Suppressing the Polysulfide Shuttle Effect by Heteroatom-Doping for High-Performance Lithium–Sulfur Batteries

Abstract

In order to restrict the polysulfide shuttle effect and enhance sulfur utilization of lithium–sulfur batteries (LSBs) especially at low charge/discharge rates, a facile hydrothermal synthesis and subsequent heating melting treatment are used to synthesize the heteroatom-doped carbon nanotubes/sulfur composite cathode. The composition analysis and structure characteristics of samples are examined by X-ray photoelectron spectroscopy, X-ray powder diffraction, and transmission electron microscopy. The electrochemical performances of samples are measured by cyclic voltammetry and charge/discharge experiments. The results show that N, B, S tridoped active carbon nanotubes (ACNTs) with abundant mesoporous structure enable fast Li+ transmittal and provide strong polysulfide adsorption ability. More importantly, they offer enough mechanical strength to support high sulfur loading (77 wt %) that maximizes their chemical role and can accommodate large volume changes. The N, B, S tridoped ACNTs/S composite exhibits a superb incipient capacity of 1166 mAh/g-S at 0.3 C and large reversible capacity of 881 mAh/g-S at the 700th cycle. To further promote the cyclic lifespan of LSB, the as-prepared N, B, S tridoped ACNTs acted as both sulfur matrix and spring functional layer and achieved a large reversible specific capacity of about 713 mAh/g-S at the 1400th cycle at lofty current density of 0.5 C with a slow capacity decay of 0.014% 1/cycle and a higher sulfur loading of 90 wt %. Accordingly, reasonable design for the heteroatom doping element in carbon material and separator modification will be distinctly vital for enhancing the electrochemical performance of the LSB and boosting its industrial application.

Rational Fabrication of Nitrogen and Sulfur Codoped Carbon Nanotubes/MoS2 for High‐Performance Lithium–Sulfur Batteries

“…To investigate their crystal structures, the NSCNTs, MoS 2 , and NSCNTs/MoS 2 samples were submitted to XRD analysis (Figure c). An amorphous feature was evident for the NSCNTs, with only two broad diffraction peaks at approximately 24 and 44°, which were indexed to the (0 0 2) and (1 0 0) peaks of carbon . The XRD pattern of the NSCNTs/MoS 2 showed a combination of the two components, confirming that the complex structure was successfully formed.…”

“…In these images, the flower‐shaped MoS 2 was separately wrapped by the NSCNTs, which is the key for a consistent and constant electrical conduction. Besides being the conduction channel of electrons, the NSCNTs also provided extra active sites for sulfur loading . At a higher resolution, the HRTEM image of NSCNTs/MoS 2 contained lattice fringes of both the NSCNTs and MoS 2 , confirming that a cross‐linked 3D network was successfully constructed.…”

“…The primary strategy is to couple sulfur with appropriate anchors or hosts. A series of carbonaceous materials, such as hierarchical macro‐, meso‐, and microporous carbon, carbon spheres, and nanotubes, have usually been employed in the design of the structure of materials used in Li–S batteries . These carbon matrices can physically trap polysulfides in their pore structures and provide rapid pathways and a conductive framework for ion/electron (Li + /e − ) transport to improve the utilization of sulfur .…”

“…Doping or surface functionalization of the carbon matrix with heteroatoms (e.g., O, N, S, B, and P) provides a suitable pathway for anchoring LiPSs through chemical interactions . Doped carbon can improve the absorbability of LiPSs by providing polar sites and chemical bonds, which results in a high abundance of active sites and enhanced conductivity . Besides the aforementioned methods, inorganic polar compounds as hosts, such as metal sulfides, oxides, and nitrides, and metal–organic frameworks, have been used to chemically anchor LiPSs .…”

Intertwined Nitrogen‐Doped Carbon Nanotube Microsphere as Polysulfide Grappler for High‐Performance Lithium‐Sulfur Batteries

“…[10] Additionally, the nonuniform deposition of lithium can lead to lithium dendrite formation and short-circuit within the cell. Employing various carbon materials (one/two/three-dimensional carbon materials) [12][13][14] and conductive polymer modification, metal oxides and metalorganic frameworks as sulfur hosts and/or polysulfide adsorbents are the main approaches to realize high capacity and enhanced cycle life. Employing various carbon materials (one/two/three-dimensional carbon materials) [12][13][14] and conductive polymer modification, metal oxides and metalorganic frameworks as sulfur hosts and/or polysulfide adsorbents are the main approaches to realize high capacity and enhanced cycle life.…”