Hybrid electrochemical capacitor with high performance built by Co2.1Ni2.1Zn1.8(CO3)2(OH)8·H2O ternary basic carbonate

Abstract

Metal basic carbonate materials (M-CH), which are employed as precursors of metal hydroxides/oxides, have recently popularity as battery-type electrodes due to their exceptional energy storage performance. However, a unitary metal basic carbonate is insufficient to meet today’s challenges. To make hybrid electrochemical capacitors, multiple-metals basic carbonate materials must to be designed and synthesized. Herein, a one-step hydrothermal method is used to produce Co basic carbonate doped with Ni and Zn (Co, Ni, Zn-CH). The results of X-ray diffractometer refinement demonstrate that following Ni, Zn co-substitution for Co ions, the crystal cell parameters of Co-CH drop. In a three-electrode system, such changes facilitate the electronic transfer, resulting in a high specific capacity of 91.80 mAh g−1 at 1 A g−1, a high rate performance of 52.42% at 20 A g−1, and a 5000-cycle stability of 91.85% at 10 A g−1. Furthermore, an assembled hybrid electrochemical capacitor (HEC) can provide an energy density of 36.10 Wh kg−1 at a power density of 1009.65 W kg−1 and a capacity retention of up to 91.93% after 5000 cycles. Two homemade hybrid electrochemical capacitors connected in series impressively maintain eight LEDs glowing for 30 min, demonstrating superior energy storage capability.