In this work, we propose a novel and delicate strategy to significantly boost the supercapacitive performance of graphite felt (GF)@Co-2(OH)(2)CO3 hybrid via a facile Ni-P electrodeposition on the pre-hydrothermally generated GF@Co-2(OH)(2)CO3 (denoted as GF@Co-2(OH)(2)CO3@Ni-P). Electrochemical measurements show that the areal specific capacitances of the resulting GF@Ni-P, GF@Co-2(OH)(2)CO3 and GF@Co-2(OH)(2)CO3@Ni-P are 118, 1022 and 1360 mF cm(-2) at a current density of 1 mAcm(-2). Besides, 72.8% of specific capacitance can be maintained upon rising the current density from 1 to 20 mAcm(-2) for GF@Co-2(OH)2CO(3)@Ni-P, far higher than 47.0% for GF@Co-2(OH)(2)CO3. More strikingly, the assembled all-solid-state flexible symmetric supercapacitor GF@Co-2(OH)(2)CO3@Ni-P//KOH//GF@Co-2(C>H)(2)CO3@Ni-P delivers high energy densities of 46.8 Wh kg(-1) at a power density of 0.5 kW kg(-1), and 20.7 Wh kg(-1) at elevated 5.0 kW kg(-1), surpassing most of the reported analogues. Moreover, the device holds 92.9% capacitance retention after 2500 cycles at a current density of 10 mA cm(-2). Such substantially enhanced electrochemical performance of GF@Co-2(OH)(2)CO3@Ni-P owes to the improvement of the electronic conductivity by the Ni-P coating and the reinforced synergic effect contributing to the capacitance between the active Co-2(OH)(2)CO3 and Ni species including Ni-P and Ni-OH species. To the best of our knowledge, this is the first report on the coating of Ni-P onto inorganic metal compounds for energystorage/conversion systems. (C) 2018 Elsevier Ltd. All rights reserved.