Enhanced Sodium Ion Storage in Interlayer Expanded Multiwall Carbon Nanotubes

Abstract

We report an effective approach of utilizing multiwalled carbon nanotubes (MWCNTs) as an active anode material in sodium ion batteries by expanding the interlayer distance in a few outer layers of multiwalled carbon nanotubes. The performance enhancement was investigated using a density functional tight binding (DFTB) molecular dynamics simulation. It is found that a sodium atom forms a stable bonding with the partially expanded MWCNT (PECNT) with the binding energy of -1.50 eV based on the density functional theory calculation with van der Waals correction, where a sodium atom is caged between the two carbon hexagons in the two consecutive MWCNTs. Wave function and charge density analyses show that this binding is physisorption in nature. This larger exothermic nature of binding energy favors the stable bonding between the PECNT and a sodium atom, and thereby, it helps to enhance the electrochemical performance. In the experimental works, partial opening of the MWCNT with the expanded interlayer has been designed by the well-known Hummer's method. It has been found that the introduction of functional groups causes a partial opening of the outer few layers of a MWCNT, with the inner core remaining undisturbed. The enhanced performance is due to an expanded interlayer of carbon nanotubes, which provide sufficient active sites for the sodium ions to adsorb as well as to intercalate into the carbon structure. The PECNT shows a high specific capacity of 510 mAh g at a current density of 20 mA g, which is about 2.3 times the specific capacity obtained for a pristine MWCNT at the same current density. This specific capacity is higher when compared to other carbon-based materials. The PECNT also shows a satisfactory cyclic stability at a current density of 200 mA g for 100 cycles. Based on our experimental and theoretical results, an alternative perspective for the storage of sodium ions in MWCNTs is proposed.

Thin Film Mechano-Energy Induced Slicing of Carbon Nanotubes under Flow

“…In the case of the sliced SWCNTs, the weight loss was about 15 wt % between temperatures from 350 to 650 °C. This is possible due to removal of functional groups attached on the both ends of sliced SWCNTs . For temperatures <550 °C the as-received MWCNTs are stable with a significant weight loss >600 °C due to the decomposition of the MWCNTs .…”

“…This is possible due to removal of functional groups attached on the both ends of sliced SWCNTs. 52 For temperatures <550 °C the as-received MWCNTs are stable with a significant weight loss >600 °C due to the decomposition of the MWCNTs. 52 For the sliced MWCNTs there are two regions of weight loss: 10 and 20 wt % between 160 and 390 °C and between 400 and 650 °C, respectively.…”

Biomass derived hierarchically porous carbon inherent structure as an effective metal free cathode for Li‐O2/air battery

“…[1][2][3] The conventional secondary batteries, such as Li-ion, Ni-cadmium, lead-acid batteries, and capacitors are turning out to be hopeful power sources for electric vehicles to overcome these problems. [4][5][6][7][8][9][10][11][12][13][14] However, conventional Li-ion battery shows a less energy density, which is attributed to both the aqueous electrolyte and poor cell voltage of electrode materials. [15] At this stage, research focuses on the This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.…”

In‐Situ Fabrication of Bone‐Like CoSe2 Nano‐Thorn Loaded on Porous Carbon Cloth as a Flexible Electrode for Na‐Ion Storage

“…Sodium ion batteries (SIBs) have become a research hotspot in recent years as a promising large-scale energy-storage application in consideration of low-cost and abundant resource nature of sodium. [1][2][3] Although the ion storage mechanism of SIBs is similar to lithium ion batteries (LIBs), [4] fallaciously, a large proportion of electrode materials recently available for LIBs is not suitable for SIBs, owing to the larger ionic radium of Na + (1 .02 Å) than that of Li + (~0.76 Å). [5,6] Furthermore, the relatively low energy density is also an urgent issue for Na-ion storage devices.…”