**7. Conclusion**

*Novel Nanomaterials*

**Figure 8.**

of 92% after 5000 cycles (**Figure 8(d-f )**). In addition, the VACNTF@MoSe2/NF composite based ASC displays a high energy density with 22 W h kg−1 for a power density of 330 W kg−1. Kirubasankar *et al.* MoSe2/graphene nanohybrid based electrode prepared by a simple and facile sonochemical route, which showed higher specific capacitance (945 F g−1) as compared to MoSe2 nanosheets (576 F g−1) at 1 A g−1 current density. Further, as fabricated ASC device based on MoSe2/

*(a) Schematic illustration of synthetic processes of WS2/N,S-rGO hybrid, (b) HRTEM, STEM and EDS elemental mapping images of WS2/N,S-rGO hybrid, and (c) The specific capacitances of the WS2, N,S-rGO and WS2/N,S-rGO hybrid at different current densities [78]. (d) Schematic illustration of the synthesis process of the VACNTF@MoSe2/NF composite electrode, (e) SEM images of the VACNTF@MoSe2 composites (inset: high magnification), and (f) The specific capacitance comparison of the MoSe2/NF, VACNTF/NF and VACNTF@MoSe2/NF electrodes at various current densities [80]. (g) Specific capacitance of the MoSe2 NS and MoSe2/G nanohybrid based electrodes as a function of current density, and (h) Ragone plot for the* 

graphene nanohybrid retains 88% of its capacitance over 3000 cycles and delivers an energy density of 26.6 W h kg−1 at a power density of 0.8 kW kg−1 (**Figure 8(g, h)**) [81]. The high specific capacitance with better rate capability is due to the effective penetration and migration of electrolyte, reduction of the contact resistance and shortness of the diffusion path of ions between the electrode-electrolyte interface, which enhances the redox kinetics and provide maximum utilization of the electroactive area, so providing a high structural stability during charge-discharge processes. Similarly, Huang *et al*. demonstrated MoSe2/ graphene on flexible Ni electrode, which could deliver a specific capacitance of 1422 F g−1and fully retention of initial capacitance over 1500 cycles [82]. Wei *et al*. first time fabricated free-standing SC anode based on 3D MoSe2 nanoflowers (MoSe2 NFs) and hierarchically porous anisotropic carbonized delignified wood (CDW), which exhibited ultrahigh capacitance of 1043 mF cm−2 at a current density of 1 mA cm−2 and excellent cycling stability less than 5% capacitance loss over 5000 cycles. The ASC device was made by integration of 3D MoSe2 NFs@CDW anode and a common MnO2-based cathode, which exhibited a high capacitance of 415 mF cm−2 at a current density of 2.5 mA cm−2 with high energy density of 147 mW h cm−2 at power density of 2 mW cm−2. These results confirm that 3D MoSe2 NFs@CDW based anode can be used as a potential anode for the development of

*MoSe2G||AC ASC device (inset: photograph of ASC device) [81].*

**132**

high-performance SCs [83].

In the past few decades, SCs have been extensively studied as energy storage devices and more focusing area in the multidisciplinary science over the world. The selection of high performance SC electrode materials based on high specific capacitance, low internal resistance and good stability. In this article, we have reviewed the carbon-based composite materials (*i.e.*, metal oxide, metal hydroxide, TMDs composited with carbon materials) as promising SC electrode materials due to the synergic effect of the composite materials such as high surface area, interconnected porous structure, high electrical conductivity, excellent wettability towards the electrolyte, and presence of electrochemically active surface functionalities of the carbon supports which improves the EDL capacitance while metal oxide or metal hydroxide or TMDs enhances electrochemical performance through pseudocapacitive/faradaic charge-storage process. The carbon-based composite materials demonstrated herein usually possesses high specific capacity, impressive energy density and maintain long term stability with better mechanical flexibility. We also observe the microstructural changes in the carbon-based composite materials would be more favorable for fabrication of high performance supercapacitor. We also explained how the composite materials overcome the traditional obstacles while formulating the standard electrode designs as compare to individual components.
