Abstract
In this work, a facile two-step strategy is adopted to construct hierarchical polyaniline/NiCo-layered double hydroxide (PANI/NiCo-LDH) core-shell composite nanofiber networks on carbon cloth (CC). Three-dimensional (3D) porous PANI nanofiber networks are firstly uniformly anchored on CC by in-situ oxidative polymerization, followed by growth of NiCo-LDH nanoflakes on the crosslinked PANI framework via electrochemical deposition. The morphology and electrochemical properties of PANI/NiCo-LDH composites are controlled by the deposition time of LDH. Benefiting from rapid electron transport and ion diffusion, the well-defined PANI/NiCo-LDH hierarchical composite with 200 s deposition of LDH delivers a large capacitance of 1845 F g−1 at 0.5 A g−1 and excellent cycling stability of 82% capacitance retention after 5000 cycles at a very high current density of 10.0 A g−1. Furthermore, an asymmetric supercapacitor (ASC) assembled with PANI/NiCo-LDH as a positive electrode and activated carbon (AC) as a negative electrode exhibits a high capacitance of 147.2 F g−1 in a potential range from 0 to 1.5 V and superior energy density of 46.0 Wh kg−1 at a power density of 351.6 W kg−1.
Highlights
With the ever-growing concern of energy shortage and environmental pollution, the exploitation of renewable, clean energy and efficient energy storage systems has become extremely imperative
To address the above-mentioned issues, we report a well-connected hierarchical composite structure consisting of a conductive PANI nanofibers core and NiCo-LDH nanosheets shell via in-situ polymerization and electrodeposition method
PANI nanofibers are firstly formed on carbon cloth (CC) via in-situ oxidative polymerization with the aid of phytic acid, which acts as a 3D conductive framework for growth of LDH nanosheets by electrodeposition
Summary
With the ever-growing concern of energy shortage and environmental pollution, the exploitation of renewable, clean energy and efficient energy storage systems has become extremely imperative. It has been demonstrated that the performance of SCs mainly depends on the kinetic characteristics and electrochemical activity of the electrodes [5] It is of scientific and engineering significance to develop novel electrode materials with more electroactive sites, fast electron transfer rate and short ion-diffusion paths. Transition metal oxides/hydroxides, especially NiCo-LDHs, have received much more attention as SC electrodes due to their highly specific capacitance, superior redox activity, low cost and being environmental benign [15,16,17,18,19]. NiCo-LDHs exhibit better electrochemical performance than the corresponding single hydroxides, they cannot meet the increasing energy demands for new energy storage systems because of their intrinsic properties such as low electrical conductivity, slow ion transfer rate and easy aggregation of active species [20,21]. The fabricated asymmetric supercapacitor (ASC) exhibits a high energy density of 46.0 Wh kg−1 at a power density of 351.6 W kg−1 and impressive specific capacitance of 147.2 F g−1
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