Preparation of functional groups-rich graphene oxide for high-performance lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) battery has promising application prospect owing to the high energy density. Yet, its cycling life and Coulombic efficiency are always low due to shuttle effect of the mid-product, Li2Sn (4 ≤ n ≤ 8), on the cathode. Herein, oxygen-containing functional groups rich/defect-rich graphene oxide (D-GO) with large size and porous network structure is developed, which exhibits outstanding adsorption ability to S and Li2Sn. S can be uniformly deposited onto the D-GO (S@D-GO), and the proportion of S is as high as 89.5 wt% in the composite. As cathode of Li–S batteries, the S@D-GO can deliver a high capacity of 1370 mAh/g at 0.05 C. The capacity is still as high as 1011 mAh/g at 1 C, and 95% of the initial value is remained after 400 cycles' cycling, exhibiting good rate performance and cycling stability. Meanwhile, the Coulombic efficiency is close to 100% during the whole test, suggesting that the D-GO can inhibit the shuttle of polysulfide effectively. Most important, with a high loading amount of 14.8 mg/cm2 for the S@D-GO, areal capacity of the cathode still can reach 14.85 mAh/cm2 at 0.1 C, indicating high practical and commercial value in energy storage field.