In-situ Synthesis of N, O, P-doped Hierarchical Porous Carbon from Poly-bis(phenoxy)phosphazene for Polysulfide-Trapping Interlayer in Lithium-Sulfur Batteries.

The shuttling of polysulfides is the most detrimental problem that degrades the capacity and cycle stability of lithium-sulfur (Li-S) batteries. Adding a carbon interlayer is feasible to prevent the polysulfides from migration, and a rational design of the structures and surface properties of the carbon layer is the essential enabler to increasing its effectiveness. Here, we report a hierarchical porous carbon (HPC) via carbonization of bis(phenoxy)phosphazene and in-situ doping of triple heteroatoms into the carbon lattice for fabricating an effective polysulfide-trapping interlayer. The generated carbon integrates the advantages of the hierarchical porous structure, high specific area and rich dopants (N, O and P), yielding chemisorption and physical confinement for polysulfides and fast ion-transport synergistically . The HPC interlayer significantly improves the electrochemical performance of Li-S batteries, including an exceptional discharge capacity of 1509 mA h/g at 0.06C and a high capacity retention of 83.7% after 250 cycles at 0.3C . This work proposes a facile in-situ synthesis of heteroatom-doped carbon with rational porous structures for suppressing the shuttle effect.