Nitrogen-Doped CoP with optimized d-Band center as bidirectional electrocatalyst for high areal capacity of Li-S...

Lithium polysulfide (LiPSs) shuttle effect and difficulties with Li₂S oxidation are hinder the marketization of lithium-sulfur batteries. We suggest using a bidirectional catalyst in the sulfur host to solve these problems. We produced a nitrogen-doped cobalt phosphide (N-CoP@NC) as a sulfur carrier in this work. The introduction of nitrogen into cobalt phosphide enhances the electron transmission speed and forms shorter Co-N bonds. As a result, new defect energy levels are introduced, leading to an increase in the charge number of Co central atoms, which abate the Li-S and SS bonds in Li₂S and Li₂S₄, thereby promoting the oxidation of Li₂S during charging, as well as the alteration process of LiPSs during charge and discharge. Additionally, the crystal flaws that result in increased Co-S bond formation help to boost polysulfides' adsorption ability. The Li-S batteries shows outstanding cyclability when paired with this electrocatalyst, demonstrating a minimal capacity degradation rate of only 0.07 % per cycle over 500 cycles at a rate of 0.5C. As a result, incorporating anion doping in the host emerges as a promising method for crafting materials tailored for Li-S batteries.