Nanoscale Blended MnO₂Nanoparticles in Electro-polymerized Polypyrrole Conducting Polymer for Energy Storage in Supercapacitors

Abstract

Polypyrrole (pPy) conducting polymer films embedded with MnO2 nanoparticles have been synthesized by electrochemical polymerization and anodic oxidation processes. MnO2 nanoparticles coexist in the hydrated Mn(II) and Mn(IV) states and undergo valence state change along side pPy anion doping-dedoping contributing to the system pseudocapacitance. Increased density of sequestered MnO2 nanoparticles in pPy significantly improves charge storage properties as shown by increased electrodic specific capacitance from 200 to 620 Fg-1 based on cyclic voltammetry studies. MnO2 nanoparticle dispersion in open porous pPy microstructure is affected by current density in excess of 4 mA.cm-2 used in synthesis and results in MnO2 particle agglomeration that excludes open surface access reducing specific capacitance. Charge-discharge studies show stable capacitance retention for ∼1000 cycles. The redox performance of MnO2-pPy composite electrodes is suitable for application in the high energy density supercapacitors.

Composite-modified anode by MnO2/polypyrrole in marine benthic microbial fuel cells and its electrochemical performance

“…These peaks are consistent with PPy, indicating that MnO 2 /PPy composites have the basic characteristic of PPy. It is noteworthy that some of these peaks shifted as a result of the interaction between MnO 2 and PPy . The blue shift of composite material characteristic peak indicates that molecular vibration requires larger energy, and the group of composite is more stable.…”

“…Another difference is that the unmodified electrode has a sharp decline over the highest point, which strongly relates with its anti‐polarization performance when the current density is about 600 mA m −2 . The curves of PPy‐modified anode and MnO 2 /PPy composite‐modified anode are relatively flat near the highest point, because they have larger capacitance performance . It indicates that there is a strong correlation of anti‐polarization performance with maximum power density, which has intrinsic inevitability.…”

“…With the variation of scanning potential, the unmodified and PPy electrode curves show a little gradual increase, but the response current of the MnO 2 /PPy composite increases much bigger. It suggests that under the same conditions, the MnO 2 /PPy composite‐modified anode could transmit more electrons (manganese ions from Mn 4+ turn to Mn 2+ , act as electronic intermediaries) and has higher electrochemical activity .…”

“…The maximum power densities of unmodified, PPymodified, and MnO 2 /PPy composite-modified anodes are 268.5 ± 10, 378.4 ± 10, and 562.7 ± 10 mW m À2 , respectively ( Figure 7). The power density and the corresponding current density have been improved greatly after the [28,30]. It indicates that there is a strong correlation of anti-polarization performance with maximum power density, which has intrinsic inevitability.…”

“…Manganese dioxide (MnO 2 ) has been widely used as the electrode material of rechargeable battery [23][24][25] because of its high capacitance, reaction reversibility, and low cost. PPy/MnO 2 composite has been used as electrode material for supercapacitor in many researches [21,[26][27][28][29][30][31]. Li Juan et al utilized methyl orange as a template, ferric chloride as an oxidant to fabricate a PPy/MnO 2 supercapacitance composite material (300 F g À1 ) [26].…”