Improved performance of lithium-sulfur batteries at elevated temperature by porous aluminum

Abstract

With high theoretical capacity and energy density, lithium-sulfur batteries have gained a competitive edge for promising applications, but they still face challenges like poor conductivity of sulfur and volume expansion. Herein, combining the advantages of multidimensional carbon materials, S/C composites consisting of sulfur and Activated Carbon (AC), Carbon Nanotubes (CNTs), Graphene (G) were obtained in a closed system at 155 °C, and 3D electrodes were prepared using porous aluminum (PAl) as current collectors. The as-obtained electrode exhibits a high initial discharge capacity of 1256 mAh/g at 0.1C, about 200 mAh/g higher than that of the electrode using traditional non-porous aluminum (NPAl) current collector. As NPAl is substituted by PAl, the oxidation peak current density of S/C composite is increased from 3.59 to 4.95 A/g, and the charge transfer resistance is decreased from 32.03 to 17.37 Ω. In comparison with the very poor performance of S/C using NPAl at 60 °C, the initial discharge capacity of S/C using PAl can reach 803 mAh/g at 1C rate with a capacity retention rate of 71.7% after 50 cycles, while the corresponding stress decreases to 10.35 MPa. The improved mechanisms of S/C composites using PAl were discussed. Porous aluminum is attractive to improve the electrochemical performance and safety of batteries.