In-situ growth of Ni(OH)2 nanoplates on highly oxidized graphene for all-solid-state flexible supercapacitors

•In-situ growth of Ni(OH)2 nanoplates on highly-oxidized graphene were achieved.•The Ni(OH)2/HGO composites deliver a specific capacitance of 1430.9F/g at 5 A/g.•The Ni(OH)2/HGO//AC AFSCs exhibit a high areal specific capacitance of 322 mF/cm2.•Multiple Ni(OH)2/HGO//AC AFSCs were integrated together with a flexible electronic.