Q.K. Meng

Facile synthesis of NiCo2S4 spheres with granular core used as supercapacitor electrode materials

NiCo2S4 spheres with granular core were designed and fabricated via an easy two-step hydrothermal reation: carbon sphere clusters were used as templates to obtain NiCo2(OH)6/C precursor, which reacted with sodium sulfide to synthesize granular NiCo2S4 and then, the precursor of NiCo2S4 was grown on the periphery of granular NiCo2S4 to form the unique structure. The NiCo2S4 spheres with granular core specific surface area reaches 26.61xa0m2 g−1, which is about twofold of granular NiCo2S4 (11.41xa0m2 g−1). Electrochemical performance of the electrodes has been investigated. The electrode of NiCo2S4 spheres with granular core displays high specific capacitance of 1156xa0F g−1 at a current density of 1xa0A g−1, which increases by 71% compared to that of granular NiCo2S4 (675xa0F g−1). Upon 1000 charge/discharge cycles, the NiCo2S4 spheres with granular core electrode exhibits excellent cycling stability with 82% capacitance retention at 5xa0A g−1. In view of the low cost and superior electrochemical performance, the NiCo2S4 spheres with granular core synthesized using carbon sphere clusters as templates could be a promising electrode material for supercapacitors.

Morphology-controlled synthesis of porous Co3O4 nanostructures by in-situ dealloying and oxidation route for application in supercapacitors

Synthesis of electrode materials with desirable morphology and size for supercapacitor applications is an important and challenging research topic. In this work, four types of Co3O4 nanostructures, namely hexagonal-shaped nanosheets, nanoflake arrays, nanoflowers and oval-shaped nanospheres were synthesized via a facile in-situ dealloying method. Applied as electrode material for supercapacitiors, the Co3O4 nanospheres achieves highest areal capacitance of 16.58xa0Fxa0cm−2 at current density of 10xa0mAxa0cm−2. The Co3O4 nanoflowers exhibited promising capacitive properties and excellent retention. Its areal capacitance can reach 9.27xa0Fxa0cm−2 at the current density of 10xa0mA cm−2 and retain 98.5% of its initial capacitance at the current density of mAxa0cm−2 after 1000 charge–discharge cycles. This work could provide a deeper understanding of the morphology effect on the supercapacitive performance, and also suggests the importance of rational design and synthesis of electrode materials with desirable morphology and size for high performance supercapacitor applications.

Nanoporous Cu/Co alloy based Cu2O/CoO nanoneedle arrays hybrid as a binder-free electrode for supercapacitors

In this paper, Cu2O/CoO nanoneedle arrays (Cu2O/CoO-NNAs) are vertically grown on nanoporous Cu/Co (NPs-Co/Cu) conductive substrate through a facile dealloying and oxidation method. Benefiting from their intriguing structural features, the NPs-Cu/Co alloy based Cu2O/CoO-NNAs hybrid possesses fascinating electrochemical performance as an integrated binder-free electrode for symmetric supercapacitors (SSCs). High areal capacitances of 0.21xa0F cm−2 can be achieved at a current densities of 5xa0mA cm−2. Moreover, electrode has an excellent long-term cycling stability with 100% capacitance retention after 10000 cycles. A maximum of volumetric energy density (0.81xa0mW h cm−3) and volumetric power density (3xa0W cm−3) were achieved for the as-fabricated SSCs device. Therefore, the present work holds a great promise for future design and large-scale production of high volumetric energy density and volumetric energy density electrodes by dealloying and oxidation method for energy storage devices.