Nanocrystalline Cellulose Confined in Amorphous Carbon Fibers as Capacitor Material for Efficient Energy Storage

Abstract

The development of sustainable and renewable energy storage systems is a promising approach toward steady and reliable energy supply. In this study, cellulosic palm loofah fibers were used as a precursor to produce amorphous carbon (Am-C) with retained crystalline cellulosic planes via a simple activation method. The Am-C exhibits a fairly high BET surface area of 2000 m2/g and a 3D-microporous structure with small mesopores. The symmetric Am-C//Am-C supercapacitor device tested in 1.0 M NaCl aqueous electrolyte showed specific capacitances of 201 F/g at 5 mV/s and 337 F/g at 1 A/g. The device exhibits a stable performance across a potential window of 1.8 V with ultrahigh energy and power densities of 51.4 Wh/kg at 4.5 kW/kg and 16.95 Wh/kg at 18 kW/kg. The device showed extraordinary increasing capacitive behavior upon cycling at 10 A/g for over 25000 cycles. The exceptional device performance could be ascribed to the electrochemical graphitization during long-term cycling together with the enhanced wettability as confirmed via Raman, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and contact angle measurements.

Fullerene C76: An Unexplored Superior Electrode Material with Wide Operating Potential Window for High‐Performance Supercapacitors

“…have been used as the supercapacitor electrode material. Carbon materials can provide high surface area for the EDL and high stability to the Faradic materials in the electrode assembly . One of the interesting carbon sets is the Fullerenes.…”

Flax-Derived Carbon: A Highly Durable Electrode Material for Electrochemical Double-Layer Supercapacitors

“…It is worth noting that the C-Flax sample had a high micropore ratio with the V mi /V total = 75%, which makes it highly competitive with other porous carbon derived from natural products such as hemp [ 39 ], animal bones [ 40 ], and argan seed shells [ 21 ]. The high SSA together with the microporous structure of C-Flax provides extra space for electrolyte ions, which is crucial for EDLC systems [ 41 , 42 , 43 ] and therefore predispose C-Flax for supercapacitor applications.…”

N,P‐Codoped, Low‐Density, Amorphous Carbon Foam for High‐Performance Supercapacitors: Polymer‐Based Scalable Production at Low Cost

“…A maximum specific energy of 43.11 Wh kg À1 was obtained, whereas the power density reached to a maximum value of 20 kW kg À1 , which are well comparable to the best performing supercapacitors available in the literature as compared in Figure 4f and Table 1 as well. [33][34][35][36][37][38][39][40][41][42][43] The superior electrochemical energy storage performance by ATA 700 char as compared with other chars can be attributed to the combined physical as well as chemical characteristics. The hierarchical porous architecture with distributed pore width has played crucial role in addition to the moderate pore volume and specific surface area, and balanced chemical contents, such as considerable sp 2 -C proportion and moderate amount of heteroatoms-especially the higher graphitic/N─C and C─P bonding networks.…”

“…[2,4] A clear conclusion on the best heteroatom(s), the atomic configuration of the dopant(s), and/or the defect-type in a graphitic carbon lattice for energy storage has not yet been achieved, because the related parameters are exclusively interdependent.In a complete contrast, very recently, the amorphous carbon-based materials have been reported to demonstrate attractive energy storage and conversion applications, such as in electrochemical batteries with high storage capacity and long-term stability, primarily owing to their disordered and defect-rich structures. [6][7][8][9][10][11][12][13][14][15] As such, it has been reported that the N-doped amorphous carbon sphere is more active for oxygen reduction reaction in 0.5 M H 2 SO 4 medium than their graphitic counterparts due to the fact that the micropores in amorphous carbon phase close down during graphitization process along with the decrease in N content. [14] Honda et al reported that the disordered sp 2 clusters in amorphous carbon or a mixed carbon state (sp 2 þ sp 3 C matrix) are more beneficial to electrocatalytic activities than pure graphitic carbons due to abundance in trapped charged centers.…”

“…[10] Moreover, nanocrystalline cellulose confined amorphous carbon has demonstrated 201 F g À1 capacitance at 5 mV s À1 in 1.0 M NaCl along with excellent chargedischarge cycling up to 25 000 cycles without any degradation even at 10 A g À1 . [15] These examples indicate that the amorphous carbon could be a potential material for electrochemical energy applications. However, there has not been any systematic study on EDLC using completely amorphous carbon materials to conclude about a clear mechanistic understanding toward realizing a low cost but efficient electrochemical energy storage technique.…”