The origin of the enhanced performance of nitrogen-doped MoS₂in lithium ion batteries

Abstract

MoS2 with a similar layered structure to graphene has been widely applied in various areas including lithium ion batteries. However, low conductivity, capacity fading and poor rate performance are still the main challenges for MoS2 anode materials. In this work, for the first time, we prepared nitrogen-doped MoS2 (N-MoS2) nanosheets through a simple two-step method involving the preparation of MoS2 with defects by the hydrothermal method, followed by sintering in a NH3 atmosphere. Our electrochemical characterizations and density functional theory calculations demonstrated that nitrogen doping could enhance the electron conductivity and showed higher specific capacity than pristine MoS2 as anode materials of lithium ion batteries, which can be attributed to the faster transportation of electrons and ions because of nitrogen doping. This work helps us understand the origin of the enhanced performance of N-doped MoS2 in lithium ion batteries.

Nitrogen‐Doped MoS2 Foam for Fast Sodium Ion Storage

“…The diffraction peak (002) with a d‐spacing of 0.625 nm indicating that the layered MoS 2 grows well along the c ‐axis, which correlates with reported TEM image in Figure e . Specially, it is worth noting that, NMF shows a broadened and lower intensity diffraction peak (002) after nitrogen doping compared to that of pristine MoS 2 , implying that more disordered structure was introduced . In addition, the diffraction peaks of carbon can be detected at 22.7° with a large d‐space of 0.39 nm rather than the standard position of 24°, which is a result of N doping and is beneficial for Na + transportation and storage…”

“…Nitrogen‐doped hollow MoS 2 /C nanospheres have also been reported by Cai et al, with a good rate performance range of 300 mAh g −1 under a current density of 1000 mA g −1 . Liu et al reported N‐doped MoS 2 with improved electrochemical performance in LIB application …”

“…More importantly, nitrogen‐containing polymeric template not only prevents the restacking of MoS 2 nanosheets during drying process, but also acts as efficient nitrogen source to be doped in MoS 2 and residual carbon. Because of the additional MoN bonds after high temperature treatment, the electrical conductivity of N‐doped MoS 2 was enhanced by replacing S with N . Furthermore, owing to the large specific surface area of NMF achieved by the novel templating‐drying‐calcination procedure, pseudocapacitive storage of sodium ions on NMF surface, edges, and defective sites was greatly enhanced, which is helpful in improving the stability and cyclability of NMF even at high current densities .…”

Enhanced Li‐Ion‐Storage Performance of MoS2 through Multistage Structural Design

“…[38] Compared with the commercial MoS 2 (E 1 2g : 382.6 cm À 1 , A 1g : 407.6 cm À 1 ), the PÀ MoS 2 exhibits a red-shift shown in Figure S4b. [40] Two major peaks at 231.8 eV and 228.6 eV (red curve) can be assigned to the characteristic Mo 3d 5/2 and Mo 2d 3/2 orbitals of 1T phase of metallic MoS 2 , respectively. The Mo-terminated or S-terminated edges could be easily facilitated by adjusting the Mo/S ratios.…”

“…For instance, two major characteristic peaks of arising from Mo 3d 5/2 and Mo 2d 3/2 orbitals are located at 231.8 eV and 228.6 eV; while the S 2p components have binding energies of 162.82 eV and 161.6 eV corresponding to the S 2p 3/2 and S 2p 1/2 orbitals of MoS 2 , respectively, which can be assigned to the binding energies of S 2À species. [40] Two major peaks at 231.8 eV and 228.6 eV (red curve) can be assigned to the characteristic Mo 3d 5/2 and Mo 2d 3/2 orbitals of 1T phase of metallic MoS 2 , respectively. While another two major peaks at relatively higher binding energy of 229.6 eV and 232.8 eV can be attributed to the 2H phase of semiconducting MoS 2 .…”