Enhanced energy density of a supercapacitor using 2D CoMoO₄ ultrathin nanosheets and asymmetric configuration

Abstract

Developing a high energy density micro-supercapacitor still remains a big challenge. In this paper, a two-dimensional (2D) CoMoO ultrathin nanosheet (NS)-based asymmetric supercapacitor (ASC) is fabricated. It is found that the CoMoO NS electrode processes a high specific capacitance (153.2 F g) at a current density of 1 mA cm and this ASC can deliver an energy density of 0.313 mWh cm at a power density of 80 mW cm, which is higher than that reported in the literature. Moreover, the ASC can drive a light emitting diode (3 mm diameter, red) to work for 6 min after being charged for 10 s. After 5000 cycles, 77.37% of capacitance still remains. We maintain that the ultrathin thickness can significantly shorten the diffusion paths for both electrons and ions, thus leading to fast electron transport and ion diffusion rates. Our results demonstrate that 2D ultrathin NSs could be a new, promising candidate for energy conversion/storage devices, which could offer more accommodating sites for ion intercalation.

Boosting the energy storage performance of cobalt molybdate microspheres constructed from urotropin‐induced ultrathin nanosheets

“… According to Equation , the CoMoO 4 with 3 mmol of added urotropin exhibits the highest specific capacity values of 89, 77, 75, 73, 67, and 65 mAh/g at 0.25, 0.50, 0.75, 1.00, 2.00, and 2.50 A/g, respectively (Figure E). These results are superior to reports of similar CoMoO 4 , such as CoMoO 4 using F127 as a template (25 mAh/g at 0.2 A/g), CoMoO 4 nanorods/carbon (53 mAh/g at 1 A/g) and CoMoO 4 nanorods/graphene (51 mAh/g at 1 A/g), and CoMoO 4 nanosheets (21 mAh/g at 1 mA/cm 2 ) . The reasons are as follows: (a) the high specific surface area can allow CoMoO 4 access to electrolyte OH − ions; (b) the mesoporous structure can also accelerate the diffusion of OH − electrolyte ions into the CoMoO 4 phase; (c) the interconnected nanosheet structure can contribute to rapid charge migration and shorten the path of charge transfer.…”

“…No obvious decay can be found after 10 000‐cycle, indicating the excellent stability of assembled CoMoO 4 //AC device. To the best of our knowledge, the cycle stability of our prepared device exceeds almost all the CoMoO 4 ‐based hybrid supercapacitors reported in the literature, such as CoMoO 4 nanosheets//AC hybrid supercapacitor (77.37% after 5000 cycles), hierarchical CuCo 2 O 4 @CoMoO 4 nanowire/nanoplate//activated carbon (84.1% after 2000 cycles), and CoMoO 4 ‐MnO 2 @3D graphene foam (92.1% after 10 000 cycles) . This excellent cycle stability is favorable for the practical application of the CoMoO 4 //AC hybrid devices.…”

“…Recently, some CoMoO 4 materials with unique structures have been prepared to improve the supercapacitor performance. For example, CoMoO 4 nanosheets prepared by hydrothermal methods exhibit 21 mAh/g at 1 mA/cm 2 ; CoMoO 4 nanowires obtained by combining a “directional attachment” technique possess the excellent electrochemical performance of 0.7 F/cm 2 at 2 mA/cm 2 ; CoMoO 4 nanorods synthesized by microwave methods own 53 mAh/g at 1 A/g; globular CoMoO 4 possess a specific capacitance of 384 F/g at 1 A/g . Encouraged by this fact, interconnected CoMoO 4 nanosheets can boost supercapacitor performance owing to the porous structure, high‐surface area, and rapid charge transfer.…”

Hydrothermal Synthesized of CoMoO4 Microspheres as Excellent Electrode Material for Supercapacitor

“…The BET specific surface areas of CMO-1, CMO-4, CMO-8, CMO-12, and CMO-24 were calculated to be 18.4, 29.2, 42.8, 74.1, and 26.2 m 2 g −1 , respectively. Sample CMO-12 shows the highest BET surface area, and the high BET surface area could increase the contact area of electrode/electrolyte and provide more active sites for efficient transport of electrons and ions in electrode system [ 35 ]. As shown in Fig.…”

“…The EIS results show that the CMO-12 sample has lower values of R s and R ct than the other four samples. This indicates that the CMO-12 sample has higher electronic and ionic conductivities than the other samples [ 35 , 50 , 51 ]. Besides, CMO-12 with mesopores structure has higher BET surface area than the other samples.…”