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

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.