Ultrathin MoS ₂ nanosheets homogenously embedded in a N,O-codoped carbon matrix for high-performance lithium and sodium storage

MoS ₂ nanosheets, which possess a high theoretical capacity, have drawn wide attention as an anode material for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). However, MoS ₂ nanosheets suffer from poor cycling stability and rate performance caused by structural deterioration, large volume change upon cycling, poor conductivity, and aggregation of nanosheets. Here, a MoS ₂ /C nanocomposite with ultrathin MoS ₂ nanosheets homogenously embedded in a N,O-codoped carbon matrix is obtained under high pressure by pyrolysis of a solution of ammonium tetrathiomolybdate dissolved in dimethylformamide in a sealed vessel. The MoS ₂ /C nanocomposite possesses a unique structure with an expanded interlayer spacing of 10.5 Å for the MoS ₂ nanosheets and formation of Mo-O-C and Mo-N-C bonds at the interface between the MoS ₂ nanosheets and carbon matrix. The expansion of the interlayer spacing for the MoS ₂ nanosheets may result from insertion of single-layer carbon atoms in between MoS ₂ layers. The unique structure is beneficial for solving the above-mentioned problems and thus obtaining superior lithium and sodium storage performances. As an anode for LIBs, MoS ₂ /C delivers excellent cyclability (capacity retention of 115.4% after 2700 cycles) and superior rate capability (234.7 mA h g ^-1 at 20C). As an anode for SIBs, MoS ₂ /C exhibits excellent cycling performance (capacity retention of 91.5% after 100 cycles) and outstanding rate performance (187.9 mA h g ^-1 at 5C).