Quinone molecules encapsulated in SWCNTs for low-temperature Na ion batteries

Abstract

We have performed Li and Na ion charge-discharge experiments of 9,10-phenanthrene quinone (PhQ) molecules encapsulated in single-walled carbon nanotubes (SWCNTs) with mean tube diameters of 1.5 and 2.5 nm at room temperature and also at low temperatures. The Na ion reversible capacity of PhQ encapsulated in the larger diameter SWCNTs, measured at a low temperature of 0 °C, remained as high as that measured at room temperature (RT), while the capacity of PhQ in the smaller diameter SWCNTs at 0 °C was about a half of that at RT. The diameter dependence of the capacity should be attributed to the difference in the interactions between the encapsulated PhQ molecules and the host SWCNTs, which was revealed by Raman peak profile analysis. Charge-transfer reaction from metallic tubes to PhQ molecules encapsulated in the smaller diameter SWCNTs was detected by Raman measurements. The electrostatic interaction between charged SWCNTs and PhQ molecules, induced by the charge-transfer reaction, would partly contribute to the stabilization of PhQ molecules in the smaller diameter SWCNTs, while only van der Waals interaction stabilizes PhQ molecules in the larger diameter SWCNTs. The difference in stability was confirmed by thermogravimetric, x-ray photoelectron spectroscopy, and Raman measurements. Charge-discharge curves of PhQ encapsulated in SWCNTs were also discussed based on the stability difference.

Alkali Metal Ion Storage of Quinone Molecules Grafted on Single-Walled Carbon Nanotubes at Low Temperature

“…In the case of the bulk PhQ sample with carbon black conductive additive, severe capacity fading was observed in a few cycles because of the dissolution of PhQ molecules into the electrolyte. The dissolution of PhQ molecules was suppressed by the encapsulation treatment, as reported in our previous paper 15,16 (see Figure 5b). The capacity loss of PhQ/SWCNT-2.5 is much smaller than that of PhQ@SWCNT-2.5 because PhQs are covalently connected to SWCNTs.…”

“…The detailed purification procedure is described in our previous papers. 15,16,25,37−39 Then, we grafted quinone molecules onto SWCNTs typically as follows. First, a PhQ powder sample was refluxed with nitric acid at 130 °C for 1 h to obtain nitrated PhQ.…”

Constraint spaces in carbon materials

“…33 The effect of the tube diameter of SWCNT on the Li-ion storage was studied using two SWCNTs with different diameters of 1.5 and 2.5 nm (SWCNT-1.5 and -2.5, respectively), of which encapsulated PhQ amount was determined by thermogravimetric measurement to be 22 and 38 wt%, respectively. 34 The charge-discharge proles and the reversible capacities of PhQ@SWCNTs at room temperature were quite similar for Li and Na ions, associating with two steps at 2.8 and 2.4 V for Li and those at 2.3 and 1.9 V for Na. Because the tube diameters of both SWCNTs are larger than the Li and Na ions and do not discriminate between these two ions.…”

“…Encapsulation of 9,10-anthraquinone (AQ) and 9,10-phenanthrene quinone (PhQ) molecules into SWCNTs was performed by heating their mixture at 200 C in an evacuated glasstube. 33,34 Aer the heat treatment, AQ@SWCNTs and PhQ@SWCNTs were recovered by washing with organic solvents (N,N-dimethylformamide for AQ and acetone for PhQ) to remove the excess AQ and PhQ deposited on the outer surface of the SWCNTs. Self-supported lms of AQ@SWCNTs and PhQ@SWCNTs were obtained in this step.…”

A Review of Supercapacitors Based on Graphene and Redox-Active Organic Materials

“…Among all the potential alternative organic molecules, quinones are well-known as electrochemically active organic molecules, and have been applied as energy storage materials for supercapacitors, Na-ion batteries, and aqueous rechargeable batteries [100,101,102]. However, similar to most of organic molecules, quinones have poor electrical conductivity.…”