Here, we demonstrate the successful synthesis of (1T/2H) MoS2/α-MoO3 heterostructured nanoflowers at a low temperature of 200 °C by a one-step hydrothermal method.
In the scenario of renewable clean energy gradually replacing fossil energy, grid‐scale energy storage systems are urgently necessary, where Na‐ion batteries (SIBs) could supply crucial support, due to abundant Na raw materials and a similar electrochemical mechanism to Li‐ion batteries. The limited energy density is one of the major challenges hindering the commercialization of SIBs. Alloy‐type anodes with high theoretical capacities provide good opportunities to address this issue. However, these anodes suffer from the large volume expansion and inferior conductivity, which induce rapid capacity fading, poor rate properties, and safety issues. Carbon‐based alloy‐type composites (CAC) have been extensively applied in the effective construction of anodes that improved electrochemical performance, as the carbon component could alleviate the volume change and increase the conductivity. Here, state‐of‐the‐art CAC anode materials applied in SIBs are summarized, including their design principle, characterization, and electrochemical performance. The corresponding alloying mechanism along with its advantages and disadvantages is briefly presented. The crucial roles and working mechanism of the carbon matrix in CAC anodes are discussed in depth. Lastly, the existing challenges and the perspectives are proposed. Such an understanding critically paves the way for tailoring and designing suitable alloy‐type anodes toward practical applications.
This study describes the synthesis of nitrogen-containing carbon (N-C) and an approach to apply the N-C material as a surface encapsulant of LiMn2O4 (LMO) cathode material. The N heteroatoms in the N-C material improve the electrochemical performance of LMO. A low-cost wet coating method was used to prepare N-C@LMO particles. The N-C@LMO was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), high-resolution Raman spectroscopy (HR-Raman), field emission scanning electron microscopy (FE-SEM), and field emission scanning transmission electron microscopy (FE-TEM) with elemental mapping. Furthermore, the prepared samples were electrochemically studied using the AC electrochemical impedance spectroscopy (EIS) and the electrochemical cycler. XPS suggested that the N-C coating greatly reduced the dissolution of Mn and EIS showed that the coating greatly suppressed the charge transfer resistance, even after long-term cycling. The control of Mn dissolution and inner resistance allowed faster Li-ion transport between the two electrodes resulting in improved discharge capacity and cycling stability.
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