Nanophase-segregation in the dielectric layer enhances the charge storage capacity of polymeric electrochemical supercapacitors

Abstract

Properties related with the charge storage capacity have been evaluated for threelayered films made with two sheets of poly(3,4-ethylenedioxythiophene) separated by an sheet of poly(N-methylpyrrole) or poly(3,4-ethylenedioxythiophene-co-Nmethylpyrrole) (3l-PEDOT/PNMPy or 3l-PEDOT/P(EDOT-co-NMPy), respectively).The most distinctive trend of the copolymer, which shows electrochemical properties intermediate between those of the two homopolymers, is the formation of a biphasic structure, EDOT-and NMPy-rich blocks organizing separately. The ability to exchange charge reversibly is higher for 3l-PEDOT/P(EDOT-co-NMPy) than for 3l-PEDOT/PNMPy, the electroactivity and electrostability of such two 3-layered films being significantly better than that of single-layered PEDOT. Advantages of 3l-PEDOT/P(EDOT-co-NMPy) are mainly based on the nanophase-segregated structure of the copolymer. Thus, the intermediate layer can be considered as random disposition of ultrathin dielectrics having nanometric length and width. In terms of charge storage, the intermediate layer of 3l-PEDOT/P(EDOT-co-NMPy) can be viewed as a thin reservoir filled of heterogeneously distributed nanometric supercapacitors that are connected in series among them and in parallel to the PEDOT layers. The superiority of 3l-PEDOT/P(EDOT-co-NMPy) as organic electrochemical supercapacitor compared to other 3-layered systems, has been proved by powering a red LED bulb.

Interface porosity in multilayered all‐conducting polymer electrodes

“…Consequently, the interface that separates the two CP layers in PEDOT/p/PEDOT causes an increment of ~19% in both Q 2nd and SC 2nd with respect to PEDOT/PEDOT. On the other hand, the SC 2nd determined for 3l‐PEDOT/PNMPy and 3l‐PEDOT/COP single electrodes was of 35 and 72 F/g, respectively. Accordingly, the replacement of the PNMPy or COP dielectric layer by a porous interface between the two PEDOT layers enhances the charge storage capacity by 151% and 22%, respectively.…”

“…In the last decade, we used the layer‐by‐layer (LbL) electrodeposition technique to prepare nanostructured conducting systems based on three alternated layers of poly(3,4‐ethylenedioxythiophene) (PEDOT) and poly( N ‐methylpyrrole) (PNMPy) , hereafter abbreviated 3l‐PEDOT/PNMPy (i.e., PEDOT/PNMPy/PEDOT). These multilayered materials showed better electrochemical properties and a higher ability to store charge than each of the two individual CPs and the corresponding copolymer, poly(3,4‐ethylenedioxythiophene‐ co ‐ N ‐methylpyrrole), hereafter named COP .…”

“…This synergy was proved considering three‐layered systems with different physical characteristics, composition, and/or polymerization conditions. These included systems that differ in the thickness of the layers (i.e., micro‐ and nanometric layers), systems prepared using dynamical conditions rather than conventional quiescent solutions , and systems modified with clays at the dielectric layer or with an octanethiol self‐assembled monolayer at the first PEDOT layer .…”

“…On the other hand, three‐layered electrodes has been also prepared replacing the PNMPy dielectrics by COP , poly(indole‐5‐carboxylic acid) , poly[5,5′‐bis(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐5‐yl)‐2,2′‐bithiophene] . Results obtained for PEDOT/COP/PEDOT three‐layered systems, hereafter after denoted 3l‐PEDOT/COP, were particularly noticeable since the copolymer organized forming nanophase‐segregated structures . Accordingly, the intermediate layer of 3l‐PEDOT/COP was described as a random disposition of ultrathin dielectrics having nanometric length and width.…”

“…Accordingly, the intermediate layer of 3l‐PEDOT/COP was described as a random disposition of ultrathin dielectrics having nanometric length and width. In terms of charge storage, the intermediate layer of 3l‐PEDOT/COP was viewed as a thin reservoir filled with heterogeneously distributed nanometric supercapacitors that are connected in series among them and in parallel to the PEDOT layers .…”