Functionalization of Polypyrrole Nanopipes with Redox‐Active Polyoxometalates for High Energy Density Supercapacitors

Abstract

Hybrid materials are very attractive for the fabrication of high‐performance supercapacitors. Here, we have explored organic–inorganic hybrid materials based on open‐end porous 1 D polypyrrole nanopipes (PPy‐NPipes) and heteropolyoxometalates (phosphotungstate ([PW12O40]3−, PW12) or phosphomolybdate ([PMo12O40]3−, PMo12)) that display excellent areal capacitances. Two different hybrid materials (PMo12@PPy and PW12@PPy) were effectively synthesized and used for symmetric supercapacitors. The anchoring of the inorganic nanoclusters onto the conducting polymer nanopipes led to electrodes that stood up to our best expectations exhibiting outstanding areal capacitances that are almost 1.5 to 2 fold higher than that of pristine PPy‐NPipes. In addition, symmetric cells based on PMo12@PPy and PW12@PPy hybrid electrodes were fabricated and showed significant improvement in cell performance with very high volumetric capacitances in the range of 6.3–6.8 F cm−3 (considering the volume of whole device). Indeed, they provide extended potential windows in acidic electrolytes (up to 1.5 V) which led to ultrahigh energy densities of 1.5 and 2.2 mWh cm−3 for PMo12@PPy and PW12@PPy cells, respectively. Thus, these unique organic‐inorganic hybrid symmetric cells displayed extraordinary electrochemical performances far exceeding those of more complex asymmetric systems.

o‐Benzenediol‐Functionalized Carbon Nanosheets as Low Self‐Discharge Aqueous Supercapacitors

“…[21][22][23][24] By cycling the electrode in the electrolyte containing the target species, the charge density of the electrode can be influenced, due to chemical grafting. However,t he Widening the voltage window is often proposed as aw ay to increaset he energy density of aqueous supercapacitors.…”

Asymmetric Supercapacitors Based on Reduced Graphene Oxide with Different Polyoxometalates as Positive and Negative Electrodes

“…linked with oxygen atoms to form a three dimensional cluster . These nanometric molecular clusters are very stable and have a stable interaction with various electrode materials such as graphene or conducting polymers . One of the most noteworthy properties of POMs is the ability to accept and release electrons without changing structural features; this makes POMs suitable electrode materials for SCs.…”

Polypyrrole Nanopipes as a Promising Cathode Material for Li‐ion Batteries and Li‐ion Capacitors: Two‐in‐One Approach

“…The appreciable surface contribution in the present case is attributed to the nanopipe‐like structure of the PPy material which facilitates high surface area as well as open channels for electrolyte diffusion. The good conductivity and interconnections between PPy‐NPipes help to advance the electronic diffusion through the electrode network . Figure d shows galvanostatic charge‐discharge (GCD) curves of PPy‐NPipes recorded at different current densities from 0.14 A/g to 13.8 A/g.…”