Insight into the Storage Mechanism of Sandwich-Like Molybdenum Disulphide/Carbon Nanofibers Composite in Aluminum-Ion Batteries.

Aluminum-ion batteries (AIBs) have become a research hotspot in the field of energy storage due to their high energy density, safety, environmental friendliness, and low cost. However, the actual capacity of AIBs is much lower than the theoretical specific capacity, and their cycling stability is poor. The exploration of energy storage mechanisms may help in the design of stable electrode materials, thereby contributing to improving performance. In this work, molybdenum disulfide (MoS2) was selected as the host material for AIBs, and carbon nanofibers (CNFs) were used as the substrate to prepare a molybdenum disulfide/carbon nanofibers (MoS2/CNFs) electrode, exhibiting a residual reversible capacity of 53 mAh g-1 at 100 mA g-1 after 260 cycles. The energy storage mechanism was understood through a combination of electrochemical characterization and first-principles calculations. The purpose of this study is to investigate the diffusion behavior of ions in different channels in the host material and its potential energy storage mechanism. The computational analysis and experimental results indicate that the electrochemical behavior of the battery is determined by the ion transport mechanism between MoS2 layers. The insertion of ions leads to lattice distortion in the host material, significantly impacting its initial stability. CNFs, serving as a support material, not only reduce the agglomeration of MoS2 grown on its surface, but also effectively alleviate the volume expansion caused by the host material during charging and discharging cycles.

Synthesis and characterization of electrospun molybdenum dioxide-carbon nanofibers as sulfur matrix additives for rechargeable lithium-sulfur battery applications.

One-dimensional molybdenum dioxide-carbon nanofibers (MoO2-CNFs) were prepared using an electrospinning technique followed by calcination, using sol-gel precursors and polyacrylonitrile (PAN) as a processing aid. The resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Brunauer-Emmet-Teller (BET) surface area measurements, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MoO2-CNFs with an average diameter of 425-575 nm obtained after heat treatment were used as a matrix to prepare sulfur/MoO2-CNF cathodes for lithium-sulfur (Li-S) batteries. The polysulfide adsorption and electrochemical performance tests demonstrated that MoO2-CNFs did not only act as polysulfide reservoirs to alleviate the shuttle effect, but also improve the electrochemical reaction kinetics during the charge-discharge processes. The effect of MoO2-CNF heat treatment on the cycle performance of sulfur/MoO2-CNFs electrodes was examined, and the data showed that MoO2-CNFs calcined at 850 °C delivered optimal performance with an initial capacity of 1095 mAh g-1 and 860 mAh g-1 after 50 cycles. The results demonstrated that sulfur/MoO2-CNF composites display a remarkably high lithium-ion diffusion coefficient, low interfacial resistance and much better electrochemical performance than pristine sulfur cathodes.