Constructing heterojunction on N-doped porous carbon nanofibers for Li-S batteries: Effect of built-in electric field on efficient catalytic transformation kinetics

In this study, the CoP-Co2P heterojunction nanoparticles embedded in N-doping porous carbon nanofibers (CoP-Co2P/NPCNFs) are designed and prepared. The highly conductive grid of NPCNFs can physically confining lithium polysulfide (LiPS) and provide facilitated channels for Li+ transport. Furthermore, due to the spontaneous built-in electric field (BIEF) based on at the formed heterogeneous interfaces of CoP-Co2P, the heterojunction can significantly catalyze bi-directional conversion of LiPS and chemically adsorb LiPS which confirmed by the DFT calculations, suppressing the "shuttle effect" of LiPS. Thus, the Li-S batteries with the CoP-Co2P/NPCNFs modified separators exhibit a high initial specific capacity of 1322.86 mAh g−1 at 1 mA cm−2 and stable 695 cycles with a low decay rate (0.069 %). More importantly, the assembled pouch cell also can run with ultra-low specific capacity decay rate. Additionally, the pouch battery can also be applied to the operation of fans, temperature and humidity meters, mobile phone charging, etc.