Redox Poly‐Counterion Doped Conducting Polymers for Pseudocapacitive Energy Storage

Abstract

Conducting polymers (CPs) have been widely studied for electrochemical energy storage. However, the dopants in CPs are often electrochemically inactive, introducing “dead‐weight” to the materials. Moreover, commercial‐level electrode materials with high mass loadings (e.g., >10 mg cm−2) often encounter the problems of inferior electrical and ionic conductivity. Here, a redox‐active poly‐counterion doping concept is proposed to improve the electrochemical performance of CPs with ultra‐high mass loadings. As a study prototype, heptamolybdate anion (Mo7O246−) doped polypyrrole (PPy) is synthesized by electro‐polymerization. A 2 mm thick PPy electrode with mass loading of ≈192 mg cm−2 reaches a record‐high areal capacitance of ≈47 F cm−2, competitive gravimetric capacitance of 235 F g−1, and volumetric capacitance of 235 F cm−3. With poly‐counterion doping, the dopants also undergo redox reactions during charge/discharge processes, providing additional capacitance to the electrode. The interaction between polymer chains and the poly‐counterions enhances the electrical conductivity of CPs. Besides, the poly‐counterions with large steric hindrance could act as structural pillars and endow CPs with open structures for facile ion transport. The concept proposed in this work enriches the electrochemistry of CPs and promotes their practical applications.

pH-Responsive Polyoxometalates that Achieve Efficient Wastewater Reclamation and Source Recovery via Forward Osmosis

“…Single-crystal X-ray crystallography analysis shows that (NH 4 ) 6 Mo 7 O 24 and Na 6 Mo 7 O 24 both contain a cage-like anion and six cations (Figure c). This polyoxometalate anion has a typical Lindqvist structure, which is composed of seven MoO 6 octahedral units . Each peripheral MoO 6 shares four sides with the other adjacent octahedrons, and the central MoO 6 octahedron shares all sides with the surrounding octahedrons, consistent with the chemical formula of the proposed polyoxometalates.…”

Polyaniline Protrusions on MoS2 Nanosheets for PVDF Scaffolds with Improved Electrical Stimulation

“…From the elemental distribution of PANI-MoS 2 in Figure f, Mo and S elements from MoS 2 and C and N elements resulting from PANI were found to be simultaneously present. These results implied that PANI interspersed in the adjacent MoS 2 nanosheets, which acted as a steric hindrance to prevent stacking and aggregating of MoS 2 …”

“…These results implied that PANI interspersed in the adjacent MoS 2 nanosheets, which acted as a steric hindrance to prevent stacking and aggregating of MoS 2 . 28 The XRD spectra of MoS 2 , PANI, and PANI-MoS 2 are shown in Figure 3a, aiming to study their phase structure. Obviously, the diffraction peaks at 2θ = 14.4, 33.2, 39.5, 49.9, 58.8, and 60.8°were ascribed to the (002), (100), ( 103), (105), (110), and (112) planes of MoS 2 , respectively.…”

Switchable PNIPAm/PPyNT Hydrogel for Smart Supercapacitors: External Control of Capacitance for Pulsed Energy Generation or Prolongation of Discharge Time

“…The supercapacitor was prepared by intertwining the PNIPAm/PPy film, used as a negative electrode against the RGO/MWCNT paper (positive electrode) with a cellulose membrane as a separator. − The three-dimensional printed sample holder, equipped with elastic loading to prevent the plane shrinkage of gel films, was used to ensure the contact between films in the supercapacitor.…”