Hollow porous titanium nitride tubes as a cathode electrode for extremely stable Li-S batteries

Because of their high theoretical capacity and environmental friendliness, lithium-sulfur (Li-S) batteries have been regarded as a promising option for energy storage. However, due to their serious "shuttle effect" and low conductivity, the cycling stability of Li-S batteries is usually poor and the coulombic efficiency is low, which restrict their practical applications. Here, we have synthesized porous titanium nitride (TiN) tubes which possess high conductivity. The strong interaction between the TiN and lithium polysulfides greatly reduces the "shuttle effect" during the discharge/charge process. The cyclic voltammetric data indicated that TiN also plays an important catalytic role in promoting the oxidation process in Li-S batteries. When hollow TiN tubes were used as a sulfur host material with a high sulfur loading of 73.8 wt%, the TiN/S cathode presented a high specific capacity, high coulombic efficiency and excellent cycling performance. The initial discharge capacity at a high current density of 5.0C could be as high as 1026 mA h g(-1), and the battery exhibited a large reversible capacity of above 840 mA h g(-1) at 0.5C after 450 cycles.