Core–Shell Structured Cellulose Nanofibers/Graphene@Polypyrrole Microfibers for All‐Solid‐State Wearable Supercapacitors with Enhanced Electrochemical Performance

Abstract

Thanks to their considerable electrochemical and mechanical properties, fiber‐shaped supercapacitors have become the most potential energy storage devices for portable and wearable electronics in the future; however, challenges still exist in the pursuit of practical applications among them. In this work, ternary microfibers, which are composed of TEMPO‐oxidized cellulose nanofibers/reduced graphene oxide microfiber cores coated with polypyrrole shell layers, are successfully fabricated through industrializable and sustainable wet‐spinning and interfacial polymerization strategies. The prepared microfibers possess well‐defined microstructures and outstanding mechanical properties (559 MPa). When assembled into symmetrical all‐solid‐state fiber‐shaped supercapacitors (FSCs), they exhibit remarkable electrochemical properties (647 mF cm−2, 14.37 µWh cm−2 at 0.1 mA cm−2), prominent cycling stability (92.5% capacitance retention and 92.6% coulomb efficiency after 10 000 cycles), and extraordinary flexibility (no significant decay in capacitance after 5000 bending cycles), which are superior to all the congeneric FSCs reported to date. The prominent performances are ascribed to the synergistic effect of the well‐designed ternary system and synergistic effects between interior components. The advantages in electrochemical, mechanical, and industrial properties of the ternary FSCs can provide reference and boost the development of flexible energy storage applications.

Mesoporous Carbon Microfibers for Electroactive Materials Derived from Lignocellulose Nanofibrils

“…With optimized parameters, fibres have been manufactured with high stiffness (86 GPa) and tensile stress (1.57 GPa) (Mittal et al 2018); these values are much higher compared to the properties of known natural or synthetic biopolymeric materials. Finally, functional systems, e.g., magnetic (Walther et al 2011), superabsorbent (Lundahl et al 2018b), electroconductive (Wan et al 2019;Chen et al 2020), water-resistant (Cunha et al 2018Tripathi et al 2018), bioactive (Vuoriluoto et al 2017) fibres can be obtained by modification of the spinning dope, coagulants, and subsequent post-treatment.…”

“…Regarding colloidal wet spinning, aqueous electrolytes have been investigated as coagulants, such as acidic solution including HCl, CH3COOH, H2SO4, and H3PO4 (Mittal et al 2017;Nechyporchuk et al 2017;Hagström et al 2018), and salt electrolytes including CaCl2 (Kafy et al 2017;Kim et al 2019a;Gao et al 2020) and FeCl3 (Wan et al 2019;Mittal et al 2019;Chen et al 2020). In all these processes, the possibility for continuous wet-spinning have been demonstrated, which is challenged in wet-spinning with organic coagulants.…”

“…However, as discussed before, multifunctional fibres can be fabricated from nanocellulose via wet spinning that broadens the potential applications. They include uses as sensors (Wan et al 2019), electronics, water purification systems (Vuoriluoto et al 2017), reinforcement in composites (Mittal et al 2018), energy storage devices (Chen et al 2020), as well as smart textiles (Wang et al 2017). Due to high carbon content, lignin-based fibres are mainly applied as precursors for carbon fibre production in various areas such as for composite as well as energy conversion systems (Baker and Rials 2013;Nowak et al 2018).…”

Integrated Conductive Hybrid Electrode Materials Based on PPy@ZIF-67-Derived Oxyhydroxide@CFs Composites for Energy Storage

“…The diffraction peaks at 15.6° and 22.5° are attributable to the characteristic peaks of CFs. In addition, the characteristic peak of PPy in PC composites is about 22.9° [ 38 ], which coincided with the (002) diffraction plane of CFs. There were some extra peaks in ZCC-2 and PZCC-2 composites at 18.8°, 39.1°, 44.3°, and 65.1°, corresponding to the (003), (111), (140), and (002) planes of cobalt oxyhydroxide (ICDD/JCPDS 26-0480, space group: Pbnm (62), a = 4.353 nm, b = 9.402 nm, c = 2.840 nm).…”

Vegetable Oil‐Based Waterborne Polyurethane as Eco‐Binders for Sulfur Cathodes in Lithium–Sulfur Batteries

“…[15][16][17] Many efforts have been made to overcome these challenges. Most efforts have focused on developing sulfur-containing carbon materials for the cathodes, such as porous/mesoporous carbon, [18,19] graphene, [20][21][22] carbon nanotubes, [23] and carbon nanofibers. [24] Although these approaches effectively improved the LSB performance on the laboratory scale, the material synthesis is complex and expensive, and it is difficult to extend these materials to large scale production for their wide use.…”