Integrated hybrid architecture of metal and biochar for high performance asymmetric supercapacitors

Abstract

Two state-of-the-art electrodes were successfully synthesized and used to assemble both symmetric and asymmetric type supercapacitors. 3DFAB was fabricated by direct pyrolysis of green macroalgae in the presence of NaOH. Possible NaOH activation mechanisms are proposed, which explains the formation of oxygen functional groups through quick penetration of OH- and NaOH into the vacancies. To obtain CoTLM, the tile-like architecture of cobalt oxides was introduced to the 3D interconnected functional algal biochar (3DFAB) by a simple one-pot hydrothermal method under mild conditions. For the symmetric supercapacitors, the maximum specific capacitance of RAB, 3DFAB, and CoTLM were 158, 296, and 445 F g−1 at the current density of 1 A g−1. Regarding cobalt-based asymmetric systems, the maximum capacitance for the 3DFAB//CoTLM was 411 F g−1. This asymmetric supercapacitor device also retained 100.9% of its initial capacitance after 4000 cycles at the current density of 4 A g−1. Unbuffered aqueous electrolyte and the unique morphological structure used in this study might catapult forward commercialization of such advanced energy storage devices.

Effects of FeCl3 Catalytic Hydrothermal Carbonization on Chemical Activation of Corn Wet Distillers’ Fiber

“…According to the literature, during the KOH activation, carboxylic, carbonyl, hydroxyl, and aldehyde functional groups attached to the hydrochar surface chemically react with KOH to release H 2 , CO, and CO 2 gases and form K and K 2 CO 3 ( eqs 3 and 4 ). 38 , 39 Meanwhile, KOH may undergo a reaction with carbon fragments ( eqs 5 and 6 ). Since the temperature is set to a high temperature of 800 °C, K 2 CO 3 , which is the prevalent product of the KOH activation process, can be further converted to K 2 O and K, along with the release of CO and CO 2 .…”

Hierarchical flaky porous carbon derived from waste polyimide film for high‐performance aqueous supercapacitor electrodes

“…XRD and Raman spectra were employed to investigate the microstructures of samples PI-700 and CAC-800-n (Figure 4). In Figure 4A, PI-700 has two obvious broad diffraction peaks at 23 and 44 corresponding to the 002 and 100 planes of carbon crystallite, 41 respectively, indicating that PI-700 has a certain amount of graphitization structuring. However, the 002 peak gradually weakens as the alkali-carbon ratio increases from 0.5 to 2 and disappears in samples CAC-800-3 and CAC-800-4, implying that the graphite crystallites of the porous carbon are gradually destroyed and the degree of disorder increases.…”

Preparation of Porous Carbons Using NaOH, K2CO3, Na2CO3 and Na2S2O3 Activating Agents and Their Supercapacitor Application: A Comparative Study

“…The GCD curves of representative C‐NaOH sample were illustrated at the current density from 1 to 20 A g −1 in Figure 4d. The curves present the almost symmetrical linear characteristic even at high current densities, signifying its outstanding reversible charge and discharge behavior [53] . Figure 4e provides the specific capacitance of the C‐NaOH, C‐K 2 CO 3 , C‐Na 2 CO 3 and C‐Na 2 S 2 O 3 samples based on the current density.…”

“…The curves present the almost symmetrical linear characteristic even at high current densities, signifying its outstanding reversible charge and discharge behavior. [53] Figure 4e provides the specific capacitance of the…”