Facile synthesis of mesoporous graphene platelets with in situ nitrogen and sulfur doping for lithium–sulfur batteries

Abstract

The interaction between lithium polysulfides and doped heteroatoms could prevent the loss of soluble polysulfides in the cathode and mitigate the shuttle effect in lithium-sulfur batteries. Herein, a facile synthesis of mesoporous graphene platelets (NSGs) with in situ nitrogen and sulfur doping by the pyrolysis of a self-assembled L-cysteine precursor on sodium chloride crystal surface for structuredirecting is presented. The mesoporous lamellar structure of the NSG possesses a uniform distribution of pyrrolic N, pyridinic N, and thiosulphate structured heteroatoms originating from in situ doping, which promotes the confinement of intermediate polysulfides. Combining the strong interactions with soluble polysulfide, flexible mesoporous architecture, and high conductivity of graphene, the prepared NSG material exhibited a high initial capacity of 1433 mA h g À1 at a 2C rate as well as a reversible capacity of 684 mA h g À1 after 200 cycles. This demonstrates that the in situ nitrogen and sulfur doped thin lamellar structure of graphene would be a promising cathode material for high performance lithium-sulfur batteries.

Sulfur‐Immobilized Nitrogen and Oxygen Co–Doped Hierarchically Porous Biomass Carbon for Lithium‐Sulfur Batteries: Influence of Sulfur Content and Distribution on Its Performance

“…The N1s spectrum (Figure c) contains 4 contributions at 398.2 eV, 400 eV, 401.7 eV and 403.7 eV which are assigned to the pyridinic, pyrrolic, graphitic and nitrogen oxide respectively, which includes 27 at. % pyridinic nitrogen, 34 at.% pyrrolic nitrogen, 25 at.% graphitic nitrogen and 14 at.% N−O species ,. These functional groups are consistent with the FTIR spectral results.…”

“…The nitrogen (2.22%) and oxygen (14.67%) content obtained from XPS analysis (Table S2) are very close to the CHNS results. The high resolution C1s (Figure a) peak divided into 5 components, C−C bond (284.7 eV) of SP 2 , C−N (285.4), C−O bond (286.6 eV), C=N bond (287.3 eV) and C=O (288.6 eV) . The high resolution O1s spectrum (Figure b) is subdivided into three components: N−O bond (530.5), C−O bond (531.7 eV), and C=O bond (533.1 eV).…”

“…Conventional porous carbon materials are hydrophobic in nature, have weak interactions with polysulfides . Doping of hetero atoms (Nitrogen (N)/ Sulfur (S)/ Oxygen (O)/ Boron (B)/ Phosphorous (P)) in the carbon matrix reduces the charge transfer resistance, improves the electronic conductivity, and enhances the active sites to immobilize the sulfur/polysulfides . Co‐doping is a more effective strategy to improve the physical adsorption and chemical bonding to trap lithium polysulphides .…”

“…These functional groups with lone pair of electrons help to improve the electronic conductivity and wettability of the carbon matrices, which facilitate the confinement of polysulfides. Thus, dual doping of N and O atoms with high surface area is expected to enhance the performance of cathode material synergistically . The porous structure with oxygen and nitrogen group species help to retain the active material and relieve the volumetric expansion during cycling .…”

Nanostructured Host Materials for Trapping Sulfur in Rechargeable Li–S Batteries: Structure Design and Interfacial Chemistry

“…To adjust the physical and chemical characteristics of carbon materials and thereby to enhance the electrochemical performance of S/C composites, heteroatoms, including boron, nitrogen, oxygen, phosphorus, and sulfur, are often doped into the carbon hosts, especially graphene. By XPS, Guo et al found that the surface of carbon was positively polarized by doping with boron and showed the strong chemisorption ability of sulfur species.…”