-OTTPs possess remarkable electrochemical property due to the coordination effect on metal ions and N atoms, and the volume hindrance caused from metal ions entering affects the π-π accumulation in the skeleton of the Schiff base. This study provides an innovative strategy to prepare electrode materials with prominent electrochemical performances by conjugated Schiff bases synthesis and metal ion coordination.