Electroactive cellulose-supported graphene oxide interlayers for Li-S batteries

Electroactive graphene oxide (GO) interlayers between cathode and separator are examined in a lithium-sulfur cell. The GO interlayer is bifunctional and capable for lithium storage and polysulfide trapping depending on the specific surface properties. The corresponding electrochemical behaviors were evaluated by using galvanostatic charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy. A series of GO with different oxidation degrees were synthesized by tuning modified Hummer's method. The results revealed that hydroxyl was formed at insufficient oxidation while epoxide appeared at strong oxidation. The residual graphitic structures in weakly oxidized GO can donate electrons to improve polysulfide utilization while the enriched oxygen functional groups can react with lithium ion giving rise to higher cathode capacity.