LAUSR

Although some experiments have shown that point defects in a cathode host material may enhance its performance for lithium-sulfur battery (LSB), the enhancement mechanism needs to be well investigated for the design of desired sulfur host. Herein, the first principle density functional theory (DFT) is adopted to investigate a high-performance sulfur host material based on oxygen-defective TiO 2 (D-TiO 2 ). The adsorption energy comparisons and Gibbs free energy analyses verify that D-TiO 2 has relatively better performances than defect-free TiO 2 in terms of anchoring effect and catalytic conversion of polysulfides. Meanwhile, D-TiO 2 is capable of absorbing the most soluble and diffusive long-chain polysulfides. The newly designed D-TiO 2 composited with three-dimensional graphene aerogel (D-TiO 2 @Gr) has been shown to be an excellent sulfur host, maintaining a specific discharge capacity of 1,049.3 mAhg −1 after 100 cycles at 1C with a sulfur loading of 3.2 mgcm −2 . Even with the sulfur mass loading increasing to 13.7 mgcm −2 , an impressive stable cycling is obtained with an initial areal capacity of 14.6 mAhcm −2 , confirming the effective enhancement of electrochemical performance by the oxygen defects. The DFT calculations shed lights on the enhancement mechanism of the oxygen defects and provide some guidance for designing advanced sulfur host materials.