Ce-Doped Three-Dimensional Ni/Fe LDH Composite as a Sulfur Host for Lithium-Sulfur Batteries.

Abstract

Lithium-sulfur batteries (LSBs) have become the most promising choice in the new generation of energy storage/conversion equipment due to their high theoretical capacity of 1675 mAh g-1 and theoretical energy density of 2600 Wh kg-1. Nevertheless, the continuous shuttling of lithium polysulfides (LiPSs) restricts the commercial application of LSBs. The appearance of layered double hydroxides (LDH) plays a certain role in the anchoring of LiPSs, but its unsatisfactory electronic conductivity and poor active sites hinder its realization as a sulfur host for high-performance LSBs. In this paper, metal organic framework-derived and Ce ion-doped LDH (Ce-Ni/Fe LDH) with a hollow capsule configuration is designed rationally. The hollow structure of Ce-Ni/Fe LDH contains a sufficient amount of sulfur. Fe, Ni, and Ce metal ions effectively trap LiPSs; speed up the conversion of LiPSs; and firmly anchor LiPSs, thus effectively inhibiting the shuttle of LiPSs. The electrochemical testing results demonstrate that a lithium-sulfur battery with capsule-type S@Ce-Ni/Fe LDH delivers the initial discharge capacities of 1207 mAh g-1 at 0.1 C and 1056 mAh g-1 at 0.2 C, respectively. Even at 1 C, a lithium-sulfur battery with S@Ce-Ni/Fe LDH can also cycle 1000 times. This work provides new ideas to enhance the electrochemical properties of LSBs by constructing a hollow capsule configuration.