Abstract
Lithium–sulfur battery hasreceived widespread attention because of its high energy density, low cost, environmental friendliness, and nontoxicity. However, the insulating properties of elemental sulfur, huge volume changes, and dissolution of polysulfides in electrolytes that result in the shuttle effect, low sulfur utilization, and low rate performance seriously hinder the commercialization of lithium–sulfur batteries. In this work, a composite material of nitrogen-doped multiwalled carbon nanotubes and V2O5 was designed and fabricated to serve as the positive electrode of lithium–sulfur battery via the hydrothermal method. The positive electrode of the V2O5@N-CNTs composite material could reach an initial discharge specific capacity of 1,453 mAh g−1at a rate of 0.1C. Moreover, the composite material could maintain a discharge ratio of 538 mAh g−1 at a rate of 0.5C even after 200 charge and discharge cycles. After 400 cycles, the composite had a specific discharge capacity of 439 mAh g−1 at a rate of 1.0C. The excellent electrochemical performance of the V2O5@N-CNT/S composite cathode material was due to the fact that V2O5 contains oxygen ions and has a strong polarized surface. Furthermore, nitrogen doping changed the hybrid structure of carbon atoms and provided additional active sites, thereby improving the conductivity of the material itself and effectively inhibiting the dissolution and diffusion of polysulfides.
Highlights
Lithium-ion batteries are widely used in energy storage and portable electronic device applications (Goodenough and Park, 2013; Wu et al, 2018; Yang et al, 2018a; Yang et al, 2018b; Zhang et al, 2018; Leng et al, 2019; Ye et al, 2019)
The length of the Multiwalled CNTs (MWCNTs) could be extended from tens to hundreds of nanometers (Figure 1C), effectively improving the overall conductivity of the composite materials
The V2O5 particles loaded onto the surface of the MWCNTs promoted the rapid transmission of lithium ions and exerted a certain catalytic effect, thereby accelerating the conversion process of the intermediate product lithium polysulfide
Summary
Lithium-ion batteries are widely used in energy storage and portable electronic device applications (Goodenough and Park, 2013; Wu et al, 2018; Yang et al, 2018a; Yang et al, 2018b; Zhang et al, 2018; Leng et al, 2019; Ye et al, 2019). The electrochemical performance of lithium–sulfur batteries can be improved to solve polysulfide dissolution and diffusion Various cathode materials, such as carbon nanotubes (CNTs), conductive. The cathode based on pyridine nitrogen-doped carbon has higher capacity and better cycle stability (Yuan et al, 2018) Their studies proved that the introduction of nitrogen atoms can change the hybrid structure of carbon atoms to increase the conductivity of the composite material and the adsorption of polysulfides (Ding et al, 2016; Chen et al, 2018; Yin et al, 2018; Fan et al, 2019; Fang et al, 2019). A nitrogen-doped 3D conductive network structure, namely, MWCNT/V2O5/S composite cathode, was prepared via simple melting and hydrothermal synthesis methods. The ratio of electrolyte to sulfur is 20 μl mg−1
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