Co-doped 1T-MoS2 nanosheets embedded in N, S-doped carbon nanobowls for high-rate and ultra-stable sodium-ion batteries

Despite various 2H-MoS2/carbon hybrid nanostructures have been constructed and committed to improve the performance for sodium-ion batteries (SIBs), they still show the limited cycle stability due to the relatively large volumetric expansion during the charge-discharge process. Herein, we report the construction of cobalt-doped few-layered 1T-MoS2 nanosheets embedded in N, S-doped carbon (CMS/NSC) nanobowls derived from metal-organic framework (MOF) precursor via a simple in situ sulfurization process. This unique hierarchical structure enables the uniformly dispersed Co-doped 1T-MoS2 nanosheets intimately couple with the highly conductive carbon nanobowls, thus efficiently preventing the aggregation. In particular, the Co-doping plays a crucial role in maintaining the integrity of structure for MoS2 during cycling tests, confirmed by first-principles calculations. Compared with pristine MoS2, the volume deformation of Co-doped MoS2 can be shrunk by a prominent value of 52% during cycling. Furthermore, the few-layered MoS2 nanosheets with 1T metallic phase endow higher conductivity, and thus can surpass its counterpart 2H semiconducting phase in battery performance. By virtue of the synergistic effect of stable structure, appropriate doping and high conductivity, the resulting CMS/NSC hybrid shows superior rate capability and cycle stability. The capacity of CMS/NSC can still be 235.9 mAh center dot g(-1) even at 25 A center dot g(-1), which is 51.3% of the capacity at 0.2 A center dot g(-1). Moreover, the capacity can still remain 218.6 mAh center dot g(-1) even over 8,240 cycles at 5 A center dot g(-1) with a low decay of 0.0044% per cycle, one of the best performances among the reported MoS2-based anode materials for SIBs.