High capacitive performance of exfoliated biochar nanosheets from biomass waste corn cob

Abstract

A high performance exfoliated biochar carbon with a layered nanosheet structure was prepared from a low cost agricultural residue (corn cob) via a novel synthesis strategy involving biomass pre-treatment, nitrogen pyrolysis, and a high temperature thermal-chemical flash exfoliation. The exfoliation strategy resulted in porous carbon nanosheets with BET specific surface area of 543.7 m 2 g -1 , far higher than the 7.9 m 2 g -1 of the natural biochar produced without any pre-or post-treatment modifications. The 10 exfoliated material also showed increased oxygen functionality in the form of electrochemically active quinone and pyrone surface groups. This combination of high specific surface area and highly active surface functional groups resulted in very promising capacitive performance, demonstrating a high capacitance of 221 F g -1 , over 100 times greater than the natural biochar. The exfoliated biochar electrodes fabricated without any conductive additives showed outstanding high rate capability retaining 15 78 % of their low rate capacitance at a fast 40 A g -1 discharge. This combination of high capacitance and fast charge-discharge capability distinguishes this material from most other high surface area activated carbons; in fact, the electrochemical behaviour more closely resembles that of designer nanomaterials such as graphene and carbon nanotubes. The biochar electrodes were also extremely durable showing only a 3 % reduction in capacitance after 5000 successive potential cycles. The exfoliation strategy 20 developed here could provide a novel route for the low cost production of high performance energy storage materials from a variety of waste biomass feedstocks. 65 pseudocapacitance. Thus, highly porous and highly functionalized activated carbon has been shown to demonstrate both high specific capacitance and energy density [24][25][26].Although porosity and surface chemistry are important

The enhancement of electrochemical capacitance of biomass-carbon by pyrolysis of extracted nanofibers

“…Similar enhancement in the capacitance of corn 4 cob-derived carbon has also been observed by removing the lignin and carbonizing the crystalline cellulose only [14]. It is proposed that carbonizing the components separately instead of the whole biomass might increase the surface area and improve the uniformity of the derived carbon, which are crucial for practical applications.…”

Flexible and Self-Healing Aqueous Supercapacitors for Low Temperature Applications: Polyampholyte Gel Electrolytes with Biochar Electrodes

“…Pure BC is not suitable as an electrode material for three reasons: low specific capacitance, the powdery nature of the material, and low electrical conductivity. Nitric acid treatment and thermal flashing can increase the specific capacitance of exfoliated biochar electrodes from 2.1 to 221.3 F g −1   28 . Structural integrity and electrical conductivity are remedied by adding polymeric binders and conductive additives, respectively.…”

Influence of chemical structure of dyes on capacitive dye removal from solutions

“…The research in EC focuses on various aspects of capacitor technology, including advanced electrode materials, electrolytes, design and modeling [6][7][8][9]. Of particular interest are new porous electrode materials with high surface area [10][11][12][13]. Recent advances in porous electrode materials enabled novel applications of EC, such as capacitive deionization (CDI) of water.…”