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Even though NiCo2O4 is considered to be one of the most promising materials for supercapacitor applications, its unsatisfactory rate performance and cycling stability, due to inherently low electrical conductivity, have limited its further growth as a supercapacitor electrode. The present study tries to profitably exploit reduced graphene oxide (rGO) nanosheets as a conducting unit to enhance the electronic conductivity, by a simple hydrothermal technique assisted by ammonia hydroxide, to improve the overall electrochemical performance of NiCo2O4 in supercapacitors. The as-prepared NiCo2O4–rGO nanocomposite consists of NiCo2O4 hexagons wrapped in conducting rGO sheets, which ensure a short ion diffusion distance, percolating electron conducting pathways, and stable structural integrity. Such a feasible design provides good synergism between the rGO and the NiCo2O4, resulting in better electrochemical performance. As a result, this nanocomposite displays impressive overall electrochemical performance, in aspects such as promising capacitance (1185 F g−1 at a current density of 2 A g−1) and remarkable cycling stability (98% capacitance retention after 10 000 charge–discharge cycles at 2 A g−1). This facile method could be beneficial for preparing similar materials that require high electronic conductivity. [ABSTRACT FROM AUTHOR]

Even though Na3V2(PO4)3 (NVP) is regarded as one of the next-generation cathode materials in sodium-ion batteries (SIBs), its undesirable rate performance due to its inherently low electrical conductivity has limited its application in demanding fields such as electric vehicles. Motivated by this fact, the present study profitably employed a conductive carbon grown in situ to obtain an NVP@C composite with a pomegranate-like structure by a simple sol–gel assisted hydrothermal technique. The as-prepared NVP@C composite consists of small carbon-coated NVP particles (∼200 nm) embedded in a conductive carbon matrix, which ensures short ion diffusion distances, percolating electron/ion conduction pathways and stable structural integrity. As a result, the pomegranate-structured NVP@C composite displayed remarkable overall electrochemical performance: a high discharge capacity (110 mA h g−1 at 1C), excellent rate capability (92 mA h g−1 even at 50C) and impressive cycling stability (capacity retention of 91.3% over 2000 cycles at 10C). Such a feasible and beneficial design provides a good strategy for other materials that require both size reduction and high electronic/ionic conductivity. [ABSTRACT FROM AUTHOR]