Development of asymmetric supercapacitors (ASCs) using hierarchical three-dimensional (3D) morphologies is becoming crucial in energy storage applications due to the greater power density rather than batteries. Herein, 3D flower-like Co-3(PO4)(2)center dot 8H(2)O (CPH) and nickel doped CPH (Ni-CPH) microarchitectures were synthesized by a silicone oil bath method at low temperatures without calcination. The synthesized microarchitectures-based electrodes (bare CPH and Ni-CPH) revealed battery-like properties during the electrochemical study. Importantly, the Ni-CPH electrode showed improved electrochemical performance compared to the bare CPH electrode material. The specific capacity values of the CPH and Ni-CPH electrode materials were calculated to be 74 and 108 mAh g(-1) at 0.5 A g(-1), respectively. Furthermore, for the Ni-CPH electrode, 78% of capacity retention was obtained after 9000 cycles at 5 A g(-1). Additionally, an ASC was developed while employing the optimized Ni-CPH electrode (positive-type) and activated carbon (negative-type) and it showed superior electrochemical results. The ASC device exhibited excellent capacity retention (94%) after 9000 cycles at 2 A g(-1). Also, this device delivered a high energy density of 23.4 Wh kg(-1) and a power density of 2103Wkg(-1). Finally, several portable electronic devices were successfully tested using the obtained good energy and power density results from the ASC device for energy storage applications. (C) 2021 Elsevier Inc. All rights reserved.