Polarity-induced precipitation of S/Li2S confined into N and S co-doped porous graphene layered matrix for lithium sulfur batteries

The large-scale application of lithium sulfur batteries is impeded by their cycling stability and power performance mainly due to the polysulfide shuttle effect and low conductivity of sulfur. Herein, a multifunctional sulfur host of N/S co-doped porous graphene layered matrix (NSPG) is fabricated. High specific surface area of NSPG can guarantee the homogeneous deposition and high utilization of S/Li2S. Moreover, the layered graphene skeleton with abundant crumples can not only construct efficient channels for fast electrolyte ion/electron transfer but also effectively buffer the volume expansion of S during long-time charge/discharge process. DFT calculations verify that the N/S co-doping can promote the redox reaction rate and inhibit the polysulfides shuttle effect through chemical bonding interaction. Benefiting from the above synergistic effects, the NSPG/S electrode exhibits excellent rate performance (646 mAh g−1 at 10C) and outstanding cycle stability (693 mAh g−1 after 500 cycles). Even at a high mass loading of 4.5 mg cm−2, a capacity of 786 mAh g−1 can be retained after 100 cycles. This work might offer a feasible solution for developing sulfur host with multifunctionality and electrocatalytic activity for high-performance lithium sulfur batteries. The high specific surface area N, S co-doped porous graphene layered matrix (NSPG) with many crumples on the graphene sheets enable high cycle and rate performance as the sulfur hosts for lithium-sulfur batteries because of the strong physicochemical confinement, homogeneous deposition and high utilization of S/Li2S, and abundant ion transport paths. [Display omitted]