Synthesis of Size‐Controllable Lignin‐Based Nanosperes and Its Application in Electrical Double Layer Capacitors

Abstract

As one of the most popular biomass materials, lignin is mainly used for incineration for providing heat. However, the large amount of CO2 emission results in serious environmental pollutions. To avoid the environmental issues, the transformation of lignin into high value‐added products has attracted increasing attention. In this study, a simple strategy is introduced to prepare lignin‐based nanospheres in acetone/water binary solution and the mechanisms related to the particle formation and particle size‐control are studied. By adjusting the ratio of solvent (acetone/water =55%‐95%) and the initial concentration of lignin (0.25%‐2.5%), the particle size of lignin microspheres ranges from 100 nm to 4 μm. After activation, the lignin microspheres with high specific surface area (2566 m2 g−1) and suitable pore size distribution are applied in electrical double layer capacitors (EDLCs). Among all the prepared samples, the activated lignin microspheres in nanoscale exhibit the best electrochemical performance in EDLCs. It displays a high gravimetric specific capacitance of 147 and 150 F g−1 at the current density of 0.05 A g−1, and maintains 117 and 108 F g−1 even at the higher current density of 10 A g−1 in 1 M TEABF4/PC electrolyte and [EMIM]BF4 ionic liquid, respectively. Therefore, the activated lignin‐based nanospheres can realize the high value‐added utilization of lignin, and have great prospects in the field of energy storage.

Two Birds with One Stone: Hydrogel-Derived Hierarchical Porous Activated Carbon toward the Capacitive Performance for Symmetric Supercapacitors and Lithium-Ion Capacitors

“…Moreover, the accelerated experiment conducted in the voltage range from 1.35 to 2.7 V (i.e., 50% of the state of discharge) at the current of 5 mA (0.45 A/g) was utilized to explore its cycling stability of the symmetric cell (Figure e). According to the same electrolyte and similar voltage window, our H-HPAC shows reasonable energy (29.1 to 13.7 Wh/kg) and power (116.3 to 833 W/kg) densities, and promising cycling performance (capacitance retention: 76% after 10 000 cycles, and ≥99.5% of Coulombic efficiency), which were comparable with previously reported results (Figure d) and Table . ,− …”

Constructing a Carbon-Encapsulated Carbon Composite Material with Hierarchically Porous Architectures for Efficient Capacitive Storage in Organic Supercapacitors

“…To compare with the H-HPAC electrode, ~74% of the power density was outputted by the H@H electrode for all current densities. On the basis of the same electrolyte and similar voltage window, the H@H electrode exhibits reasonable energy and power densities, comparable with the results reported previously ( Figure 7 d) [ 9 , 15 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. Considering the cycling stability, the accelerated experiment conducted in the voltage ranged from 1.35 to 2.7 V (i.e., 50% of the state of discharge) and the current of 5 mA was used; the corresponding result is displayed in Figure 7 e. The initial capacitance discharge to 1.35 V was ~0.5 F. After 30,000 cycles, about 76.6% of capacitance retention and ≥99.5% of Coulombic efficiency were found, respectively.…”