A high mass loading flexible electrode with a sheet-like Mn3O4/NiMoO4@NiCo LDH on a carbon cloth for supercapacitors† † Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3ra06937k
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SUBMITTER: Liang R
PROVIDER: S-EPMC10646476 | biostudies-literature | 2023 Nov
REPOSITORIES: biostudies-literature
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Project description:Recent research and development of energy storage devices has focused on new electrode materials because of the critical effects on the electrochemical properties of supercapacitors. In particular, MnO2 and Fe2O3 have drawn extensive attention because of their low cost, high theoretical specific capacity, environmental friendliness, and natural abundance. In this study, MnO2 ultrathin nanosheet arrays and Fe2O3 nanoparticles are fabricated on TiN nanowires to produce binder-free core-shell positive and negative electrodes for a flexible and ultra-fast hybrid supercapacitor. The MnO2/TiN/CC electrode shows larger pseudocapacitance contributions than MnO2/CC. For example, at a scanning rate of 2 mV s-1, the pseudocapacitance contribution of MnO2/TiN/CC is 87.81% which is nearly 25% bigger than that of MnO2/CC (71.26%). The supercapacitor can withstand a high scanning rate of 5000 mV s-1 in the 2 V window and exhibits a maximum energy density of 71.19 W h kg-1 at a power density of 499.79 W kg-1. Even at 5999.99 W kg-1, it still shows an energy density of 31.3 W h kg-1 and after 10 000 cycles, the device retains 81.16% of the initial specific capacitance. The activation mechanism is explored and explained.
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Project description:Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport. Herein, rationally designed CNT/MnO2/graphene-grafted carbon cloth electrodes are prepared by a "graft-deposit-coat" strategy. Due to the large surface area and good conductivity, graphene grafted on carbon cloth offers additional surface areas for the uniform deposition of MnO2 (9.1 mg cm-2) and facilitates charge transfer. Meanwhile, the nanostructured MnO2 provides abundant electroactive sites and short ion transport distance, and CNT coated on MnO2 acts as interconnected conductive "highways" to accelerate the electron transport, significantly improving redox reaction kinetics. Benefiting from high mass loading of electroactive materials, favorable conductivity, and a porous structure, the electrode achieves large areal capacitances without compromising rate capability. The assembled asymmetric supercapacitor demonstrates a wide working voltage (2.2 V) and high energy density of 10.18 mWh cm-3.
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Project description:The rational fabrication of composite structures made of mixed components has shown great potential for boosting the energy density of supercapacitors. Herein, an elaborate hierarchical MOF-derived NiCo2S4@Mo-doped Co-LDH arrays hybrid electrode was fabricated through a step-wise method. By leveraging the synergistic effects of a uniform array of NiCo2S4 nanowires as the core and an MOF-derived porous shell, the NiCo2S4@Mo-doped Co-LDH hybrid electrode demonstrates an exceptional specific capacitance of 3049.3 F g-1 at 1 A g-1. Even at a higher current density of 20 A g-1, the capacitance remains high at 2458.8 F g-1. Moreover, the electrode exhibits remarkable cycling stability, with 91% of the initial capacitance maintained after 10,000 cycles at 10 A g-1. Additionally, the as-fabricated asymmetric supercapacitor (ASC) based on the NiCo2S4@Mo-doped Co-LDH electrode achieves an impressive energy density of 97.5 Wh kg-1 at a power density of 835.6 W kg-1. These findings provide a promising approach for the development of hybrid-structured electrodes, enabling the realization of high-energy-density asymmetric supercapacitors.
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Project description: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.
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