title: Potassium-sulfur batteries: a new member of room-temperature rechargeable metal-sulfur batteries.
abstract: We report room-temperature rechargeable potassium-sulfur (K-S) batteries using ordered mesoporous carbon (CMK-3)/sulfur and polyanilime (PANI) coated CMK-3/sulfur composites as the cathode and metallic potassium as the anode. The electrochemical reaction mechanism was investigated by electrochemical tests, TEM, XRD, and Raman spectra. It was found that K-S batteries delivered two reduction peaks located at about 2.1 and 1.8 V and one oxidation peak at about 2.2 V, respectively. Meanwhile, K2S3 was the major discharge product that could be charged to reversibly form S and K ion. Through optimization of sulfur content, the CMK-3/sulfur composite with 40.8 wt % S displayed an initial discharge capacity of 512.7 mAh g(-1) and a capacity of 202.3 mAh g(-1) after 50 cycles at a current density of 50 mA g(-1). A coating of conductive polyanilime (PANI) on the CMK-3/sulfur composite is effective in enhancing the cycling performance. In comparison, PANI@CMK-3/sulfur composite showed a capacity of 329.3 mAh g(-1) after 50 cycles at 50 mA g(-1). The results shed light on the basic study of rechargeable K-S batteries.
authors.affiliation: Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University , Tianjin 300071, People's Republic of China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Hu
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Chen