Cellulose Nanofiber Composite with Bimetallic Zeolite Imidazole Framework for Electrochemical Supercapacitors

Cellulose nanofiber (CNF) and hybrid zeolite imidazole framework (HZ) are an emerging biomaterial and a porous carbonous material, respectively. The composite of these two materials could have versatile physiochemical characteristics. A cellulose nanofiber and cobalt-containing zeolite framework-based composite was prepared using an in-situ and eco-friendly chemical method followed by pyrolysis. The composite was comprised of cobalt nanoparticles decorated on highly graphitized N-doped nanoporous carbons (NPC) wrapped with carbon nanotubes (CNTs) produced from the direct carbonization of HZ. By varying the ratio of CNF in the composite, we determined the optimal concentration and characterized the derived samples using sophisticated techniques. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the functionalization of CNF in the metallic cobalt-covered N-doped NPC wrapped with CNTs. The CNF–HZNPC composite electrodes show superior electrochemical performance, which is suitable for supercapacitor applications; its specific capacitance is 146 F/g at 1 A/g. Furthermore, the composite electrodes retain a cycling stability of about 90% over 2000 charge–discharge cycles at 10 A/g. The superior electrochemical properties of the cellulose make it a promising candidate for developing electrodes for energy storage applications.

Nickel-Embedded Carbon Materials Derived from Wheat Flour for Li-Ion Storage

The biomass-based carbons anode materials have drawn significant attention because of admirable electrochemical performance on account of their nontoxicity and abundance resources. Herein, a novel type of nickel-embedded carbon material (nickel@carbon) is prepared by carbonizing the dough which is synthesized by mixing wheat flour and nickel nitrate as anode material in lithium-ion batteries. In the course of the carbonization process, the wheat flour is employed as a carbon precursor, while the nickel nitrate is introduced as both a graphitization catalyst and a pore-forming agent. The in situ formed Ni nanoparticles play a crucial role in catalyzing graphitization and regulating the carbon nanocrystalline structure. Mainly owing to the graphite-like carbon microcrystalline structure and the microporosity structure, the NC-600 sample exhibits a favorable reversible capacity (700.8 mAh g−1 at 0.1 A g−1 after 200 cycles), good rate performance (51.3 mAh g−1 at 20 A g−1), and long-cycling durability (257.25 mAh g−1 at 1 A g−1 after 800 cycles). Hence, this work proposes a promising inexpensive and highly sustainable biomass-based carbon anode material with superior electrochemical properties in LIBs.

Ti3SiC2/Carbon Nanofibers Fabricated by Electrospinning as Electrode Material for High-Performance Supercapacitors

As an Mn+1AXn phase ternary layered carbide, Ti3SiC2 possesses the advantages of both excellent stability and high electrical conductivity, which are considered to be promising electrode materials for supercapacitors. Ti3SiC2/Carbon nanofiber composites with one-dimensional nanostructures were successfully synthesized via electrospinning. Systematic electrochemical tests showed that the Ti3SiC2/Carbon composite possesses a large specific capacitance of 133.1 F/g at the current density of 1 A/g, high rate capability of 113.7% capacitance retention from 1 to 10 A/g, and low resistance of 1.07 Ω. After assembling the asymmetrical supercapacitor, Ti3SiC2/Carbon provides the energy density of 7.02 Wh/kg at the power density of 140 W/kg. In addition, Ti3SiC2/Carbon composite is highly stable, with 74.6% capacity retention after 4000 cycles. Ti3SiC2/Carbon’s superior electrochemical properties are ascribed to the 1D nanowire structure and the high specific surface area. Ti3SiC2/Carbon is a prospective electrode material for future supercapacitors.