Sulfur-Doped Mesoporous Carbon Nitride with an Ordered Porous Structure for Sodium-Ion Batteries

Abstract

Mesoporous carbon nitride (MCN) with well-ordered porous structures is a promising anode material for secondary ion batteries owing to their unique physico-and electrochemical properties. However, the practical application of these MCNs in sodium-ion batteries (SIBs) is still limited because of their confined interlayer distance, which results in restricted accommodation of Na ions inside the lattice. Here, we report on the synthesis of highly ordered sulfur-doped MCN (S-MCN) through a hard template approach by employing dithiooxamide (DTO) as a single molecular precursor containing carbon, nitrogen, and sulfur elements. The interlayer distance of carbon nitride is significantly expanded upon the introduction of larger S ions on the MCN lattice, which enables high capability of Na ion accommodation. We also demonstrate through the first-principles density functional theory calculation that the present S-MCN is highly optimized not only for the chemical structure but also for uptaking abundant Na ions with high adsorption energy. The specific discharge capacity of SIBs appears to be remarkably enhanced for S-MCN (304.2 mA h g −1 ) compared to the nonporous S-CN (167.9 mA h g −1 ) and g-C 3 N 4 (5.4 mA h g −1 ), highlighting the pivotal roles of the highly ordered mesoporous structure and S-doping in enhancing the electrochemical functionality of carbon nitride as an anode material for SIBs.

Single‐Step Synthesis of Mesoporous Carbon Nitride/Molybdenum Sulfide Nanohybrids for High‐Performance Sodium‐Ion Batteries

“…The intensity of the peaks at 286.5 and 285.0 eV becomes strong for the CN/MoS 2 -800, suggesting replacement of a number of C=N bonds with C=C bonds in its CN framework. [21,27] The effect of the calcination temperature in the CN framework is more clearly observed in N K-edge NEXAFS spectra ( Figure 2C). Absorption peaks at 398.5, 399.6 and 401.2 eV are responsible for excitations to π* pyridinic N , π* N=CÀ N and π* tertiary N , respectively.…”

“…[39] The mass of the carbonaceous component cannot be the main factor governing capacity of the hybrids, but the large proportion of electronic conductive CN with the ordered porous structure contributes to fast charge transfer kinetics in SIBs. [21] The charge and discharge potential profiles ( Figure 3D) and cyclic voltammograms ( Figure 3E) of the CN/MoS 2 -600 show that its charging and discharging operating potentials are 2.0 and 1.7 V respectively. The operating potentials below 2.0 V vs. Na/Na + suggest that the CN/MoS 2 -600 hybrid is a suitable candidate as an anode material for the battery component of hybrid sodium-ion capacitors.…”

“…It is a calcination process of precursors impregnated in a silica template with 2D or 3D porous structure, which is followed by an etching process for the silica template. [20][21][22] The resultant materials could gain advantages including large pore volume, high surface area and short transportation pathways through connected pores, which lead to enhancement in the kinetics of charge carriers. [23][24][25] By integrating the synthesis of nanostructured carbon and MoS 2 in a single system, facile approach for the synthesis of binary carbonaceous MoS 2 could be achieved.…”

“…When it comes to S K-edge NEXAFS spectra ( Figure 2D), all the samples commonly display two peaks at 2471.3 and 2482.3 eV. [21,36,37] The peak at 2471.3 eV corresponds to excitation to S 3p states hybridized with Mo 4p states in pure MoS 2 , while the peak at 2482.3 eV is responsible for excitation to S 3p states of CÀ SÀ O bond. The CÀ SÀ O bond character is enhanced as the calcination temperature increases, which is in good agreement with the fact of formation of MoO 3 at temperatures of 700 and 800°C.…”

DFT-Guided Design and Fabrication of Carbon-Nitride-Based Materials for Energy Storage Devices: A Review

“…b Charge density profile of S-MCN, blue color-lowest electron density (0%), and red color-highest electron density (100%). Reproduced with permission from Ref [31]…”