Improved-performance lithium-sulfur batteries modified by magnetron sputtering

The cathode material S/AC for lithium-sulfur batteries was synthesized with elemental sulfur as the active material and activated carbon (AC) as the conductive matrix. Al and Ti were respectively deposited onto the surface of S/AC electrodes by the method of radio-frequency magnetron sputtering to modify the electrodes and improve the battery performance. The properties of S/AC and the sputtered cathode materials, labeled S/AC/Ti and S/AC/Al, were characterized by XRD and FESEM. Electrochemical performances of the Li/S batteries with the three cathode materials were determined by alternating-current impedance, cyclic voltammetry (CV) and constant-current charge and discharge. Experiments showed that S/AC, S/AC/Ti and S/AC/Al delivered initial specific capacity of 1197 mA h g(-1), 1255 mA h g(-1) and 1257 mA h g(-1) respectively under the current rate of 0.5C. And the modified batteries operated reversibly over 100 cycles and maintained a discharge specific capacity of 722 mA h g(-1) and 977 mA h g(-1) after 100 cycles, superior to 634 mA h g(-1) of S/AC. Besides, the coulombic efficiencies of the sputtered electrodes were over 0.97 after 100 cycles.