Rational Design of Porous N-Ti3C2 MXene@CNT Microspheres for High Cycling Stability in Li–S Battery

Abstract

HIGHLIGHTS • N-Ti 3 C 2 @CNT microspheres are successfully synthesized by the simple spray drying and one-step pyrolysis. • Within the microsphere, MXene nanosheets intimately interact with CNTs constructing porous and highly conductive network, which can provide strong immobilization for polysulfides. • N-Ti 3 C 2 @CNT microsphere/S cathode shows highly cycling stability in lithium-sulfur battery. ABSTRACT Herein, N-Ti 3 C 2 @CNT microspheres are successfully synthesized by the simple spray drying method. In the preparation process, HCl-treated melamine (HTM) is selected as the sources of carbon and nitrogen. It not only realizes in situ growth of CNTs on the surface of MXene nanosheets with the catalysis of Ni, but also introduces efficient N-doping in both MXene and CNTs. Within the microsphere, MXene nanosheets interconnect with CNTs to form porous and conductive network. In addition, N-doped MXene and CNTs can provide strong chemical immobilization for polysulfides and effectively entrap them within the porous microspheres. Above-mentioned merits enable N-Ti 3 C 2 @CNT microspheres to be ideal sulfur host. When used in lithium-sulfur (Li-S) battery, the N-Ti 3 C 2 @CNT microspheres/S cathode delivers initial specific capacity of 927 mAh g −1 at 1 C and retains high capacity of 775 mAh g −1 after 1000 cycles with extremely low fading rate (FR) of 0.016% per cycle. Furthermore, the cathode still shows high cycling stability at high Crate of 4 C (capacity of 647 mAh g −1 after 650 cycles, FR 0.027%) and high sulfur loading of 3 and 6 mg cm −2 for Li-S batteries.

Study of Interfacial Charge Transfer from an Electron Rich Organic Molecule to CdTe Quantum Dot by using Stern‐Volmer and Stochastic Kinetic Models

“…For an instance, Wang et al studied antibody-antigen interaction by labeling the antigen (bovine serum albumin) with a red emitting CdTe QD, while the antibody (IgG) was labeled with a green emitting CdTe QD. [33] Biologists find great advantage of using QDs (rather than fluorescent dyes) in imaging studies because one can easily get less harmful near IR/Red emissions from QDs by tuning their sizes. [34][35] Although a few dye molecules exhibit red emission, but their low photo-stability has remained a serious concern in imaging studies.…”

Photo‐synergetic nitrogen‐doped MXene /reduced graphene oxide sandwich‐like architecture for high‐performance lithium‐sulfur batteries

“…The N 1s spectrum (Figure 4B) was deconvoluted into four peaks centered at 396.1 (N–Ti), 397.2 (pyridinic‐N), 399.5 (pyrrolic‐N), and 400.9 eV (graphitic‐N), which demonstrate that the nitrogen atom was successfully doped into the composite. Among the three N elements, pyridinic N is believed to be a dominant adsorption site for LiPSs in N‐doped materials 41 . The N–Ti bonding in the N 1s spectra also demonstrates N doping in the Ti 3 C 2 Tx nanosheet.…”

“…Among the three N elements, pyridinic N is believed to be a dominant adsorption site for LiPSs in N-doped materials. 41 The N-Ti bonding in the N 1s spectra also demonstrates N doping in the Ti 3 C 2 Tx nanosheet. The Ti 2p spectrum ( Figure 4C) was divided into four peaks centered at 455.4 (Ti-C), 456.1 (Ti-S), 456.8 eV (Ti-N), and 458.5 eV (Ti-O).…”

Recent Advances in Functional 2D MXene‐Based Nanostructures for Next‐Generation Devices

“…[26,52,53] In addition, the modification of 2D layered MXenes with other multidimensional (0D, 1D, and 2D) nanomaterials has come to the foreground in recent years. [35,36,54,55] The currently reported 2D MXene/0D nanomaterial, 2D MXene/1D nanomaterial, 2D MXene/2D nanosheet, and 2D MXene-based 3D hierarchical heterostructures, can be divided into three models, that is, 2D MXenes are employed as the loaded model, sandwiched model, and encapsulated model, respectively. In the loaded model, 2D MXenes uniformly load 0D/1D/2D active nanomaterials due to their high-surface-area 2D substrate, where the terminal groups chemically anchor them with high stability; in the sandwiched model, the 0D/1D/2D nanomaterials are sandwiched between 2D MXene nanosheets, and they still display 2D nanostructure; in the encapsulated model, the nanostructures of 0D/1D/2D active materials are entirely encapsulated by 2D MXene nanosheets to form 2D MXene structures or 2D MXene-based 3D hierarchical heterostructures.…”

“…[113][114][115][116][117][118][119] The synergistic effects are expected for 2D MXene/1D nanomaterial heterostructures to combine both structural advantages of 1D nanostructure and 2D MXene for desirable performances. [32,33,54,[66][67][68][69][120][121][122] For example, Xiao et al [66] anchored well-defined CdS nanorods on ultrathin Ti 3 C 2 T x nanosheets through electrostatically driven assembly and hydrothermal methods (Figure 6a). The SEM image shows that CdS nanorods are tightly anchored on the surface of 2D MXene Ti 3 C 2 T x nanosheets ( Figure 6b).…”