For the first time, a co-modification strategy using carbon and RGO was carried out to improve the electrochemical performance of SiO-based materials for their use in LIBs.
At the moment, sulfur immobilizers for lithium–sulfur batteries have been extensively studied. Herein, a facile synthesis of stable TiO2/TiC composite materials as sulfur immobilizers for cathodes of lithium–sulfur batteries is shown; the conductivity of TiC and strong adsorption of the Ti—O bond on sulfur in TiO2 are combined together to achieve excellent conductivity and effectively inhibit the shuttle effect of polysulfides. X‐ray diffraction, scanning electron microscopy, and Raman spectrogram peak tests show that the TiC surface is successfully coated by a layer of TiO2 with a stable structure and excellent porosity. Physical and chemical adsorption of sulfur hosting with the TiO2/TiC composite material is formed by a hot‐melting method. Electrochemical performance tests show that when the proportion of sulfur hosting is 55%, the cathode has better reversibility, lower charge transfer impedance, and higher lithium‐ion diffusion rate. Charge and discharge results prove that the specific capacities are 1044.68, 870.62, and 696.06 mAh g−1 at 0.1, 0.2, and 0.5 C, respectively, and after 400 cycles, the capacity retention rate is over 50%. This proves that TiO2/TiC composite materials are well‐suited to act as sulfur immobilizers for lithium–sulfur batteries.
Summary
Vanadium pentoxide (V2O5) is a common cathode material for lithium‐ion battery, but its low electronic and ionic conductivity seriously affect its electrochemical performances. In this paper, a type of carbon‐coated V2O5 and S composite cathode material with PVA as the carbon source is utilized to lithium‐ion batteries. X‐ray diffraction and Raman test results illustrate that sulfur can make the V2O5 lose part of oxygen atoms and become nonstoichiometric vanadium oxide (V2O5‐x). Electrochemical test results show that sulfur can provide a considerable proportion of the specific capacity of the whole cathode. This illustrates that the synergistic effect of sulfur can optimize the structure of vanadium pentoxide in order to increase more electron transfer channels, and at the same time, it also can provide additional specific capacity for the whole cathode. When the ratio of V2O5 and sulfur is 1:3, the discharge specific capacity can reach 923.02, 688.37, and 592.70 mAh g−1 at 80, 160, and 320‐mA g−1 current density, respectively, and after 100 times charge and discharge cycles at 320‐mA g−1 current density, the capacity retention rate can achieve to more than 60%.
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