Investigation of nickel/cobalt-imidazolate based electrode for supercapacitor application / Atiqah Husna Abdul Rahim

Atiqah Husna , Abdul Rahim (2022) Investigation of nickel/cobalt-imidazolate based electrode for supercapacitor application / Atiqah Husna Abdul Rahim. Masters thesis, Universiti Malaya.

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Abstract

This work presents an exploration of co-precipitated Zeolitic-Imidazolate Frameworks (ZIF) as direct use electrode materials for supercapacitors. The different ratios of metal salts and 2- methylimidazolate based linkers have been synthesized in 3: 10, 1:1 and 10:3 mmol, accordingly. In three-electrode system, Ni-ZIF-R3 and Co-ZIF-R3 with high metal content exhibit the highest specific capacitance of 433 F g-1 and 420 F g-1 at the current density of 0.25 A g-1 in 1 M KOH electrolyte, respectively. An asymmetrical supercapacitor (ASC) was fabricated using the configuration of Ni-ZIF- R3||KOH||AC and Co-ZIF-R3||KOH||AC. Within potential range of 1.70 V, both cells have delivered a high specific capacitance of 85 and 56 F g-1, respectively at current density of 0.25 A g-1. Moreover, Ni-ZIF-R3||KOH||AC revealed an excellence cycling stability of 93 % after 1500 cycles test. Similarly, Co-ZIF- R3||KOH||AC able to retain 87 % of its initial capacity after 2500 cycles at 0.50 A g-1 until 1.0 A g-1. Furthered, NiCo-ZIF with interconnected rod-shape like particles is studied as the comparison for the direct used-bimetallic with heated ZIFs. Surprisingly, the as-synthesized NiCo-ZIF delivered a better specific capacitance performance of 924 F g-1 at a current density of 0.50 A g-1. The optimization of all the samples are conducted in X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FESEM) and Energy dispersive X-Ray (EDX) to identify the role of molar ratio and the information of direct-used ZIF. Thus, this work highlighted the prospect of single and bimetallic based-ZIF prepared in co-precipitation with an appropriate parameter can be a potential electrode material for the next generation of high performance and stability of supercapacitors.

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