High performance asymmetric supercapacitor based on MnO2 electrode in ionic liquid electrolyte

Abstract

In this work, the electrochemical properties of a MnO 2 nanocomposite electrode were investigated in 1butyl-3-methyl-imidazolium hexafluorophosphate ([Bmim]PF 6 )/N,N-dimethylformamide (DMF) electrolyte. The [Bmim]PF 6 /DMF electrolyte with different volume fractions exhibits significant influence on the electrochemical properties of the electrode. When the volume ratio of [Bmim]PF 6 and DMF was 1 : 1, the electrode showed the best electrochemical performance. The operation potential window of the MnO 2 nanocomposite electrode in ionic liquids was 2.1 V and the specific capacitance according to the mass of MnO 2 was 523.3 F g À1 at 3 A g À1 . Then, a high-voltage (3 V) MnO 2 asymmetric supercapacitor was successfully fabricated, using the MnO 2 nanocomposite electrode, activated carbon and [Bmim]PF 6 /DMF as the positive electrode, negative electrode and electrolyte, respectively. The MnO 2 asymmetric supercapacitor displayed a maximum specific energy of 67.5 W h kg À1 at a specific power of 593.8 W kg À1 and a maximum specific power of 20.4 kW kg À1 at a specific energy of 8.5 W h kg À1 . The impressive results showed that [Bmim]PF 6 /DMF could be a promising electrolyte for MnO 2 supercapacitors.

A review of electrolyte materials and compositions for electrochemical supercapacitors

“…304 For example, Zhang et al 304 found that the introduction of DMF to [BMIM][PF 6 ] IL increased the capacitance and at the same time decreased the internal resistance of the asymmetric AC//MnO 2 ES. 304 For example, Zhang et al 304 found that the introduction of DMF to [BMIM][PF 6 ] IL increased the capacitance and at the same time decreased the internal resistance of the asymmetric AC//MnO 2 ES.…”

“…ILs have also been explored as electrolytes for hybrid ESs with asymmetric electrode configurations (e.g., AC//poly-(3-methylthiophene), 302,303 AC//MnO 2 ,304 and AC//graphene-À1 , respectively, after the first thousand cycles at 10 mA cm À2 and 60 1C. Sun et al296 used [EMIM][BF…”

Materials and fabrication of electrode scaffolds for deposition of MnO2 and their true performance in supercapacitors

“…Firstly, the energy density of the asymmetric systems is generally higher than that of the symmetric systems due to the increased cell voltage from 0.8e1.0 V (symmetric) to 1.6e2.0 V (asymmetric). The asymmetric system combined with ionic liquid electrolyte further boosted the cell voltage to 3.0 V, and high energy density to 67.5 W h kg À1 , however, the cycling stability of such system still needs to be thoroughly understood [88]. Secondly, a rod-shaped supercapacitor assembled by two robust graphene/CNTs/MnO 2 composite films (3.2 mg, 2.2 mg cm À2 ) without metallic current collector could deliver an energy density of 2.2 W h kg À1 and a maximum power density of 42 kW kg À1 based on all the components of the packaged cell [89], which are better than that of the commercial device (0.9 W h kg À1 ; 2400 W kg…”

“…[142,143], electrophoretic deposition [88,144], layer by layer assembly [145] and electrostatic spray deposition [146].…”

Manganese dioxide nanoparticles incorporated within ionic liquid derived fibrillated mesoporous carbon: electrode material for high-performance supercapacitors

“…10,14,15,18,[22][23][24][25][26][27][28] Among them, manganese oxides and hydroxides are of particular importance due to their low price, high theoretical specic capacitance and low toxicity. 7,10,13,23,[32][33][34][35][36][37][38][39][40][41][42] It could therefore be possible to overcome the low specic capacitance of carbon materials. 2,11,30,31 For carbon based materials incorporated with transition metal oxides, the charge storage mechanism relies on both electrical double-layer mechanisms in addition to the contribution of the redox reactions.…”