Design of CoP-CoO heterostructure to enhance the polysulfide redox conversion for lithium-sulfur batteries

The design of effective cathode materials is the significant to the development of lithium-sulfur batteries. Herein, a spindle-shaped CoP-CoO heterostructures sulfur cathode substrate composed of countless fine needle-like structures is prepared through a facile two-step process by controlling the sulfurization degree. The as-prepared heterostructures combine the advantages of high adsorbability (by CoO) and conductivity (by CoP), and realizes the smooth capture-diffusion-transformation of polysulfides at the interface. CoO has a high adsorption capacity for polysulfides, while CoP promotes the redox kinetics towards polysulfides conversion. The rapid transfer of polysulfide from CoO surface to CoP surface helps to accelerate the nucleation of polysulfide and improve the capture efficiency. Therefore, the battery with [email protected] cathode reaches a high initial capacity of 1456.7 mAh g−1 at 0.2 C, and the capacity retains 832 mAh g−1 after 100 cycles. Even the specific capacity of 500 mAh g−1 can achieved at 1C after 300 cycles. Our study offers the potential perpective for the rational design of lithium-sulfur batteries cathode materials, which can realize immobilization and conversion of polysulfides at the same time, and further promote the actual application of Li-S batteries.