Proportion of composition in a composite does matter for advanced supercapacitor behavior

We report an advanced aqueous asymmetric supercapacitor (AAS) comprised of Ni3V2O8@MWCNT (CNV) composite as the positive electrode and beta FeOOH@rGO (GF) composite as the negative electrode. According to the literature surveyed, this new Ni3V2O8@MWCNT composite has been exploited for the first time as a positive electrode. We have prepared different Ni3V2O8@MWCNT composites using variable proportions of participating materials via our laboratory-developed modified hydrothermal (MHT) technique. Among them, the as-synthesized CNV composite exhibited excellent pseudocapacitive activity (specific capacitance value of 2920 F g(-1) at 2 A g(-1) specific current, excellent rate capability and 96% capacitance retention after 10 000 cycles). Similarly, different b FeOOH@rGO composites were also synthesized using the same MHT, again with different proportions of the iron component and rGO. Among them, GF exhibited specific capacitance values of 1306 F g(-1) at 1 A g(-1) specific current with excellent rate capability and extraordinary cyclic durability. Furthermore, the assembled Ni3V2O8@ MWCNT//beta FeOOH@rGO asymmetric supercapacitor exhibited very impressive electrochemical activity. It exhibited a specific capacitance of 976 F g(-1) at 0.25 A g(-1) specific current and maximum specific energy of 86.7 W h k g(-1) at a specific power of 198.71 W k g(-1). Due to the impressive specific energy value, the as-fabricated asymmetric supercapacitor could be a good alternative for rechargeable batteries.