Recent Progress in Polyaniline and its Composites for Supercapacitors

Synthesis of NiMn2O4/PANI nanosized composite with increased specific capacitance for energy storage applications

Polyaniline (PANI) stands out as a highly promising conducting polymer with potential for advanced utilization in high-performance pseudocapacitors. Therefore, there exists a pressing need to bolster the structural durability of PANI, achievable by developing composite materials that can enhance its viability for supercapacitor applications. In this particular study, a pioneering approach was undertaken to produce a novel NiMn2O4/PANI supercapacitor electrode material. A comprehensive array of analytical techniques was employed to ascertain the structural configuration, morphology, oxidation states of elements, composition, and surface characteristics of the electrode material. The electrochemical evaluation of the NiMn2O4/PANI composite shows a specific capacitance (Cs) of 1530 ± 2 F g-1 at 1 A g-1. Significantly, the composite material displays an outstanding 93.61% retention of its capacity after an extensive 10 000 cycles, signifying remarkable cycling stability, while the 2-electrode configuration reveals a Cs value of 764 F g-1 at 5 mV s-1 and 826 F g-1 at 1 A g-1 with a smaller charge transfer resistance (Rct) value of 0.67 Ω. Chronoamperometric tests showed excellent stability of the fabricated material up to 50 h. This significant advancement bears immense promise for its potential implementation in high-efficiency energy storage systems and heralds a new phase in the development of supercapacitor technology with improved stability and performance metrics.

Advanced High-Energy All-Solid-State Hybrid Supercapacitor with Nickel-Cobalt-Layered Double Hydroxide Nanoflowers Supported on Jute Stick-Derived Activated Carbon Nanosheets

Developing efficient, lightweight, and durable all-solid-state supercapacitors is crucial for future energy storage systems. The study focuses on optimizing electrode materials to achieve high capacitance and stability. This study introduces a novel two-step pyrolysis process to synthesize activated carbon nanosheets from jute sticks (JAC), resulting in an optimized JAC-2 material with a high yield (≈24%) and specific surface area (≈2600 m2 g-1). Furthermore, an innovative in situ synthesis approach is employed to synthesize hybrid nanocomposites (NiCoLDH-1@JAC-2) by integrating JAC nanosheets with nickel-cobalt-layered double hydroxide nanoflowers (NiCoLDH). These nanocomposites serve as positive electrode materials and JAC-2 as the negative electrode material in all-solid-state asymmetric hybrid supercapacitors (HSCs), exhibiting remarkable performance metrics. The HSCs achieve a specific capacitance of 750 F g-1, a specific capacity of 209 mAh g-1 (at 0.5 A g-1), and an energy density of 100 Wh kg-1 (at 250 W kg-1) using PVA/KOH solid electrolyte, while maintaining outstanding cyclic stability. Importantly, a density functional theory framework is utilized to validate the experimental findings, underscoring the potential of this novel approach for enhancing HSC performance and enabling the large-scale production of transition metal-based layered double hydroxides.

Enhancing supercapacitor performance of Ni-Co-Mn metal-organic frameworks by compositing it with polyaniline and reduced graphene oxide

Metal-organic frameworks (MOFs) are one of the most sought-after materials in the domain of supercapacitors and can be tailored to accommodate diverse compositions, making them amenable to facile functionalization. However, their intrinsic specific capacitance as well as energy density is minimal, which hinders their usage for advanced energy storage applications. Therefore, herein, we have prepared six electrodes, i.e., Ni-Co-Mn MOFs, polyaniline (PANI), and reduced graphene oxide (rGO) along with their novel nanocomposites, i.e., C1, C2, and C3, comprising MOFs : PANI : rGO in a mass ratio of 100 : 1 : 0.5, 100 : 1 : 1, and 100 : 1 : 10, respectively. The polyaniline conducting polymer and rGO enabled efficient electron transport, enhanced charge storage processes, substantial surface area facilitating higher loading of active materials, promoting electrochemical reactions, and ultimately enhanced nanocomposite system performance. As a result, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques confirmed the successful synthesis and revealed distinct morphological features of the materials. Following electrochemical testing, it was observed that composition C2 exhibited the highest performance, demonstrating a groundbreaking specific capacitance of 1007 F g-1 at 1 A g-1. The device showed a good energy density of 25.11 W h kg-1 and a power density of 860 W kg-1. Remarkably, the device demonstrated a capacity retention of 115% after 1500 cycles, which is a clear indication of the wettability factor, according to the literature. The power law indicated b-values in a range of 0.58-0.64, verifying the hybrid-type behavior of supercapacitors.