Xiang-Yu YouPin-Yan LeeSu-Ching WangChutima KongvarhodomMuhammad SaukaniSibidou YougbaréHung-Ming ChenKUO-CHUAN HOYung-Fu WuLu-Yin Lin2025-01-212025-01-212025-02-15https://www.scopus.com/record/display.uri?eid=2-s2.0-85213516708&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/724977Nickel hydroxide (Ni(OH)2) is widely applied as the electroactive material for energy storage, due to its large theoretical capacitance and high stability in alkaline electrolytes. Morphology of electroactive material plays an important role in energy storage. Structure directing agent (SDA) is incorporated to design favorable morphology of electroactive materials. Ammonium fluoroborate has been reported as efficient SDA to design ZIF-67 derivatives for energy storage. The BF4− ion acts as steric obstacles for regulating material growth. In this study, nickel tetrafluoroborate (Ni(BF4)2) is firstly applied as the nickel precursor and SDA to synthesize Ni(OH)2 as the electroactive material for energy storage. To mimic the environment for synthesizing ZIF-67 derivatives, 2-methylimidazole is incorporated to control the pH value to induce precipitations. The solvent effects based on ethanol, methanol and deionized water are investigated due to the novel combination of precursors. The Ni(OH)2 electrode synthesized using ethanol shows a specific capacitance (CF) of 1404.0 F/g at 20 mV/s, due to the largest electrochemical surface area and the pure alpha phase. An asymmetric supercapacitor composed of optimal Ni(OH)2 obtains a maximum energy density of 63.1 Wh/kg at 700.0 W/kg. The CF retention of 93.1% and Coulombic efficiency of 96.3% after 7000 cycles are also attained.falseAsymmetric supercapacitorMorphologyNickel hydroxideNickel tetrafluoroborateSolventStructure directing agentjournal article10.1016/j.est.2024.1151352-s2.0-85213516708