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Current energy crises are inspiring researchers to focus intensively on development of feasible ways to produce high performing composite electrode materials for increasing energy demands. The present work addresses this objective by developing a novel structure of NiFe2O4 (NFO) nanoparticles coated on graphene capsules (GCs) by a simple hydrothermal technique. This NFO–GCs electrode material was subjected to different types of electrochemical performance evaluations to investigate its feasibility as a supercapacitor electrode. The as-prepared NFO–GCs nanocomposite electrode exhibits high specific capacitance of 1028 F g−1 at a current density of 2 A g−1 and 94% capacitance retention at the end of 10 000 charge–discharge cycles, whereas pristine NFO electrode shows 720 F g−1 specific capacitance with 88% capacitance retention. The high specific capacitance, good rate capability, and excellent cycling stability of NFO–GCs composite can be attributed to effective synergism between the GCs and NFO. The superior electrochemical performance of NFO–GCs nanocomposite demonstrates possible application of this material as a working electrode for fully functional supercapacitor devices. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of MnCo 2 O 4 nanoflake/graphene nanoplatelets composite is reported here for high performance supercapacitor electrode applications. The MnCo 2 O 4 nanoflakes with different morphologies were synthesized successfully via a hydrothermal technique by changing the amount of NH 4 F. The MnCo 2 O 4 nanoflakes in combination with the graphene nanoplatelets was deposited on Ni foam using an electrophoretic deposition technique. The as prepared composite electrode showed superior performance in terms of specific capacitance and cycling stability, as compared to the pristine MnCo 2 O 4 system, due to the enhanced electronic conductivity resulted from bond formation between carbon and MnCo 2 O 4. A high specific capacitance of ∼1268 F g −1 was observed at 1 mV s −1 scan rate. Noteworthy cycling stability was observed even at the end of 10,000 cycles of consecutive charging and discharging at a current density of 7.81Ag −1 . [ABSTRACT FROM AUTHOR]

3D lithium vanadium phosphate/reduced graphene oxide porous structures are prepared using a facile lyophilization process. The 3D porous nature of these lyophilized electrodes along with their high surface area lead to high rate capability and specific capacity. A high specific discharge capacity of ≈192 mAh g−1 is observed at 0.5 C. The cycling performance is noteworthy, as these lyophilized samples at 0.5 and 1 C do not show any fading, even after 1000 and 5000 cycles, respectively. Capacity retention of ≈96.2% is observed at the end of 10 000 cycles at 20 C. This remarkable cycling performance is attributed to the structural stability of the 3D porous network and is confirmed using scanning electron microscopy and selected area electron diffraction after 10 000 cycles of consecutive charging and discharging at 20 C. [ABSTRACT FROM AUTHOR]