NC@CoP–Co3O4 composite as sulfur cathode for high-energy lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have attracted much attention because of their high theoretical capacity and energy density and the advantages of sulfur, such as its low price, abundant reserves, low toxicity, and environmental friendliness. Li–S batteries are considered one of the most promising energy storage devices but suffer from shortcomings, such as their rapid capacity decay, short cycle life, and low Coulomb efficiency. We designed and prepared a new type of sulfur cathode material (NC@CoP–Co3O4) that consisted of a CoP–Co3O4 heterojunction uniformly distributed on the surface of hollow nitrogen-doped carbon tubes to overcome these problems. The NC@CoP–Co3O4 hybrid nanocomposite can provide excellent electrical conductivity and effectively suppress the shuttle effect through the synergetic effect of physical confinement and chemical bonding. As a result, the Li–S battery maintained a capacity of 476 mAh g−1 at 700 cycles at 1 C and a long-term cycle stability of 70.3% after 700 cycles with an average capacity decay rate of only 0.057% per cycle.