Hierarchical Porous and Sandwich-like Sulfur-Doped Carbon Nanosheets as High-Performance Anodes for Sodium-Ion Batteries

Abstract

The development of high-performance carbon-based anodes for Na-ion batteries is highly desired but still remains challenging because of carbon materials with a low reversible capacity and poor cyclic performance. Herein, novel S-doped carbon nanosheets (SCNs) were prepared by a hydrothermal self-assembly process in the presence of graphene oxide (GO) as the matrix, starch as the carbon source, and dibenzyl disulfide as the sulfur source. The obtained SCNs with hierarchical pores and a sandwich-like structure were utilized as anode materials for Na-ion batteries, exhibiting a high reversible discharging capacity of 207.3 mAh g–1 after 100 cycles at 50 mA g–1. When the current density is up to 1 A g–1, a reversible discharge capacity of 118.8 mAh g–1 can also be acquired. Moreover, the prominent long-term cycling stability of more than 500 cycles can be obtained at 200 mA g–1. The outstanding electrochemical property (high reversible capacity, high rate performance, and long-term cycling stability) of the SCN electrode may be due to the synergistic effect of S doping, hierarchical pores, and the sandwich-like structure. Furthermore, electrochemical kinetic analysis also confirmed that the sodium storage mechanism of the SCN electrode reinforced pseudocapacitive-control behavior. The present study not only shows a high-performance anode material for Na-ion batteries but also provides a new method to prepare S-doped carbon materials for various applications.

Rational Design of Sulfur-Doped Carbon with Expanded Inter-layer Spacing toward Anode Material of Sodium-Ion Batteries

“…Figure e,f shows the high-resolution C 1s and S 2p XPS images. CC and C–C bonding were seen in the C 1s XPS spectra at 284.1 and 285.0 eV, respectively, while C–S and CO bonding were verified at the higher binding energy levels with peak positions of 286 and 288 eV . The S 2p spectrum was separated into three peaks: two major peaks located at 163.37 and 164.64 eV correspond to S 2p 3/2 and S 2p 1/2 peaks of the covalent C–S bond of thiophene-type sulfur because of the spin–orbit coupling, and a broad peak located at 167.8 eV is assigned to the C-(SOx)-C bond. , Additionally, using CHNS analysis, it was shown that the proportion (weight %) of S in the carbon framework reduced from 9.6 for CS-1000 to 5.5 for CS-1100 and 3.25 for CS-1200, respectively.…”

“…The increase in the G-band from CS-1000 to CS-1100 with an increase in annealing temperature could be responsible for the decrease in the R CT value. The following equations, eqs and , were used to compute the ionic diffusion coefficient ( D Na+ ) for each of the three electrode materials where T stands for the absolute temperature, F stands for the Faraday constant, A stands for the electrode’s area, ω is the angular frequency, σ is the Warburg factor value, C represents the concentration of sodium ions, n stands for the number of electrons, and R stands for the gas constant.…”

“…Several investigations have been undertaken to improve their specific capacity and cyclic performance. Major efforts such as controlling morphology, particle-size engineering, controlling porosity, and incorporation of heteroatoms have been devoted to availing more active sites, improving charge transfer, and providing conductivity. Porous architectures or reduced particle sizes, on the other hand, invariably result in increased surface area of the material, resulting in reduced initial Coulombic efficiency, low energy density, and poor cycle performance when employed in a full cell system .…”

Single-Source-Derived Nitrogen-Doped Soft Carbons for Application as Anode for Sodium-Ion Storage

“…The synthesized N-doped carbons prepared at four different temperatures (Scheme ) were subjected to powdered X-ray diffraction (p-XRD) analysis. Figure a presents the p-XRD patterns of NC-800, 1000, 1200, and 1400 with the presence of sharp diffraction peaks positioned at a 2θ value of 26.3° corresponding to the (002) plane of carbon and other small peaks at a 2θ value of 43° corresponding to the (100) plane of carbon . With the rise in annealing temperature from 800 to 1400 °C, the sharp rise in the (002) plane indicates the increase in the graphitic nature of the material.…”

“…The decrease in the R CT value with rise in annealation temperature may be attributed to the significant rise in graphitic domains from NC-800 to NC-1400. The ionic diffusion coefficient ( D Na+ ) was calculated for all of the four electrode materials using the following eqs and where R represents the gas constant, T stands for absolute temperature, A represents the area of the electrode, F denotes Faraday constant, n stands for the quantity of electrons, C is the Na + concentration, σ presents the value of Warburg factor, and ω represents the angular frequency.…”