Synthesis of morphology controlled NiCo-LDH microflowers derived from ZIF-67 using binary additives and their excellent asymmetric supercapacitor properties

• DOI: 10.1016/j.apsusc.2020.147073
• Publication Date: 2020-06-30T00:45:07Z
• Authors: M. Usman Tahir; Hina Arshad; Wenyu Xie; Xianglong Wang; Muhammad Nawaz; Chao Yang; Xintai Su
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract Dodecahedral imidazolium framework-67 (ZIF-67) is synthesized in aqueous solution and used as a sacrificial template for the synthesis of uniform three-dimensional (3-D) hierarchical hexagonal flower-like nickel–cobalt layered double hydroxides (NiCo-LDH) by facile hydrothermal treatment. TEM and SEM results reveal that each microflower is composed of abundant two-dimensional (2D) ultrathin wrinkled nanosheets. The induction of 2,3,5,6-terafluroterephthalic acid (H2tfbdc) and hexamethylenetetramine (HMT) as an additive along with nickel nitrate hexahydrate plays a vital role to tune uniform hierarchical morphology and augmented electrochemical performance. The supercapacitor performance results show that (NiCo-LDH)SHH electrode has the best supercapacitor performance when it is used as a pseudo-capacitor. The maximum specific capacitance is 1765 F g−1 at the current density of 1 A g−1 with stable cycling performance. An asymmetric supercapacitor device assembled using (NiCo-LDH)SHH as the positive and activated carbon (AC) as the negative electrode attains a high energy density of 53.31 Wh kg−1 at a power density of 749.7 W kg−1 with 84.3% capacitance retention after 6000 cycles. This work provides a novel route for the design and synthesis of two-component hydrotalcite with 2D nanosheets having a large interlayer spacing of 9.3 d(A) and its potential application in electrochemical energy storage.