Porous g-C3N4 with high pyridine N/sulfur composites as the cathode for high performance lithium-sulfur battery

Lithium-sulfur battery has become to be one of the most promising electrochemical energy storage systems on account of the high theoretical specific capacity (1673 mAh/g) and high energy density (2600 Wh/kg). However, the relatively complicated producing process of the host materials and lithium-sulfur battery' cycling instability still hinder the commercialization of Li-S battery. Herein, a facile, inexpensive and scalable thermal treatment method was designed to synthesize the host material porous g-C3N4 composed by graphite-like two-dimensional rippled sheets and high content of pyridine N, improving the properties of Li-S batteries. Because of the high charge polarity and peculiar porous structure, the porous g-C3N4/S cathode delivered high initial discharge capacity of 1050 mAh/g. Furthermore, it possesses excellent cycling stability for 200 cycles with a low capacity fading rate of 0.2% per cycle at 0.1C and a high-rate capacity of ∼400 mAh/g even at 1C rate. Therefore, this study presents a new enlightenment for researchers to realize the practical application of Li-S batteries and an effective reference for the design of other porous materials.