context: Commercial sublimated sulfur (S) was mixed with AB (C) in a mass ratio of 8:2, and the mixture (C/S) was fully ground and heat-treated at 155 °C for 6 h in an argon atmosphere. Then, the as-obtained composite was mixed with AB and PVDF (8:1:1 by weight), followed by dispersing in NMP solvent and stirred for 12 h. Next, the slurry was uniformly cast onto an Al foil substrate and dried in a vacuum for 12 h at 60 °C. Afterwards, the coated-Al foil was cut into 12 mm wafers with a sulfur loading of ∼2.0 mg cm−2. Moreover, a cathode wafer with a high sulfur loading of ∼5.6 mg cm−2 was also prepared in the same procedure by controlling the thickness of the coating. The as-prepared C/S disc, above separators (BFO/GO/AB@PP, GO/AB@PP, and PP) and lithium plate (diameter of 15.6 mm, thickness of 250 µm) were applied to assemble a 2025-type button battery, in which the electrolyte was 1 M LiTFSI in DOL/DME (v/v = 1:1) with 1 wt% LiNO3. The electrolyte/sulfur (E/S) ratio was fixed as 12:1 (µL mg−1). The battery was charged and discharged on a Neware battery test station (5V20 mA). The cyclic voltammetry (CV) curves were operated in a voltage window between 1.7 and 2.8 V with a scanning rate of 0.1 mV s−1. The electrochemical impedance spectroscopy (EIS) plots were obtained in the frequency range from 0.1 to 100 kHz with an amplitude of 5 mV. Both CV and EIS were carried out on an electrochemical workstation (Shanghai, Chenhua, CHI660D).
answer: sulfur