Promotional role of Li 4 Ti 5 O 12 as polysulfide adsorbent and fast Li + conductor on electrochemical performances of sulfur cathode

Abstract

Abstract Lithium-sulfur (Li-S) batteries attract much attention due to its high specific capacity and energy density compared to lithium-ion batteries (LiBs). Herein, a novel composite named as (void/nano-Li 4 Ti 5 O 12 pieces)@C [(v/n-L)@C] was designed and prepared as a sulfur host. Spinel Li 4 Ti 5 O 12 here as a multifunctional additive played as polysulfide adsorbent agent and fast Li + conductor, and carbon shell was designed as electronic conductor, as well as volume barrier to limit the volume expansion caused by sulfur. As-prepared (S/nano-Li 4 Ti 5 O 12 pieces)@C [(S/n-L)@C] are core-shell spheres, which are about 200 nm in size. Nano-Li 4 Ti 5 O 12 and sulfur were coated by the outer carbon shell with a thickness of about 20 nm. The experimental results show that electrochemical performances of (S/n-L)@C cathode were enhanced effectively compared to S@C cathode. At 0.5C and 1C, the discharge capacity of (S/n-L)@C was 33.5% and 40.1% higher than that of S@C at 500 th cycle. Even at 2C, its capacity reached 600.9 mAh g −1 at 1000 th cycle. Li + conductivity of (S/n-L)@C was one order of magnitude higher than that of S@C, which was reach to 2.55 × 10 −8 S cm −1 . The experiment results indicate Li 4 Ti 5 O 12 plays a promotional role on electrochemical performances of sulfur cathode, especially for stable cycling performance and high rate performance.