Highly Exfoliated and Functionalized Single-Walled Carbon Nanotubes as Fast-Charging, High-Capacity Cathodes for Rechargeable Lithium-Ion Batteries

Abstract

Compared with traditional metal-oxide lithium-ion battery (LIB) cathodes, nanocarbon-based cathode materials have received much attention for potential application in LIBs because of their superior power density and long-term cyclability. However, their lithium-ion storage capacity needs further improvement for practical applications, and the trade-off between capacity and conductivity, when oxygen functional groups as lithium-ion storage sites are introduced to the nanocarbon materials, needs to be addressed. Here, we report a sequential oxidation–reduction process for the synthesis of single-walled carbon nanotubes (SWCNTs) for LIB cathodes with fast charging, long-term cyclability, and high gravimetric capacity. A LIB cathode based on highly exfoliated (d bundle < 10 nm) and oxygen-functionalized single-walled carbon nanotubes is obtained via the modified Brodie’s method using fuming nitric acid and a mild oxidant (B-SWCNTs). Post treatment including horn sonication and hydrogen thermal reduction developed surface defects and removed the unnecessary C–O groups, resulting in an increase in the Li-ion storage capacity. The B-SWCNTs exhibit a high reversible gravimetric capacity of 344 mA h g–1 at 0.1 A g–1 without noticeable capacity fading after 1000 cycles. Furthermore, it delivers a high gravimetric energy density of 797 W h kgelectrode –1 at a low gravimetric power density of 300 W kgelectrode –1 and retains its high gravimetric energy density of ∼100 W h kgelectrode –1 at a high gravimetric power of 105 W kgelectrode –1. These results suggest that the highly exfoliated, oxygen-functionalized single-walled carbon nanotubes can be applied to LIBs designed for high-rate operations and long cycling.

Surface functional group‐tailored B and N co‐doped carbon quantum dot anode for lithium‐ion batteries

“…The 0.5BN‐CQD sample showed the largest C═O bonding ratio of 72.9% with the smallest CO bonding (16.2%) and COH bonding (10.9%) ratio, which is attributed to the catalytic effect on oxygen chemisorption by boron dopant 30 . This increased ratio of C═O bonding facilitates redox‐mediated Li + storage with high Li + acceptability, resulting in the enhancement of the energy storage performance of LIB anodes 31 . Further, the estimated atomic percentages of B and N within all samples were also calculated using the C 1s XPS data.…”

“…30 This increased ratio of C═O bonding facilitates redox-mediated Li + storage with high Li + acceptability, resulting in the enhancement of the energy storage performance of LIB anodes. 31 Further, the estimated atomic percentages of B and N within all samples were also calculated using the C 1s XPS data. Owing to the fixed dopant concentration, the atomic percentage of nitrogen was similar in all the samples (2.1% for N-CQD, 2.0% for 0.1BN-CQD, 2.2% for 0.5BN-CQD, and 2.0% for 1.0BN-CQD), and the atomic percentage of boron increased from 0.7% to 1.9% and 3.3% for 0.1BN-CQD, 0.5BN-CQD, and 1.0BN-CQD, respectively as the amount of boric acid increased.…”

All-Printed Paper-Based Micro-supercapacitors Using Water-Based Additive-Free Oxidized Single-Walled Carbon Nanotube Pastes

“…TEM analyses showed that the oxidation treatment effectively reduced the bundle size of the SWCNTs (Figure a,b). The TGA results in Figure c indicate that approximately 30% of the weight loss occurred below 300 °C because of the decomposition of the functionalized moieties and highly defective SWCNTs . The increased D-band of the Ox-SWCNTs in their Raman spectra (Figure d) suggests the formation of disordered or defective carbon structures, as shown in Figure b .…”

“…Ox-SWCNTs were obtained by the oxidation of pristine SWCNT (p-SWCNT, TUBALL, and OCSiAl) powders using a modified Brodie’s method. , Subsequently, 1 g of p-SWCNT and 8 g of sodium chlorate (NaClO 3 , Sigma-Aldrich) were mixed and ground in a mortar using a pestle. Thereafter, 20 mL of fuming nitric acid (>90%, Sigma-Aldrich) was added dropwise to the mixture.…”

Introducing Electrochemically Active Oxygen Species to Boost the Pseudocapacitance of Carbon‐based Supercapacitor

“…So far, the reported methods for the fabrication of oxygenrich carbon materials majorly include: (i) heating the oxygencontaining precursor at a proper temperature to retain the oxygen-containing functional groups partially, [18][19][20][21] (ii) treating carbon materials with chemical oxidants to increase the concentration of oxygen species, [22][23][24] etc. However, since neither the oxidizing ability of the oxidant nor the extent of oxidation can be easily controlled, these conventional methods could not selectively modify the surface chemistry of the carbon materials.…”