Mahmoud, Badr Ahmed MohammedMirghni, Abdulmajid AbdallahFasakin, OladepoOyedotun, Kabir OyeniranManyala, Ncholu I.2021-04-142021-04-142020-04Mahmoud, B.A., Mirghni, A.A., Fasakin, O. et al. Bullet-like microstructured nickel ammonium phosphate/graphene foam composite as positive electrode for asymmetric supercapacitors. RSC Advances, 2020, 10(28):16349-16360.2046-2069 (online)10.1039/d0ra02300khttp://hdl.handle.net/2263/79440Unique microstructured nickel ammonium phosphate Ni(NH4)2(PO3)4$4H2O and Ni(NH4)2(PO3)4$4H2O/GF composite were successfully synthesized through the hydrothermal method with different graphene foam (GF) mass loading of 30, 60 and 90 mg as a positive electrode for asymmetric supercapacitors. The crystal structure, vibrational mode, texture and morphology of the samples were studied with X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis and scanning electron microscopy (SEM). The prepared materials were tested in both 3-and 2-electrode measurements using 6 M KOH electrolyte. The composite material Ni(NH4)2(PO3)4$4H2O/60 mg exhibited a remarkable gravimetric capacity of 52 mA h g 1, higher than the 34 mA h g 1 obtained for the Ni(NH4)2(PO3)4$4H2O pristine sample, both at 0.5 A g 1. For the fabrication of the asymmetric device, activated carbon from pepper seed (ppAC) was used as a negative electrode while Ni(NH4)2(PO3)4$4H2O/60 mg GF was adopted as the positive electrode. The Ni(NH4)2(PO3)4$4H2O/60 mg GF//ppAC asymmetric device delivered a specific energy of 52 Wh kg 1 with an equivalent specific power of 861 W kg 1 at 1.0 A g 1 within a potential range of 0.0–1.5 V. Moreover, the asymmetric device displayed a capacity retention of about 76% for over 10 000 cycles at a high specific current of 10.0 A g 1.en© The Royal Society of Chemistry 2020. This article is licensed under the Creative Commons Attribution License.Hydrothermal methodSupercapacitorsX-ray diffraction (XRD)Graphene foamRaman spectroscopyScanning electron microscopy (SEM)Brunauer–Emmett–Teller (BET)Article