Honeycomb-like Hierarchical Porous Activated Carbons from Biomass Waste with Ultrahigh Specific Surface Area for High-Rate Electrochemical Capacitors

Abstract

Although highly porous carbon electrode materials from biomass wastes for high-performance electric double-layer capacitors (EDLCs) have attracted great attention recently, the fast charge−discharge performance under ultrahigh current density (100 A g −1 ) still remains a challenge. Herein, we develop a promising route to massively prepare honeycomb-like activated carbon (AC) with hierarchical porous features from spent lotus stems (SLSs) exhibiting an ultrahigh specific surface area of 4190 m 2 g −1 . The preparation process of the SLSAC samples includes carbonization at 400 °C in argon (denoted as c-SLS) and followed a KOH chemical activation using various KOH/c-SLS mass ratios at 800 °C for 1 h. The SLSAC-5-based electrode (KOH/c-SLS = 5/1) displays a good gravimetric capacitance of 330 F g −1 at 0.5 A g −1 with a superior high-rate capacitance of 243 F g −1 at 100 A g −1 and presents remarkable cycling stability with a capacitance retention near 100% over 10,000 cycles at 2 A g −1 using 6 M KOH aqueous electrolyte. Additionally, the SLSAC-5-based sample delivers an energy density of 18.6 W h kg −1 at 199.2 W kg −1 with 1 M Na 2 SO 4 electrolyte. Herein, we reveal a simple, promising route to massively generate SLSAC-based samples and investigate prominent electrochemical properties in ultra-fast charge−discharge EDLCs.

InSitu Fabricated Small Organic Molecule-Anchored Bimetallic Hydroxide-based Nanohybrids for Symmetric Supercapacitor

“…The electrochemical measurements of the fabricated SSCs were evaluated by CV, GCD, and cyclic stability test. The following formulas were used to estimate the C s value, energy density ( E ), and power density ( P ) of the SSCs ,, C normals = 2 ( I · Δ t ) m · normalΔ V ( F g − 1 ) E = C normals × normalΔ V 2 8 × 3.6 ( W h k g − 1 ) P = 3600 × E normalΔ t ( W k g − 1 ) Here, I (A) is the discharge current, Δ t represents the discharge time (s), m (g) stands for the active material mass on one electrode, and Δ V (V) represents the operating potential window after resistance drop.…”

“…The electrochemical performance of the BSeYW/NCDH(2:2) nanohybrid is considerably better than previously reported materials (Table S3). ,,− In addition, the SSC device can efficiently light-up a light-emitting diode (LED) for few minutes (Figure S18) as well as spinning of a small fan (insets of Figure d,e).…”

“…Therefore, the control over micro- and nanoscale architectures and the optimized concentration of the materials are important in electrochemical processes for efficient ion and electron transportation at the electrode–electrolyte interface, which improves the electrochemically active sites and facilitates the intercalation/deintercalation of the ions. − Therefore, sol–gel, atomic layer deposition, hydrothermal, solvothermal, and electrodeposition methods have been used to synthesize efficient materials including metal oxides, sulfides, nitrides, hydroxides, conducting polymers, and organic–inorganic hybrid materials. ,,,− However, the electrodeposition method enables low-cost, simple handling, binder-free, controlled growth and uniform distribution to exploit the high surface area and exposes more electrochemically active sites for smooth electrolyte ions diffusion and transport of electrons during electrochemical measurements to achieve high energy storage property . Moreover, sustainable bio-derived nanomaterials have attracted enormous attention due to their eco-friendly, easy to handle, light weight, renewable, and highly stable properties. − The fabrication of nanohybrid materials with distinct characteristics and functions could be achieved by the cross-linking of organic and inorganic components. The aromatic rings and heteroatoms in the organic molecules can enhance the intermolecular interactions through π–π stacking, hydrogen bonding, and Van der Waals interactions, which stabilize the nanoscale architecture of the nanohybrids through the self-assembly process.…”

Nitrogen-/Boron-Doped Carbon from Poplar Powder and Carbon Nanotube Composite as Electrode Material for Supercapacitors

“…From the perspective of environmental protection and cost saving, biomass carbon material is one of the best electrode material choices. , In general, naturally abundant biomass resources and their derivatives have multilevel structures, , so they are highly promising for the fabrication of unique microstructures and advanced carbon materials that can constitute high-characteristic supercapacitors . Biomass and its derivatives have been extensively produced as carbon materials with porosity because they are reproducible and cheap (e.g., rice husk, soybean, lotus, and spruce bark). The surface properties exhibited by porous carbon materials are critical to the improvement of the electrochemical characteristic exhibited by supercapacitors .…”

Bioinspired Sustainable Sheetlike Porous Carbon Derived from Cassia fistula Flower Petal as an Electrode for High-Performance Supercapacitors

“…Nowadays, research is moving toward the use of carbon materials as an electrode for SCs, due to their electrical conductivity, thermal stability, high specific surface area, and porosity in numerous forms . Examples include carbon nanotubes, graphene, carbon nanofibers, heteroatom-doped carbons, templated carbons, and carbon aerogels. − Porous carbon electrodes can store charges by the electrostatic adsorption of charges onto electrode surfaces, forming an electric double-layer (EDL) structure. , Mostly, porous carbon materials are produced by using polymeric precursors, chemical process, hard or soft template routes, hydrothermal carbonization, and activation process, − but it remains challenging to find sustainable and reasonable sources to produce highly porous carbon materials.…”