Al and Co co-doped α-Ni(OH)2/graphene hybrid materials with high electrochemical performances for supercapacitors

• The successful phase transmission from β-Ni(OH)2 to α-Ni(OH)2 after Al3+ doping.
• The doped mesoporous α-Ni(OH)2 anchored on graphene with a turbostratic structure.
• An ultrahigh specific capacitance of 2257 F g−1 was obtained.
• The cycle performance was obviously enhanced by the incorporation of graphene.

Metal ions (Al3+ and Co2+) co-doped α-Ni(OH)2/graphene hybrid materials had been successfully synthesized by a facile chemical co-precipitation route. X-ray diffraction (XRD) patterns revealed the successful phase transmission from β-Ni(OH)2 to α-Ni(OH)2 after Al3+ doping and the continuously enlarged interlayer distance of α-Ni(OH)2 after subsequent Co2+ doping. Due to its large interlayer distance, mesoporous structure and highly conductively graphene (GNS), the as-obtained Al-Co co-doped α-Ni(OH)2/GNS composite (Al-Co-Ni/GNS) showed an ultrahigh specific capacitance of 2257 F g−1 at 2 mV s−1 as well as good cycling stability with 77% of the initial capacitance retention after 1000 cycles in 6 M KOH aqueous solution.

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