Sulfur Nanodots Electrodeposited on Ni Foam as High-Performance Cathode for Li-S Batteries

In this Letter, we report the preparation of sulfur nanodots (2 nm average) electrodeposited on flexible nickel foam and their application as high-performance cathode of Li-S batteries. An electrodepostion method was applied to prepare the cathode at room temperature and the sulfur mass was controllable from 0.21 to 4.79 mg/cm² in a large area of over 100 cm². The optimized cathode with 0.45 mg/cm² S on Ni foam displayed high initial discharge capacity (1458 mAh/g at 0.1 C), high rate capability (521 mAh/g at 10 C), and long cycling stability (895 mAh/g after 300 cycles at 0.5 C and 528 mAh/g after 1400 cycles at 5 C). Moreover, in situ Raman and transmission electron microscopy analysis demonstrated the fundamentals of reversible electrochemical reaction between S and Li₂S nanodots. This fast, facile, and one-step cathode preparation method with excellent electrochemical performance will lead to technological advances of S cathode in Li-S batteries.