Ultra-long lifespan asymmetrical hybrid supercapacitor device based on hierarchical NiCoP@C@LDHs electrode

Abstract Supercapacitors (SCs) are intensively explored as bright energy-storage devices for the energy supply of emerging wearable devices. Exploring high performance electrode materials and designing ingenious architectures are regarded as effective measures to develop high-performance SCs. Herein, battery-type NiCoP@C@LDHs electrode with hierarchical core-shell structure, which NiCoP@C nanowires array is taken for the core, to support the NiCo-based nanosheets shell has been successfully assembled. The nanowires NiCoP@C core, which acts as a highly conductive and solid skeleton, accelerates the electron transfer in addition to prevent the agglomeration of nanosheets. The cooperative effects of the both of active compounds of NiCoP@C@LDHs electrode exhibit an outstanding specific capacity of 1353 C g−1 at 1 A g−1, and high rate performance with 78.0% capacitance holding ratio at 10 A g−1 and maintains 80.0% of initial capacity after 4000 charge-discharge process. Furthermore, an asymmetric supercapacitor (ASC) is successfully fabricated for practical application, in which NiCoP@C@LDHs as the positive electrode and the activated carbon (AC) as the negative electrode, which achieves an operating voltage window of 1.6 V and a high-energy density of 48.3 Wh kg−1 at a power density of 800.0 W kg−1. Notably, the device shows capacitance retention of about 160% over 10000 cycles, manifesting the excellent cycle performance of the ASC. Such NiCoP@C@LDHs electrode demonstrates a facile method for manufacturing heterojunction devices with obvious structural superiority for energy storage devices.