Development of 3D Urchin-Shaped Coaxial Manganese Dioxide@Polyaniline (MnO₂@PANI) Composite and Self-Assembled 3D Pillared Graphene Foam for Asymmetric All-Solid-State Flexible Supercapacitor Application

Abstract

We have fabricated high-energy-density all-solid-state flexible asymmetric supercapacitor by using a facile novel 3D hollow urchin-shaped coaxial manganese dioxide@polyaniline (MnO@PANI) composite as positive electrode and 3D graphene foam (GF) as negative electrode materials with polyvinyl alcohol (PVA)/KOH gel electrolyte. The coaxial MnO@PANI composite was fabricated by hydrothermal route followed by oxidation without use of an external oxidant. The formation mechanism of the 3D hollow MnO@PANI composite occurs first by nucleation and growth of the MnO crystal species via dissolution-recrystallization and oriented attachment mechanisms followed by the oxidation of aniline monomers on the MnO crystalline template. The self-assembled 3D graphene block was synthesized by hydrothermal route using vitamin C as a reducing agent. The microstructures of the composites are analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The morphology is characterized by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), which clearly showed the formation of urchin-shaped coaxial MnO@PANI composite. The electrochemical studies are explored by cyclic voltammetry, electrochemical impedance spectrometry, and cyclic charge-discharge tests. The symmetric all-solid-state flexible MnO@PANI//MnO@PANI and GF//GF supercapacitors exhibit the specific capacitance of 129.2 and 82.1 F g at 0.5 A/g current density, respectively. The solid-state asymmetric supercapacitor shows higher energy density (37 Wh kg) with respect to the solid-state symmetric supercapacitors MnO@PANI//MnO@PANI and GF//GF, where the obtained energy density are found to be 17.9 and 11.4 Wh kg, respectively, at 0.5 A/g current density. Surprisingly, the asymmetric supercapacitor shows a high energy density of 22.3 Wh kg at a high current density of 5 A g. The solid-state asymmetric supercapacitor shows a good cyclic stability in which ∼11% capacitance loss was observed after 5000 cycles.

Electrochemical Performance of Manganese Coordinated Polyaniline

“…The electrodes and membranes were overlapped and packaged by ultra-thin plastic film. Obviously, the maximum energy density of PANI-Mn supercapacitor is 51.38 Wh kg −1 at the power density of 850 W kg −1 , presenting a higher energy density and power density compared to analogous PANI supercapacitors, such as NPCNFs//NPCNFs (NPCNF means nitrogen-doped porous carbon nanofibers, 9.2 Wh kg −1 at 0.25 kW kg −1 ), [50] rGO/PANI (28.06 Wh kg −1 at 0.25 kW kg −1 ), [51] MnO 2 /HGNF// PANI/HGNF (HGNF means hybrid graphene/Ni 3D scaffolds, 41.0 W h kg −1 at 787.3 W kg −1 ), [52] MnO 2 @PANI// MnO 2 @PANI (37 Wh kg −1 at 386 W kg −1 ), [19] SPAN/FC// SPAN/FC (SPAN means self-doped polyaniline, 9.2 Wh kg −1 at 1000 W kg −1 ), [53] BNC/CNT/ion gel (BNC means bacterial Slight polarization is observed when the voltage range expands from 1.5 to 1.8 V. The PANI-Mn supercapacitor is investigated at the voltage window of 1.7 V. Figure 8C,D shows CV curve at different scanning rates and GCD curve at different current densities.…”

“…[12] The continuous volume change can destroy the polymer chain structure of PANI and weaken electron transport. [18] Moreover, the PANI/transition metal composite materials, such as PANI/MnO 2 , [19] PANI/ SnO 2 , [20] PANI/MoS 2 [21] are also used to improve the cyclic stability of PANI due to high stability and capacitance of transition metal compounds. [14] Generally, the PANI/carbon composite materials, such as PANI/carbon fibers, [15] PANI/carbon nanotubes, [16] and PANI/graphene [17] are adopted to improve cyclic stability of PANI since carbon materials have high surface area, excellent structural stability, and high connectivity.…”

Facile Synthesis of Single‐ and Multi‐Layer Graphene/Mn3O4 Integrated 3D Urchin‐Shaped Hybrid Composite Electrodes by Core‐Shell Electrospinning

“…The peak at 645 cm −1 is attributed to the symmetric stretching vibration of Mn−O whereby the intensity of this peak significantly increased after heat treatment and this verifies the successful oxidation of manganese during heat treatment. Also, this peak is shifted to the left after PANI decoration owing to the H‐bonding interactions between Mn 3 O 4 , graphene, and PANI together . Moreover, PANI@Mn 3 O 4 /TEGO−CF and PANI@Mn 3 O 4 /GNP−CF hybrids have additional peaks at 1157 cm −1 corresponding to the aromatic C−H in‐plane bending of benzoid ring, 1399 cm −1 attributed to C−N + stretching, 1529 cm −1 due to the stretching vibrations of C=N of emeraldine base, and 1648 cm −1 related to the C−C stretching of the benzenoid ring .…”

AgCoO2−Co3O4/CMC Cloudy Architecture as High Performance Electrodes for Asymmetric Supercapacitors

“…Supercapacitors can store charges either by ion adsorption phenomenon (electric double layer capacitor, EDLC) or fast Faradic reactions (pseudocapacitor) . Conventionally, carbonaceous materials (graphene, CNT, activated carbon) and pseudocapacitive materials (transition metal oxides and conducting polymers) serve as electrode materials in supercapacitors …”

“…[4] Conventionally, carbonaceous materials (graphene, CNT, activated carbon) and pseudocapacitive materials (transition metal oxides and conducting polymers) serve as electrode materials in supercapacitors. [5][6][7][8] Cobalt oxide (Co 3 O 4 ) has attracted special interest widely as an electrode material for supercapacitors owing to its multiple redox states (Co + , Co 2 + , Co 3 + , Co 4 + ), high theoretical capacitance (~3560 F g À 1 ), excellent thermal and electrochemical stability, etc. [9][10][11][12] Nevertheless, its poor conductivity (10 À 3 to 10 À 4 S cm À 1 ), low rate capability and limited availability (3 0 ppm in earth curst) restricts its commercialization as an electrode in supercapacitor applications .…”