Enhancing Chemical Interaction of Polysulfide and Carbon through Synergetic Nitrogen and Phosphorus Doping

Abstract

The shuttling effect of the polysulfide (PS) is the most detrimental factor that causes capacity fading of Li-S batteries. By substituting carbon atoms with heteroatoms, the host materials can provide a chemical interaction with PS to trap it within the electrochemically active range of the cathode. In this study, first-principles-based calculations identify the most stable nitrogen (N) and phosphorus (P) codoped atomic structures and their corresponding adsorption energy toward different PS species. Based on the simulated predictions, we introduce a glucosamine-derived carbon nanotube aerogel (CNA) with a secondary dopant of P during the synergetic polymerization and carbonization process. The N-P codoped CNA and S composite (NPCNA-S) renders a highly stable performance even at a sulfur loading of 3.5 mg cm-2. The specific capacity is >900 mAh g-1 and the stabilized capacity retention is >70% over 450 cycles at 0.2 C rate (1 C = 1675 mA g-1).